Influence of different head and neck positions on performance characteristics of second generation supraglottic airway devices

Background: Various head and neck positions alter the performance of supraglottic airway devices (SAD). We compared the influence of flexion, extension, neutral and rotation of the neck on performance characteristics of second generation airway devices namely Proseal (PLMA), i-gel and Auragain laryngeal mask. Methods: This study was conducted in 90 ASA physical status I and II patients 18-65 years of age. Patients were randomised into three groups with 30 patients in each: PLMA, i-gel and Auragain. The primary objective was to compare oropharyngeal leak pressure (OPLP) among PLMA, i-gel and Auragain in neutral, flexion, extension and lateral rotation of the neck. The secondary objective was to compare Peak inspiratory pressure (PIP), ventilation score, expired tidal volume, fiberoptic grading of laryngeal view, end tidal carbon dioxide and OPLP-PIP difference. Results: PLMA, i-gel and Auragain have the highest OPLP in flexion (34.4 +/- 2.5, 31.6 +/- 2.3, 32.8 +/- 1.7) followed by neutral, left lateral rotation and lowest in extension (26.7 +/- 1.6, 25.4 +/- 3.19, 29.6 +/- 1.0) respectively. PLMA and Auragain have significantly higher OPLP when compared to i-gel in all positions p < 0.05. In extension, OPLP with Auragain (29.6 + 1.0) was significantly higher than PLMA (26.7 + 1.6) and i-gel (25.4 + 3.1), p < 0.001. PIP was significantly higher in flexion position for all the three devices. No significant difference in fibre optic grading and ventilation score was seen for three devices in various neck positions. Conclusions: PLMA and Auragain have better sealing pressure than i-gel in all the positions. Flexion position during surgery is best for maintaining OPLP. Auragain should be preferred over PLMA and i-gel in surgeries involving extension of neck.