Examination notes
How is an apnoea test performed?
Preoxygenate with 100% O2. Disconnect the ventilator (high-flow O2 may be administered through a catheter).
Serial ABGs should be performed. A pCO2 > 6.7 kPa without respiratory effort confirms apnoea. If hypoxia (pO2 < 8 kPa) develops, the test must be stopped.
How is the vestibulo-ocular reflex elicited?
One ear canal is irrigated with ice-cold water. Eye deviation and nystagmus (slow phase towards the irrigated ear) should result if brainstem function is preserved. The test can be repeated on the other side after 5 minutes.
Examining the level of consciousness
Ensure the unconscious patient has had a primary survey and non-neurological causes of a low Glasgow Coma Scale (GCS) have been excluded.
Assess GCS:
Speak to the patient and establish orientation in time, place and person:
– What is the time?
– What is the date?
– Where are you?
– What’s my job?
A patient answering promptly and correctly has a GCS of 15.
If GCS is < 15, proceed to:
Ask patient clearly and repeatedly to:
– open the eyes
– stick the tongue out
If this fails to elicit a response, exert firm pressure over the supraorbital ridge:
Score M5 for localising only if the patient’s hand reaches above the shoulder in response, otherwise M4 for withdrawal.
Score M3 for abnormal ‘decorticate’ flexion of elbows and wrists.
Score M2 for ‘decerebrate’ extensor posturing.
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