CARE FOR MECHANICAL VENTILATION

A.) DEFINITION OF MECHANICAL VENTILATION

Mechanical ventilation is a life support treatment. It is also called a ventilator, respirator, or breathing machine.

It is a form of artificial respiration that uses a breathing machine (mechanical ventilator) to assist patients with breathing during surgery or during treatment of severe head injury. It is used when the lungs are not functioning properly.

It is a positive- or negative pressure breathing device that can maintain ventilation and oxygen delivery for a prolonged period. 

B.) PURPOSES OF MECHANICAL VENTILATION

Mechanical ventilation provides the force needed to deliver air to the lungs in a patient whose own ventilatory abilities are diminished or lost or inadequate, and t orest the respiratory muscles, among others.

To get oxygen into the lungs and body. To help the lungs get rid of carbon dioxide. To ease the work of breathing—Some people can breathe but it is very hard. They feel short of

breath and uncomfortable. To breathe for a patient who is not breathing because of brain damage or injury (like a coma) or

high spinal cord injury or very weak muscles. If a person has had a serious injury or illness that causes breathing effort to stop, a ventilator can be used to help the lungs breathe until the person recovers.

C.) INDICATIONS FOR MECHANICAL VENTILATION

If a patient has a continuous decrease in oxygenation (PaO2) - Hypoxemic Respiratory Failure (PaO2 < 50mmHg);

If a patient has an increase in arterial carbon dioxide levels (PaCO2) - Hypercapnic Respiratory

Failure (PaCO2 > 50mmHg); If a patient has a persistent acidosis (decreased pH); Airway Compromise – airway patency is in doubt or patient may be at risk of losing patency; Respiratory rate above 35 cpm; and If a patient has conditions such as:

o Thoracic or abdominal surgery;o Drug overdose;o Neuromuscular disorders;o Inhalation injury;o COPD;o Multiple trauma;o Shock;

o Multi-system failure; ando coma

D.) CLASSIFICATION OF VENTILATORS

1. Negative-Pressure Ventilators

It exerts a negative pressure on the external chest. Decreasing the intrathoracic pressure during inspiration allows air to flow into the lung, filling its volume.

It is similar to spontaneous ventilation physiologically. It is used mainly in chronic respiratory failure associated with neuromuscular conditions, such as poliomyelitis, muscular dystrophy, myasthenia gravis.

These are simple to use and do not require intubation of the airway; and Adaptable for home use. Types:

i. Iron Lung (Drinker Respirator Tank)ii. Body Wrap (Pnemo-wrap) and Chest Cuirass

2. Positive-Pressure Ventilator

Inflate the lungs by exerting positive pressure on the airway, similar to a bellows mechanism, forcing the alveoli to expand during inspiration. And expiration occurs passively;

Endotracheal intubation or tracheostomy is necessary in most cases. Types:

i. Pressure-Cycled Ventilatorsii. Time-Cycled Ventilators

iii. Volume-Cycled Ventilatorsiv. Noninvasive Positive-Pressure Ventilation

E.) MODES OF MECHANICAL VENTILATION

Ventilator modes refer to how breaths are delivered to the patient.

1. Assist-control ventilation – (volume control, pressure control, and pressure regulated volume control) the ventilator guarantees that the patient will receive the set minimum number of breaths, although he/she is able to demand (trigger) more.

2. Intermittent mandatory ventilation (IMV) – set breath delivered at a fixed interval. No patient interaction, pressure or volume modes

3. Synchronized intermittent mandatory ventilation (SIMV) – set breath delivered within an interval based on the set respiratory rate. Ventilator spends part of the interval waiting for spontaneous breath from the patient, which it will use as a trigger to deliver a full breath. If not sensed it will automatically give a breath at the end of the period. Any other breaths during the cycle are not supplemented.

4. Pressure support Ventilation (PSV) – modes the patient only receives breaths when he/she triggers the ventilator.

5. Airway pressure release ventilation (APRV)6. Proportional assist Ventilation (PAV)

F.) HOW DOES MECHANICAL VENTILATOR WORK?

