Anesthesiology Anesthesia – is a reversible condition of comfort, quiescence and physiological stability in a patient before, during and after performance of a procedure. General anesthesia – for surgical procedure to render the patient unaware / unresponsive to the painful stimuli.
Original in the Royal College of Surgeons of England, London.
Anesthetics are associated with
Hallmark of anesthesia:
General anesthetics have therapeutic indices of about 2 - 4.
It is the use of drugs prior to anesthesia to make it more safe and pleasant.
Stages of anesthesia:
behavior – dangerous state
respiratory and vasomotor
Molecular mechanism of the GA :
The main target of inhalation anesthetics is the brain.
There are two types of anesthetics :
Inhalational anesthetics :
The important characteristics of Inhalational anesthetics which govern the anesthesia are :
Blood : gas partition co-efficient:
Blood gas partition co-efficient affecting rate of induction and recovery
Agents with low solubility in blood quickly saturate the blood. The additional anesthetic molecules are then readily transferred to the brain.
BLOOD GAS PARTITION COEFFICIENT
Oil: gas partition co-efficient:
Higher the Oil: Gas Partition Co-efficient lower the MAC . E.g., Halothane
Parenteral anesthetics (IV):
Ketamine : Dissociative anesthesia