Heart rate changes during resuscitation of newly born infants <30 weeks gestation: an observational study

The International Liaison Committee on Resuscitation recommends starting positive pressure ventilation (PPV) in the delivery room when heart rate (HR) <100 beats per min (bpm) and giving cardiac compressions when HR <60 bpm.

To describe the effect of PPV on HR in infants <30 weeks gestation with HR <100 bpm in the first minutes after birth.

Retrospective observational study of infants, <30 weeks gestation, born between 14 February 2007 and 28 February 2009 with HR <100 bpm soon after birth.

Infants with a HR <100 bpm receiving PPV at birth were eligible for the study. Video recordings and respiratory physiological data were obtained during delivery room resuscitation and analysed to determine if the rate of change in HR varied with measures of PPV, for example, expiratory tidal volume.

It took a median (IQR) 73 (24-165) seconds of PPV for infants' HR to rise above 100 bpm and a median (IQR) 243 (191-351) seconds to rise above 120 bpm. There were large fluctuations in HR after reaching 100 bpm and before reaching 120 bpm. In 18/27 (67%) of infants the HR did not remain stable until a threshold of approximately 150 bpm was reached. In 6/27 (20%) of the infants the rise in HR was almost instantaneous. In the remaining 21/27 (80%) HR rise was more gradual. There was a poor correlation between time of HR increase to 120 bpm and tidal volume (p=0.13).

It takes more than a minute for newly born infants <30 weeks gestation with a HR <100 bpm to achieve a HR above 100 bpm. In these infants HR does not stabilise until it reaches 120 bpm.