Oxygen Therepy

DEFINITION

• Oxygen therapy is a treatment that provides you with extra oxygen, a gas that your body needs to work well.

Oxygen is in the air we breathe and is necessary to live. O2 therapy is the administration of oxygen at concentrations greater than that in room air to treat or prevent hypoxemia (not enough oxygen in the blood) . Normally, your lungs absorb oxygen from the air. However, some diseases and conditions can prevent you from getting enough oxygen.

  PURPOSE

• To increase oxygen saturation in tissues where the saturation levels are too low due to illness or injury.

The body is constantly taking in O2  & releasing CO2.

If this process is inadequate, oxygen levels in the blood decrease, and the patient may need supplemental oxygen. Oxygen therapy is a key treatment in respiratory care.

THREE CLINICAL GOALS OF O2 THERAPY

1. Treat hypoxemia
2. Decrease work of breathing
3. Decrease myocardial work

O2 delivery methods

• Low flow oxygen delivery system
• High flow oxygen delivery system

Low flow O2 delivery system

• Nasal cannula
• Medium Concentration Mask

Fio2 depends on O2 flow, patient factors and device factors

Nasal cannula

• • • • Simple plastic tubing + prongs
      • Flow from 1-6 LPM of O2
      • Fio2 ranges from 24-44% of O2

  1 – 24%

  2 – 28%   

  3 – 32%

  4 – 36%

  5 – 40%

  6 – 44%

Flow rates of 4L or less do not need to be humidified, Can be used at very low flow rates with children Lightweight and generally comfortable Patients are able to drink, eat and speak Mouth breathers will benefit from this device.

Low flow O2 delivery system

• Nasal cannula
• Medium concentration Mask

Fio2 depends on O2 flow, patient factors and device factors

Medium concentration Mask

This may be used to achieve higher oxygen concentration than nasal cannula or nostrils are not available

High flow O2 delivery system

• Not appropriate for patients with chronic lung disease & C02 retention (hypoxic drive is lost)

• Non – Rebreathing Mask
• Venturi mask

Provides sufficient flow of gas to meet all of the patients minute ventilation requirements

Non – Rebreathing Mask

Used in medical emergencies that require oxygen therapy, critically ill or unstable patients

• Delivers up to 80% Fi02 at 10 – 15lpm

Patient does not breathe room air

CAUTION: Minimum flow 10lpm to ensure that the reservoir bag does not empty completely

High flow O2 delivery system

• Non – rebreathing mask
• Venturi mask

Provides sufficient flow of gas to meet all of the patients minute ventilation requirements

Venturi Mask

• Increase gas flow to the patient
• Delivers accurate oxygen concentration

CAUTION: Increasing the oxygen flow rate does not increase the oxygen concentration

Fixed VENTURI VALVE

Most common is RED (40%) valve – provides spontaneously breathing intubated patients with supplementary oxygen during transport and in the recovery room

To change oxygen concentration, it is necessary to change the valve

Venturi Valve

Adjustable VENTURI VALVE

• • • Same valve can deliver wide range of oxygen concentration
    • Not to be replaced by different valves as per oxygen concentration

HUMIDIFICATION

• • • Humidifier
    • Nebulizer

device that adds molecular water to gas

• • • Bubble Humidifier – commonly used in low flow devices

Use the bubble through humidification process to bring dry oxygen gas to ambient levels of humidity

HUMIDIFICATION

• • • Humidifier
    • Nebulizer

• • • Humidifier Nebulizer – commonly used in patients with aerosol and tracheostomy mask

IMPORTANT POINTS

• All critically ill patients require oxygen
• Central cyanosis is caused by both cardiac and pulmonary disease
• Peripheral cyanosis results from a sluggish peripheral circulation
• Hypoventilation and disorders affecting ventilation perfusion matching are the most frequent acute causes of cyanosis seen in acute emergencies

• High concentrations of inspired oxygen do not depress ventilation in patients with acute respiratory failure
• Oxygen therapy must be prescribed and monitored
• Patients do not die From a raised C02 level alone, they die from HYPOXEMIA
• Pulse Oximeters measure oxygenation, not ventilation

FACTORS THAT DETERMINE WHICH SYSTEM TO USE

1. Patient comfort / acceptance by the patient
2. The level of FiO2 that is needed
3. The requirement that the FiO2 be controlled within a certain range
4. The level of humidification and /or nebulization
5. Minimal resistance to breathing
6. Efficient & economical use of oxygen

How to assess oxygenation ?

• Arterial blood gases
• Pulse oximetry

How to assess oxygenation ?

• Arterial blood gases
• Pulse oximetry

Errors in pulse oximetry

• Artificial fingernails
• Dark pigmentation
• Electrical
• Intravenous dyes
• Movement
• Nail Polish
• Pulsatile venous system
• Radiated Light
• Edema

Indications of O2 therapy

• Documented hypoxemia
• An acute care situation in which hypoxemia is  suspected
• Severe trauma
• Acute myocardial infarction
• Short-term therapy (e.g., post-anesthesia recovery)
• Increased metabolic demands, i.e. burns, multiple injuries, and severe infections.

LIMITATIONS

• Oxygen therapy should not be used in lieu of but in addition to mechanical ventilation when the ventilator support is indicated

When to stop oxygen therapy

• Weaning should be considered when the patient’s underlying disease is stabilized
• Weaning can be gradually attempted by discontinuing oxygen or lowering its concentration for a fixed period and reevaluating the clinical parameters and SpO2 periodically.

Impact on the patient:

• Fear death is likely to occur sooner
• Become less active
• Experience a sense of loss of freedom
• May become more socially isolated

Hazards and Complications

• Oxygen-induced hypoventilation
• Oxygen toxicity / O2 narcosis
• Absorption atelectasis
• Retinopathy
• Drying of mucous membranes
• Infection
• Fire hazards