Oxygen therapyFrom Wikipedia, the free encyclopedia

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Oxygen piping and regulator, for oxygen therapy, mounted on the wall of an ambulance

Oxygen therapy is the administration of oxygen as a medical intervention, which can be for a variety of purposes in both chronic and acute patient care. Oxygen is essential for cell metabolism, and in turn, tissue oxygenation is essential for all normal physiological functions.[1]

High blood and tissue levels of oxygen can be helpful or damaging, depending on circumstances and oxygen therapy should be used to benefit the patient by increasing the supply of oxygen to the lungs and thereby increasing the availability of oxygen to the body tissues, especially when the patient is suffering from hypoxia and/or hypoxaemia.

Oxygen can be administered in a number of ways, including specific treatments at raised air pressure, such as hyperbaric oxygen therapy.

Contents[hide]

1 Indications for use o 1.1 Use in chronic conditions o 1.2 Use in acute conditions

2 Storage and sources 3 Delivery

o 3.1 Supplemental oxygen

o 3.2 High flow oxygen delivery o 3.3 Positive pressure delivery o 3.4 As a drug delivery route o 3.5 Filtered oxygen masks

4 Contraindications and cautions 5 Negative effects 6 Oxygen therapy while on aircraft 7 See also 8 References 9 External links

[edit] Indications for useOxygen is used as a medical treatment in both chronic and acute cases, and can be used in hospital, pre-hospital or entirely out of hospital, dependant on the needs of the patient and the views of the medical professional advising.

[edit] Use in chronic conditions

A common use of supplementary oxygen is in patients with chronic obstructive pulmonary disease (COPD), a common long term effect of smoking, who may require additional oxygen to breathe either during a temporary worsening of their condition, or throughout the day and night. It is indicated in COPD patients with PaO2 ≤ 55mmHg or SaO2 ≤ 88% and has been shown to increase lifespan.[2]

[edit] Use in acute conditions

Oxygen is widely used in emergency medicine, both in hospital and by emergency medical services or advanced first aiders.

In the pre-hospital environment, high flow oxygen is definitively indicated for use in resuscitation, major trauma, anaphylaxis, major haemorrhage, shock, active convulsions and hypothermia.[1][3]

It may also be indicated for any other patient where their injury or illness has caused hypoxaemia, although in this case oxygen flow should be moderated to achieve target oxygen saturation levels, based on pulse oximetry (with a target level of 94-98% in most patients, or 88-92% in COPD patients).[1]

For personal use, high concentration oxygen is used as home therapy to abort cluster headache attacks, due to its vaso-constrictive effects.[4]

[edit] Storage and sources

Gas canisters containing oxygen to be used at home. When in use a pipe is attached to the top of the can and then to a mask that fits over the patient's nose and mouth.

A home oxygen concentrator in situ in an Emphysema patient's house. The model shown is the DeVILBISS LT 4000.

Oxygen can be separated by a number of methods, including chemical reaction and fractional distillation, and then either used immediately or stored for future use. The main types sources for oxygen therapy are:

1. Liquid storage - Liquid oxygen is stored in chilled tanks until required, and then allowed to boil (at a temperature of 90.188 K (−182.96 °C)) to release oxygen as a gas. This is widely used at hospitals due to their high usage requirements, but can also be used in other settings. See Vacuum Insulated Evaporator for more information on this method of storage.

2. Compressed gas storage - The oxygen gas is compressed in a gas cylinder, which provides a convenient storage, without the requirement for refrigeration found with liquid storage. See Oxygen cylinder manifold for more information.

3. Instant usage - The use of an electrically powered oxygen concentrator [5] or a chemical reaction based unit[6] can create sufficient oxygen for a patient to use immediately, and these units (especially the electrically powered versions) are in widespread usage for home oxygen therapy and portable personal oxygen, with the advantage of being continuous supply without the need for additional deliveries of bulky cylinders.

[edit] Delivery

Various devices are used for administration of oxygen, from whichever source. In most cases, the oxygen will first pass through a pressure regulator, used to control the high pressure of oxygen delivered from a cylinder (or other source) to a lower pressure. This lower pressure is then controlled by a flowmeter, which may be preset or selectable, and this controls the flow in a measure such as litres per minute (lpm). The typical flowmeter range for medical oxygen is between 0 and 25 lpm.

[edit] Supplemental oxygen

A patient wearing a simple face mask.

Many patients require only a supplementary level of oxygen in the room air they are breathing, rather than pure or near pure oxygen,[7] and this can be delivered through a number of devices dependant on the situation, flow required and in some instances patient preference.

A nasal cannula (NC) is a thin tube with two small nozzles that protrude into the patient's nostrils. It can only comfortably provide oxygen at low flow rates, 0.25-6 litres per minute (LPM), delivering a concentration of 24-40%.

There are also a number of face mask options, such as the simple face mask, often used at between 5 and 15 LPM, with a concentration of oxygen to the patient of between 28% and 50%. This is closely related to the more controlled air-entrainment masks, also known as Venturi masks, which can accurately deliver a predetermined oxygen concentration to the trachea up to 40%.

In some instances, a Partial rebreathing mask can be used, which is based on a simple mask, but featuring a reservoir bag, which increases the provided oxygen rate to 40-70% oxygen at 5 to 15 LPM.

[edit] High flow oxygen delivery

A tightly sealed aviators oxygen mask

In cases where the patient requires a flow of up to 100% oxygen, a number of devices are available, with the most common being the non-rebreather mask (or reservoir mask), which is similar to the partial rebreathing mask except it has a series of one-way valves preventing exhaled air from returning to the bag. There should be a minimum flow of 10 L/min. The delivered FIO2 of this system is 60-80%, depending on the oxygen flow and breathing pattern.[8],[9]

In specialist applications such as aviation, tight fitting masks can be used, and these also have applications in anaesthesia, carbon monoxide poisoning treatment and in hyperbaric oxygen therapy

[edit] Positive pressure delivery

Patients who are unable to breathe on their own will require positive pressure to move oxygen in to their lungs for gaseous exchange to take place. Systems for delivering this vary in complexity (and cost), starting with a basic pocket mask adjunct which can be used by a basically trained first aider to manually deliver artificial respiration with supplemental oxygen delivered through a port in the mask.

Many emergency medical service and first aid personnel, as well as hospitals, will use a bag-valve-mask (BVM), which is a maleable bag attached to a face mask (or invasive airway such as an endotracheal tube or laryngeal mask airway), usually with a reservoir bag attached, which is manually manipulated by the healthcare professional to push oxygen (or air) in to the lungs. This is only procedure allowed for initial treatment of cyanide poisoning in the UK workplace[10].

Automated versions of the BVM system, known as a resuscitator or pneupac can also deliver measured and timed doses of oxygen direct to patient through a facemask or airway. These systems are related to the anaesthetic machines used in operations under general anaesthesia that allows a variable amount of oxygen to be delivered, along with other gases including air, nitrous oxide and inhalational anaesthetics.

[edit] As a drug delivery route

Oxygen therapy can also be used as part of a strategy for delivering drugs to a patient, with the usual example of this being through a nebulizer mask, which delivers nebulizable drugs such as salbutamol or epinephrine into the airways by creating a vapor-mist from the liquid form of the drug.

[edit] Filtered oxygen masks

Filtered oxygen masks have the ability to prevent exhaled, potentially infectious particles from being released into the surrounding environment. These masks are normally of a closed design such that leaks are minimized and breathing of room air is controlled through a series of one-way valves. Filtration of exhaled breaths is accomplished either by placing a filter on the exhalation port, or through an integral filter that is part of the mask itself. These masks first became popular in the Toronto (Canada) healthcare community during the 2003 SARS Crisis. SARS was identified as being respiratory based and it was determined that conventional oxygen therapy devices were not designed for the containment of exhaled particles.[11],[12],[13] Common practices of having suspected patients wear a surgical mask was confounded by the use of standard oxygen therapy equipment. In 2003, the HiOx80 oxygen mask was released for sale. The HiOx80 mask is a closed design mask that allows a filter to be placed on the exhalation port. Several new designs have emerged in the global healthcare community for the containment and filtration of potentially infectious particles. Other designs include the ISO-O2 oxygen mask,the Flo2Max oxygen mask, and the O-Mask. The use of oxygen masks that are capable of filtering exhaled particles is gradually becoming a recommended practice for pandemic preparation in many jurisdictions.

Because filtered oxygen masks use a closed design that minimizes or eliminates inadvertent exposure to room air, delivered oxygen concentrations to the patient have been found to be higher than conventional non-rebreather masks, approaching 99% using adequate oxygen flows. Because all exhaled particles are contained within the mask, nebulized medications are also prevented from being released into the surrounding atmosphere, decreasing the occupational exposure to healthcare staff and other patients.

[edit] Contraindications and cautionsOxygen should never be used in explosive environments, and its use is cautioned against when there is a risk of sparks or materials combusting as oxygen accelerates combustion. Smoking during oxygen therapy is a fire hazard and a danger to life and limb, especially with home oxygen if compliance is poor.[14] Oxygen may worsen the effects of paraquat poisoning and is therefore contraindicated in such cases. Oxygen therapy is not recommended for patients who have suffered pulmonary fibrosis or other lung damage resulting from Bleomycin treatment.

[edit] Negative effectsAlthough most EMS jurisdictions hold that oxygen should not be withheld from any patient, there are certain situations in which oxygen therapy can have a negative impact on a patient’s condition.

Oxygen has vasoconstrictive effects on the circulatory system, reducing peripheral circulation and was once thought to potentially increase the effects of stroke. However, when additional oxygen is given to the patient, additional oxygen is dissolved in the plasma according to Henry's Law. This allows a compensating change to occur and the dissolved oxygen in plasma supports embarrassed (oxygen-starved) neurons, reduces inflammation and post-stroke cerebral edema. Since 1990, hyperbaric oxygen therapy has been used in the treatments of stroke on a worldwide basis. In rare instances, hyperbaric oxygen therapy patients have had seizures. However, because of the aforementioned Henry's Law effect of extra available dissolved oxygen to neurons, there is usually no negative sequel to the event. Such seizures are generally a result of oxygen toxicity,[15]

[16] although hypoglycemia may be a contributing factor, but the latter risk can be eradicated or reduced by carefully monitoring the patient's nutritional intake prior to oxygen treatment.

High levels of oxygen given to infants causes blindness by promoting overgrowth of new blood vessels in the eye obstructing sight. This is Retinopathy of prematurity (ROP). Administration of high levels of oxygen in patients with severe emphysema and high blood carbon dioxide reduces respiratory drive, which can precipitate respiratory failure and death.

