Randomized evaluation of the size 2 laryngeal tube and classical laryngeal mask airway in different head and neck positions in children under positive pressure ventilation

The aim of this study was to evaluate the applicability of the laryngeal tube (LT) size 2 and the classical laryngeal mask airway (LMA) size 2 in different head-neck positions under positive pressure ventilation in children by measuring leak pressures, peak pressures and the achievable tidal volumes under positive pressure ventilation. Forty children were randomized to receive airway management by either the LT or LMA as the primary device. Leak pressures, peak pressures and tidal volumes under positive pressure ventilation were measured in the neutral, anteflection, retroversion, left-rotation and right-rotation head-neck positions. In all head-neck positions, the leak pressures were significantly higher for the LT than for the LMA (neutral 25.9 +/- A 7.0 vs. 19.1 +/- A 5.7 cmH(2)O; anteflection 29.7 +/- A 7.1 vs. 24.2 +/- A 8.9 cmH(2)O; retroversion 24.1 +/- A 7.6 vs. 17.2 +/- A 6.9 cmH(2)O). In both devices, the peak ventilation pressures were higher in the anteflection position (LT 27.1 +/- A 6.3 cmH(2)O; LMA 17.8 +/- A 6.7 cmH(2)O) than in the retroversion position (LT 13.7 +/- A 3.9 cmH(2)O; LMA 12.7 +/- A 3.6 cmH(2)O). Compared to the respirator settings, lower tidal volumes were achieved in the anteflection position (LT 65 +/- A 48 vs. 129 +/- A 38 ml, LMA 100 +/- A 21 vs. 125 +/- A 29 ml) as compared to the other positions. Based on our results, we suggest that in anaesthetized children, the size 2 LT, compared to the size 2 LMA, may be more suitable for positive pressure ventilation due to favorable leak and peak pressures. Both devices can be safely used in head-neck positions other than neutral. Most disadvantageous with regards to the measured parameters was the anteflection position, especially for the LT.