They put him under anaesthetic when he was fasting, then make him inhale something to wake him up

Praise be to Allah.

The anaesthesia that is given to patients in order to carry out surgical procedures or medical exams is of different types: 

- Some anaesthetics are administered nasally, using a gas that anaesthetises the patient

- Some anaesthetics are administered via acupuncture

- Some anaesthetics are administered by injection, and may be a local anaesthetic or a general anaesthetic.

The most correct view in all these cases is that it does not break the fast, because it is not food or drink and is not regarded as being like food or drink. 

If an injection providing nutrients is also given along with the anaesthetic – as may happen in some cases – then that does break the fast, because it is regarded as being like food and drink. Please see the answer to question no. 49706. 

Similarly, if he inhales something to wake him up, that does not break the fast, because it is like the puffer for asthma, unless this thing has moisture, and some of this moisture enters the stomach. He can ask the doctor about that. 

The basic principle is that whatever is not food or drink, and is not regarded as being like food or drink, does not break the fast. The fact that he merely noticed the taste of something in his mouth or throat does not count for anything. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

Detecting a taste in the throat does not count for anything with regard to things that are not food or drink. 

End quote from Majmoo‘ Fataawa wa Rasaa’il al-‘Uthaymeen (20/284). 

He also said: 

There is nothing wrong with the fasting person applying kohl to the eyes, or putting drops in his eyes or in his nose, even if he notices the taste of that in his throat. That does not break his fast, because it is not food or drink, and it is not like food or drink. The evidence only speaks of the prohibition on food and drink, and things that do not come under the same category are not to be included with them. What we have mentioned is the view favoured by Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) and it is the correct view. 

End quote from Majmoo‘ Fataawa wa Rasaa’il al-‘Uthaymeen (19/205) 

He also said: 

If he experiences difficulty in breathing, so he uses a puffer in order to help him breathe more easily, this does not break the fast, because that does not reach the stomach, so it is not food or drink. 

End quote from Majmoo‘ Fataawa wa Rasaa’il al-‘Uthaymeen (19/206) 

For more information, please see the answer to question no. 65632 and 78459 

And Allah knows best.