A breathing machine (mechanical ventilator) pushes air into the lungs. It includes controls to adjust the rate and size of each breath, a humidifier to warm and moisten the air going into the lungs, special tubing for the air to pass through, and a trap to collect unused moisture from the tubing. The breathing machine insures that adequate oxygen gets into the blood stream and carbon dioxide is exhaled.

Tubing, called breathing maching tubing or ventilator tubing, runs from the breathing machine to thebreathing tube (endotracheal tube), which is inserted through the patient's mouth or nose. Sometimes the breathing machine tubing is connected to a tracheostomy tube. The breathing machine tubing, which is the larger "corrugated" tubing consists of two parts: one delivers the oxygen to be inhaled and the other part carries away the exhaled gas, including carbon dioxide. They meet at the junction with the breathing tube (endotracheal tube) or tracheostomy tube. 

G.) COMPLICATIONS OF MECHANICAL VENTIALTION

1. Associated with patient’s response to mechanical ventilation:

A. Decreased Cardiac Output

1. Cause - venous return to the right atrium impeded by the dramatically increased intrathoracic pressures during inspiration from positive pressure ventilation. Also reduced sympatho-adrenal stimulation leading to a decrease in peripheral vascular resistance and reduced blood pressure.

2. Symptoms – increased heart rate, decreased blood pressure and perfusion to vital organs, decreased CVP, and cool clammy skin.

3. Treatment – aimed at increasing preload (e.g. fluid administration) and decreasing the airway pressures exerted during mechanical ventilation by decreasing inspiratory flow rates and TV, or using other methods to decrease airway pressures (e.g. different modes of ventilation).

B. Barotrauma

1. Cause – damage to pulmonary system due to alveolar rupture from excessive airway pressures and/or overdistention of alveoli.

2. Symptoms – may result in pneumothorax, pneumomediastinum, pneumoperitoneum, or subcutaneous emphysema.

3. Treatment - aimed at reducing TV, cautious use of PEEP, and avoidance of high airway pressures resulting in development of auto-PEEP in high risk patients (patients with obstructive lung diseases (asthma, bronchospasm), unevenly distributed lung diseases (lobar pneumonia), or hyperinflated lungs (emphysema).

C. Nosocomial Pneumonia

1. Cause – invasive device in critically ill patients becomes colonized with pathological bacteria within 24 hours in almost all patients. 20-60% of these, develop nosocomial pneumonia.

2. Treatment – aimed at prevention by the following:

Avoid cross-contamination by frequent handwashing

Decrease risk of aspiration (cuff occlusion of trachea, positioning, use of small-bore NG tubes)

Suction only when clinically indicated, using sterile technique

Maintain closed system setup on ventilator circuitry and avoid pooling of condensation in the tubing

Ensure adequate nutrition

Avoid neutralization of gastric contents with antacids and H2 blockers

D. Positive Water Balance

1. Syndrome of Inappropriate Antidiuretic Hormone (SIADH) – due to vagal stretch receptors in right atrium sensing a decrease in venous return and see it as hypovolemia, leading to a release of ADH from the posterior pituitary gland and retention of sodium and water. Treatment is aimed at decreasing fluid intake.

2. Decrease of normal insensible water loss due to closed ventilator circuit preventing water loss from lungs. This fluid overload evidenced by decreased urine specific gravity, dilutional hyponatremia, increased heart rate and BP.

E. Decreased Renal Perfusion – can be treated with low dose dopamine therapy.

F. Increased Intracranial Pressure (ICP) – reduce PEEP

G. Hepatic congestion – reduce PEEP

H. Worsening of intracardiac shunts –reduce PEEP

2. Associated with ventilator malfunction:

A. Alarms turned off or nonfunctional – may lead to apnea and respiratory arrest

Troubleshooting Ventilator Alarms

Low exhaled volume: Cuff leak, Tubing disconnect, Patient disconnected

Evaluate cuff; reinflate prn; if ruptured, tube will need to be replaced. Evaluate connections; tighten or replace as needed; check ETT placement, Reconnect to ventilator

High pressure: Secretions in airway, Patient biting tubing, Tube kinked, Cuff herniation, Increased airway resistance/decreased lung compliance (caused by bronchospasm, right mainstem bronchus intubation, pneumothorax, pneumonia), Patient coughing and/or fighting the ventilator; anxiety; fear; pain.

