One-off Blackout

[Danie]

My buddy collapsed last November and was unconscious (breathing fine) for about 3 minutes.
He's been through numerous tests - MRI, ECG etc. etc. and noone can find anything wrong with him. But by the same reasoning they can't determine what caused the blackout.

What sort of time is he looking at before he's certified fit to dive again?

 

[scubadoc]

An undiagnosed blackout would generally pose two main problems with diving: the possibility of epilepsy and the possibility of the condition having been due to cardiac arrhythmia. You do not describe seizure and the person's diagnostic workup failed to throw any light on other conditions that can cause temporary loss of consciousness, such as fainting (hypotension), obscure head injury and conversion reaction.

Diving may be resumed after head injury if no drugs are required, there has not been loss of consciousness greater than 30 minutes, no localizing signs and if there has not been amnesia longer than one hour. Hypotension can be worsened from immersion (pooling of fluids) and conversion reaction (hysteria) can lead to panic underwater with devastating results.

Your friend should be aware that brief unconsciousness underwater generally can lead to drowning; your friend should be able to return to diving if he/she has the approval of the physician, has not had seizures and has not had a reduction in abilities to perform the task-loading required in safe diving, self-rescue and rescue of buddies.