• Oxygen is a drug

• Has a Drug Identification Number (DIN)• Colorless, odorless, tasteless gas• Makes up 21% of room air• Is NOT flammable but does support

combustion

• NITROGEN ( N2 ) 78.08 %• OXYGEN ( O2 ) 20.95 %• ARGON ( Ar ) 0.99 %• CARBON DIOXIDE ( CO2 ) 0.03 %

HYPOXIA :

• Decrease in actual content of O2 in the blood• Inadequate supply of O2 for cell function• Each cell requires O2 to fuel normal metabolic

processes

5

Definition :

Low levels of oxygen in the blood

• PaO2 of less than 60 mmHg (moderate)• SpO2 of less than 90%

HYPOXIA

vs

HYPOXAEMIA

“Most commonly prescribed drug in pre hospital and hospital setting”

RX > 21% O2

To treat or prevent

- symptoms & manifestations

of hypoxia

DEFINITION

Indications for

oxygen therapy

“Oxygen therapy is indicated

whenever

tissue oxygenation is impaired !”

INDICATIONS:

• Cardiac and respiratory arrest

• Hypoxaemia (PaO2<60mmHg, SaO2<90%)

• Hypotension (systolic blood pressure <100 mm Hg)

• Low cardiac output and metabolic acidosis

(bicarbonate<18 mmol/l)

• Respiratory distress (respiratory rate >24/min)

(American College of Chest Physicians and National Heart Lung and Blood Institute recommendations for instituting

oxygen therapy)

HYPOXIA !!!

• Inadequate O2 in the lungs

• Abnormality in the hemoglobin

• Impaired diffusion of O2

• Abnormality in the balance between the amount of air moving into the lungs & the amount of blood circulating through the lungs ( V/Q mismatch)

• Chemical interference

• Mild- SpO2 < 97% ( PaO2-75mmHg)• Moderate- SpO2 < 90%( PaO2 -

60mmHg)• Severe- SpO2<75%( PaO2 - 30mmHg)

A PaO2 of <20 mmHg for significant length of time produces brain death

• Respiration: increase ventilation via peripheral chemoreceptors

• CNS: drowsiness, disorientation, reduced pain sensibility, emotional outbursts, tremors, cheyne-stoke respiration, death (when %O2 falls below 60)

• CVS: increase HR and BP

• Tachycardia**• Agitation• Diaphoresis• Cyanosis

• Tachypnea• Dyspnea• Use of accessory

muscles

**Adult response – pediatric and neonatal patients experience bradycardia

The obvious need in hypoxia is OXYGEN, to preserve the life of body cells. Supplemental oxygen is administered to treat hypoxia

What is supplemental O2 therapy :

• to administer O2 at concentration greater than 21%

• to raise the level of O2 entering the lungs with each breath

Does the patient have a normally sensitive respiratory center and a normal control over respiration

• Improvement in cell function involving various organ systems

• Decrease in the work of breathing• Decreased in the myocardial work

• Patient receives supplemental O2 in excess of 21 % from O2 sources such as piped O2 system, a compressed gas cylinder or O2 concentrator

• Patient also requires a pressure and flow regulating device, humidifier, connecting tubing, and device that fits in the nose and on the face through which O2 can be breathed

Vacuum Insulated Evaporator

Vacuum Insulated Evaporator (VIE). A VIE is a container designed to store liquid oxygen. It has to be designed to allow the liquid oxygen inside to remain very cold. It consists of two layers, where the outer carbon steel shell is separated by a vacuum from an inner stainless steel shell, which contains the oxygen (figure 1). The oxygen temperature inside is about -170°C and the container is pressurised to 10.5 atmospheres (10.5 bar). Gaseous oxygen above the liquid is passed through the superheater to raise the temperature to ambient (outside) levels. It then flows into the hospital pipeline system giving a continuous supply of piped oxygen to outlets on the wards and in theatre. Heat is always able to get into the container and provides the energy to evaporate the liquid oxygen, changing it into oxygen gas which is continuously drawn off into the pipeline system. This escape of gas into the pipeline system prevents the pressure inside the container from rising. If the pressure rises too much (above 17 bar), oxygen is allowed to escape via a safety valve into the atmosphere.

superheater

Temperature -170°C insidePressurised to 10.5 atmosphere

• Oxygen cylinders: come in several sizes.• : colour coding

• In Malaysia oxygen cylinders are black • with white shoulders. ( UK)

• The pressure inside at 15°C is 137 bar.

