Changing gas flow during neonatal resuscitation: a manikin study.

INTRODUCTION: When using a T-piece device, resuscitators may try to improve airway pressures by increasing gas flow instead of correcting face mask position.

AIM: To measure the effects of changing gas flow during positive pressure ventilation (PPV) on peak inspiratory pressure (PIP), positive end expiratory pressure (PEEP), expiratory tidal volume (V(Te)) and mask leak.

METHODS: Using a Neopuff T-piece device, 20 neonatal staff members delivered PPV to a modified, leak-free manikin. Resuscitation parameters were recorded. Study A: PPV for 4 min at PIP 30 cm H(2)O and PEEP 5 cm H(2)O. Each minute gas flow was increased (5, 8, 10, and 15 L/min). PIP and PEEP settings were unchanged. Study B: same pressure settings; PPV for 1 min with 5, 8, 10, and 15 L/min in a random order, at a rate of ∼ 60/min. The pressures were adjusted to maintain the same PIP and PEEP after each flow change.

RESULTS: Study A: As gas flow increased (5, 8, 10 and 15 L/min) the median PEEP increased from 4.7 to 26.4 cm H(2)O (p<0.002). Median V(Te) decreased from 10.0 to 0.8 mL (p<0.001). PIP increased slightly from 30 cm H(2)O to 36 cm H(2)O at 15 L/min (p<0.005). Mask leak increased from 14% to 98% (p<0.001) because mask pressure increased. Study B: when PIP and PEEP were maintained there were no significant differences in V(Te) (p=0.42) or mask leak (p=0.51) with changing gas flow.

CONCLUSION: During PPV increasing gas flow dramatically increased PEEP and mask leak and in consequence reduced V(Te). Gas flow should rarely be changed during T-piece resuscitation.