Effect of Varying Time Intervals Between Fentanyl and Propofol Administration on Propofol Requirement for Induction of Anesthesia - An Observational Study

Objective: The objective of the study is to determine the dose of propofol required for induction when fentanyl was administered just before, 3 min, and 5 min before propofol administration. Furthermore, to determine changes in heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP), when fentanyl was given at varying time intervals. Methods: A prospective observational study was conducted in a tertiary care teaching hospital for 12 months. A total of 150 patients belonging to ASA 1 and 2 in the age group of 18–60 years scheduled for elective surgery under general anesthesia were allocated into three groups. Group 1 received propofol immediately after a 2 mcg/kg fentanyl injection and Group 2 and Group 3 received propofol 3 and 5 min, respectively, after the administration of fentanyl. The total dose of propofol required for induction is noted. Heart rate, systolic, diastolic, and MAPs after induction were also noted. Data analysis was done using SPSS version 25. Results: All three groups were comparable concerning demographic variables. The total dose of propofol required for induction was highest in Group 1, where propofol was given immediately after fentanyl, followed by Group 2, and lowest in Group 3 where propofol was given 5 min after fentanyl. Fall in heart rate, SBP, DBP, and MAP after propofol administration was highest in Group 1, followed by Group 2, and least in Group 3 where fentanyl was administered 5 min before propofol. The results were statistically significant. Conclusion: Administering fentanyl 5 min before propofol causes a marked reduction in the dose requirement of propofol along with a significantly decreased incidence of hypotension after induction.