Comparative Evaluation of Effective Dose 50 (ED 50) of Propofol in Adult Patients with Saline-Propofol, Dexmedetomidine-Propofol and Fentanyl - Propofol for Laryngeal Mask Airway Insertion

Abstract

Introduction: Propofol a short acting intravenous anaesthetic is widely used with various adjuncts to facilitate improved insertion conditions of Proseal Laryneal Mask Airway (PLMA). We compared the median effective dose (ED 50) propofol requirement and insertion conditions of PLMA with saline propofol, dexmedetomidine propofol and fentanyl propofol. Material and Methods: This was a prospective randomized double blind study conducted in 100 adult patients of American Society of Anaesthesiology (ASA) class I/II scheduled to undergo elective surgical procedures. They were randomly allocated into four groups of 25 each Group N normal saline, Group F1 fentanyl 1 mcg/kg, Group F2 fentanyl 2mcg/kg and Group D dexmedetomidine 1mcg/kg. The study drug was diluted in 50ml saline and infused over 10 minutes followed by a predetermined dose of propofol as per Dixon’s up and down method. The ease of PLMA insertion was assessed as per Muzi mouth opening score. Hemodynamic parameters were observed starting from baseline (T0), at 10 min post test drug infusion (T1), post propofol injection (T2), 1min post LMA insertion (T3) and till 3 minutes post LMA insertion (T4). Results: The ED50 of propofol for the insertion of PLMA with normal saline, fentanyl (1mcg/kg), fentanyl (2 mcg/kg) and dexmedetomidine (1mcg/kg) as adjuncts were found out to be 3.25mg/kg, 2mg/kg, and 1.67mg/kg and 1.92mg/kg respectively. PLMA insertion conditions and hemodynamic parameters were comparable between the four groups. Least incidence of apnoea was noted in group D with only 8 patients requiring assisted ventilation. Conclusion: Dexmedetomidine significantly reduces the requirement of induction dose propofol for PLMA insertion while providing stable hemodynamic and excellent insertion conditions.