Comparison of Total Intravenous Anesthesia vs. Inhalational Anesthesia in Acute Subdural Hematoma Patients

Patients meeting inclusion criteria will be enrolled in the study and randomized into one of the two group's propofol - P and isoflurane - I. Preoperative Glasgow coma scale (GCS) and computer tomography (CT) findings will be recorded. Intraoperatively peripheral intravenous line will be secured, standard monitors including non invasive blood pressure (NIBP), electrocardiogram (ECG), heart rate (HR), pulse oximetry, SPO2 probe will be connected. Pre-oxygenation will be done with 100% O2 for 3 minutes. In both the groups induction will be done using 3 mcg/kg fentanyl, 2 mg/kg propofol and muscle relaxation will be achieved with 0.1mg/kg vecuronium. Post induction patients will be intubated with appropriate size endotracheal tube (male with 8.0 and female with 7.0) and radial artery will be cannulated with zero pressure adjustment at mid axillary line for continuous blood pressure monitoring and blood sampling. Central line will be secured using 7 French triple lumen central venous catheter in the subclavian vein or internal jugular vein. Cardiac output monitor (EV1000) will be connected to arterial and central line and values of stroke volume (SV), systemic vascular resistance (SVR), cardiac output (CO) and cardiac index (CI) will be obtained. Intraoperative anesthesia will be maintained using propofol 100-150 mcg/kg/min, oxygen and air and FiO2 of 40% in propofol group (GROUP P) whereas in isoflurane group (GROUP I) maintenance will be done with 1 MAC of isoflurane, oxygen and air and FiO2 of 40%. In both the groups Etco2 will be maintained at 32-33 mmHg. HR and IBP will be kept within +/- 20% of the baseline values. If the systolic blood pressure decreases more 20% of base line, crystalloids will be given as initial management and failing to improve blood pressure, vasopressors namely phenylephrine or dopamine will be given intravenously. At the time of scalp incision mannitol 1 gm/kg will be given over 20min. On creating first burr hole a 22G/0.8mm venflon cannula will be placed under dura and connected to a pressure transducer system via a polyethylene catheter. Zero level of ICP will be adjusted with the transducer kept at the level of mastoid process(6). The pressure measured will be the estimate for intracranial pressure. Cerebral perfusion pressure (CPP) will be calculated as the difference between mean arterial pressure MAP and ICP. If the intracranial pressure is more than 25 mmHg then moderate hyperventilation will be given with Etco2 of 25-28 mmHg. Once the dura is opened brain relaxation score will be assessed on four point scale, using tactile evaluation by neurosurgeon who will be blinded to anaesthetic technique. The tension will be categorized as follows:

1. Perfectly relaxed
2. Satisfactorily relaxed
3. Firm brain
4. Bulging brain Meanwhile hemodynamic stability in terms of heart rate, blood pressure, MAP, cardiac output, stroke volume , stroke volume variation, systemic vascular resistance, cardiac index, and cerebral perfusion pressure will be measured before induction, at the time of induction and at 1 , 2, 3, 4, 5th minute after induction and thereafter every 15 minutes until surgery is completed.