Humans are still CONSCIOUS when under general anaesthetic, study says

Humans are partially conscious when under general anaesthetic, new research suggests.

According to The Daily Mail, half of people given a sedative can be woken with a brief shake and a loud shout, while 42 per cent of those under general anaesthetic can be roused into consciousness, a study found.

Although they are unable to feel pain while under the knife, their brains keep track of what is going on around them, particularly if they hear worrying noises, the research adds.

Some are even able to remember parts of operations, albeit a little hazily.

Study author Antti Revonsuo, from the University of Turku, Finland, said: 'Nearly all participants reported dream-like experiences that sometimes mixed with the reality.'

How the research was carried out   

The researchers analysed 47 healthy people who were given either the sedative dexmedetomidine or the general anaesthetic propofol until they were unable to respond.

While the drugs were being infused, attempts were made to rouse the participants.

Drug concentrations were then increased until the participants appeared to lose consciousness. 

The participants brain waves were recorded throughout the experiment.

All the participants were also played recordings of sentences that ended unexpectedly, such as 'the night sky was filled with shimmering tomatoes', while other sound bites were completely normal. 

'Anaesthesia just disconnects the patient from the environment'

Brain-wave results suggest people alternate between deep sleep and a higher sense of consciousness while supposedly out cold. 

The brain waves of sedated people suggest they can hear unusual phrases and try to make sense of them, while those on propofol continue snoozing.

Yet when the participants were played unpleasant noises, all seemed to be paying attention. They also reacted faster to the noises when played them again when awake. 

Study author Harry Scheinin said: 'In other words, the brain can process sounds and words even though the subject did not recall it afterwards.

'Against common belief, anaesthesia does not require full loss of consciousness, as it is sufficient to just disconnect the patient from the environment.' 

The findings were published in the journal Anesthesiology.

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