A Study Comparing Propofol Auto-coinduction and Standard Propofol Induction in Patients Undergoing General Anesthesia Without Midazolam Pretreatment: A Prospective Randomized Control Trial.

Background: Propofol has emerged as an induction agent of choice over the past two decades due to its quick, smooth induction and rapid recovery. The main concern for an anesthesiologist is the hemodynamic instability caused by the standard induction dose of propofol (2-3 mg/kg).

Aim: We aim to study the efficacy of propofol auto-coinduction technique in comparison to the standard propofol induction technique in terms of the total induction dose requirement of propofol, the incidence of hemodynamic side effects and pain on injection, and the incidence of fentanyl-induced cough (FIC) in the absence of a synergistic agent like midazolam.

Materials and Methods: This was a prospective, observer-blinded, randomized controlled trial. The study was initiated after obtaining the institutional ethics committee approval and is registered in the Clinical Trials Registry India. Eighty American Society of Anesthesiology Physical Status I and II patients, of either sex, aged between 18 and 55 years, and scheduled for elective surgeries under general anesthesia were randomized into two equal groups. Patients allocated to Group I (auto-coinduction) received 20% of the calculated dose of injection propofol 2 mg/kg (i.e., 0.4 mg/kg) as the priming dose followed by injection fentanyl 1 μg/kg after 1 min and the remaining propofol was administered in titrated doses till loss of verbal response after 2 min. In Group II (control), patients received injection fentanyl 1 μg/kg followed by single bolus dose of injection propofol up to 2 mg/kg till loss of verbal response. Midazolam was not used for premedication or induction. Intubation was carried out only after ensuring achievement of optimum depth of anesthesia using bispectral index scale. The total dose of propofol administrated for induction, occurrence of pain on injection, severity of cough after fentanyl administration, hemodynamic parameters, and apneic episodes were recorded.

Statistical Analysis: All data were expressed as mean ± 2 standard deviation. For statistical analysis, SPSS software version 16 (SPSS Inc., 2007, Chicago, IL, USA) was used.

Results: The mean dose of injection propofol required for induction was significantly lower in Group I (67.0 ± 17.9 mg) when compared with Group II (111.3 ± 17.6 mg) ( P < 0.01). The mean heart rate was significantly higher ( P < 0.01) and the mean blood pressure was significantly lower in Group II ( P < 0.01) when compared to Group I at 1 min postinduction, immediately after intubation, and 5 min after induction. The incidence of complications such as hypotension, pain on injection, and FIC was higher in Group II (50%) as compared to Group I (18%).

Conclusion: In our study, we found that the induction dose requirement of propofol was significantly lower in the auto-coinduction group when compared to the conventional induction group. The auto-coinduction technique offered a stable hemodynamic profile, reduced pain on injection, and less incidence of FIC as compared to the conventional propofol induction technique.