Pain on Injection of MCT/LCT Preparations of Propofol and Etomidate: A Double-blind Randomised Comparative Study

Abstract

Introduction: Propofol and etomidate are both very popular in routine practice as they have very rapid onset and offset of action when used as intravenous agents. Both these drugs have newer Medium Chain Triglyceride and Long Chain Triglyceride (MCT/LCT) preparations, which claim to decrease pain on injection. Aim: This study compared the pain on injection of etomidate and propofol when administered simultaneously in both the arms of same patients to avoid any subjective variation of pain sensation of the patients. Materials and Methods: Sixty five patients (i.e., total study arm is 130) were randomly selected, in between the age of 18 to 60 years, with American Society of Anaesthesiologists (ASA) physical status I or II, posted for elective surgical procedure under general anaesthesia for this study. Each subject received 5 mL of propofol-MCT/LCT i.v. through either right or left arm and simultaneously 5 mL of etomidate-MCT/LCT through the other arm. The incidence of pain on injection was observed on a 4 point rating scale (0-3) based on severity as well as haemodynamic variables in terms of systolic, diastolic and mean blood pressure at time of injection, at laryngoscopy and at intubation. The patients were also observed for any side effects. Results: Of the 65 patients 37 were males and 28 females. The average age of the patients was 35.1±10.7 years. Propofol-MCT/ LCT administration was associated with pain in 40.0% patients (Grade 1-35.4%, Grade 2-4.6%), whereas etomidate-MCT/LCT administration was associated with only Grade 1 pain in 9.2% of patients. The mean pain score with propofol administration was significantly more than etomidate administration (0.45 vs 0.09; p-value<0.001). There was significant increase in systolic, diastolic as well as mean blood pressure during laryngosopy and intubation compared to their baseline values (p<0.01). Myoclonus was observed in 19 patients (29.23%). Conclusion: To conclude, MCT/LCT preparations of propofol causes significantly more pain than MCT/LCT preparation of etomidate without any subjective variation.

Keywords

• general anaesthesia
• induction agents
• intravenous
• pain score