Impact of anesthetic induction with etomidate, thiopentone, and propofol on regional cerebral oxygenation: An observational study in patients with traumatic brain injury

Anesthetic induction plays a pivotal role in determining the operative course and the outcome in patients with acute traumatic brain injury (TBI). The present study compared the effect of anesthetic induction with etomidate, thiopentone, and propofol primarily on systemic hemodynamics and regional cerebral oxygenation (rScO2) and secondarily on the serum cortisol levels in TBI patients. In this prospective observational study, eligible patients were recruited and divided into three groups as per the induction agent received. Data collected were hemodynamic parameters and rScO2 levels at baseline, following 3 min of preoxygenation, and over 10 min of induction. Serum cortisol levels were measured before and after 24 h of induction. The statistical analysis was done using R software. A total of 115 patients were included: 32, 33, and 50 in thiopentone, propofol, and etomidate groups, respectively. A significant increase (P < 0.001) in bilateral rScO2 was noted in all three groups following anesthetic induction. Intergroup comparison of the propofol and the etomidate groups revealed significantly lesser increase in contralateral rScO2 (P = 0.019) and a greater fall in mean arterial pressure (P = 0.003) on using propofol as an induction agent. Trend changes in bilateral rScO2 and hemodynamic parameters were comparable between thiopentone and etomidate groups. An insignificant fall in serum cortisol was observed in etomidate (P = 0.332) and thiopentone (P = 0.364) groups, but a significant increase was observed in the propofol group (P = 0.004). The Glasgow coma scale (GCS) score at discharge improved significantly in all the groups (P < 0.001). In TBI patients, anesthetic induction with etomidate resulted in least hemodynamic changes compared to induction with thiopentone and propofol. The rScO2 increased in all three groups after induction, with the maximal increase observed with etomidate compared to propofol and thiopentone. Insignificant fall in serum cortisol was observed with etomidate and thiopentone, but not with propofol. Outcome at discharge, assessed with GCS, was comparable in all the groups. Key Messages: Anesthetic induction with etomidate produced least hemodynamic changes compared to induction with thiopentone and propofol in patients with traumatic brain injury. Consequently, maximal increase in cerebral oxygen saturation occurred with etomidate among the three induction agents. An insignificant decrease in serum cortisol was observed with etomidate and thiopentone, but not with propofol. Neurological outcome at discharge was similar with all drugs.