Hormonal and Hemodynamic Changes Induced by Pentolinium and Propranolol during Surgical Correction of Scoliosis

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Abstract
Deliberate hypotension has had variable success in decreasing blood losses and facilitating extensive surgical procedures. Hemodynamic variables, catecholamines, plasma renin activity and angiotensin II levels were studied in 11 patients undergoing operative correction of idiopathic scoliosis. Deliberate hypotension with mean arterial blood pressures ranging from 55-42 torr was provided with the ganglionic blocking agent, pentolinium tartrate, supplemented by .beta. blockade with propranolol during morphine N2O anesthesia. Stroke volume index, systemic vascular resistance and left ventricular stroke work index decreased 16, 19 and 40%, respectively, with blood pressure reduction. Following the return to normal blood pressure, stroke volume index increased to a value 28% greater than control, while systemic vascular resistance remained decreased. At this time left ventricular stoke work index increased slightly, but the increase was not statistically significant compared with control. The epinephrine level had risen from 59-270 pg/ml 1 h after hypotension, probably secondary to infiltration of the skin prior to the surgical procedure. It had decreased to control levels by the end of the procedure. Norepinephrine and dopamine concentrations and plasma renin activity were unchanged. The angiotensin II level was significantly decreased, from 60-40 pg/ml, during deliberate hypotension. Blood loss correlated with left ventricular stroke work index, while changes in systemic vascular resistance and heart rate correlated well with changes in angiotensin II and plasma renin activity, respectively. The ability of ganglionic blockade and propranolol to inhibit the increases in catecholamines and angiotensin II during morphine N2O anesthesia, hypotension and surgical intervention may be of considerable importance.