Hemodynamic and hormonal response to induced hypotension with isosorbide dinitrate and nitroglycerin during...

Changes in hemodynamics, plasma catecholamines, and PRA in response to controlled hypotension induced with ISDN (n = 10, mean dose 15.5 micrograms kg-1 min-1) and NTG (n = 7, mean dose 5.5 micrograms kg-1 min-1) were studied during neuroleptanesthesia in patients undergoing facial and neck surgery. Before the commencement of vasodilator infusion the patients were pretreated with metoprolol 0.1 mg kg-1. In addition, enflurane was used to obtain the desired hypotensive level. During ISDN induced hypotension, MAP was reduced from 83 to 63 mm Hg (p less than 0.001). Continuous infusion of NTG resulted in a decrease of MAP from 81 to 53 mm Hg (p less than 0.01). In both groups, HR decreased by 10% (p less than 0.05). For both vasodilators the reduction of MAP was associated with a marked decrease in SVRI (p less than 0.01), while Cl remained largely unchanged. The hemodynamic responses to the two vasodilators were similar, except that NTG reduced PAMP (p less than 0.01) and increased intrapulmonary shunt volume (p less than 0.01). The anesthetic technique attenuated catecholamine and renin release, suppressed reflex tachycardia, and prevented rebound hypertension.