Introduction

Oxygen (O2) therapy is essential in virtually all cases of serious or potentially serious illness or injury.

Description

Oxygen is delivered to the patient in a variety of flow rates via standard or high concentration, high flow reservoir bag masks. It assists in reversing Hypoxia, by raising the concentration of inspired oxygen. Hypoxia will however only improve if respiratory effort or ventilation is adequate. If ventilation is inadequate or absent, assisting or completely taking over the patient's ventilation is essential to reverse hypoxia.

Oxygen is provided in compressed form in portable D-sized and, on ambulances fixed F-sized cylinders. It is fed via a regulator and flowmeter to the patient by means of plastic tubing and an oxygen mask.

Method

Oxygen therapy should be applied after considering any relevant co-existing conditions which may influence the actual provision or concentration of oxygen administered. The presence of poisoning with Paraquat, and Chronic Obstructive Pulmonary Disease (COPD) are two of the rare examples where withholding or limiting oxygen therapy is appropriate.

The importance and procedure of O2 therapy must be explained to the patient.

Dosage

Dosage is dependent on the condition being treated, but in the majority of cases where the patient is moderately or seriously ill or injured, 100% high flow oxygen is indicated. In cardiac and respiratory arrest, acute respiratory and cardiac conditions and serious trauma, then the administration of 100% O2 is vital.

In cases of serious respiratory distress in COPD patients, high flow oxygen may be required. Patients with Paraquat poisoning should not receive O2 therapy.

Administration

O2 therapy is administered via a mask and tubing. Masks are either the standard, non – reservoir bag or reservoir bag mask and tubing.

High concentration oxygen can be provided at flow rates of 10 –15 litres per minute through a high concentration, reservoir bag mask.

Low flow, 24 – 28% oxygen, can be provided at flow rates of 2 litres per minute through a medium concentration, non reservoir bag mask.

Additional Information

  • Hypoxic drive is found in COPD patients with chronic lung damage, where as a result of long standing respiratory failure, a higher than normal O2 level is retained in the blood stream. This would normally trigger a persistent high respiratory rate to attempt to lower the CO2 level. To compensate, the body becomes less sensitive to raised CO2, and begins to react to a lowered O2 level, to act as a trigger to breathe.

  • Giving high flow O2 will raise the O2 level in the blood stream, and prevent the natural lowering of O2 occurring to stimulate breathing. If this occurs on high flow O2, cease O2 therapy and wait until ventilation returns to normal and restart O2 at 24 - 28%. In cases of respiratory arrest in COAD, apply assisted or IPPV, and inform ambulance control immediately of the situation.

  • Patients with acute asthma DO NOT have COPD and require high flow O2 (10-15 lpm).

  • Some elderly patients have a mixture of COPD which causes irreversible bronchospasm and asthma which is reversible. The priority in treating these patients is to ensure adequate oxygenation.

  • Less seriously ill or injured patients still require O2 therapy as per individual guidelines.

  • In cardiac arrest 100% O2 must be delivered via face mask and port during ventilation.

  • In carbon monoxide poisoning administering 100% O2 increases the speed of elimination of CO from red cells.

  • Side effects:

    • Non-humidified O2 is drying and irritating to mucous membranes over a period of time.

  • Contra-Indications:

    • None when administered for short periods (less than 24 hours)

    • Paraquat poisoning

    • Explosive environments