Cerebral metabolic rate of oxygen, intracranial tension and blood flow equivalent during isoflurane or sevoflurane anaesthesia in brain surgery

ABSTRACT

This study included 28 patients of ASA physical status I-II, aged 18-55 years, subjected to craniotomies for supratentorial brain tumor. They were randomly allocated into two groups to receive either isoflurane [group I] or sevoflurane [group II] anesthesia. Cerebral venous monitoring through bulb catheterization to allow assessment of global oxygen delivery adequacy. A fiberoptic extradural sensor was inserted in extramural space to monitor the ICP. Anesthesia was induced by thiopentone/fentanyl/pepecurium/isoflurane in group I, and thiopentone/pepecurium/sevoflurane in group II. Anesthesia was maintained with 1.5 MAC [1.5%] isoflurane in group I and 1.5 MAC [3%] sevoflurane in group II in FiO2 100%. The patients were mechanically ventilated in such a rate to maintain PaCO2 between 32-35 mmHg. Mean arterial blood pressure [MAP], intracranial pressure, arterial and jugular venous blood gases, arterial and jugular venous lactate concentrations were measured and times of recovery parameters were recorded. Cerebral perfusion pressure [CPP], arterial oxygen content [CaO2], jugular venous oxygen content [VjvO2], arteriojugular venous oxygen content difference [AJVDO2], cerebral oxygen extraction ratio [OER], arteriojugular lactate difference [AJVLS], lactate oxygen index [LOI], cerebral blood flow equivalent [CBF equivalent] were calculated. Times elapsed, till recovery parameters occurred, were recorded