The laryngeal mask airway in infants and children

Purpose: To compare the effectiveness of various laryngeal mask airway (LMA ) sizes and their performance during positive pressure ventilation (PPV) in paralyzed pediatric patients. Methods: Pediatric patients (n = 158), < 30 kg, ASA 1 or 2 were studied. Af ter paralysis, an LMA of the recommended size was inserted and connected to a volume ventilator. Fibreoptic bronchoscopy (FOB) was performed and grade d: I, larynx only seen; 2, larynx and epiglottis posterior surface seen; 3, larynx. and epiglottis tip or anterior surface seen-visual obstruction of epiglottis to larynx: ( 50%; 4, epiglottis down-folded, and its anterior su rface seen-visual obstruction of epiglottis to larynx: > 50%; 5, epiglottis down-folded and larynx not seen directly. Inspiratory and expiratory tidal volumes (V-T), and airway pressure were measured by a pneumo-tachometer, a nd the fraction of leakage (F-L) was calculated. In 79 cases. LMA was used for airway maintenance throughout surgery. Results: Successful LMA placement was achieved in 98% of cases: three failu res were due to gastric insufflation. For FMA # 1, 1.5, 2, and 2.5, FOE gra des [median (range)] were 3(1-5), 3(1-5), 1(1-5) and 1(1-3) respectively, I n smaller LMAs, the cuff more frequently enclosed the epiglottis (P < .001) . F, of LMA # I was higher than those of LMA # 1.5 and LMA # 2.5 (P <less t han> .05), and F-L of LMA # 2 was higher than that of LMA # 2.5 (P (.05). I n the 79 patients, the number of patients experiencing complications decrea sed as LMA size increased (P < .05), Conclusion: Use of the LMA in smaller children results in more airway obstr uction, higher ventilatory pressures, larger inspiratory leak, and more com plications than in older children.