Preoperative beta blocker induced controlled, hypotension for nasal surgery

ABSTRACT

The purpose of this study was to compare surgical conditions for nasal surgery under general anesthesia during controlled hypotension, using either preoperative oral beta blocker atenolol [50mg twice before surgery] or intraoperative infusion of sodium nitroprusside [SNP] or esmolol. Thirty patients, assigned to receive either of the drugs as the primary hypotensive agent, were studied. The same surgeon, blinded to the hypotensive agents 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 15° reverse Trendelenburg position and the mean arterial blood pressure [MABP] was reduced in steps of 5 mmHg. The anesthetist 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 three groups. At mild sodium nitroprusside [SNP] induced hypotensive anesthesia surgical conditions were poor [ACS 3.8 +/- 0.53 mean +/- SEM], while in the atenolol and esmolol groups, ideal surgical conditions [ACS 2.7 +/- 0.74 and 2.8 +/- 0.63] were recorded at MABP > 60 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 atenolol and esmolol groups [as opposed to vasodilatation in the SNP group] probably caused the superior surgical conditions. Preoperative oral Beta blocker was effective in reducing surgical bleeding during nasal surgery, provide good quality of surgical field, reduce operative time, simple in use, not need complex technique for infusion, more convenient for patients and save method for induce mild hypotensive anesthesia during nasal surgery