Oral nifedipine as a premedication for induced hypotension in functional endoscopic sinus surgery (FESS)

Abstract

Objective: To evaluate the effects of oral nifedipine as pretreatment, quality of surgical field and amount of hypotensive agent during functional endoscopic sinus surgery (FESS) under general anesthesia. Methods: Sixty patients ASA I or II scheduled for FESS were randomly allocated into two equal groups. Oral nifedipine 20 mg was given one hour before induction of anesthesia (nifedipine) group and placebo. In the other group (control), all the patients received standard anesthesia and monitoring. Nitroglycerin (GTN) was administrated in a dose of 2 μg/kg/min after induction of anesthesia till it achieved a target mean arterial blood pressure (MAP) of 50–60 mmHg, followed by a continuous i.v. infusion (1 μg/kg/min) intraoperative when needed. Hemodynamic variables were recorded at baseline preoperatively, intraoperatively and till the end of operation. The surgical field score was assessed by average category scale (ACS) and intraoperative blood loss and amount of GTN was estimated. Emergence time and total recovery from anesthesia (Aldrete score ⩾9) were recorded. Results: There were no statistically significant differences between two groups with respect to the amount of blood loss and scores for a bloodless surgical field. Emergence time and time needed to achieve 9 of modified Aldrete score were significantly shorter in Control group than nifedipine group (4.46 ± 1.25 min and 7.46 ± 2 min versus 8 ± 1.62 min and 9.5 ± 2.41 min, respectively) (P 0.05) but at 5 and 10 min after stoppage of hypotensive anesthesia, at the end of surgery and after recovery, MAP was significantly lower in nifedipine group than Control group (p 0.05). At 5 and 10 min after stoppage of hypotensive anesthesia, at end of surgery and after recovery, HR was significantly lower in nifedipine group than Control group (p < 0.001). The amount of GTN used in nifedipine group was significantly lower than Control group (p < 0.001). Conclusion: Administration of a single preoperative dose of nifedipine (20 mg) can significantly reduce the blood loss during FESS and improves the visualization of the operative field and it also lowers the amount of GTN needed to achieve target hypotension.

Keywords

• Induced hypotensive anesthesia
• Oral nifedipine
• Nitroglycerin
• Functional endoscopic sinus surgery