The use of general anesthesia is a routine stage in surgical operations in hospitals around the world, yet the mechanism of action of anesthetics on our brain and the entire body is not fully understood.
Scientists from the USA decided to compare the processes of sleep, anesthesia and coma based on the available scientific data. The results of this analysis were published in the New England Journal of Medicine. Dr. Emery Brown of Massachusetts General Hospital describes the work of his team as follows: We started by summarizing the characteristics of general anesthesia such as unconsciousness, amnesia, pain relief, immobility – all while maintaining the circulatory, respiratory and thermoregulation systems. Later we checked the similarities and differences between general anesthesia, sleep and coma.
Researchers also compared EEG (electorencephalogram) records of people under general anesthesia and sleepers. It turned out that anesthesia and sleep were more different than previously assumed, only the deepest stage of sleep resembled the shallowest states of drug induced anesthesia. The authors of the study stated that the state of the body during anesthesia resembles a coma – but safe because it is fully controlled by the anesthesiologist.
One of the stages of the research was to find out how different substances used in anesthesia work on the brain – here scientists found conflicting information coexisting. Some drugs, such as ketamine, activate rather than inhibit neuronal activity and cause hallucinations in low doses. Ketamine blocks receptors for the excitatory neurotransmitter glutamate, but has a preferential effect on receptors located on inhibitory neurons, which in turn stimulates neuronal activity (by inhibiting inhibition).
Such excessive brain activity leads to an unconscious state – which can be compared to a situation where a large amount of disordered information is transmitted over an electronic link and blocks all logical signals.
Scientists emphasize the need to further investigate the mechanisms of action of drugs used for general anesthesia of patients and suggest a method of comparing sleep, anesthetic coma as a good way to analyze the changes occurring in our body during these three different states of unconsciousness. (PAP)