Care needs to be exercised in patients with chronic obstructive pulmonary disease, especially in those known to retain carbon dioxide (type II respiratory failure) who lose their respiratory drive and accumulate carbon dioxide if administered oxygen in moderate concentration. However the risk of the loss of respiratory drive are far outweighed by the risks of withholding emergency oxygen, and therefore emergency administration of oxygen is never contraindicated.

Oxygen first aid has been used as an emergency treatment for diving injuries for years.[17] The success of recompression therapy as well as a decrease in the number of recompression treatments required has been shown if first aid oxygen is given within four hours after surfacing.[18] There are suggestions that oxygen administration may not be the most effective measure for the treatment of DCI/DCS and that heliox may be a better alternative.[19] Recompression in a hyperbaric chamber with the patient breathing 100% oxygen is the standard hospital and military medical response to decompression illness and decompression sickness.[17][20][21]

Oxygen should never be given to a patient who is suffering from paraquat poisoning unless they are suffering from severe respiratory distress or respiratory arrest, as this can increase the toxicity. (Paraquat poisoning is rare - for example 200 deaths globally from 1958-1978)[22]

[edit] Oxygen therapy while on aircraftIn the United States, most airlines restrict the devices allowed on board aircraft. As a result passengers are restricted in what devices they can use. Some airlines will provide cylinders for passengers with an associated fee. Other airlines allow passengers to carry on approved portable concentrators. However the lists of approved devices varies by airline so passengers need to check with any airline they are planning to fly on. Passengers are generally not allowed to carry on their own cylinders. In all cases, passengers need to notify the airline in advance of their equipment.

asal cannulaFrom Wikipedia, the free encyclopedia

Jump to: navigation, search

Illustration of a nasal cannula

The nasal cannula (NC) is a device used to deliver supplemental oxygen to a patient or person in need of extra oxygen. This device consists of a plastic tube which fits behind the ears, and a set of two prongs which are placed in the nostrils. Oxygen flows from these prongs.[1] The nasal cannula is connected to an oxygen tank, a portable oxygen generator, or a wall connection in a hospital via a flowmeter. The nasal cannula carries 1–6 litres of oxygen per minute. There are also infant or neonatal nasal cannulas which carry less than one litre per minute; these also have smaller prongs. The oxygen fraction provided to the patient ranges roughly from 24% to 35%.

The nasal cannula was invented by Wilfred Jones and patented in 1949 by his employer, BOC.

Contents[hide]

1 Applications 2 See also 3 References 4 External links

[edit] ApplicationsA nasal cannula can be used wherever small amounts of supplemental oxygen without rigid control of respiration are required, such as in oxygen therapy. It can only provide oxygen at low flow rates—up to 6 litres per minute (L/min)—delivering an oxygen concentration of 28–44%. Rates above 6 L/min can result in discomfort to the patient, drying of the nasal passages, and possibly nose bleeds (epistaxis).

The nasal cannula is often used in elderly patients or patients who can benefit from oxygen therapy but do not require it to self respirate. These patients do not need oxygen to the degree of wearing a non-rebreather mask. It is especially useful in those patients where vasoconstriction could negatively impact their condition, such as those suffering from strokes.

It may also be used by pilots and passengers in small, unpressurized aircraft that do not exceed certain altitudes. The cannula provides extra oxygen to compensate for the lower oxygen content available for breathing at the low ambient air pressures of high altitude, preventing hypoxia. Special aviation cannula systems are manufactured for this purpose

Storage and Delivery of Medical Gases

Scanlan-chapter 37

In the Beginning…

•     “Oxygen Service” was the beginning of the present day skilled technology of Respiratory Care

•     Ensuring a safe, uninterrupted supply of medical gases is still a key responsibility of therapists

Medical gas classification

•      Laboratory Gases

–    Used for equipment calibration and diagnostic testing

•      Therapeutic Gases

–    Used to relieve symptoms and improve patient’s oxygenation

•      Anesthetic Gases

–    Combined with oxygen to provide anesthesia during surgery

Gases

•      Symbols

•      Physical characteristics

•      Ability to support life

•      Fire risk

–    Flammable (burns readily, potentially explosive)

–    Nonflammable (do not burn)

–    Nonflammable, but support combustion (oxidizing)

Oxygen

•     Colorless, odorless, transparent, tasteless

•     Exists naturally as molecular oxygen

•     Nonflammable, but accelerates combustion

•     Production

–   Fractional distillation (most large quantities)

–   Physical separation

Air

•     Colorless, odorless, naturally occurring

•     Oxygen, nitrogen, trace gases

•     Medical grade air produced by filtering and compressing atmospheric air

Carbon Dioxide

•      Colorless and odorless, does not support combustion or maintain animal life

•      Produced by heating limestone in contact with rater

•      Mixtures of oxygen and 5% to 10% carbon dioxide once used for therapeutics

–    Treat hiccups and atelectasis

•      Limited therapeutic use today

•      Calibrate blood gas analyzers

Helium

•     Second lightest gas of all

•     Cannot support life, breathing 100% He would result in suffocation

•     Helium must be mixed with at least 20% oxygen for therapeutics

•     Heliox used to manage severe cases of large airway obstruction

Nitrous Oxide

•     Can support combustion, but cannot support life if inhaled in a pure form

•     Only dangerously high levels of nitrous provide true anesthesia, so generally a mix of nitrous oxide and oxygen are combined with other anesthetic agents

•     Long term exposure associated with neuropathy and fetal disorders

Nitric Oxide

•     FDA approved for use in the treatment of term and near-term infants for hypoxic respiratory failure

Storage of Medical Gases

•     Medical gases are stored in portable high pressure cylinders or in large bulk reservoirs

Gas cylinders

•     Made of seamless steel

•     Classified by the federal DOT

–   3A from carbon steel

–   3AA from steel alloy tempered for higher strength

Markings and Identification

Safety Tests

•     Conducted every 5 or 10 years

•     Cylinders are pressurized to 5/3 of their service pressure

•     An asterisk denotes approval for 10-year testing

•     A plus sign means the cylinder is approved for filling to 10% above its service pressure (2200 psi)

Color Codes (US)

•     Oxygen Green

•     Carbon dioxide Gray

•     Nitrous oxide Blue

•     Helium Brown

•     CO2/O2 Gray/Green

•     He/O2 Brown/Green

•     Air Yellow

Colors

•     Colors should only be a guide

•     Always identify though inspection of the label

•     Analyze oxygen concentration prior to use

Cylinder Sizes

•     “Small” E through AA—post valve and yoke connector

–   Transport and anesthetic gases

•     “Large” F through H—threaded valve outlet

Cylinder Sizes

Cylinder Safety Relief Valves

•      An increase in gas temperature increases gas pressure

–    If temperature increases too much, cylinder can explode

•      Frangible disk (ruptures at specific pressure)

•      Fusible plug (melts at a specific temperature)

–    Small cylinders

•      Spring-loaded valve (opens and vents gas at a set high pressure)

–    Large cylinders

•      Located in the cylinder valve stems

Valve outlets

Filling Cylinders

•      Depends upon if the contents are gaseous or liquid

•      Compressed Gas

–    Filled to service pressure (or 10% above, if approved)

•      Liquefied Gas

–    Carbon dioxide and nitrous oxide can be stored as liquids at room temperature

•    Filled to a specified filling density

Measuring Cylinder Contents

•     Compressed Gas

–   Volume of gas is proportional to its pressure at a constant temperature

•     Liquid Gas

–   Weighing is the only accurate method for determining contents

Cylinder Duration

•     To estimate:

–   Gas flow

–   Cylinder size

–   Cylinder pressure at the start of therapy

•     For a given flow, the more gas a cylinder holds, the longer it will last

•     The higher the flow, the shorter the emptying time

Cylinder Factors

•     Gas volume conversion 28.3 L =1 cubic foot

•     Derived for each common gas and cylinder size.

•     Cu feet (full) x 28.3/pressure (full)

•     O2 and air

–   E (0.28) H (3.14)

Cylinder Duration (Gas)

•     Duration of flow

–   (Pressure x Cylinder factor)/Flow

•     Must be sure the cylinder does not run dry during transport, have a safety cushio

Example

•     Patient A is traveling to X-ray with an e cylinder. The tank has 2000 psi. The patient is on a 4 L nasal cannula. How long will the tank last?

Cylinder Duration (Liquid)

•     Only accurate method for determining volume in a liquid cylinder is by weight

•     1L of liquid weighs 2.5 lbs and produces 860L of oxygen in its gaseous state

•     Amount of gas = Liquid weight x 860

2.5 lb/L

•     Duration – Amount of gas (L)/Flow (L/min)

Example

•     How long will Patient A’s liquid container last if it contains 4 pounds of liquid oxygen and her nasal cannula is running at 3 L/min?

Cylinder Safety

•     Guidelines by the National Fire Protection Agency and the Compressed Gas Association

–   Cylinder Storage

–   Cylinder Transport

–   Cylinder use

•   “Crack” the cylinder

Bulk Oxygen

•      Large acute care facilities use huge amounts of oxygen daily

–    Bulk storage and delivery systems are required

•    Initially expensive, but less expensive than cylinders over the long term

•    Less prone to interruption

•    Eliminate the inconvenience and hazard of transporting and storing large numbers of cylinders

•    Regulate delivery pressures centrally, eliminating the need for separate pressure reducing valves at each outlet

Gas Supply Systems

•     Alternating supply system or cylinder manifold system

•     Cylinder supply system with reserve supply

•     Bulk gas system with a reserve

Alternating Supply System

Alternating Supply System

Liquid Stand Tank

Bulk Oxygen Safety

•      NFPA sets standards for the design, construction, placement and use of bulk systems

•      Must have a reserve or backup supply to equal the average daily gas usage of the hospital

•      Respiratory care personnel must have a protocol to identify and prioritize affected patients during a gas failure

•      Back-up equipment

•      Engineers responsible for fixing the problem

Distribution and Regulation of Medical Gases

•     Before it can be administered to a patient, a medical gas must be delivered to the bedside and the pressure reduced to a workable level

•     Modern hospitals use an elaborate piping network (vacuum sources may also be included)

•     Transport still used cylinders

Central Piping Systems

•     Gas pressure reduced to a standard woking pressure of 50 psi at the bulk location

•     Main alarm warns of pressure drops or disruption of flow

•     Zone valves

•     Wall or station outlets

Central Piping Systems

Safety Indexed Connector System

•     One risk in medical gas therapy is giving the wrong gas to a patient

–   Carefully reading the cylinder or outlet labels is the best way to avoid accidents

–   Safety systems have been developed to avoid misconnection between equipment and gases

Safety Indexed Connector System

•      ASSS

–    Threaded, large cylinders

•      PISS

–    Small cylinders, pin system

•    Oxygen (2-5); Air (1-5)

•      DISS

–    Low pressure (<200 psi) gas connectors

•    Outlets of pressure reducing valves

•    Station outlets

•    Inlets of blenders, flowmeters, ventilators

ASSS

PISS

DISS

Quick Connect Systems

Regulating Gas Pressure and Flow

•     If the goal is solely a reduction in gas pressure, a reducing valve is used

•     To control gas flow to a patient, a flowmeter is used

•     If control of pressure and flow is needed, a regulator is used

Working Pressure

•     In the US, 50 PSI is the working pressure

•     For bulk systems, built in reducing valves decrease the pressure prior to the station outlet.