Suction patient, Insert bite block, Reposition patient’s head/neck; check all tubing lengths, Deflate and reinflate cuff, Auscultate breath sounds, Evaluate compliance and tube position; stabilize tube, Explain all procedures to patient in calm, reassuring manner, Sedate/medicate as necessar

Low oxygen pressure: Oxygen malfunction

Disconnect patient from ventilator; manually bag with ambu; call R.T

 3. Other complications related to endotracheal intubation.

A. Sinusitis and nasal injury – obstruction of paranasal sinus drainage; pressure necrosis of nares

1. Prevention: avoid nasal intubations; cushion nares from tube and tape/ties.

2. Treatment: remove all tubes from nasal passages; administer antibiotics.

B. Tracheoesophageal fistula – pressure necrosis of posterior tracheal wall resulting from overinflated cuff and rigid nasogastric tube

1. Prevention: inflate cuff with minimal amount of air necessary; monitor cuff pressures q. 8 h.

2. Treatment: position cuff of tube distal to fistula; place gastrostomy tube for enteral feedings; place esophageal tube for secretion clearance proximal to fistula.

C. Mucosal lesions – pressure at tube and mucosal interface

1. Prevention: Inflate cuff with minimal amount of air necessary; monitor cuff pressure q. 8 h.; use appropriate size tube.

2. Treatment: may resolve spontaneously; perform surgical interventions.

D. Laryngeal or tracheal stenosis – injury to area from end of tube or cuff, resulting in scar tissue formation and narrowing of airway

1. Prevention: inflate cuff with minimal amount of air necessary; monitor cuff pressure q. 8.h.; suction area above cuff frequently.

2. Treatment: perform tracheostomy; place laryngeal stint; perform surgical repair.

E. Cricoid abcess – mucosal injury with bacterial invasion

1. Prevention: inflate cuff with minimal amount of air necessary; monitor cuff pressure q. 8 h.; suction area above cuff frequently.

2. Treatment: perform incision and drainage of area; administer antibiotics.

4. Other common potential problems related to mechanical ventilation:

Aspiration, GI bleeding, Inappropriate ventilation (respiratory acidosis or alkalosis, Thick secretions, Patient discomfort due to pulling or jarring of ETT or tracheostomy, High PaO2, Low PaO2, Anxiety and fear, Dysrhythmias or vagal reactions during or after suctioning, Incorrect PEEP setting, Inability to tolerate ventilator mode.

Problems that can develop from using a ventilator include:

■ Infections—The ET or trach tube allows germs (bacteria) to get into the lungs more easily. This can cause an infection like pneumonia. Pneumonia can be a serious problem and may mean a person has to stay on the machine longer. Pneumonia can damage the lungs. People who are very sick can be more prone to infection. Pneumonia can often be treated with antibiotic medicines.

■ Collapsed lung (pneumothorax)—Sometimes, a part of the lung that is weak can become too full of air and start to leak. The leak lets air get into the empty space between the lung and the chest wall. Air in this space takes up room so the lung starts to collapse. If this air leak happens, the air needs to be removed from this space. Doctors can place a different kind of tube (chest tube) into the chest between the ribs to drain out the extra air. The tube allows the lung to re-expand and seal the leak. The chest tube usually has to stay in for some time to make sure the leak has stopped and get all the extra air out. Rarely, a sudden collapse of the lung can cause death.

■ Lung damage—The pressure of putting air into the lungs with a ventilator can damage the lungs. Doctors try to keep this risk at a minimum by using the lowest amount of pressure that is needed. Very high levels of oxygen may be harmful to the lungs as well. Doctors only give as much oxygen as it takes to make sure the body is getting enough to supply vital organs. Sometimes it is hard to reduce this risk when the lungs are damaged.This damage can sometimes heal if a person is able to recover from the serious illness.

■ Side effects of medications—At times sedation medicines can build up and the patient may remain in a deep sleep for hours to days, even after the medicine is stopped. The doctors and nurses try to adjust the right amount of medication for a patient. Different patients will react to each

medicine differently. If muscle paralysis is needed, at times the muscles are weak for a while after it is stopped. This will get better over time.

