[An examination of current techniques in anaesthesia (author's transl)]

The techniques of general anaesthesia may be divided into 2 major groups: those used in very brief surgical or diagnostic operations and those used in longer and more pain-producing interventions. The former normally involve a single drug which is very short-acting and allows consciousness to be recovered rapidly and well. The latter are anaesthetics using several drugs together, which allows very precise control of the degree of analgesia, neuro-vegetative protection, muscle relaxation and sleep. The depth of anaesthesia is judged from the patient's sympathetic-adrenergic reactivity to noxious stimuli. It is not possible to direct anaesthesia by reference to the electrical activity of the brain, since there are no electro-clinical correlations. Brain activity depends on a large number of factors related not only to the anaesthetic and nature of its administration, but also the extent of the surgery and the state of the patient. The E.E.G. remains a technique of choice for studying recovery, and any sequels of hypoxia during the operation. This should, of course, be accompanied by a clinical evaluation which is particularly important in assessing the state of ventilation (residual curarisation, depression by central analgesics).