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Achieving satisfactory hemostasis during orthognathic surgery may be difficult because of the extensive vascularity of facial structures. Hypotensive anesthetic techniques provide clear operative fields by altering regional tissue perfusion through the use of systemic vasodilators, ganglionic blocking agents, and positioning of the patient. Thorough monitoring during surgery, careful selection of patients, and close communication between the surgeon and anesthesiologist permit safe anesthesia, can decrease operating time, and usually obviate the need for transfusions.

The investigation of the volume of the circulating blood in 129 patients operated for gastro-intestinal hemorrhage has shown that by the end of the operation there was an increasing deficiency of the circulating blood volume and HO in spite of hemotransfusion therapy. The use of prolonged ganglionic blockade resulted in the increased circulating blood volume and HO in patients by the end of operation at the expense of redeposition of blood.

Beginning in the early 1950s, when a ganglioplegic agent and a vasodilator were used in combination to provide long-term control of severe hypertension, which neither drug alone could control, much has been learned about the management of hypertension from the use of new antihypertensive agents in man and from clinical trials of antihypertensive regimens. Some of this information includes: the unexpected yet very real hazards as well as benefits associated with the long-term use of powerful drugs, in particular the original description of hydralazine-induced lupus, its relation to genetic markers and its association with control of hypertension; the apparently decreasing need for antihypertensive drugs in subjects with well-controlled severe and moderate hypertension; the identification of risk factors for the complications of hypertension and the quantitation of their effects; the decrease in the incidence of hypertensive complications associated with the pharmacologic treatment of severe, moderate and, at least, the upper ranges of mild hypertension; the possibility of designing a chemical to block a specific reaction and the realization that it would have broader than expected effects; and the primary prevention of myocardial infarction in very high risk subjects.