Cecil Gray

A reassessment of the signs and levels of anaesthesia

ConclusionI suggest, in conclusion, that the changes in respiration, eye movements, pupils and other reflexes should be taught from the view point of their aetiological significance and not as signs of the depth of anaesthesia—they are signs of muscle relaxation, of respiratory obstruction or of reflex activity. The attention of the anaesthetist should be directed towards producing various “modalities” of anaesthesia such as sleep, relaxation and depression of undesirable reflex responses to injury. Hypotension and depression of metabolism by hypothermia, when they are required for adequate reasons, are other modalities of normal physiological function which can be controlled by modern anaesthetists.