[Effect of the depth of anesthesia on the postoperative course]

An assessment of the influence of several variables during the perioperative period revealed a cause-determining correlation between the explanatory variables age, body size, weight, duration of operation, loss of blood, and pain level and the physiologic variables adrenaline, total protein, blood glucose level, transferrin, cholinesterase and immunoglobulin G that could be statistically be proven. An evaluation of the influence of the depth of anesthesia on this cause-determining correlation demonstrated significant advantages for a deep level of anesthesia. The depth of anesthesia should be seen as an influential factor during the perioperative period. Anesthesia should therefore not be regarded simply as analgesia and loss of consciousness; rather, one should stress the psychophysiological attenuation and its negative influence on the sensorimotor functions that are accompanied by changes in physiology. The central organ of regulation controls the physiological levels of the organism, and changes in brain function result in changes in physiology. During the perioperative period, rapid and programmed functional mechanisms that are controlled by more primitive parts of the brain and thus are not influenced by individual inappropriate decisions of the "higher" brain centers are needed for the patient's convalescence. This would explain the advantage of a deep level of anesthesia. The usual grading of stages of anesthesia according to Güdel provides little help in this respect; therefore, an assessment of the depth of anesthesia using EEGs and evoked potentials should be combined with an evaluation of physiological variables at several other levels of the organism such that further information can be obtained on the conditions existing at the onset of the postoperative course.