■ Maintenance of Life—For patients who are very sick, at times the ventilator only postpones death. Not every patient improves just because they use a ventilator. It is hard to predict or know for sure if a person will recover with treatment. Sometimes the doctors feel very sure the ventilator will help and the patient will recover. Other times, the doctors can only give a rough idea of the chances that a person will survive. Doctors may have to ask the patient (or next of kin) if the ventilator should be continued if the patient is not recovering or is getting worse. While patients can die even though they are hooked up to a ventilator, sometimes the ventilator seems to prolong the dying process.

H.) TROUBLESHOOTING

AssessmentThe first priority in dealing with mechanical ventilation problems is to assess the patient.

1)How severe is the problem?2)Does the patient require immediate resuscitation?

Check:1) Is the chest moving and is it moving symmetrically?2) Is the patient cyanotic?3) What is the arterial saturation?4)Is the patient haemodynamically stable?

The next step is to diagnose the problem.

Ventilator/circuit problems can be distinguished from endotracheal tube/patient problems by taking the patient off the ventilator and manually bagging the patient.

1.) High airway pressureWhy does it matter?1) High airway pressure may cause barotrauma2) It signifies a deterioration in the patient's clinical state3) It may result in hypoventilation of the patient

--Many ventilators cycle from inspiration to expiration immediately if the upper pressure alarm limit is reached. As a result inspiration is terminated early and the tidal volume is reduced.CausesVentilator problems1) Inappropriate settings-- Excessive tidal volume--excessive flow or excessively short inspiratory time

--high airway pressure alarm limit too low2) Ventilator malfunction - rareCircuit problems1) Fluid pooling in circuit2) Fluid pooling in filter3) Kinking of circuit

Endotracheal tube obstruction i.e. due to sputum, kinking, biting

Increased airway resistance i.e. bronchospasm

Decreased respiratory system compliance1) Parenchymal disease2) Pleural disease i.e. pneumothorax3) Decreased chest wall compliance i.e. due to patient "fighting" ventilator4) Decreased ventilated lung volume--sputum plugging--lobar/lung collapse--endobronchial intubationManagement1) Assess patient.2) Disconnect patient from ventilator and manually ventilate.--Assess the "feel" of the lungs. Is the patient difficult to ventilate?-- If the patient is not difficult to ventilate, it is a problem with the ventilator or the circuit.--If the patient is difficult to ventilate, it is a problem with the endotracheal tube or the respiratory system.3) For ventilator and circuit problems, check ventilator settings and function, and check circuit for obstruction or kinking.4) For patient or ETT problems examine the patient looking particularly for bronchospasm, asymmetrical chest expansion and evidence of collapse.5) Pass a suction catheter through the ETT to check its patency.6) CXR

If the cause is still not clear, measure inspiratory pause pressure (approximates alveolar pressure).--If both airway and alveolar pressure are high the problem is due to poor compliance.--If only the airway pressure is high the problem is one of high resistance.

HypotensionThe most important causes of hypotension occurring soon after the initiation of mechanical ventilation are:1) Relative hypovolemia--Reduction in venous return exacerbated by positive intrathoracic pressure2) Drug induced vasodilation and myocardial depression--All anesthetic induction agents have some short lived vasodilatory ± myocardial depressant effects

3) Gas trapping (dynamic hyperinflation)4) Tension pneumothoraxHypotension due to relative hypovolemia or anesthetic induction agents usually responds rapidly to fluid. Hypotension due to gas trapping can be diagnosed and treated by disconnecting the patient from the ventilator. This results in a rapid reversal of the hypotension.

Patient-ventilator dysynchronyThere are a large number of causes of patient-ventilator dysynchrony which need to be considered. It is important to identify and treat these causes and not simply to sedate the patient more heavily. As well as all the possible causes of agitation there are a number of ventilator parameters which must be considered. These include:

1) Mode of ventilation--Spontaneous modes are more comfortable than control modes2) I:E ratio--Ratios that are similar to the 1:2 ratio of a normal breathing pattern are more comfortable.3) Triggering--if the patient is having difficulty triggering the ventilator despite a sensitive setting consider the possibility that there is auto-PEEP due to dynamic hyperinflation.

