What are the physiologic effects of ECT?
The goal of ECT is the generation of a generalized seizure. This is accomplished by the placement of cuta-neous electrodes over various points on the scalp through which an electric current is produced. There is a direct rela-tionship between seizure duration and the success of ECT treatment. Successful treatments provide seizure activity of between 15 and 120 seconds. In addition to the local con-traction of the facial muscles, there is a dramatic systemic hormonal response. Initially a parasympathetic discharge resulting in bradycardia, heart block, or asystole may occur. This is typically followed by a sympathetic discharge, which manifests as tachycardia, hypertension, and increased secre-tions. As a result, there are increases in cerebral blood flow, cerebral metabolic rate and oxygen demand, intracranial pressure, cardiac output, and myocardial oxygen demand. Patients with questionable myocardial reserve as well as organic brain lesions are at significant risk for ischemic sequelae, cardiac dysrhythmias, and cerebral hemorrhage. Along with these circulatory effects, there are violent muscular contractions. The seizures generated by ECT are self-limited, and these derangements subside within minutes of seizure termination. It is the goal of the anes-thesiologist to limit the physical manifestations of these physiologic responses and prevent the sequelae associated with them.