Leak during Manual Neonatal Ventilation and Its Effect on the Delivered Pressures and Volumes: An in vitro Study

Background: Mask leak is a frequent problem during manual ventilation. Our aim was to investigate the effect of predefined leaks on delivered peak inflation pressure (PIP), positive end-expiratory pressure (PEEP) and tidal volume (V-t) when using different neonatal manual ventilation devices. Methods: A neonatal-lung model was ventilated at different respiratory rates (RRs, 40, 60, 80/min) using a mechanically operated self-inflating bag (SIB) and a manually operated T-piece resuscitator (PIP = 20 cm H2O, PEEP = 5 cm H2O). Four open tubes of different lengths, which produced up to 90% leak, were consecutively attached between the ventilation device and the lung model. A pneumotachograph was used to measure pressures, flow and volume. Results: With increasing leak (0-90%) PIP and PEEP decreased significantly (p < 0.001) for both devices. Using the SIB, the mean +/- SD PIP fell from 20.1 +/- 0.3 to 15.9 8 7 cm H2O and PEEP fell from 5.0 +/- 0 to 0.3 +/- 0.5 cm H2O, leading to an increased pressure difference (Delta p); V-t increased from 8.8 +/- 0.7 to 11.1 +/- 0.8 ml (p < 0.001). With increasing RRs, the leak-dependent changes were significantly lower (p < 0.001). Using the T-piece resuscitator, PIP dropped independent of RRs from 20.3 +/- 0.5 to 18.5 +/- 0.6 cm H2O and PEEP from 5.1 +/- 0.4 to 4.0 +/- 0 cm H2O, while Delta p and V-t did not differ significantly. Conclusion: The decrease in PIP and PEEP with increasing leak is RR dependent and distinctly higher when using an SIB compared to a T-piece device. In contrast to V-t delivered with the SIB, V-t delivered by the T-piece resuscitator was nearly constant even for leaks up to 90%. Copyright (c) 2012 S. Karger AG, Basel