•     Flow must still be controlled with a flowmeter, if oxygen therapy or nebulized medications are to be given

High Pressure Reducing Valves

•     Single Stage

–   Satisfactory for most routine hospital work

•     Multiple stage

–   The number of stages can be determined by noting the number of relief vents present

•     Preset

•     Adjustable

•     Box 34-1

Preset reducing valve

Adjustable reducing valve

Low Pressure Gas Flowmeters

•     Needed to set and control the rate of gas flow to a patient

–   When the gas source is a high-pressure cylinder, a regulator (reducing valve plus flowmeter) is required

–   For bulk systems, the pressure is reduced when it reaches the outlet station, so only a flowmeter is required

Flowmeters

•     Flow restrictor

•     Bourdon gauge

•     Thorpe tube

Flow Restrictor

•     Simplest and least expensive flow-metering device

•     A fixed orifice calibrated to deliver a specific flow at a constant pressure (50 psi)

•     Common for home oxygen delivery

•     Box 34-2

Flow restrictor

Bourdon Gauge

•      A flow-metering device that is always used in combination with an adjustable pressure reducing valve

–    Operates under variable pressures, but is fixed orifice

•      The gauge actually measures pressure changes, but displays the corresponding flow

•      Gravity does not affect a Bourdon Gauge

–    Good for transport

–    Disadvantage is the inaccuracy when pressure distal to the orifice changes

Bourdon Gauge

•     If high-resistance equipment is used, downstream pressure increases. The flow reading on the gauge depends on upstream pressure which stays constant. The gauge will read falsely higher than the actual flow.

•     If the outlet is completely occluded, it will still register flow because upstream pressure is being measured

Bourdon Gauge

Bourdon Gauge

Bourdon Gauge

Thorpe Tube

•     Always attached to a 50 psi source, either a preset reducing valve or a bedside outlet

•     Variable orifice, constant pressure flow-metering device

•     To read, one simply compares the float position to an adjacent calibrated scale, normally l/min

Thorpe Tube

•      Measures True flow

•      Pressure compensated

–    Prevents back pressure from affecting meter accuracy

–    Manufacturers now supply only this type for medical gas administration

•      Uncompensated

–    Problems occur when certain types of equipment are connected (increase in downstream resistance)

•    Thorpe tube will falsely read a flow lower than is actually delivered to the patient

Thorpe tube

•     When compensated Thorpe tubes are connected to a 50 psi source with the needle valve closed, the float “jumps” then returns to zero

•     The only factor limiting the use of a compensated Thorpe tube is gravity

–   Only accurate in an upright position, not ideal for transport

Bronchial Hygiene Therapy Scanlan Chapter 37

  Physiology of Airway Clearance

•     Normal Clearance

•   Requires a patent airway, a functional mucociliary escalator, and an effective cough. •   Cough reflex (a reserve mechanism)

–   Irritation, inspiration, compression, expulsion –   Figure 37-1  

Abnormal Clearance

•      Any abnormality that alters airway patency, mucociliary function, or the effectiveness of the cough reflex can impair clearance and cause retained secretions. •      Full obstruction or mucus-plugging results in atelectasis and impaired oxygenation •      Partial obstruction can result in increased WOB and air trapping, overdistention due to restricted airflow. •      Role of infection    

Abnormal Clearance

•     Impaired cough reflex –  Table 37-1

•     Artificial Airways

•     Impaired mucociliary clearance –  Box 37-1

Diseases associated with abnormal clearance

•     Internal obstruction (foreign bodies, kyphoscoliosis, tumors, mucus hypersecretion as with asthma) •     Alter mucociliary clearance (CF, bronchiectasis)  

General Goals and indications

•     Mobilize and remove retained secretions, with the ultimate aim to improve gas exchange and reduce the WOB.

•     Acute conditions

•     Chronic Conditions

•     Prevention of retained secretions

•     Box 37-2  

Generally not helpful for the following acute conditions

•     Acute exacerbation COPD

•     Pneumonia without significant sputum production

•     Uncomplicated asthma  

Determining the need for BH

•     Requires proper initial and ongoing patient assessment

•     Key factors (Box 37-3)

•     AARC GUIDELINES 892-893  

Postural Drainage

•     Involves the use of gravity and mechanical energy to help mobilize secretions.

–  Turning •   Rotation of the body around the longitudinal axis •   By self or by a caregiver or via a special bed •   Benefits •   contraindications

  Postural drainage

•     Uses gravity to help move respiratory tract secretions from distal lung lobes into the central airways, where they can be removed by cough or suctioning •     Place the segment to be drained up

•     Hold positions 3-15 minutes

•     Most effective for conditions with excess sputum production  

Technique  

•     Before or at least 1½ -2hours after meals or tube feeds

•     Modify head down positions as needed

•     Coordinate with pain meds as needed

•     Use caution with IV’s, vent tubing, and other equipment

•     Restore patient as you found them

•     Positions fig 37-3 Percussion and vibration

•      Application of mechanical energy to the chest wall by using either the hands or various electrical or pneumatic devices. •      Designed to augment secretion clearance •      Percussion—jars the retained secretions loose, making removal easier •      Vibration—should aid movement of secretions to the central airways during exhalation. •      Manual •      Mechanical  

Cough Techniques

•     Most BH therapies only help move secretions into the central airway. Actual clearance must be accomplished by cough or suctioning. •     Cough is an essential component of ALL therapies  

Directed cough

•      Deliberate maneuver that is taught, supervised, and monitored •      Mimics an effective spontaneous cough, helps provide voluntary control over the reflex, and compensate for physical limitations that can impair this reflex

•      Most effective in clearing secretions from the central, but not peripheral airways  

Limitations

•     Paralyzed or uncooperative patients. Some patients with advanced COPD or severe restrictive disorders may not be able to achieve an effective spontaneous cough. •     Pain may limit success.

Patient teaching

•     Instructing proper position

•     Instructing breathing control

•     Exercises to strengthen the expiratory muscles  

Modifications

•     Pre-op training if possible

•     Splinting

•     For some COPD patients, a moderate breath may be more effective

•     Pursed lip exhalation

•     “huff, huff, huff”    

manually assisted cough or “chest compression”

 

•     external application of pressure to the thoracic cage or epigastric region, coordinated with forced exhalation •     Contraindications

•     Complications –  Table 37-2

 

 

Forced Expiration technique (FET) or huff cough

•      A modification of the normal directed cough •      Consists of one or two forced expirations of middle to low lung volume without closure of the glottis, followed by a period of diaphragmatic breathing and relaxation •      Helps clear secretions with less change in pleural pressure and less likelihood of bronchiolar collapse  

Uses

•     Patients prone to airway collapse during normal coughing: emphysema, CF, bronchiectasis. •     Note

–  Requires patients generate high expiratory airflow, may not be attainable in intubated patients with respiratory failure

  Active cycle of breathing

•     Renamed FET to emphasize the importance of breathing exercises

•     Cycles –  Box 37-4

Breathing control

•     Gentle diaphragmatic breathing at normal tidal volumes with relaxation of the upper chest and shoulders •     Intended to help prevent bronchospasm    

Thoracic expansion

•     Involves deep inhalation with relaxed exhalation

•     Helps loosen secretions, improves distribution of ventilation, provides volume for FET

FET

•     Moves secretions into the central airways

•     Most beneficial combined with postural drainage

•     Not useful with young children (<2 years old) or the extremely ill  

  Autogenic Drainage

•       Utilizes 3 distinct phases of varying lung volumes and expiratory airflow (Fig 37-7)

–    Full inspiratory capacity maneuver, followed by breathing at low lung volumes –    Designed to unstuck peripheral mucus –    Breathing at low to middle lung volumes –    Collects mucus in the middle airways –    Increasing larger volumes –    Evacuation phase

•       Coughing should be suppressed until all three phases are complete •    Difficult to teach patients

Mechanical insufflation-exsufflation

•     Used with patients with neuromuscular disorders

•     Delivers a positive-pressure breath of 30-50 cm H2O over 1-3 seconds via an oral nasal mask or airway. •     Pressure abruptly reversed to –30 to –50 cm H2O and maintained for 2 to 3 seconds.  

Mechanical insufflation-exsufflation

•     Typically consists of five cycles followed by a period of normal breathing (avoids hyperventilation) •     Repeat five or more times until secretions cleared

•     Hazards  

Positive Airway Pressure  

•     Help mobilize secretions and treat atelectasis

•     Always combined with directed cough or other airway clearance technique

•     CPAP

•     EPAP  

PEP

•      Involves active expiration against a variable flow resistance •      Theory of moving secretions into the larger airways

–   Fills underaerated or nonaerated segments via collateral ventilation –   Prevents airway collapse during expiration

•      Useful for CF, COPD, prevent or reverse atelectasis •      Procedure (box 37-5)  

High Frequency Compression/Oscillation

•     Rapid vibratory movement of small volumes of air back and forth in the respiratory tract  

Types

•     Airway application –  Flutter valve –  Combines EPAP with high frequency oscillations at the airway opening –  Pipe shaped device with a heavy steel ball sitting in an angled “bowl” –  Creates a positive pressure of 10-25 cm H2O and ball flutters at about 15 Hz. –  Still mixed results

  Intrapulmonary percussive ventilation (IPV)

 

•     Uses a pneumatic device to deliver a series of pressurized gas minibursts at rates of 100 to 255 cycles per minute to the respiratory tract, usually via a mouthpiece. •     Encompasses a pneumatic nebulizer for delivery of aerosol.  

External (chest wall) application

•      High frequency chest wall compression (HFCC) –   Two part system –   Variable air pulse generator –   Nonstretch inflatable vest that covers the patient’s entire torso (ThAIRapy vest)

•    Small gas volumes are alternately injected into and withdrawn from the vest by the air-pulse generator at a fast rate, creating an oscillatory motion against the patient’s thorax.

HFCC

•     30 minute sessions at frequencies between 5 and 25 Hz.