DesaturationCauses1) Endobronchial intubation2) Accidental extubation3) Pneumothorax4) Pulmonary embolus5) Any cause of increased intrapulmonary shunt6) Any cause of hypoxic respiratory failure7) Ventilator malfunctionManagement1) Increase FIO2 to 100%2) Check to make sure chest is moving3) Briefly examine chest to determine cause of desaturation4) If cause is not obvious manually ventilate patient with 100% oxygen to exclude ventilator malfunction as the cause5) Treat underlying cause6) Alter ventilator settings to improve oxygenation7) CXR

Weaning- process by which a ventilator-dependent patient is removed from ventilator- only 10-20% of patients who require ventilation are difficult to wean and most of these have required ventilation for over 1 month- potentially reversible reasons for difficult weaning:

1) Inadequate respiratory drive2) Poor gas exchange3) Psychological dependency4) Ventilatory pump failure (usually due to inspiratory muscle weakness or fatigue)Causes for inspiratory muscle weakness or fatigue:1) Nutritional or metabolic deficiencies: hypokalemia, hypomagnesaemia, hypocalcemia,hypophosphatemia, hypothyroidism2) Steroids3) Chronic renal failure4) Decreased protein synthesis and increased degradation5) Decreased glycogen stores6) Anemia7) Persistently increased work of breathing8) Cardiovascular failure9) Neuromuscular blockers10) Polyneuropathy of critical illnessThere is no objective data to determine when to attempt weaning. In general, the problem which led to the initiation of mechanical ventilation should have been reversed or stabilized.Standard criteria for initiating weaning:1) Clinically and radiologically resolving lung disease2) FiO2 <40%3) PEEP ≤ 54) Minimal endotracheal secretions5) Patient awake and cooperative6) Vital Capacity > 10ml/kg7) NIF (negative inspiratory force) > -20cm H20

I.) CARE

The nurse must be able to do the following:

1. Identify the indications for mechanical ventilation.2. List the steps in preparing a patient for intubation.3. Determine the FIO2, tidal volume, rate and mode of ventilation on a given ventilator.4. Describe the various modes of ventilation and their implications.5. Describe at least two complications associated with patient’s response to mechanical ventilation and their signs and symptoms.6. Describe the causes and nursing measures taken when trouble-shooting ventilator alarms.7. Describe preventative measures aimed at preventing selected other complications related to endotracheal intubation.8. Give rationale for selected nursing interventions in the plan of care for the ventilated patient.9. Complete the care of the ventilated patient checklist.10. Complete the suctioning checklist.

-To review indications for and basic modes of mechanical ventilation, possible complications that can occur, and nursing observations and procedures to detect and/or prevent such complications.-To provide a systematic nursing assessment procedure to ensure early detection of complications associated with mechanical ventilation.

PLAN OF CARE FOR THE VENTILATED PATIENT

Patient Goals:- Patient will have effective breathing pattern.- Patient will have adequate gas exchange.- Patient’s nutritional status will be maintained to meet body needs.- Patient will not develop a pulmonary infection.- Patient will not develop problems related to immobility.- Patient and/or family will indicate understanding of the purpose for mechanical ventilation.

Nursing Diagnosis Nursing Interventions Rationale

1.) Ineffective breathing pattern r/t _________________

Observe changes in respiratory rate and depth; observe for SOB and use of accessory muscles.

An increase in the work of breathing will add to fatigue; may indicate patient fighting ventilator.

Observe for tube misplacement- note and post cm. Marking at lip/teeth/nares after x-ray confirmation and q. 2 h.

Indicates correct position to provide adequate ventilation.

Prevent accidental extubation by taping tube securely, checking q.2h.; restraining/sedating as needed.

Avoid trauma from accidental extubation, prevent inadequate ventilation and potential respiratory arrest.

Inspect thorax for symmetry of movement.

Determines adequacy of breathing pattern; asymmetry may indicate hemothorax or pneumothorax.

