Background: Facemask leak and airway obstruction are common during mask ventilation of newborn infants and can lead to ineffective resuscitation. Physiological instability has been reported at birth during newborn positive pressure ventilation (PPV) in 30-50% of infants. We aimed to study the quality of positive pressure ventilation (PPV) provided to preterm infants through respiratory function analysis, and its’ relationship with physiological stability.
Methods: This was an observational study of preterm infants (<33 weeks) undergoing semi-elective intubation in the Royal Women’s Hospital NICU between November 2015 and April 2017. All infants were administered muscle relaxants and sedation. Positive pressure ventilation episodes delivered before intubation, or between intubation attempts were analysed. Data were collected using a respiratory function monitor, pulse oximeter and video. Physiological instability was defined as bradycardia (heart rate <100 bpm) or desaturation (oxygen saturation <80%).
Results: 50 preterm infants were studied, with a median (IQR) birth gestation of 27 (25-29) weeks and birth weight of 949g (773-1214). Physiological instability occurred in 28/50 infants with a median (IQR) lowest oxygen saturation of 35% (25-58), compared to 92% (85-95) in the stable infants p<0.0001. The infants’ lowest oxygen saturation during PPV was weakly correlated with the mean facemask leak rs=-0.30 p=0.047. The lowest heart rate during PPV increased with increasing expired tidal volume (VTe) r=0.31 p=0.03. The mean VTe was also correlated with mean leak during PPV rs=-0.49 p<0.001.
Conclusions: Preterm infants frequently become physiologically unstable during neonatal facemask ventilation, even under controlled conditions. Facemask leak contributes to this instability.