Unilateral supraglottic edema after the use of a laryngeal mask airway

Lower cuff pressures improve the seal of pediatric laryngeal mask airways

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Laryngeal edema associated with the ProSeal laryngeal mask airway in upper respiratory tract infection

PURPOSE

We report an unusual case of vocal cord edema associated with the use of a ProSeal laryngeal mask airway (PLMA) in an adult patient with an undiagnosed upper respiratory tract infection (URTI).

CLINICAL FEATURES

A 55-yr-old woman had fixation of a radial fracture under general anesthesia with muscle relaxation. She developed audible wheezing 30 min after PLMA insertion. Bronchoscopic examination revealed significant vocal cord edema. Adequate ventilation was possible at increased airway pressures, and the administration of dexamethasone 4 mg iv produced clinical resolution of the stridor and airway obstruction. The patient admitted to having mild symptoms of an URTI on postoperative questioning.

CONCLUSION

Airway hyperreactivity secondary to the URTI is the most likely etiological factor; other possibilities include trauma from insertion and chemical irritation. Although pediatric studies suggest that the LMA-Classic carries less risk than endotracheal intubation in the presence of URTI, this case report demonstrates that caution is still warranted when using supraglottic airways. The PLMA permitted effective ventilation despite increased airway resistance; nevertheless its role in patients with URTI is unclear. It is possible that the bulkier cuff design of the PLMA, compared to that of the LMA-Classic, may have partly contributed to the development of edema in this setting.