The requirement of propofol for induction of anesthesia in patients with traumatic brain injury determined using bilateral bispectral index and target controlled infusion – An observational cohort study

BACKGROUND AND AIMS: Patients with traumatic brain injury (TBI) frequently require emergency surgery. There is a paucity of literature with regard to anesthetic requirements in these patients. The aim of the study was to compare the dose of propofol required for induction of anesthesia in patients with different grades of TBI. MATERIAL AND METHODS: This prospective, observational study included patients with mild, moderate, and severe grades of TBI undergoing emergency surgery within 48 h of injury. Bispectral Index (BIS) values were recorded using a bilateral BIS sensor. Anesthesia was induced with a target controlled infusion (TCI) pump. Once BIS reached 40, plasma (Cp) and effect-site (Ce) concentration and total dose of propofol required were noted from the TCI pump. RESULTS: Of the 96 patients recruited, 27, 36, and 33 patients belonged to mild, moderate, and severe TBI (sTBI) groups, respectively. The Ce of propofol in mild, moderate, and sTBI groups was 6 ± 0.9, 5.82 ± 0.98, and 4.48 ± 1.5 μg/mL (P < 0.001), and the dose of propofol required was 1.9 ± 0.2, 1.8 ± 0.4, 1.41 ± 0.5 mg/kg, respectively (P < 0.001). Baseline BIS on the injured side was 80 ± 7.8, 71 ± 9.4, 55 ± 11.6, and on the uninjured side was 89 ± 5.5, 81 ± 8.4, and 65 ± 12 in mild, moderate, and sTBI groups, respectively. CONCLUSIONS: The requirement of propofol was reduced in patients with sTBI. The dose of propofol required for induction of anesthesia as determined using Ce was significantly lower only between sTBI and mild TBI and not between patients with sTBI and moderate TBI or between mild and moderate head injury. BIS values were significantly different between the groups (highest in mild TBI and lowest in sTBI) and between normal and injured sides within each group.