Stability of the LMA-ProSeal® and standard laryngeal mask airway in different head and neck positions:: a randomized crossover study

Background and objective: The LMA-ProSeal(R) laryngeal mask airway is a new laryngeal mask airway with a modified cuff and drainage tube. We compared oropharyngeal leak pressure, intracuff pressure and anatomical position (assessed fibreoptically) for the Size 5 LMA-ProSeal(R) laryngeal mask airway and the classic laryngeal mask airway in different head-neck positions and using different intracuff inflation volumes. Methods: Thirty paralysed anaesthetized adult male patients were studied. The LMA-ProSeal(R) laryngeal mask airway and the classic laryngeal mask airway were inserted into each patient in random order. The oropharyngeal leak pressure, intracuff pressure, and anatomical position of the airway tube and drainage tube (LMA-ProSeal(R) laryngeal mask airway only) were documented in four head and neck positions (neutral first, then flexion, extension and rotation in random order), and at 0-40 mL cuff volumes in the neutral position in 10 mL increments. Results: Compared with the neutral position, the oropharyngeal leak pressure for both the LMA-ProSeal(R) laryngeal mask airway and the classic laryngeal mask airway was higher in flexion and rotation (all P less than or equal to 0.02), but lower in extension (all P less than or equal to 0.01). Changes in head-neck position did not alter the anatomical position of the airway tube or the drainage tube. The oropharyngeal leak pressure was always higher for the LMA-ProSeal(R) laryngeal mask airway (all P less than or equal to 0.005) and anatomical position better for the classic laryngeal mask airway (all P less than or equal to 0.04). Conclusions: The anatomical position of the LMA-ProSeal(R) and the classic laryngeal mask airway is stable in different head-neck positions, but head-neck flexion and rotation are associated with an increase, and head-neck extension a decrease, in oropharyngeal leak pressure and intracuff pressure. The Size 5 LMA-ProSeal(R) laryngeal mask airway is capable of forming a more effective seal than the Size 5 classic laryngeal mask airway in males.