Abstract

Electrocardiogram, heart rate, blood pressure, and pattern of respiration were recorded continuously in 8 newborn babies having apnoeic attacks. Apnoeic attacks usually occurred without any premonitory changes in respiration, heart rate, or blood pressure. The heart rate usually fell during an apneoic attack and did so after the onset of apnoea. The pulse pressure most commonly rose as the heart rate fell. If the pulse pressure did not rise as the heart rate fell, major resuscitative procedures were often required. A fall in pulse pressure during apnoeic attacks was only seen in severely ill babies and usually only shortly before they died.

It is suggested that the fall in heart rate during apnoea is the direct effect of hypoxia on the heart or a chemoreceptor reflex, and that the rise in pulse pressure is the result of increased filling volume in accordance with Starling's Law.