Frequency and severity of apnoea in lower respiratory tract infection in infancy.

Twenty four hour recordings of heart rate and respiration were made on 60 infants with lower respiratory tract infection (LRTI) during the acute phase of the illness, on 20 infants with upper respiratory tract infection (URTI) and on 21 control infants. Infants with LRTI and URTI had more apnoeic episodes of longer than 10 seconds compared with controls. The length of apnoeic episodes was greatest in the LRTI group but their frequency decreased with age. In both the LRTI and URTI groups apnoea was associated with bradycardia but the LRTI group also suffered an appreciable number of episodes of bradycardia without apnoea.