C hemical agents in the form of natural drugs have been used since primitive times to relieve suffering. Despite the continuing development of chemical anesthesias with increased efficacy and safety, the search continues for a more perfect agent that would include all of the following attributes: (a) rapidity of induction, (b) the possibility of controlled levels of unconsciousness from light to deep surgical anesthesia, (c) relaxation of musculature, (d) minimal side effects and aftereffects, and (e) rapid reversibility of effects with rapid recovery. Since no present chemical agent satisfies these requirements, attention has turned to electrical means for producing "unconsciousness."The first serious studies of electroanesthesia were made by Leduc and Rouxeau (1903), and continued by Robinovitch (1914), a pupil of Leduc, who also reported the successful use of electrical anesthesia in major human surgery.Electroanesthesia research was revived in the 1940s. Knutson, Tichy, and Reitman (19S6) added the preliminaries of chemical anesthesia (atropine, curare, and intubation) to electroanesthesia. Although they were able to induce "electronarcosis" in 25 dogs and five humans, the severe side effects induced them to discontinue the experiments.The situation remained thus for several years until Anan'ev, Golubeva, Gorova, Kaschevskaia, Levitskaia, and Khudyi (1960) published a landmark study that initiated a third, current cycle of investigations. Their major procedural innovations were (a) the use of a combination of pulsed and direct currents (because separately both were ineffectual); (b) the very slow increase of current levels (using 10-15 minutes to attain a 1-mA level); and (c) the use of a generator that minimized changes in electrode impedance resulting from polarization. They reported that with these techniques skin and muscle surgery could be performed painlessly.This discovery prompted a resurgence of investigations. While scientists saw a nonchemical means for modifying level of consciousness, the military envisioned the possibilities of quick and simple battlefield surgery, with instant recovery of patients to a functional status.The most lucid early report in this third phase of electroanesthesia research was that of Smith

Clinical, psychophysiological, and psychometric measurements were made on 20 normal controls and 30 anxious patients during rest and experimental stress. Resting forearm blood flow, a relatively new physiological index of anxiety, was found to correlate significantly with clinical and subjective ratings of anxiety, and with heart rate, number of spontaneous fluctuations of skin resistance, and amplitude of forearm EMG. It did not correlate significantly with any of the measures of depression. Resting forearm blood flow and heart rate were found to be better measures of arousal in this study than skin resistance, EMG, or cutaneous vasomotor status, since the latter did not show significant differences between anxious patients and normal controls. The psychological traits of the two groups were also assessed by the Maudsley Personality Inventory, Taylor Manifest Anxiety Scale, and Zung Depression Scale; and their emotional state evaluated by the Clyde Mood Scale and Semantic Differential Scale. Twenty‐one variables showed significant differences between the two groups. Some of these measures have subsequently been used, with advantage, to monitor emotional changes brought about by psychiatric treatment.

A survey of the literature on human salivation is presented with emphasis upon the influence of normal and psychopathologic emotional states as they affect alterations in factors relating to flow rate. Discussion includes neurological and physiological features of the gland, individuality of response, results of classical and operant conditioning, and suggested areas for future research.

Four plethysmographic techniques‐rheoplethysmography, electrical impedance plethysmography, girth plethysmography, and photoplethysmography–are described and their theoretic bases discussed. Advantages and limitations are noted, and particular emphasis is given to the optical methods and the use of glass fiber light guides in the construction of the transducer. Typical examples of current plethysmographic research are presented.

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