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Comparison between Sevoflurane and Isoflurane for Controlled Hypotensive Anaesthesia in Patients undergoing Craniotomy for Supratentorial Intracranial Surgery: A Randomised Single-blinded Study

Introduction: The controlled hypotensive anaesthesia technique is widely used for decades to create a bloodless surgical field and decrease intraoperative blood loss during neurosurgical procedures. Inhalation agents like isoflurane and sevoflurane provide the benefit of being hypnotic and hypotensive agents at clinical concentrations and predictable dose-dependent effects made them popular in neurosurgery. Aim: To compare the effects of sevoflurane and isoflurane for producing controlled hypotensive anaesthesia in surgeries for supratentorial brain tumours. Materials and Methods: Sixty-six patients of either sex in the age group of 20-60 years, with American Society of Anaesthesiologists (ASA) Grade I and II posted for elective craniotomy for supratentorial brain tumour under general anaesthesia were enrolled for this study. Patients were randomly allocated to two aesthetic regimens: Group I received isoflurane 1 Minimum Alveolar Concentration (MAC), and Group S received sevoflurane 1 MAC. The Systolic Blood Pressure (SBP) was lowered to less than 100 mmHg before the skin incision and was maintained throughout the surgery.If the blood pressure was not maintained within the above-mentioned range, then injection propofol bolus dose of 20 mg was given intravenously. The quality of the surgical field, brain relaxation, blood loss, duration of surgery, and postoperative complications were compared. Time taken for onset and recovery of controlled hypotension and the requirement of propofol for maintaining controlled hypotension in both groups were also compared. Results: The group S had better brain relaxation (N=26 vs N=20), less blood loss (241.5±61.62 vs 380.65±203.9 mL), and a shorter duration of surgery (135.45±25.6 vs 171.4±60.5 minutes) than group I. Group S had a few patients who required propofol (5 vs 17) to maintain controlled hypotension. The mean time to achieve the target Mean Arterial Pressure (MAP) and time to recovery was faster in group S (10.55±2.54 minutes) vs 15.35±0.99 minutes in group I and 12.95±3.24 minutes in Group S vs 17.85±2.21 minutes in Group I, respectively; p<0.001). Conclusion: Sevoflurane is a safer and more potent drug than isoflurane to achieve controlled hypotension during surgery for a supratentorial brain tumour.