Comparison of sodium nitroprusside- and esmolol-induced controlled hypotension for functional endoscopic sinus surgery

• Published in: Canadian journal of anesthesia Vol. 42; no. 5; pp. 373 - 376
• Main Authors: BOEZAART, A. P, VAN DER MERWE, J, COETZEE, A
• Format: Journal Article
• Language: English
• Published: Toronto, ON Canadian Anesthesiologists' Society 01.05.1995
• Subjects: Adrenergic beta-Antagonists - therapeutic use; Anesthesia, General; Biological and medical sciences; Blood Loss, Surgical; Blood Pressure - drug effects; Capillaries - drug effects; Cardiovascular system; Endoscopy; Heart Rate - drug effects; Humans; Hypotension, Controlled; Maxillary Sinus - blood supply; Maxillary Sinus - surgery; Medical sciences; Mucous Membrane - blood supply; Mucous Membrane - drug effects; Nitroprusside - therapeutic use; Pharmacology. Drug treatments; Posture; Propanolamines - therapeutic use; Single-Blind Method; Vasoconstriction; Vasodilator agents. Cerebral vasodilators; Human; Induced arterial hypotension; Hypotensive drug; β1-Adrenergic receptor; Vasodilator agent; Surgery; ENT disease; General anesthesia; Paranasal sinus disease; Endoscopy; Comparative study; Beta blocking agent
• ISSN: 0832-610X; 1496-8975
• DOI: 10.1007/bf03015479

The purpose of this study was to compare surgical conditions for functional endoscopic sinus surgery (FESS) under general anaesthesia during controlled induced hypotension, using either sodium nitroprusside (SNP) or esmolol. Twenty patients, assigned to receive either of the drugs as the primary hypotensive agent, were studied. The same surgeon, blinded to the hypotensive agent used and the haemodynamic variables, performed all the operations. The surgeon used a category scale (0-5) to assess surgical conditions--a value of 2-3 being ideal. Patients were positioned in 5 degrees reverse Trendelenburg position and the mean arterial blood pressure (MABP) was reduced in steps of 5 mmHg. The anaesthetist prompted category scale estimations by the surgeon following a change in any of the haemodynamic variables. Average category scale (ACS) values were compared between the two groups for four data groups, i.e., MABP > 65 mmHg (mild), 60-64 mmHg, 55-59 mmHg and 50-54 mmHg. Pre-treatment MABP was 79.8 +/- 10.4 mmHg in the SNP group and 76.1 +/- 6.8 mmHg in the esmolol group. At mild SNP-induced hypotension, surgical conditions were poor (ACS = 3.63 +/- 0.22; mean +/- SEM), while in the esmolol group, ideal surgical conditions (ACS = 2.94 +/- 0.34) were recorded at MABP > 65 mmHg. The combined effects of increased venous drainage due to the reverse Trendelenburg position, hypotension as well as capillary vasoconstriction due to unopposed alpha-adrenergic effect on the mucous membrane vasculature in the esmolol group (as opposed to vasodilatation in the SNP group) probably caused the superior surgical conditions.