•     Identify the frequency that produces the highest flows and largest volumes in a given patient •     Expensive  

Hayak oscillator

•     Uses a turtle shell strapped to the anterior chest wall

  Mobilization and exercise

•     Immobility is a major factor contributing to retention of secretion. –  Exercise improves overall aeration and ventilation-perfusion matching

   

Selecting bronchial hygiene techniques

•     Box 37-6

•     Use with specific conditions (table 37-3)  

Egan’s – chapter 39

Lung Expansion Therapy

    Pulmonary complications are the most common serious problems seen in patients who have undergone thoracic or abdominal surgery

–    Atelectasis, pneumondia, acute respiratory failure

    Lung expansion therapy is the most common form of respiratory care utilized in high-risk patients

Modalities to prevent or correct atelectasis

    IPPB

    IS

    CPAP

    PEP

    It is not always clear what the best method is because there are no clear advantages of one method over another.

Causes and Types of Atelectasis

    2 primary types in post-op and bedridden patients

–    Resorption atelectasis

–    Passive atelectasis

Resorption Atelectasis

    Occurs when mucus plugs are present in the airways and block ventilation to the affected region

    Gas distal to the obstruction is absorbed by the passing blood in the pulmonary capillaries, which causes the nonventilated alveoli to partially collapse

Passive Atelectasis

     Caused by persistent use of small tidal volumes by the patient

     Common when general anesthesia is given, with the use of sedatives and bed rest, and when deep breathing is painful (broken ribs and surgery to the upper abdominal region). Weakening of the diaphragm can also can contribute.

     Results when patients do not periodically take a deep breath and full expand the lungs

Indications for Lung Expansion

     Atelectasis can occur in any patient who cannot or does not take deep breaths periodically

–     Neuromuscular disorder

–     Heavily sedated patients

–     Upper abdominal or thoracic surgery

–     Lower abdominal surgery are at less risk, but still significant

–     Spinal cord injuries

–     Bedridden patients (trauma)

Post Operative patients

     Shallow breathing

–     Problem with an effective cough

   Leads to retained secretions

     History of lung diseases with increased mucus production

     Smokers

     Patients with inadequate nutritional intake (Albumin <3.2 mg/dL)

     The closer the incision is to the diaphragm, the greater the risk for post-op atelectasis

Clinical Signs of Atelectasis

     Medical history is a first clue

–     Recent abdominal or thoracic surgery

–     History of chronic lung disease or smoking

     Physical signs (may be absent or subtle, if minimal atelectasis)

–     Respiratory rate increases

–     Late-inspiratory crackles

–     Diminished with excessive secretion blockage

–     Tachycardia, if hypoxic

     Atelectasis alone does not produce fever, unless pneumonia is present

Signs

    Chest film often used to confirm atelectasis

    Area of increased opacity

    Volume loss with patients with significant atelectasis

Lung Expansion Therapy

     All modes of lung expansion therapy increase lung volume by increasing the transpulmonary pressure gradient (difference between the alveolar pressure and the pleural pressure)

     The transpulmonary pressure gradient can be increased by:

–     decreasing the pleural pressure

   Spontaneous deep breath

–     Increasing the alveolar pressure

   Applying positive pressure to the lungs

Transpulmonary pressure gradient

Figure 39-1

Lung Expansion Therapy

     All lung expansion therapy uses one of these two approaches

     Decreasing the pleural pressure

–     IS

     Increasing the alveolar pressure

–     IPPB (inspiration)

–     PEP (expiration)

–     EPAP (expiration)

–     CPAP (Both inspiration and expiration)

Lung Expansion Therapy

    All of these approaches are used, but those methods that decrease pleural pressure (IS) have more of a physiological effect than the others and are often most effective

–    Require a patient that is alert, cooperative, and capable of taking a deep breath

Lung Expansion Therapy

     Goal of any lung expansion therapy should be to provide an effective strategy in the most efficient manner

–     Staff time and equipment are two major issues related to efficiency

     For those at minimal risk of post-op atelectasis

–     Deep breathing exercises, frequent repositioning and early ambulation are usually effective

   These can be completed with minimal clinician time and no equipment

Lung Expansion Therapy

    High risk patients usually use an IS

    Positive pressure therapy requires significantly more staff time and equipment and is reserved for the high risk patients who cannot perform IS

Incentive Spirometry

    Designed to mimic natural sighing by encouraging patients to take slow, deep breaths

    Performed using a device that provides visual cues to the patients when the desired flow or volume has been achieved

–    Desired goal is set on the basis of predicted values or observation of an initial performance

Physiological Basis of IS

    A sustained, maximal inspiration (SMI)

–    Slow, deep inhalation up to the total lung capacity, followed by a 5-10 second breath hold

–    This is an inspiratory capacity (IC) followed by a breath hold

Indications for IS

    BOX 39-1

    Primary indication is to treat existing atelectasis, but may also be used as a preventive measure when conditions exist that make the development of atelectasis likely

Contraindication for IS

    Simple and Safe

    Box 39-2

    AARC Clinical Practice Guidelines p.907

Hazards and Complication of IS

     Hazards are few

     Acute Respiratory Alkalosis is most common

–     Due to breathing too fast (hyperventilation)

   Dizzingess, numbness around mouth

   Slow patient breathing

     Discomfort is usually the result of inadequate pain control in the post-op patient

–     Coordinate pain medication with IS

     Box 39-3

Equipment

    Typically simple, portable, and inexpensive

    Volume oriented

–    Measures actual volume

    Flow oriented

–    Indicate inspiratory flow

   Flow x time = volume

Administering IS

     Planning

–     Careful assessment

–     Focus on outcomes (Box 39-4)

–     Prefer to screen patient pre-op and orient to the device, if needed

     Implementation

–     Success depends on effective patient teaching

–     Set a goal that is attainable, but requires moderate effort

–     Observe for proper technique

–     Normal exhalation follow breath hold

–     Rest between maneuvers

–     Aim for at least 5-10 repetitions hourly

Administering IS

    Follow-up

–    Return visits to ensure correct technique and goal achievement

–    Once the patient has mastered, they can perform with minimal supervision

–    Box 39-5

IPPB

    Application of inspiratory positive pressure to a spontaneously breathing patient as an intermittent or short-term therapy

    Treatments usually last 15-20 minutes

    Reverses the normal spontaneous pressure gradients, during inspiration alveolar pressure increases—exhalation passive

Indication for IPPB

    May be useful for patients with clinically diagnosed atelectasis not responsive to other therapies

    May be useful for patients at high risk for developing atelectasis and not able to cooperate with a simpler technique such as IS

    AARC Guidelines p.910

Concept

    In concept, a correctly administered IPPB treatment should provide the patient with augmented tidal volumes, achieved with minimal effort

    The optimal breathing pattern to reinflate collapsed lung units with IPPB consists of slow, deep breaths that are held at end inspiration

Contraindication for IPPB

    Box 39-6

    With the exception of untreated tension pneumothorax, most of these contraindicaitons are relative

Hazards and Complications

    Box 39-7

–    Respiratory alkalosis can be avoided by proper coaching

    Gastric distension is the greatest risk in patients receiving IPPB at high pressures

Administering IPPB

    Preliminary Planning

–    Need for IPPB should be determined and desired therapeutic outcomes should be set (Box 39-8)

–    Outcomes should be as explicit and measurable as possible

Evaluating Alternatives

    Before starting IPPB, the RRT and physician must determine whether simpler and less costly methods might be as effective in achieving the desired outcomes.

–    If this is the case, simpler alternatives should be assessed first

Baseline Assessment

     Conduct baseline assessment prior to beginning therapy

     Medical History

     Should include evaluation of the patient’s clinical status and a specific assessment related to the chosen therapeutic goals

–     Measure vital signs

–     Assess appearance and sensorium

–     Breathing pattern and chest auscultation

Implementation

    Infection Control

    Equipment Preparation

–    Be sure equipment is in working order

–    Pressure cycled IPPB devices will not end inspiration if leaks in the system occur, check circuit prior to each use

   Occlude the patient connector and manually trigger a breath, if it cycles off—leak free

Implementation

    Patient Orientation

–    Carefully explain purpose of therapy to patient

   Why the physician ordered the treatment

   What the treatment does

   How it will feel

   What are the expected results

–    Be sure the patient adequately understands the procedure and the importance of cooperation

–    May need to demonstrate with a test lung

Implementation

    Patient Positioning

–    Semi-Fowlers position

–    Supine is acceptable only if upright positioning is contraindicated

Implementation

    Initial Application

–    May need nose clips until the technique is understood

–    Mouthpiece must be inserted past the lips and a tight seal made

   Mask may be used for alert and cooperative patients who otherwise cannot create a seal

–    Machine set so a breath can be initiated with minimal patient effort (1-2 cm H2O)

Implementation

     Initial Application (continued)

–     Initial system pressure 10-15 cm H2O, adjust to achieve desired volume

–     Low to moderate flow, and adjust to patient breathing pattern

–     Breathing pattern of about 6 breaths/minute with an I:E ratio of 1:3 or 1:4

–     These may need adjusted according to the patient needs

–     Careful monitoring and coaching is a must

Implementation

    Adjusting Parameters

–    Pressure and flow should be adjusted and monitored according to the goals of the therapy

–    IPPB should be volume-oriented when used to treat atelectasis

–    Determining volume goals

   Tidal volume of 10-15 mL/kg or at least 30% of the patients predicted IC

   Pressures can be gradually raised until the patient meets the goal

Implementation

    Adjusting parameters

–    Patient should encourage the patient to breath actively during the positive pressure breath

–    IPPB is only useful in the treatment of atelectasis if the volumes delivered exceed those volumes achieved by the patients spontaneous efforts

Discontinuation and Follow-up

    Posttreatment Assessment

–    Repeat patient assessment

–    Identify any side effects

–    Evaluate need at least every 72 hours or with any change of patient status

    Recordkeeping

–    Pre and post assessment

–    Unwanted patient response must be reported attending nurse and physician

Monitoring and Troubleshooting

     Machine Performance

–     Large pressure swings early in inspiration indicate an incorrect sensitivity

–     Pressure drops after inspiration begins or fails to rise until end inspiration, the flow is too low

–     Cycles of prematurely (flow too high, airflow is obstructed by kinked tubing, or active resistance to inhalation by the patient)

–     Pressure cycled IPPB will not reach it cycling pressure and cycle off (Leak—differentiate between patient and equipment as cause)

Monitoring and Troubleshooting

    Patient Response

–    If a problem arises “Triple S”

   Stop

   Stay

   Stabilize

Positive Airway Pressure (PAP)

    PAP uses positive pressure to increase the Transpulmonary Pressure gradient and enhance lung expansion

    Does not need complex machinery

Definitions and Physiological Principle

    PEP, EPAP, CPAP

    All three have been shown to be equally effective in treating atelectasis in most post-op patients

    PEP and EPAP are most often used for Bronchial Hygiene (chapter 40)

