You don't always intubate when someone's under general anaesthesia - it depends on the person, the level of anaesthesia needed, the anaesthesiologist's judgemen

You don't always intubate when someone's under general anaesthesia - it depends on the person, the level of anaesthesia needed, the anaesthesiologist's judgement call of the risks of intubating vs not intubating, the type of surgery and length of surgery. For example, I've been under GA three times, but all for oral operations (Adenoids removed, problems with a tooth not coming down properly and needing to be pulled down and forward from the roof of my mouth, and having all my wisdom teeth removed at the same time) all of which clearly can't be done with intubation! It ultimately comes down to balancing two different sets of risks against each other, and alternatives like CPAP (continuous positive air pressure, aka an oxygen mask) are often used instead. It's also entirely possible to have a cardiac arrhythmia while fully conscious - if you've had an orgasm, there's a good chance you've had a brief, though mild, period of arrhythmia in the form of skipping a heartbeat periodically until orgasm subsides. In the case of more severe cardiac fibrillation, it will take a period of time before you actually lose consciousness depending on the severity. In the case above, where more anaesthesia was being admitted, it would seem posible that fibrillation would have been caused by lowered blood oxygen to the heart in the period between the extra anaesthesia being used and it's taking enough of an effect for intubation to be done. In that case, a quick shock might be needed to restore normal heart rhythms subsequently. Source - The other half is an obstetric surgeon and her best friend is an anaesthesiologist. Any errors are my own; I'm not a doctor and don't claim to completely understand even if I do come from a medical family.