A Comparative Study for Ease of Insertion of Laryngeal Mask Airway with Propofol and Thiopentone Sodium

Background: The laryngeal mask airway (LMA) is a new form of airway which is introduced blindly into the hypo pharynx to form a seal around the larynx. Insertion of this LMA requires an adequate depth of anaesthesia, as the device is bulky and cannot be inserted unless jaw and pharynx are fully relaxed. The choice of the intravenous induction agent will influence the intubating conditions depending on its ability of obtunding the pharyngeal and laryngeal reflexes. This study was done to compare the conditions for insertion of LMA with thiopentone with fentanyl and propofol. Materials and methods: This was a randomised prospective comparative study in which 100 adults scheduled for elective procedures under general anaesthesia were allocated to one of two groups. Patients were divided into two groups of 50 in each. Results: The overall ease for insertion of LMA in thiopentone and fentanyl group was 92% and propofol group was 100% group (p< 0.05). Mouth opening and jaw relaxation were excellent in both the groups (p=1). Swallowing was present in 10% of patients in thiopentone group (p< 0.05). Conclusion: Intravenous propofol has been the preferred induction agent for LMA insertion till date. It provides smooth induction with depression of airway reflexes, allowing easier insertion of LMA with a reduced incidence of side effects such as coughing, gagging or laryngospasm. Thiopentone is easily available and commonly used compared to propofol (which is costly) in our rural setup. Induction of anaesthesia with propofol is associated with several side effects, including pain on injection, myoclonus, apnoea, hypotension, anaphylactic reaction and rarely, thrombophlebitis of the vein into which propofol is injected. Thiopentone sodium with fentanyl does increase the depth of anaesthesia to facilitate smooth insertion of LMA with minimum side effects.