    For hyperinflation, we will discuss the intermittent use of CPAP

Definitions and Physiological Principle

    CPAP maintains a positive airway pressure throughout inspiration and expiration

    CPAP elevates and maintains high alveolar and airway pressures throughout the full breathing cycle

    This increases the transpulmonary pressure gradient throughout inspiration and expiration

Definitions and Physiological Principle

     The patient typically breathes through a pressurized circuit against a resistor with pressures maintained between 5 and 20 cm H2O

     The following factors contribute to CPAP’s benefits

–     The recruitment of collapsed alveoli via increase in FRC

–     Decreased work of breathing due to increased compliance or abolition of auto PEEP

–     Improved distribution of ventilation through collateral channels

–     An increase in the efficiency of secretion removal

Indications for CPAP

    Evidence supports use of CPAP therapy in treating post op atelectasis, but the duration of beneficial effects may be limited (benefits may be lost within 10 minutes)

    Suggest using CPAP on a continuous, not intermittent basis

Contraindications for CPAP

    Hemodynamic instability

    Hypoventilating patients, may not have adequate ventilation

    Patients with nausea, facial trauma, untreated pneumothorax, and elevated ICP

Hazards and Complications of CPAP

     Increased work of breathing caused by the apparatus

     CPAP does not augment spontaneous ventilation, so patients may hypoventilate

     Barotrauma (especially in patients with emphysema and blebs)

     Gastric Distension if pressures above 15 cm H2O

–     Vomiting and aspiration

Equipment

     Key elements

–     Gas mixture from an oxygen blender

–     Flows continuously through a humidifier

–     Into the inspiratory limb

–     Reservoir bag for reserve volume if the patients demand exceeds that of the system

–     Simple t-piece connector

–     Pressure alarm system with a manometer

–     Expiratory limb

–     Connected to a threshold resistor

     Due to the closed system, there must be an emergency inlet valve—in case of gas source failure

CPAP system

Administering Intermittent CPAP

    Planning

–    Determine desired outcomes

   An improvement in breath sounds

   Vital sign improvement

   Resolution of abnormal x-ray

   Restoration of normal oxygenation

    Procedures

–    Appropriate CPAP level is determined on an individual basis

Administering Intermittent CPAP

    Monitoring and Troubleshooting

–    A real danger of hypoventilation

–    Patients must be adequately able to rid themselves of CO2 for therapy to be successful

–    Monitor closely for unwanted effects

–    CPAP device must be equipped with a means to monitor the pressure delivered and alarms to indicate the loss of pressure due to system disconnect or mechanical failure

Administering Intermittent CPAP

     Most common problem is system leaks

     When using a mask, a tight seal must be maintained

–     This may cause pain and irritation in some patients

–     New nasal CPAP units have addressed some of the comfort issues and helped with leaks

     Gastric insufflation and aspiration of stomach contents is a more serious problem

     RTs must ensure adequate gas flow to meet the patient needs (2-3 times their minute volume)

–     Flow is adequate if system pressure drops no more than 1-2 cm H2O during inspiration

Selecting an Approach

    Use the safest, simplest, most effective method for a given patient

    Need in-depth knowledge of methods and the individual patient needs

Protocol

Aerosol Drug Therapy

Scanlan – chapter 36

Aerosols

   An aerosol is a suspension of solid or liquid particles in gas

   They can occur in nature as pollens, spores, dust, smoke, smog, fog, and mist

  The upper airway must filter these.

   In clinical settings, generated by atomizers, nebulizers, or inhalers

   Can deliver bland water or drugs

  Target lungs, throat, nose

Medical aerosol therapy

   The aim is to deliver a therapeutic dose of the selected agent to the desired site of action

   Indication for any specific aerosol is based on the need for the specific drug and the targeted site of delivery

   Aerosol drugs are delivered directly to the site, resulting in therapeutic action with minimal systemic side effects

Therapeutic Index

   A high index is the result of improved therapeutic action, with less systemic side effects

Characteristics of Therapeutic Aerosols

   Aerosol output

   Particle size

   Deposition

Aerosol output

   Mass of fluid or drug contained in the aerosol produced by a nebulizer

   Emitted dose: describes the mass of drug leaving the mouthpiece of a nebulizer or inhaler as aerosol

   The mass leaving the nebulizer tells little about the amount of drug reaching the lung

   Variables include particle size and breathing patterns

Particle Size

   Particle size depends on the substance being nebulized, the nebulizer chosen, the method used to generate the aerosol and the environmental conditions surrounding the particle

   You cannot tell optimal particle size by visualization, you must perform lab measurement

Terminology

   Heterodisperse: containing particles of many sizes

   Mass median aerodynamic diameter (MMAD): an expression of average size of the aerosol particles

   Geometric standard deviation (GSD): describes the variability of particle sizes in an aerosol distribution

   Monodisperse: aerosol particles of similar size

Particle Size

   Most aerosols found in nature and used in respiratory care are composed of particles of different sizes (heterodisperse)

   Only those used in lab research and nonmedical industry tend to be monodispersed

Deposition

   Aerosol particles are deposited when they leave suspension in gas

   Inhaled dose is the amount of drug inhaled

   Respirable mass is the proportion of the drug mass of proper size to reach the lower airway

   About 1-5% of the inhaled drug may be exhaled instead of deposited

   Key mechanisms of deposition:

   Inertial impaction, sedimentation, diffusion

Inertial impaction

   Occurs when suspended particles in motion collide with and are deposited on a surface

   The primary deposition mechanism for particles larger than 5 micrometers

   Turbulent flow patterns, obstructed pathways and inspiratory flow rates greater than 30 L/min are associated with increased inertial impact

   Particles in the 5-10 micrometer range tend to deposit in the oro- and hypopharynx

Sedimentation

   Occurs when aerosol particles settle out of suspension and are deposited due to gravity

   During normal breathing, this is the primary mechanism for deposition in the 1-5 micrometer range

   Occurs most often in the central airways and increases with time

   Breath holding enhances sedimentation

   A 10 second breath hold can increase aerosol deposition as much as 10%.

Diffusion

   Brownian diffusion is the primary mechanism for deposition of small particles (<3 micrometers) mainly in the respiratory region where bulk as flow ceases and most aerosol particles reach the alveoli by diffusion

   Particles between 1 and .5 micrometers are so stable that most remain in suspension and are exhaled, particles less than .5 micrometers have a greater retention in the lungs

Rule of Thumb

   Deposition varies with particle size

   Target the desired location by using the appropriate particle size.

Aging

   The process by which an aerosol suspension changes over time

   Particles constantly grow, shrink, coalesce, and fall out of suspension

   They can change size due to evaporation or hygroscopic water absorption

   The rate of particle size change is inversely proportional to the size of a particle

   Small particles change faster than large particles

Determining deposition

   Inspiratory flow rate

   Flow pattern

   Respiratory rate

   Inhaled volume

   I:E ratio

   Breath holding

Deposition

   The presence of airway obstruction is one of the greatest factors influencing aerosol deposition.

  Pulmonary deposition is greater in smokers and patients with obstructive airway disease than in healthy persons

  Figure 36-4

Aerosol delivery Quantification

   At the bedside, quantification is based on the patient’s clinical response to the drug with either the desired effects or the unwanted adverse effects

Hazards of aerosol therapy

   Primary hazard is an adverse reaction to the medication being delivered

   Infection

   Commonly due to contaminated solutions, caregivers hands, or the patients own secretions

   Primarily gram negative bacilli (pseudomonas aeruginosa and legionella pneumophila)

   Sterilize nebulizers between patient

   Frequently replace units

   Rinse with sterile water every 24 hours and air dry

Hazards of aerosol therapy

   Airway Reactivity

   Can cause bronchospasm in some patients when exposed to cold or high-density aerosols, and some medications

   Pretreat with bronchodilator

   Pulmonary and Systemic Effects

   Associated with the site of delivery and the drug being administered

   Preliminary assessment should balance the need of therapy against the risks

   Suction may be indicated in patients unable to clear their own secretions

Hazards of aerosol therapy

   Drug Concentration

   During the evaporation, heating, baffling, and recycling of drug solution undergoing jet or ultrasonic nebulization, concentrations of the solution may increase

   Can expose patient to increasingly higher concentrations of the drug over the course of therapy

–   Large amount of drug may remain in the nebulizer at the end of therapy

   Occurs more often when nebulized for an extended time period, for example CNBT

Aerosol Drug Delivery Systems

   Effective aerosol therapy requires a device that quickly delivers sufficient drug to the desired site of action with minimal waste and at a low cost

   MDI

   DPI

   Jet nebulizers (small and large)

   USN

   Atomizers (including nasal spray pump)

MDI (pressurized MDI pMDI)

   Most commonly prescribed method of aerosol delivery in the US

   Portable, compact, and relatively easy to use

   Used correctly it is as effective as other nebulizers

   Can be used for spontaneously breathing or vent patients

   Uniform dose is dispensed

   Used for bronchodilators, anticholinergics and steroid delivery

Equipment

Equipment

   A pressurized canister containing a drug

   Drug is a micronized powder dissolved or suspended in CFC or HFA propellant

   Aerosol production takes approximately 20 milliseconds

   CFC is being replaced by HFA as a propellant

   Dispersal agents such as soya lecithin and sorbitan trioleate help keep the drug suspended in the propellant and lubricate the valve stem

MDI

   Initial dose from a new canister contains less active dose than subsequent activations

   Before initial use, prime the MDI to the atmosphere 1 to 4 times (follow label)

   Serious limitation is the lack of a “counter” to indicate the number of doses

   “Tail off” may occur after the number of labeled doses are given in which 20-60 apparent doses are give with little or no medication

MDI

   Decreased temperature (less than 10 degrees Celsius) may result in decreased output of CFC MDI’s

  Less of a problem with the HFA MDI

Aerosol Delivery Characteristics

   MDI’s produce particles in the range of 3-6 micrometers, but about 80% of the dose deposits in the oropharynx

   Pulmonary deposition ranges from 10-20%

Technique

   As many as 2/3 of patients and health professions who teach MDI use do not perform the procedure properly

   Thorough education including demonstration, practice, and confirmation of knowledge

   Demonstration with placebos

Technique

   “Cold freon effect”

   Patient stops inhaling when the cold aerosol reaches the back of the mouth

   Care with use of anticholinergic agents and an open mouth technique because they are associated with increased ocular pressure and could be dangerous with glaucoma patients

   Box 36-1

Technique

   The high percentage of oropharyngeal deposition with use of steroid MDI’s can increase the incidence of thrush and dysphonia

  Steroid MDI’s should not be used alone, always with a spacer or holding chamber

  Rinse mouth

MDI Accessory Devices

   Two primary limitations of MDI

  Hand-breath coordination

  High oropharyngeal deposition

Accessory Devices

    Breath Actuated MDI

    Activated during inhalation, reduces need for coordination for patient

    Autohaler—opens when patient’s flow exceeds 30L/min

    Spacers and Holding Chambers

    Reduce the need for coordination and incidence of oropharyngeal deposition

    A spacer is a simple valveless extension device that adds distance between the MDI and the mouth.

