Lower cuff pressures improve the seal of pediatric laryngeal mask airways

Hyperinflation of laryngeal mask airway (LMA) cuffs may be harmful because of the exertion of high pressures on pharyngeal and laryngeal structures. Although cuff manometers may be used to monitor cuff pressure, their use is not routine in many institutions and clinical endpoints are used instead. Furthermore, it is common clinical practice to add air to the cuff in the presence of an air leak to obtain a better seal.

In a prospective audit, the authors assessed air leakage around pediatric sized LMAs (n = 200) following inflation guided by common clinical endpoints (slight outward movement of the LMA) and then following adjustment of the cuff pressure to the recommended pressure range (<60 cmH(2)O) according to institutional guidelines with the use of a calibrated cuff manometer, directly after induction of anesthesia. Following induction, all children were gently ventilated with pressure control ventilation with 10 cmH(2)O and a positive end-expiratory pressure of 5 cmH(2)O.

Following inflation of the cuff guided by clinical endpoints, the median initial cuff pressure (LMA size 1-3) was 92 (size 3) to >120 cmH(2)O (size 1) and the median leakage around the cuff ranged from 0.66 to 1.07 ml x kg(-1). Following cuff pressure adjustment according to the recommended pressure range (<60 cmH(2)O), the leakage decreased significantly to 0.51-0.79 ml x kg(-1) (P = 0.002 for size 1, P < 0.001 for size 1.5-3).

The use of clinical endpoints to inflate LMA cuffs is not only associated with significant hyperinflation in the majority of patients but also with an increased leakage around the LMA cuff when compared with adjusted LMA cuff pressures. Therefore, cuff manometers should routinely be used not only to avoid unnecessary hyperinflation but also to improve cuff sealing of LMA in children.