Measure tidal volume and vital capacity.Indicates volume of air moving in and out of lungs.

Asses for painPain may prevent patient from coughing and deep breathing.

Monitor chest x-raysShows extent and location of fluid or infiltrates in lungs.

Maintain ventilator settings as ordered.Ventilator provides adequate ventilator pattern for the patient.

Elevate head of bed 60-90 degrees.This position moves the abdominal contents away from the diaphragm, which facilitates its contraction.

2.) Impaired gas exchange r/t alveolar-capillary membrane changes

Monitor ABG’s.Determines acid-base balance and need for oxygen.

Assess LOC, listlessness, and irritability. These signs may indicate hypoxia.

Observe skin color and capillary refill.Determine adequacy of blood flow needed to carry oxygen to tissues.

Monitor CBC.Indicates the oxygen carrying capacity available.

Administer oxygen as ordered.Decreases work of breathing and supplies supplemental oxygen.

Observe for tube obstruction; suction prn; ensure adequate humidification.

May result in inadequate ventilation or mucous plug.

Reposition patient q. 1-2 h.Repositioning helps all lobes of the lung to be adequately perfused and ventilated.

3.) Potential altered nutritional status: less than body requirements r/t NPO status

Monitor lymphocytes and albumin. Indicates adequate visceral protein.

Provide nutrition as ordered, e.g. TPN, lipids or enteral feedings.

Calories, minerals, vitamins, and protein are needed for energy and tissue repair.

Obtain nutrition consult.Provides guidance and continued surveillance.

4.) Potential for pulmonary infection r/t compromised tissue integrity.

Secure airway and support ventialtor tubing.

Prevent mucosal damage.

Provide good oral care q. 4 h.; suction when need indicated using sterile technique; handwashing with antimicrobial for 30 seconds before and after patient contact; do not empty condensation in tubing back into cascade.

Measures aimed at prevention of nosocomial infections.

Use disposable saline irrigation units to rinse in-line suction; ensure ventilator tubing changed q. 7 days, in-line suction

IAW Infection Control Policy and Respiratory Therapy Standards of Care for CCNS.

changed q. 24 h.; ambu bags changes between patients and whenever become soiled.

5.) Potential for complications r/t immobility.

Assess for psychosocial alterations.

Dependency on ventilator with increased anxiety when weaning; decreased ability to communicate; social isolation/alteration in family dynamics.

Assess for GI problems. Preventative measures include relieving anxiety, antacids or H2 receptor antagonist therapy, adequate sleep cycles, adequate communication system.

Most serious is stress ulcer. May develop constipation.

Observe skin integrity for pressure ulcers; preventative measures include turning patient at least q. 2 h.; keep HOB < 30 degrees with a 30 degree side-lying position; use pressure relief mattress or turning bed if indicated; follow prevention of pressure ulcers plan of care; maintain nutritional needs.

Patient is at high risk for developing pressure ulcers due to immobility and decreased tissue perfusion.

Maintain muscle strength with active/active-assistive/passive ROM and prevent contractures with use of span-aids or splints.

Patient is at risk for developing contractures due to immobility, use of paralytics and ventilator related deficiencies.

6.) Knowledge deficit r/t intubation and mechanical ventilation

Explain purpose/mode/and all treatments; encourage patient to relax and breath with the ventilator; explain alarms; teach importance of deep breathing; provide alternate method of communication; keep call bell within reach; keep informed of results of studies/progress; demonstrate confidence.

Reduce anxiety, gain cooperation and participation in plan of care.

J. REFERENCES:

Books:Smeltzer,S.C. et.al., “Mechanical Ventilation”.,Respiratory Care Modalities. Textbook of Medical-Surgical Nursing 11th Edition. Lipponcott Williams&Wilkins.2007.pp 739-754.

Websites:http://micunursing.com/ventcare.htmhttp://www.surgeryencyclopedia.com/La-Pa/Mechanical-Ventilation.htmlhttp://www.icu-usa.com/tour/procedures/vent.htm

http://patients.thoracic.org/information-series/en/resources/mechanical-ventilation.pdfhttp://www.stritch.luc.edu/depts/peds/Mechanical%20Ventilation.pdf

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