    A Holding Champer has a one-way valve that hold the aerosol particles in until the patient inhales

    Box 36-2

Holding Chamber/Spacer

   Masks are available to use for adults, children, and infants

DPI

   Breath actuated metered dosing system

   Patient creates the aerosol by drawing air through a dose of finely milled drug powder

   Do not need propellants

   Do not require hand breath coordination

   Do need to create a turbulent flow in the inhaler

   As effective as MDI’s

Equipment Design

Equipment Design

    Most DPI systems require the use of a carrier substance (lactose or glucose) mixed into the drug to enable the drug powder to flow out of the device

    Spinhaler/Rotahaler dispensed doses of drug from punctured gelatin capsules

    Turbuhaler is a multidose reservoir powder system preloaded to dispense 200 doses

    Diskhaler uses four to eight individual blishter packs

    Diskus incorporates a tape system with up to 60 sealed single doses

Equipment Design

   Particle size of dry powder ranges from 1-3 micrometers, but the carrier agent ranges from 20-65 micrometers so the carrier is deposited in the oropharynx

   Optimal performance for each design occurs at a specific inspiratory flow rate

Equipment Design

   Ambient humidity affects drug delivery from DPI’s

  Dose decreased in a humid environment, likely due to powder clumping

   DPI’s are generally convenient and easy to use

   DPI’s rely on a patient’s inspiratory effort

Technique

   Most critical factor is the need for a HIGH inspiratory flow (>60 L/min)

   Infants and children less than 5 years and those unable to follow direction cannot develop a flow this high and cannot use DPI

   BOX 36-3

Jet Nebulizers

   Small Volume Nebulizers have small (less or equal to 10 mL medication reservoirs

   Powered by high pressure air or oxygen (compressors, cylinders or wall outlet)

   Factors affecting SVN perfomance: nebulizer design, gas pressure and density, medication characteristics

   Box 36-4

Terminology

   Baffle: a surface on which large particles impact and fall out of suspension, a process that decreases the MMAD and GSD of the aerosol

  Sphere or plate, internal walls of the neb, etc

   Atomizers operate similar to the SVN but without baffling and produce aerosols with larger MMAD

Terminology

   Residual or dead volume is the medication that remains in the SVN after the device runs dry

   May be 0.5ml -2.2 ml of a 3 ml dose

   An effective nebulizer should deliver more than 50% of its total dose in the respirable range in 10 minutes or less

   The higher the flow of gas the smaller the particle size and the shorter the time to nebulizer

   Position of nebulizer will affect nebulization—some stop producing aerosol at a 30 degree tilt

Gas source

   Hospital versus home

   Gas pressure and flow affect particle size, distribution and output

   Nebulizers for home use should be matched to the compressor in order to increase efficiency

   Density

   Gas density affects both aerosol generation and delivery to the lungs

   Lower the density of a gas, the less turbulent the flow (heliox)

–   Less impaction occurs and better deposition results

Humidity and Temperature

   They affect particle size and the concentration of drug remaining in the nebulizer

  Particles entrained in warm and fully saturated gas stream increase inside

Nebulization

   Continuous nebulization wastes medication because the aerosol is produced throughout the respiratory cycle and is lost in the atmosphere

   Breath enhanced nebulizers

   Use a series of one way valves to minimize waste

   Breath-actuated nebulizers

   Synchronize to breathing pattern, generate aerosol only during inspiration

Children and Infants

   They have smaller airway diameters than adults, breathing rate is faster, nose filters out large particles, and mouthpieces often cannot be used

   Mask

   “Blow by”—not established to be effective by research

   Normal breathing is most effective,

   Never to a crying child, because it greatly reduces lower airway deposition—long expiratory phase, quick inspiration

Characteristics of Drug Formulation

   The viscosity and density affects output and particle size

   Some drugs such as antibiotics are so viscous they cannot be effectively nebulized in some standard SVN’s

   SVN’s can exhibit variable performance

  Evaluate before purchase

Technique

   SVN use is less technique and device dependent than MDI or DPI systems

   Slow inspiratory flow does improve SVN aerosol deposition

   The nose is a filter of particles, so many clinicians prefer not to use a mask—However, as long as the patient breathes through the mouth there is little difference between mask and mouthpiece.

   Box 36-5

Infection Control Issues

   CDC recommends nebulizers be cleaned and disinfected or rinsed with sterile water and air dried between uses

   Multi-dose medication solutions should be store in a refrigerator

   Discard syringes used to draw up medication every 24 hours

Large Volume Jet Nebulizers

   Used to deliver aerosolized drugs to the lung

   A large volume nebulizer is particularly useful when traditional dosing strategies are ineffective in the management of severe bronchospasm

   If a patient does not respond to standard dosages it is common to repeat the treatment every 15 minutes

   Continuous nebulization therapy is an option

CNBT

   Heart and Hope nebulizers are devices used

  Have greater than a 200 ml reservoir producing aerosols between 2.2 and 3.5 micrometers

   Monitor patients closely for signs of drug toxicity on CNBT

SPAG

   Small particle aerosol generator (Fig.36-25)

   A special purpose large volume nebulizer specifically for administration of ribavirin to RSV patients

   Regulator is connected to two flow meters that control flow to a nebulizer and a drying chamber

   Nebulizer Flow should be approximately 7 L/min with total flow of no lower than 15 L/min

Problems with SPAG

   Caregiver exposure to drug aerosol

   Delivery through a mechanical ventilation circuit

  Can occlude the circuit or jam breathing valves

SPAG

USN

   Uses a piezoelectric crystal to produce an aerosol

   Capable of higher outputs and higher densities than conventional jet nebulizers

   Large Volume USN: used for bland aerosol and sputum induction

   Small Volume: have been marketed for drug delivery

   Most designs have less dead space than SVNs and this reduces the need for large quantities of diluent to ensure drug delivery

USN

   Minimal residual drug volume

   Treatment time is reduced

Hand bulb Atomizer

   Hand bulb atomizer or nasal spray pump is used to deliver sympathomimetic, antimuscarinic, antiinflammatory, and anesthetic aerosols to the upper airway (nose, pharynx, and larynx)

   No baffles which make a high MMAD, ideal for upper airway deposition

Vibrating Mesh Nebulizers

   Active: uses a piezo ceramic element to generate droplems

   Passive: utilizes a mesh separated from an ultrasonic horn by the liquid to be nebulized

New Generation Nebulizers

   Use of soft mist aerosol, improved particle characteristics, and systems that minimize residual volume improve these devices efficiency

   Some increase deposition from 10 to almost 60%

New Generation

   AERx: uses unit dose blister packs of fluid, built in inspiratory flow rate monitoring

   Respimat: mechanical energy creates an aerosol from liquid solutions. Requires hand-breath coordination

Advantages and Disadvantages

   Table 36-2

Selecting a Delivery System

   Considerations:

  Available drug formulation

  Desired site of deposition

  Patient characteristics

  See rule of thumb

  Patient preference

  AARC Guidelines page 827

  Figure 36-28

Assessment based bronchodilator therapy

   Ultimately it is the patient response that determines the therapeutic outcome

   Protocol relies heavily on bedside assessment of the airway obstruction

  Figure 36-30

Assessing patient response

   AARC Guideline p.831

Use and Limitations of PEFR

   PEFR is effort and volume dependent, evaluation of patient performance is somewhat subjective

   PEFR can be used at the bedside, conventional PFT remains the standard for determining bronchodilator response

Other components of Patient Assessment

   Sole dependence on expiratory airflow to assess therapy response is unwise

   Interview patient to determine history and current levels of dyspnea

   Observe for signs of increased WOB

   A decrease in wheezing accompanied by decrease in breath sound intensity is a worsening condition, but a decrease in wheezing with an increase in intensity is improvement

   Oxygen status with pulse oximetry

Dose Response Assessment

   Poor response is often due to an inadequate amount of drug reaching the airway.

   To determine the “best” dose for patients , the dose-response titration

   Simple albuterol dose response titration involves giving an initial 4 puffs at 1 minute intervals via MDI with holding chamber

   If no relief after 5 minutes, 1 puff per minutes until relieved or HR increases more than 20 bpm, tremors occur, or 12 puffs delivered

   Best dose: maximum relief with highest PEFR without side effects

Frequency of Assessment

   Box 36-7

Patient Education

   The patient’s ability to understand the therapy and its goals significantly affects the therapeutic efficacy of any treatment

   Must teach basic administration tecnique

Continuous Nebulization for Refractory Bronchospasm

   Patients suffering severe exacerbation of asthma or acute bronchospasm that have taken standard dose of their bronchodilator without response

   Figure 36-31

   Mini Clini

Aerosol Administration to Intubated Patients

   Table 36-4

   Box 36-8

   Box 36-9

   SVN tends to deposit in tubing and expiratory filter

   MDI

Controlling Environmental Contamination

   Nebulized drugs that escape from the nebulizer into the atmosphere or are exhaled by the patient can be inhaled by anyone in the vicinity of the treatment

   Greatest occupational risk for the RCP

   Ribavirin and pentamidine

   Conjunctivitis, headaches, bronchospasm, SOB, and rashes

Controlling Environmental Contamination

   Negative Pressure Rooms

  HEPA filters

   Booths and Stations

   PPE

Humidity And Bland Aerosol Therapy

Scanlan – Chapter 35

Humidity Therapy

   Humidity therapy involves adding water vapor and (sometimes) heat to the inspired gas

Physiological Control of Heat & Moisture Exchange

   Heat and moisture exchange is a primary function of the upper respiratory tract, mainly the nose.

