Evaluation of the efficacy of desflurane with or without labetalol for hypotensive anesthesia in middle ear microsurgery.

Background and Aims: Hypotensive anesthesia technique is used to reduce intraoperative bleeding and to improve the visibility of the operative field. The aim was to evaluate the efficacy of desflurane with and without labetalol for producing hypotensive anesthesia.

Material and Methods: Sixty adult patients undergoing elective middle ear surgery were administered general anesthesia and randomly divided into two groups - Group D and Group L. The target mean arterial pressure (MAP) was 55-65 mmHg during hypotensive period. Group D patients received an increasing concentration of desflurane alone. Group L patients received 3% desflurane plus labetalol (loading dose 0.3 mg/kg intravenously, followed by 10 mg increments every 10 min). Student's t -test and paired t -test were used to compare the hemodynamic parameters. Visibility of the operative field, anesthetic and rescue drug requirement, partial pressure of oxygen in arterial blood, time taken for induction and reversal of hypotension and recovery characteristics were noted.

Results: Target MAP was achieved in both the groups. Group D was associated with a higher mean heart rate compared with Group L (77.3 ± 11.0/min vs. 70.5 ± 2.5/min, respectively; P < 0.001) during the hypotensive period, along with a higher requirement for desflurane ( P = 0.000) and metoprolol ( P = 0.01). Time taken to achieve target MAP was lesser in Group L compared with Group D (33.7 ± 7.1 vs. 39.8 ± 6.2 min, respectively; P = 0.000). Time taken to return to baseline MAP was faster in Group D ( P = 0.03). Emergence time was longer with desflurane alone ( P = 0.000) resulting in greater sedation ( P = 0.000) in the immediate postoperative period.

Conclusion: Although desflurane is effective for inducing deliberate hypotension in middle ear microsurgery, the combination of desflurane with labetalol is associated with decreased requirement of desflurane, absence of reflex tachycardia, faster induction of hypotension, faster recovery from anesthesia, and less postoperative sedation.