A Comparison of Labetalol and Nitroprusside for Inducing Hypotension During Major Surgery

Abstract

The hemodynamic and intrapulmonary shunt effects of intravenous labetalol and nitroprusside were compared during induced hypotension for major spinal surgery. A randomized, double-blind protocol was used in which 20 patients, ASA physical status I or II, received either nitroprusside infusion (n = 10) or labetalol bolus injections of 10 mg every 10 min (n = 10) until mean arterial blood pressure was reduced to 55-60 mm Hg. Pulmonary artery pressures were measured and mixed venous samples obtained via a pulmonary artery catheter. Nitroprusside increased heart rate significantly more than labetalol during the period of hypotension. When compared with prehypotension baseline values, nitroprusside increased heart rate significantly with a concomitant significant decrease in systemic vascular resistance. Cardiac output increased significantly 60 min after hypotension was achieved in patients treated with nitroprusside. Systemic vascular resistance decreased significantly below baseline levels in patients treated with labetalol but without changes in cardiac output, heart rate, or mean pulmonary artery pressure. There was a 122% increase in intrapulmonary shunt with nitroprusside administration, compared with an 11% increase with labetalol. Labetalol was effective for inducing hypotension and was not associated with an increase in heart rate, intrapulmonary shunt, or cardiac output as seen with nitroprusside.

THIS ARTICLE HAS BEEN RETRACTED Acute phase response to nitroprusside‐induced controlled hypotension in patients undergoing radical prostatectomy

“…Hypotensive anaesthesia offers a dry surgical ®eld and may reduce blood loss and hence the need for transfusion [1,2]. Controlled hypotension is used in a variety of surgical procedures and several hypotensive agents are used [3]; however, sodium nitroprusside is the drug used most commonly for this purpose [4]. Sodium nitroprusside is a powerful vasodilator with a rapid onset and after stopping the infusion, arterial blood pressure returns rapidly to baseline values [5,6].…”

Comparison of effect of Labetalol and fentanyl with only fentanyl for attenuating pressure responses to intubation and skull pin insertion in neurosurgery

“…Presynaptic alpha-2 receptors are spared by labetalol so that the released norepinephrine can continue to inhibit further release of catecholamines via the negative feedback mechanism resulting from the stimulation of alpha-1 receptors. Moreover this drug targets 5-10 times more specific beta blockade 11,23 and prevent rebound hypertension and tachycardia. 20,10 Researchers used Labetalol and nitroprusside to induce hypotension in major surgeries and showed that nitroprusside significantly increased the heart rate but cardiac output remain unchanged with labetalol administration.…”

“…20,10 Researchers used Labetalol and nitroprusside to induce hypotension in major surgeries and showed that nitroprusside significantly increased the heart rate but cardiac output remain unchanged with labetalol administration. 11 The arterial hypertension is due to increase in cardiac output rather than increase in systemic vascular resistance. 22 We used low doses of fentanyl because larger dose may leads to muscular rigidity, bradycardia, and postoperative respiratory depression.…”

“…10 It lowers the blood pressure by decreasing systemic vascular resistance (alpha-1 blockade) whereas reflex tachycardia triggered by vasodilation is attenuated by simultaneous betablockade and cardiac output remains unchanged. 11 It has better safety profile and haemodynamic stability. Hence, Labetalol may be the drug of choice to attenuate the adrenergic response to laryngoscopy and intubation as well as skull pin insertion in patients undergoing neurosurgery.…”

Effects of sodium nitroprusside-induced controlled hypotension on pancreatic function assessed by pancreatitis-associated protein in patients undergoing radical prostatectomy

“…It is used in many surgical procedures, including radical prostatectomy [3,4]. The most commonly used drug to induce and maintain controlled hypotension is sodium nitroprusside (SNP) [3]. However, controlled hypotension may alter organ blood flow and tissue oxygenation [5].…”