–  Heats and humidifies gas on inspiration

–  Cools and reclaims water on exhalation

–  The nasal mucosa is very vascular and actively regulates temperature changes in the nose

Mouth

   The mouth is a less efficient heat and moisture exchanger

Physiological Control

   As inspired gas moves nto the lungs, it achieves BTPS (T-37C;c barometric pressure;saturated with water vapor)

   Isothermic saturation boundary—normally approximately 5 cm below the carina

–  A number of factors can shift the ISB deeper into the lungs

ISB Shift

   Distally when a person breathes through the mouth

   When breathing cold, dry air

   Upper airway is bypassed (artificial tracheal airway)

   Minute ventilation is higher than normal

Indications for Humidification and Warming of Gas

    Primary goal of humidification is to maintain normal physiological conditions in the

lower airways

–   Proper levels of heat and humidity ensure normal function of the mucociliary transport system

–   Box 35-1

–   As the airways are exposed to cold, dry air; ciliary motility is reduced, mucus production increases and becomes thick

  Dry gases are even more hazardous if the upper airway is bypassed (maintain at least 60% of BTPS)

Recommended Heat and humidity levels

   The amount of heat and humidity that a patient needs depends on the site of delivery

   Table 35-1

Equipment

   Humidifier: a device that adds molecular water to gas

   Three variables affect the humidifier’s performance

–  Temperature

–  Surface area

–  Contact time

 

Temperature

   The greater the temperature, the more water vapor it can hold

   Easy way to improve effectiveness is to add a heater

 

Surface Area

    The greater the area of contact between water and gas, the opportunity for evaporation to occur

–   Passovers pass gas over a large surface area of water

  More space-efficient ways to increase surface area:

–   Bubble (directs a stream of gas underwater and the bubbles rise to the surface)

–   Wick (uses porous water-absorbent materials to increase surface area—capillary action)

 

Contact Time

    The longer a gas remains in contact with water, the greater the opportunity for evaporation to occur.

–   Bubble: depends on the depth of the water column—deeper column;more contact time

–   Passover & Wick: flow rate of gas through the humidifier is inversely related too the contact time (low flows; more contact time)

Types of Humidifiers

    Bubble

    Passover

    HME

    These are either Active (actively adding heat and or water to the device/patient interface) or Passive (recycling exhaled heat and humidity from the patient)

    ASTM establishes specifications for these

Bubble

   Breaks (diffuses) an underwater gas stream into small bubbles)

   Commonly used with oronasal oxygen delivery systems

   Goal is to raise the water vapor content of the gas

   Unheated they can provide absolute humidity of approximately 15-20 mg/L

Bubble

    As gas flow increases, these devices become less efficient as the reservoir cools and contact time is reduced

–   Limited effectiveness at flows higher than 10L/min

    Pressure-relief valve or “pop-off” at pressures above 2 psi

–   Provide audible alarm

  Can also use to test for leaks: If the system is obstructed by the RCP and the pop off sounds, it is leak free; failure to sound signifies a leak

Bubble

   At high flow rates, bubble humidifiers can produce aerosols.

–  May not be visible to the naked eye, but they can transmit pathogens from the reservoir to the patient

Bubble Humidifier

Passover

   A passover directs gas over a water surface

   Common types

–  Wick

–  Membrane

–  Simple Reservoir Type

 

Wick Humidifier

    The wick (a cylinder of absorbent material) is placed upright in a water reservoir and surrounded by a heating element

    Capillary action continually draws water up from the reservoir and keeps the wick saturated

    As dry gas enters the chamber it flows around the wick, picks up moisture and leaves the chamber fully saturated with water vapor

    No bubbling occurs

Wick

Membrane-type humidifier

   Separates the water from the gas stream by means of a hydrophobic membrane

   Water vapor molecules can easily pass through this membrane, but liquid water cannot

Membrane-type

Simple reservoir

   Directs gas over the surface of a volume of water

   Surface for gas-fluid interface is limited

   May be used with mechanical ventilation (heated)

   Non-invasive ventilation (unheated)

Passover Advantages

   Advantages over a bubble humidifier:

–  They can maintain saturation at high flow rates

–  They add little or no flow resistance to spontaneous breathing circuits

–  They do not generate any aerosols, and thus pose a minimal risk for spreading infection

Heat & Moisture Exchangers

    Most often a passive humidifier that has been described as an “artificial nose”

    An HME captures exhaled heat and moisture and uses it to heat and humidify the next inspiration

    Traditionally, used to provide humidification to patients receiving invasive ventilatory support via trachs or endotracheal tubes

Three types of HME

   Simple condenser humidifier

   Hygroscopic condenser humidifier

   Hydrophobic condenser humidifier

Simple condenser

   Contains a condenser element with high thermal conductivity, usually a metallic gauze or corrugated metal

   About 50% of the patients exhaled moisture is captured (50% efficiency)

Hygroscopic condenser

    Provides a higher efficiency by using a condensing element of low thermal conductivity (paper, wool, foam) and impregnating this with a hygroscopic salt (calcium or lithium chloride)

    The low thermal conductive elements retain more heat and the salt helps capture extra moisture

    70% efficiency

Hydrophobic condenser

   Use a water repellent element with a large surface area and low thermal conductivity

   70% efficiency

   Some also provide bacterial filtration

HME

    Design and performance standards are set by the International Organization for Standardization (ISO)

    Ideal HME should:

–   Operate at 70% efficiency or better (providing at least 30 mg/L) water vapor

–   Use standard conections

–   Add minimal weight, dead space, and flow resistance to a breathing circuit

HME

HME

   Moisture output of HME’s tends to fall at high volumes and rates of breathing

   High inspiratory flows and high FiO2 levels can decrease HME efficiency

   HME flow resistance increases with water absorption (some patients may not tolerate this)

HME

   They eliminate the problem of circuit condensation

   Some also help with nosocomial infection by reducing bacterial colonization in the vent circuit (especially hydrophobic filters)

 

Heating Systems

   Heat improves the water output of bubble and passover humidifiers

   Heated humidifiers are used mainly for patients with a bypassed upper airway and/or for those receiving mechanical ventilatory support

5 Types of Heaters

          “Hot plate” element at the base of the humidifier

          A “wraparound” type that surrounds the humidifier chamber

          A yolk, or collar, element that sits between the water reservoir and the gas outlet

5 Types of Heaters

4. An immersion-type heater with the element actually placed in the water reservoir

5. A heated wire in the inspiratory limb warming a saturated wick or hollow fiber

 

Heating Systems

   The systems also have a controller that regulates the element’s electric power

Heating Systems

–  In a simple system, the controller monitors the heating element, varying the current to match either a preset or adjustable temperature

The patient’s airway temperature has no effect on the controller

 

Heating Systems

    Servo-controlled heating system

–   Monitors temperature at or near the patient’s airway using a thermistor probe

–   Adjust heater power to achieve the desired airway temperature

  Thermistor probes should be placed in the inspiratory limb of the vent circuit far enough form the wye to ensure the warm exhaled gas does not fool the controller (Never place in an isolette or radiant warmer)

  Both types have alarms and alarm-activated heater shut-down

  Box 35-2

Reservoir and Feed Systems

    Heated humidifiers operating continuously in breathing circuits can evaporate more than 1 L of water per day

–   To avoid constant refilling, they employ a large water reservoir or use a gravity feed system

  These should be safe, dependable and easy to set up and use, allow for continuity of therapy, enen when the reservoir is being replenished

Simple large reservoir

   Manually refilled (with sterile or distilled water)

–  This requires a momentary interruption of humidifier operation

–  Because the system must be “opened” for refilling, cross contamination can occur

–  A small inlet that can be attached to a gravity-fed IV bag and line allows refilling without interruption of service

Automatic Feed system

   Avoid the need for constant checking and manual refilling of humidifiers

–  Simplest type is the level-compensated reservoir

–  Flotation valve controls are used to maintain humidifier reservoir fluid volume

As the water level drops, the float opens a feed valve to allow it to refill.

Automatic Feed System

   Membrane humidifiers do not require float control, they use an open gravity feed system.

–  These devices cannot overfill due to the underlying membrane.

 

The Hydrate

   Uses Capillary force vaporization.

–  This vaporizer is a thin film, high surface area boiler that combines capillary force and phase transition to apply pressure onto an expanding gas (water vapor) and ejects it.

Page 785

Clinical Practice

   Humidification during Mechanical Ventilation

–  AARC Clinical Practice Guideline (p. 786)

Setting Humidification Levels

    American National Standards Institute recommends minimum levels of humidity for intubated patients of more than 30 mg/L

    Target the temperature and level of humidity for the normal conditions for the point at which gas enters the airway

–   Air entering the carina is typically 35-40 mg/L

–   Set humidifiers to maintain airway temperatures in the range between 35-37C.

  If too cold, airway plugging can occur.

AARC Guidelines

   Recommends 33C, within 2C, with a minimum of 30mg/L of water vapor for mechanically ventilated patients with artificial airways

–  Lower than this will cause mucosal dysfuction.

–  Optimal level is 37C and 44 mg/L with 100% relative humidity.

 

Common Problems

   Condensation

   Cross Contamination

   Proper Conditioning of the Inspired Gas

Condensation

   The gas cools as it leaves the point of humidification and passes through the delivery tubing to the patient.

   As the gas cools, water vapor capacity decreases, resulting in “rain out”

 

Influencing Factors

   Temperature difference across the system

   Ambient temperature

   Gas flow

   Set airway temperature

   Length, diameter, and thermal mass of the breathing circuit

Risks

   Condensation poses risks to patients and caregivers, and can waste a lot of water

   Disrupts gas flow through the circuit

   Alter FiO2

   Can be aspirated

   Infection risk

Minimizing Problems

    Treat condensate as infectious waste

–   Wear gloves and goggles

    Water traps at low points in the circuit, both limbs

–   Drain away from patient’s airway

    Maintain a temperature in the circuit (reduce circuit cooling)

–   Insulation of the circuit or wire heating elements in the circuit

Cross Contamination

    Condensate is a known source of bacterial colonization

–   Wick and membrane passovers prevent formation of bacteria-carrying aerosols

–   High reservoir temperatures in humidifiers are bacteriocidal

–   Used to believe changing vent circuits every 24 hours reduced risk, but now it is known that it actually increased risk

  Weekly or may not need to change at all.

