Sibai An

Benzodiazepine Treatment of Penile Erection under General Anesthesia

Stimuli that elicit penile erection are either psychic or reflex (1). Reflex erection, mediated primarily by the parasympathetic nervous system, depends on a spinal reflex arc that involves the second, third, and fourth sacral segments of the spinal cord. Psychogenic impulses, probably originating from the limbic system, phylogenetically the oldest part of the brain, coordinate sensory inputs with visceral function and emotion in humans; impulses descend via the lateral column of the spinal cord to reach the so-called thoraco-lumbar erection center at T12 and L1. Impulses at this center result in sympathetic stimulation that can act synergistically with the sacral parasympathetics to mediate erection. Previous reports have shown that ketamine (2) or ketamine-physostigmine combination (3) can be used for the management of intraoperative priapism. Such therapy is based on the hypothesis that priapism is the result of reflex autonomic imbalance. However, subsequent studies (4,5) have questioned the efficacy of the ketamine-physostigmine combination. We have found that the benzodiazepine derivatives, diazepam and midazolam, are effective in treatment of erection in patients undergoing surgery under general anesthesia. In six patients, erection was observed after

Dependent PEEP during two-lung ventilation in the lateral decubitus position.

In anesthetized patients in the lateral decubitus position, the dependent lung is less ventilated and more perfused than the nondependent lung, resulting in ventilation-perfusion mismatching (1-3). A physiologic solution to the adverse effects of anesthesia and surgery in the lateral decubitus position on the distribution of ventilation and perfusion would be the application of selective positive end expiratory pressure (PEEP) to the dependent lung (2,3). Selective PEEP to the lower lung may increase ventilation of this lung by moving it up to a steeper, more favorable portion of the lung pressure-volume curve; it may also increase vascular resistance in the lower lung and shift more blood flow to the upper lung. The present report investigates the effect of selective application of dependent PEEP in patients undergoing radical nephrectomy in the lateral decubitus position. The investigation compares the differential distribution of ventilation between the dependent and the nondependent lungs, as well as the arterial PO, and PCO, levels before and after application of the dependent PEEP.