The intubating laryngeal mask airway: Effect of handle elevation on efficacy of seal, fibreoptic position, blind intubation and airway protection

Abstract

We conducted three studies to test the hypothesis that elevation of the intubating laryngeal mask (ILM) handle increases efficacy of seal, changes fibreoptic position, prevents aspiration of regurgitated fluid and improves intubation. In study 1, the ILM was inserted into 20 paralysed, anaesthetized patients and 20 cadavers. Oropharyngeal leak pressure and fibreoptic position were measured at an intracuff pressure of 0, 60 and 120 cm H2O with 0, 20 and 40 N of elevation force. In study 2, the oesophageal pressure at which regurgitation and aspiration occurred was measured in 20 cadavers with the ILM at the above intracuff pressures and elevation forces and 20 cadavers without the ILM (controls). In study 3 ease of blind intubation (first attempt only) was determined in 20 paralysed, anaesthetized patients at 0 and 40 N elevation force. In study 1, there was a significant increase in oropharyngeal leak pressure with increasing elevation force at an intracuff pressure of 0 and 60 cm H2O. There were no changes in fibreoptic position. Oropharyngeal leak pressure and fibreoptic position were similar between patients and cadavers. In study 2, oesophageal pressure for regurgitation and aspiration was usually greater for the ILM than controls (all: P < 0.05. Aspiration and regurgitation usually occurred at the same oesophageal pressure. In study 3, blind intubation was more successful at 0 N than 40 N (15/20 v 8/20, P = 0.03). We conclude that elevation of the ILM handle has little clinical utility other than as a temporary measure to improve the efficacy of the seal.