Proper conditioning of the Gas

    Most regularly monitor FIO2 levels, but few monitor the condition of the inspired gas

–   Hygrometer-thermometer systems accomplish this

–   Adjust the temperature to the point that a few drops of condensation form near the patient wye

–   Estimate that an HME is performing well at the bedside by visually confirming condensation in the flex tube

Bland Aerosol Therapy

   A bland aerosol consists of liquid particles suspended in a gas

–  Delivery of sterile water or hypotonic, isotonic, or hypertonic saline aerosols

Can be accompanied by oxygen therapy

Bland Aerosol

   Clinical Practice Guidelines (p. 791)

Equipment

   Large volume jet nebulizers

   Ultrasonic nebulizers

   Delivery systems include direct airway appliances and enclosures

Large Volume Jet Nebulizer

   Most common device for bland aerosol

   Pneumatically powered

   Aerosol is generated by passing gas at a high velocity through a small “jet” orifice

–  Resulting low pressure at the jet draws fluid from the reservoir up to the top of the tube, where it is shattered into liquid particles

Large-Volume Neb

    Large particles fall out and the small particles are carried in the gas stream

–   Baffling (Large particles impacting internal surfaces of the device)

    Variable air-entrainment ports allow FIO2 to be altered

    If heat is required, wrap around, hotplate, or immersion heaters are available

Large-Volume Neb

   Larger versions of these with 2-3L reservoirs can deliver bland aerosols into mist tents

–  Always run unheated due to heat build-up in an enclosure

 

Large Volume Neb

USN

   Electrically powered device that uses a piezoelectric crystal to generate aerosol

–  This converts radio waves into high-frequency mechanical vibrations (sound)

–  The vibrations are transmitted to a liquid surface where the intense mechanical energy creates a “geyser” of aerosol droplets

USN

USN

   Signal frequency—determines particle size

–  Usually preset

   Signal amplitude—alters the transducer’s vibrational energy and thus directly affects the amount of aerosol produced

–  Adjusted by clinician

USN

   Have unique capabilities, but in most cases their advantages over jet nebulizers are outweighed by their high cost and erratic reliability

   Use for sputum induction is an exception

–  3% Saline

Airway Appliances

   Aerosol face mask

   Face tent

   T-tube

   Tracheostomy mask

   Enclosures (Mist tents and Hoods)

–  Problems are CO2 build up and heat retention

Sputum Induction

    Useful, cost-effective, safe method for diagnosing TB, pneumocystis carinii, and slung cancer

    Involves short term application of hypertonic saline (3%) to assist in mobilizing pulmonary secretions for evacuation and recovery

    To ensure a good sample, must attempt to get true respiratory secretions, not saliva

    Box 35-3

Problems

   Cross contamination and infection

   Environmental safety

   Inadequate mist production

   Bronchospasm

   Noise

 

Troubleshooting

    Adhere to infection control guidelines

    Poor mist production can be caused by inadequate input flow, siphon tube obstruction, or jet orifice misalignment

    Overhydration is a problem with continuous use (USN’s should never be used continuously due to high water outputs)

–   Infants, small children, and those with fluid or electrolyte imbalances are at highest risk

 

Troubleshooting

    Inspissated pulmonary secretions also can swell after high-density aerosol therapy, worsening airway obstruction

    Bland aerosols can cause bronchospasm in some patients

–   May need to pretreat with a bronchodilator

    Noise generated by the large volume jet nebulizers is a problem, care with infants in incubators and oxygen hoods

–   Best to use a passover humidifer in these cases

Selecting the appropriate therapy

   Key consideration

–  Gas flow

–  Presence or absence of an artificial tracheal airway

–  Character of the pulmonary secretions

–  Need for and expected duration of mechanical ventilation

–  Contraindications to use an HME

Selecting the appropriate therapy

   Advises against using a bubble humidifier at flow rates of 4L/min or less

–  May add to the patient who complains of nasal dryness or irritation when on a low flow oxygen device

Selecting the appropriate therapy

 

  

      © WVNCC Last Updated:    

Airway Management Scanlan – Chapter 30

Airways •      Many patients have diseased lungs and impaired gas exchange. •      Adequate gas exchange is not always possible without an airway.

Three Area of Skills •      Airway Clearance •      Insert and maintain artificial airways •      Assist physicians with special procedures

Airway Obstruction •      Caused by retained secretions, foreign bodies, and structural changes (edema, tumors,or trauma)

   Increased resistance and WOB, hypoxemia, hypercapnia, atelectasis, and infection

Secretion Clearance •      Thickness or amount •      Patient’s inability to generate an effective cough

Suctioning •      Uses negative pressure (vacuum) to the airways through a collecting tube •      Upper airway (oropharynx)

   Yankauer suction •      Lower airway (trachea and bronchi)

   Flexible suction catheter    NT or ET

  Endotracheal Suctioning

•      Indication is to remove accumulated pulmonary secretions (page 656) •      No absolute contraindication •      Hazards

   Hypoxia, tracheal trauma, cardiac arrhythmias, atelectasis, infection, etc. •      Assessment of need routinely with patient/vent checks

Equipment and Procedure •       Assess for indications •       Assemble and Check Equipment (Box 30-1)

    Pressures for vacuum •       Preoxygenate and Hyperinflate •       Insert catheter •       Apply suction •       Reoxygenate and hyperinflate •       Monitor patient and assess outcomes

Catheter size •      OET internal diameter X 2, then use next smallest size catheter •      Only even numbers

Closed suction system •      Box 30-2  

Minimizing complications •      Preoxygenation

   Prevent hypoxia and atelectasis   Cardiac arrhythmias

•      Limit negative pressure and length of suctioning    Atelectasis, Mucosal trauma

•      Sterile technique   infection

   

Nasotracheal Suctioning

•      Indicated for patients who retain secretions, but do not have an artificial tracheal airway •      Guidelines page 660

Equipment and Procedure •      Similar to ET suction, highlight the differences:

   Water-soluble lubricating jelly    NPA will help reduce mucosal trauma    Gentle insertion through nostril, twist catheter if you feel resistance.

  Use sniffing position, advance until patient coughsComplications

•      Gagging or regurgitation •      Airway trauma

   Lubricate, technique •      Infection

   Sterile technique  

NT Suctioning Sputum Sampling

•      Collected to identify organisms infecting the airway •      Maintain sterile technique •      Closed container •      Label and process

Establishing Artificial Airways •      Required when the patient’s natural airway can no longer perform its proper functions •      Page 662

Routes •      Pharyngeal •      Tracheal

Pharyngeal •       Prevent airway obstruction by keeping the tongue pulled forward and away from the posterior pharynx

    Common in the unconscious patient, due to a loss of muscle tone •       Nasal pharyngeal (NPA)

    Frequent NT suctioning •       Oral pharyngeal

    Inserted into mouth and over tongue    Only in unconscious patient to avoid gagging

   Bite block Tracheal

•      Extend beyond the pharynx, into the trachea    Endotracheal tubes

  Oral or nasal insertion   Tracheostomy tubes

  Surgically inserted 

Advantages and Disadvantages •      Table 30-1

Endotracheal Tubes •       Semirigid tubes (polyvinyl chloride) •       American Society for Testing and Materials •       Standard adapter with a 15 mm external diameter •       Length marking •       Beveled tube tip •       “murphy eye” •       Tube cuff—seals off lower airway •       Pilot balloon—monitor cuff status •       Radiopaque indicator

Endotracheal Tube

Special Endotracheal Tube

•      Double lumen endotracheal tube    Independent lung ventilation

Tracheostomy Tubes •       Plastic polymer, silver •       ASTM •       Outer cannula •       Cuff •       Flange •       Removable inner cannula with a 15 mm adapter •       Pilot balloon •       Fenestration (some) •       Obturator

Jackson tracheostomy tube •      Silver •      No cuff or 15 mm adapter •      Long term airway patients who don’t need to protect their airway from aspiration or need positive pressure ventilation •      Needs an adapter for mechanical ventilation

Tracheostomy Tube Jackson Placement

•      Tube size (average)    Adult female #8 19-21 cm at teeth    Adult male #9 21-23 at teeth

•      Tube position ideally about 5 cm above the carina

  Tracheotomy

•       Procedure is a tracheostomy •       Primary route for overcoming upper airway obstruction or trauma or for long term care of patients with neuromuscular disease •       Patients needing an artificial airway for a prolonged period of time •       Completed by a surgeon •       Box 30-5

Airway Trauma with Tracheal Tubes •       Does not conform exactly to patient’s anatomy •       Creates pressure on soft tissue •       Can result in ischemia and ulceration •       Also can have friction-like injuries due to airway movement as the patient’s head or neck moves •       Damage can occur from the nose down to the lower trachea •       Evaluate for injury post extubation

Prevention •      Limiting tube movement •      Limiting cuff pressures •      Sterile technique to prevent infection

Airway Maintenance •       Securing the tube and ensuring proper placement •       Providing for patient communication •       Ensure adequate humidification •       Minimizing risk of infection •       Aiding secretion clearance Aiding secretion clearance •       Cuff care •       Trouble-shooting airway related problems

Securing the tube and ensuring proper placement

•      Cloth tape •      Trach ties •      4-6 cm above carina (tube) or 2nd-4th tracheal rings (trach) •      Movement of neck moves tubes

   Flexion down to carina; extension up to larynx    Chest x-rays

Securing the Tube Providing for patient communication

•      Frustrating for patient and caregiver •      Lipreading •      Letter or picture board •      Talking trach tubes •      Passey-Muir Valve

   Spontaneous or vent patients  

Ensure adequate humidification •      Artificial tracheal airways bypass the normal humidification, filtration, and heating functions •      Decreased humidity causes secretions to thicken •      Use heated humidifier or jet nebulizer; HME

Minimizing risk of infection •       Patients with tracheal airways are susceptible to bacterial colonization and infection •       Changes in sputum, breath sounds, x-ray, fever, leukocytosis •       Adhere to sterile technique •       Aseptic technique •       Wash hands •       Box 30-7

Facilitating secretion clearance •      Suctioning

Provide cuff care •       Cuffs seal the airway for mechanical ventilation and to prevent aspiration •       We use high volume; low-pressure cuffs now

    Cuffs do not need to be fully inflated to seal the airway     Maintain pressures of 20-25 mmHg or 25-30 cm H2O     Use the lowest inflation pressure to obtain a satisfactory seal

Alternative Cuff Design •      Lanz tube

   Limits cuff pressure between 16-18 mm Hg with an external pressure regulator

•      Foam Cuff    Deflate before insertion; never add air

Trach Care •       Daily care •       Equipment (Box 30-8) •       Suction •       Inner cannula •       Stoma •       Change ties •       Replace inner cannula •       Reassess patient

Changing a Tracheostomy Tube •      Initial performed by surgeon •      Subsequent may be performed by RT

Troubleshooting Indicators •      Inability to pass a suction catheter (obstruction) •      Airflow around the tube (leaky cuff) •      Always keep replacement airways at the bedside, manual resucitator, mask, gauze pads (to cover tracheostomy)

  Obstruction

•      Kinking of or biting on the tube •      Herniation of cuff over tube tip •      Jamming of tube orifice against tracheal wall •      Mucus plugging •      Signs

   Decreased breath sounds, increased PIP Obstruction Fix the Problem

•      Reposition patient •      Deflate cuff and attempt to pass catheter •      Suction patient •      Remove the inner cannula from a trach •      May need to remove and replace airway

Cuff Leaks •      Large leak has a rapid onset •      Small leaks will reveal decreasing cuff pressure over time •      Adjust position of tube •      May need replaced

Accidental Extubation •      Notice decreased breath sounds, decreased airflow, no cough with suctioning •      Replace  

Trach Tubes •      Fenestrated Tracheostomy Tubes •      Tracheal Button

The End