Variable hemodynamic response to sodium nitroprusside in hypertensive crisis

Five patients, three males and two females, admitted with severe hypertensive crisis underwent hemodynamic investigations before and during vasodilator therapy with sodium nitroprusside. In three hypervolemic patients with congestive heart failure and/or renal insufficiency, the drug induced a rapid fall in systemic arterial pressure and a beneficial effect on cardiac performance, as shown by a shift of the ventricular function curves to the left. In two hypovolemic patients, the hemodynamic response was quite different; vasodilator therapy induced a confusing clinical picture characterized by significant fluctuations in blood pressure, a severe fall in cardiac output and clinical signs of shock in spite of normal blood pressure. Hemodynamic response to vasodilator therapy with sodium nitroprusside in hypertensive crisis appears to be directly related to the circulating blood volume. The syndrome of hypertension associated with hypovolemia needs to be recognized promptly in order to avoid inappropriate therapy; in such cases volume expansion under precise hemodynamic monitoring appears to be an effective means of stabilizing the cardiocirculatory conditions.