The study will begin after obtaining the IEC approval. Patients posted for elective supratentorial intracranial space-occupying lesion surgery who satisfy the eligibility criteria will be included in the study. Written informed consent for participation in the study will be obtained from the patient. The randomization list will be computer-generated by a statistician using a blocked design. Allocation concealment will be achieved by packaging the study drug in serially numbered opaque envelopes marked with subject ID. These packets will be assembled by the OT technician/neuro anaesthetist who is not directly involved with the clinical trial. They will prepare the study drug according to the randomization list provided by the statistician. The neuro anaesthetists inducing the patient and involved in the intraoperative period will be unaware of the study drug being administered. The induction and maintenance will be based on the BIS values. Hence, the intraoperative neuro anesthetist collects the parameters, and the patient will be blinded to the study to avoid bias. Accordingly, they will be randomized into two groups :

Group K: Patients will receive ketamine and propofol infusion 

Group P: Patients will receive propofol infusion.

Preop- Bilateral TCD flow velocity of middle cerebral artery (MCA) will be recorded by using TCD probe before anaesthesia induction & NIRS optodes will be applied to the patient’s forehead bilaterally and the baseline readings will be noted. Before anaesthesia induction, baseline hemodynamic parameters including heart rate, mean arterial pressure (MAP), oxygen saturation (SPO2), End tidal carbon dioxide – ETCO2 (after asking the patient to take normal respiration) will be noted. Depending on the randomisation, the maintenance anaesthetic agent would be either propofol in group P or ketofol in group KP to achieve the BIS of 40-60. Upon completion of the surgery, the patients will be assessed for extubation at the discretion of the attending anaesthetist and as per standard protocol.