A Randomised Crossover Study Comparing The Disposable Laryngeal Mask Airway Supreme With The Laryngeal Mask Airway Proseal In Unparalysed Anaesthetised Patients

Abstract

Study Objective: To compare performance of the LMA Supreme and LMA ProSeal in unparalysed adult patients.Design: A randomised crossover study, using a non-inferiority study design aiming to demonstrate that first time insertion success rate with the LMA Supreme is no more than 15% lower than with the LMA ProSeal.Setting: Operating theatre.Patients: 50 ASA 1 or 2 adult patients undergoing general anaesthesia for elective surgery, without neuromuscular blocking agents. Interventions: After a standardised induction of anaesthesia and adequate jaw relaxation, the initial airway was inserted, in a randomized order. Adequate placement was confirmed by a square wave form on the capnograph. A maximum of two attempts was allowed. Measurements were taken before the device was removed and replaced by the second and the measurements repeated. Measurements: Number of insertion attempts with each device was recorded. Insertion time (from picking up the device until one complete capnograph square wave seen), oropharyngeal leak pressure, fibreoptic laryngeal view and ease of insertion and removal were recorded. Blood pressure, heart rate and oxygen saturations were recorded before and after insertion of each device.Main Results: First time insertion success rates were 88% (44/50) and 94% (47/50) (95% CI -19 to 7%) for the LMA Supreme and LMA ProSeal respectively. The lower limit of the 95% CI (-19%) lies outside the -15% limit of non-inferiority. Overall success was 96% (48/50) and 98% (49/50), (95% CI -12% to 7%), mean leak pressures were 22cmH2O and 26cmH2O (p=0.005) and insertion times were 23 and 26 seconds (p=0.198) for the LMA Supreme and LMA ProSeal respectively. There was no significant difference in the fibreoptic view obtained (p=0.086).Conclusions: We failed to demonstrate that the LMA Supreme is non-inferior to the LMA ProSeal in terms of its first time insertion success rate in unparalysed patients, and must conclude our results to be equivocal. This work was supported by Intavent Orthofix Ltd who donated all Laryngeal Mask Airways, free of charge.