1.4 OXYGEN ADMINISTRATION
Few sections contain specific instructions on oxygen and clinical
judgement is required. Oxygen does not necessarily provide benefit
and should usually only be given if the patient has:
• An abnormal airway or
• Moderate or worse respiratory distress or
• Shock or
• Inability to obey commands as a result of an acutely depressed
level of consciousness or
• Unrelieved cardiac chest pain or
• Smoke or toxic gas inhalation or
• An oxygen saturation <95% on air (unless they have COAD – see
COAD section).
Use the simplest device and lowest flow of oxygen that will achieve
the desired oxygen saturation, but do not spend time making
multiple adjustments.
Most patients will only require nasal prongs or an acute (ordinary) mask.
Non-rebreather masks should be reserved for when higher levels of inspired oxygen
are required and manual ventilation bags should be reserved for patients requiring
assistance with their airway and/or breathing.
If pulseoximetry is unreliable give oxygen as appropriate based on the above bullet points.
The oxygen flow rates to be used are:
• Nasal prongs 2-4 l/min.
• Acute (ordinary) mask 4-6 l/min.
• Nebulised drugs 8 l/min.
• Non-rebreather mask 6-8 l/min. Check that the valves are opening
and closing correctly. The flow rate should be the minimum
required to ensure that the reservoir bag does not fully deflate.
• Manual ventilation bag 8-10 l/min. Check that the valves are
opening and closing correctly. The flow rate should be the
minimum required to ensure that the reservoir bag does not fully
deflate. The most common cause of a deflating reservoir bag is an
excessive manual ventilation rate and/or an excessive tidal
volume.
Commentary
Oxygenation is not the same as ventilation. A patient can be well
oxygenated but barely breathing and a patient can be breathing
well but be poorly oxygenated. A pulseoximeter, providing it is
working correctly, tells you how much oxygen is bound to
haemoglobin as a percentage of maximum capacity, it does not tell
you how well the patient is breathing. Pulseoximeters can be
unreliable if the patient is cold, shocked, moving, shaking, has very
dirty fingers, or has been exposed to carbon monoxide. Do not
spend long periods of time trying to get a pulseoximeter reading
and always look at the patient rather than the pulseoximeter