Efficacy of Priming Principle in Propofol Induction-A Randomised Controlled Trial

Priming refers to administration of a small calculated dose of a drug before giving the total induction dose. Priming principle is well-documented with the use of non-depolarising muscle relaxants. Over the years, propofol has emerged as an effective alternative to thiopentone for intravenous induction. Aim: To evaluate whether priming with propofol reduces the total induction dose of propofol. Materials and Methods: Fifty patients with American Society of Anaesthesiologists (ASA) I and II grades, aged 18-55 years, and undergoing elective surgical procedures under general anaesthesia were randomly allocated into two groups; with 25 patients each. Patients in Control Group (CG) received calculated induction dose of injection propofol 2 mg/kg whereas patients in Study Group (SG) received 20% of total calculated induction dose of propofol 2 mg/kg as a priming dose and remaining dose after 30 seconds titrated till the loss of the eyelash reflex. The total induction dose and the associated haemodynamic parameters were noted. The data thus obtained was then analysed using Chi-square test and Student’s t-test. Results: The CG required a higher dose of inj. propofol (2.15 mg/kg) as compared with the SG (1.77 mg/kg), i.e., there was 17.43% reduction of the total dose in the SG. The preoperative baseline vitals {Heart Rate (HR), Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Mean Arterial Pressure (MAP)} in both the groups were comparable. The changes in HR, at 1 minute and 3 minutes after induction were higher in CG than SG, which was statistically significant. The MAP at 1 minute and 3 minutes after induction was higher in SG than CG and was statistically significant. Conclusion: The priming principle when applied to induction with propofol reduces the total dose requirements of propofol and reduces the hypotension that it causes, thereby proving a stable haemodynamic state.