Objective To measure tidal volumes (V_T) and describe the interactions between spontaneous breaths and positive pressure ventilation (PPV) inflations during stabilisation of preterm infants in the delivery room (DR). We used a respiratory function monitor (RFM) to evaluate the first 5 min of mask respiratory support provided to preterm infants.

Study design An observational study of infants <32 weeks gestation, born in a single tertiary perinatal centre receiving mask PPV in the DR. PPV was delivered with a round silicone facemask connected to a T-piece device and RFM. The RFM display was not visible to the resuscitator. Respiratory function parameters in the first 5 min after birth were analysed by breath-type (inflations, assisted inflations, spontaneous breaths between PPV, and breaths during continuous positive airway pressure (CPAP)). Parameters measured included V_T, peak inspiratory pressure, peak end expiratory pressure and mask leak.

Results A total of 2605 inflations and breaths from 29 subjects were analysed. Substantial leak was observed during all four breath types with median leaks ranging from 24% to 59%. Median tidal volumes were greater during inflations (8.3 ml/kg) and assisted inflations (9.3 ml/kg) than spontaneous breaths between PPV (3.2 ml/kg) and breaths during CPAP (3.3 ml/kg).

Conclusions Facemask leak is large during resuscitation of preterm infants using round silicone masks. Tidal volumes delivered during PPV inflations are much higher than those generated during spontaneous breathing by an infant on CPAP.