Bradycardia and associated respiratory changes in neonates.

Electrocardiogram and patterns of respiration were recorded continuously in 9 newborn infants having episodes of bradycardia. The episodes were not associated with demonstrable apnoea, either by using an apnoea mattress or by visual observation. The 'non-apnoea' associated bradycardia was always associated with changes in respiratory pattern, of which three different forms could be identified. These were prolonged apnoea if the apnoea alarm failed to trigger, short episodes of respiratory abnormalities associated with body movement (possibly in rapid eye movement sleep), and minor changes in respiratory pattern. It may be appropriate to incorporate a period of delay in heart rate monitoring systems before the alarm sounds, in a similar manner to apnoea alarm systems. We should rely more on heart rate in conjunction with apnoea alarms to detect problems, or produce better systems which detect respiratory flow.