26 October 2012

Secrets of anaesthesia revealed

A study found that anaesthesia drugs don't just turn wakefulness off, they also switch on important sleep circuits in the brain.


General anaesthesia drugs really do put patients to sleep, suggests research conducted in mice.

The study found that the drugs don't just turn wakefulness off, they also switch on important sleep circuits in the brain, according to the findings, which were published online in the journal Current Biology.

"Despite more than 160 years of continuous use in humans, we still do not understand how anaesthetic drugs work to produce the state of general anaesthesia," Dr Max Kelz, an anaesthesiologist at the University of Pennsylvania, said.

"We show that a commonly used inhaled anaesthetic drug directly causes sleep-promoting neurons to fire," Kelz said. "We believe that this result is not simply a coincidence. Rather, our view is that many general anaesthetics work to cause unconsciousness in part by recruiting the brain's natural sleep circuitry, which initiates our nightly journey into unconsciousness."

How the study was done

Kelz and his colleagues focused on an area of the brain deep within the hypothalamus, which is known to become more active as a person goes to sleep. They found that the anaesthesia drug isoflurane boosts activity in this area of the brain in mice. They also found that mice with non-functioning neurons in this area were more resistant to the drug.

"The development of anaesthetic drugs has been hailed as one of humankind's greatest discoveries in the last thousand years," Kelz said. "Anesthetics are annually given to over 230 million patients worldwide. Yet as a society, and even within the anaesthesia community, we seem to have lost our curiosity for how and why they work."

He noted that there are important differences between natural sleep and the unconscious state caused by general anaesthesia. Even the soundest sleeper can be awakened, but anaesthetised patients remain unconscious throughout the trauma inflicted on their bodies during surgery.

Although the research with mice was revealing, experts note that animal experiments don't always produce the same results when applied to human subjects.

Read more:
Types of anaesthesia

More information

The MedlinePlus Medical Encyclopedia has more about general anesthesia.

(Copyright © 2012 HealthDay. All rights reserved.)


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