Influence of Different Head and Neck Positions on Oropharyngeal Leak Pressure with the LMA Protector Airway: A Cross-over Study

Abstract

Introduction: The assessment of seal pressure or leak pressure in supraglottic devices has commonly been used to confirm device functionality and for research purposes regarding laryngeal mask airways (LMAs). When used for controlled ventilation, the LMA Protector provides a better oropharyngeal seal pressure. Materials and Methods: In this cross-over study, thirty-five patients of either sex, aged 18 to 70 years, American Society of Anaesthesiology (ASA) class I and II, with a weight range of 50-70 kg, scheduled for elective surgery under general anaesthesia where a supraglottic airway device was indicated, were enrolled. In all 35 patients, the position of the patient’s head and neck was changed from neutral to flexion, extension, and right and left lateral rotation. The primary objective of the study was to compare the differences in oropharyngeal leak pressure (OLP) with changes in head and neck positions using the LMA Protector airway device. Results: The mean age of the participants was 42.26 years, and the average weight was 63.34 kg. The LMA Protector was placed in 18 females and 17 males. A Mallampati grade of I was noted in 16 patients, while a grade of II was observed in 19 patients. The OLP achieved in this study was higher, providing adequate ventilation and oxygenation in all positions. The OLP and tidal volume in flexion were higher compared to the seal pressure in the neutral position (31.89 cm H2O, SD 5.080 cm H2O vs. 34.49 cm H2O, SD 4.804 cm H2O, p<0.05). No significant difference in OLP was observed when changing to different head positions, i.e., in extension, right lateral, and left lateral positions. Conclusion: The LMA Protector is an effective device in terms of achieving high oropharyngeal seal pressure. It produced better oropharyngeal seal pressure in the flexion position compared to the neutral position.

Keywords

• controlled ventilation
• extension
• flexion
• laryngeal mask airway
• peak pressure