• Electric oxygen system• Provides oxygen by

extracting it from the air• Generally use pressure swing• adsorption with zeolites• Unlimited oxygen supply

while connected to power source

• No refilling needed

Can tolerate high concentration of oxygen at a flow rate of 6-8 liters per minute

No risk of CO2 retention Conditions: Severe Interstitial Lung Disease

Pneumonia Pulmonary edema Atelectesis Acute hypoventilation of any cause

Acute severe asthma

Respiratory center comparatively insensitive to increasing pCO2 and dependant hypoxic stimulus

High concentration of oxygen will improve O2 saturation but will will result in hypoventilation and dangerous rise in pCO2

O2 therapy-Pink but obtunded, drowsy or even comatose patient

• Severe chronic obstructive pulmonary disease

• Chronic hypoventilation syndromes• Some elderly patients with asthma

• Routine oxygen therapy using low flow O2 delivery devices

• Controlled O2 therapy

• Sufficient to relieve moderate hypoxia• Can achieve oxygen concentration

(FIO2) of about 40% at a flow rate of 6-8 liters per minute

• Patients usually do not tolerate high flow rates with these devices

• Nasal catheters and prongs• Face mask• Face mask with reservoir bags• Face mask with reservoir bags and

directional valves

• O2 concentration is about 24% at flow rate of 1liter /minute

• At 6-8 liter per minute O2 concentration is about 40%

• Actual O2 delivered to lung also depends on tidal volume and minute ventilation

• Precise regulation of therapy is not possible

• Nasal catheter-tip should be advanced to the fold of soft palate, too far advancement may cause abdominal distention

• Catheter should be lubricated by xylocaine jelly

• Catheter should be changed from one nostril to other every 4 hourly

• Mask forms a small O2 reservoir at nasal opening

• the Inspired O2 concentration depends on the size of mask and flow rate of oxygen

• Higher flow rates up to 10 liter / minute can be tolerated ( SpO2 – 55%)

• Reservoir bag increases the potential reservoir of oxygen and , allows a further increase in ventilation

• Sufficiently high flow rates should be maintained (8-12 liter/minute)

• Can increase the FIO2 to 50-80%• Directional valve: FIO2-90-95%

• Necessary in all patients who show a hypercapnic response to unlimited or uncontrolled oxygen administration

• In severely hypoxic patients even a small rise in PaO2 will produce a significant greater rise in the oxygen saturation of arterial blood

• It is best to start with an inspired oxygen concentration of 24% and watch for rise in PCo2

• If increase in PCO2 is less than 10mmHg then increase FIO2 to 28-30%

• Maximal permissible limit of rise in PCO2 is 20mmHg and p H < 7.25

• Refractory hypoxemia unresponsive to supplemental oxygen

• Excessive work of breathing: RR>35/ mt Minute ventilation> 12 liter/minute

• Hemodynamic instability• Inability to protect airway • Anticipated rapid clinical deterioration

• Effective in a very small subset of minor Acute lung Injury

• C-PAP: Levels: 10-12 Cm H2O

Very high Flow rate:>70 liter/ minute• Bi- PAP:

I-PAP-15cm H2O E-PAP-7-10cm H2O• Aim –SpO2_ >90%

• fundamental concepts: Low tidal volume

PEEP to prevent collapse of alveoli Avoidance of O2 toxicity Prevention of hemodynamic instability

Low flow device - patients inhale room air along w/ O2

Recommended flow rate-1/2 LPM to 6 LPM

Deliver O2 concentrations 24% - 44% 1 LPM change in O2 flow, approx 4%

change in inspired O2 e.g 1 LPM = 24%, 2 LPM = 28%

Low flow devices - do not supply all inspiratory gases. Patient inhales some room air along with O2

Recommended flow rate : 5- 10 LPM Do not use at flow rates less than 5 LPM, as

flow rates may not flush exhaled CO2 from the mask

Deliver O2 concentration : 40% - 60% Inspired FIO2 will change with patient’s

ventilatory pattern

OXYGEN MEDIUM CONCENTRATION MASK

Low flow device - may not supply all inspiratory gases, so patient inhales some room air along with O2 if the flow is not adequate

A 750 ml reservoir bag has been added to the system to increase supply of 100% Oxygen available to the patient

Recommended flow rates : 8-12 LPM

Use the suitable flow rate necessary to keep reservoir bag well inflated and to prevent the bag from deflating more than 1/3 when the patient inhales. If patient is extremely short of breath, this may require flow rates greater than 10 LPM

Delivered O2 concentration : 60 - 80 %

Low flow device - if flow through the device is not adequate, the system will not supply sufficient gas to meet the patient’s inspiratory needs

Valves added to the system to control the O2 flow and the path of inspiration & exhalation

Recommended flow rates : 10 -12 LPM Use the flow rate necessary to keep the

reservoir bag from collapsing during inspiration. If 3 valves are in place, it’s

CLOSED SYSTEM. The flow through the mask must be adequate since the patient cannot inhale room air

Delivered O2 concentration : 80 -100 % With 3 valves in place, and proper setup,

the mask may deliver up to 100 % oxygen

High-flow device - large amounts of room air can be entrained through the mask, in addition to the O2, the total flow through the mask (41-79 LPM) can exceed the patient’s respiratory requirement

Recommended flow rates : 3 - 15 LPM Delivered O2 concentration - precise O2

concentration can be selected at: 24%, 26%, 28%, 30%, 35%, 40%, and 50%

High flow device - total flow through mask (40 - 78 LPM)

Recommended flow rates : 3 -15 LPM Recommended flow is indicated on the diluter Delivered O2 concentration - 6 precise O2

concentration : 24%, 28%, 31%, 35%, 40% and 50%