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Keywords:

  • pediatric anesthesia;
  • laryngeal mask airway;
  • airway complication;
  • cuff pressure;
  • manometer

Summary

Background:  Optimal inflation of the laryngeal mask airway (LMA) cuff should allow ventilation with low leakage volumes and minimal airway morbidity. Manufacturer’s recommendations vary, and clinical end-points have been shown to be associated with cuff hyperinflation and increased leak around the LMA. However, measurement of the intra-cuff pressure of the LMA is not routine in most pediatric institutions, and the optimal intra-cuff pressure in the LMA has not been determined in clinical studies.

Methods:  This was a prospective audit in100 pediatric patients undergoing elective general anesthesia breathing spontaneously via LMA (size 1.5–3). Cuff pressure within the LMA was adjusted using a calibrated pressure gauge to three different values (60, 40, and 20 cmH2O) within the manufacturers’ recommended LMA cuff pressure range (≤60 cmH2O). Three corresponding inspiratory and expiratory tidal volumes were recorded, and the differences were calculated as the ‘leak volume’.

Results:  Compared with 20 and 60 cmH2O intra-cuff pressure, measured leakage volumes were the lowest at cuff inflation pressures of 40 cmH2O [median (range) 0.42 (0.09–1.00) ml·kg−1] in most patients (83%), while 17% of children demonstrated minimally smaller leakages at 20 cmH2O [0.51 (0.11–1.79) ml·kg−1]. Maximum leakage values occurred with cuff pressures of 60 cmH2O in all groups [0.65 (0.18–1.27) ml·kg−1] and were not associated with the smallest value of air leakage in any patient.

Conclusion:  Using cuff manometry, an intra-cuff pressure of 40 cmH2O was associated with reduced leak around the LMA while higher (60 cmH2O) and lower (20 cmH2O) cuff pressures resulted in higher leak volumes during spontaneous ventilation. In spontaneously breathing children, reducing the intra-cuff pressure of pediatric-sized LMAs even below the manufacturers’ recommendations allows ventilation with minimized leakage around the LMA cuff.