Cardiorespiratory patterns occurring in infants during and after recovery from respiratory tract infection

During and after respiratory tract infections in 29 hospitalized infants, 12 cardiorespiratory measurements were performed on 24-hour recordings of ECG and respiratory activity. These measurements were compared with similar data obtained from 110 age-matched control infants without infection. Respiratory and heart rates during the state of regular breathing were increased during infection, as compared with recordings made after recovery. The numbers of short apneic pauses 3.6 to 6.0 seconds and greater than 6.0 to 12.0 seconds in duration, together with the duration of the overall longest apneic pause per recording, were reduced during infection compared with after recovery. The total durations of periodic breathing and of periodic apnea per recording were also reduced during infection compared with after recovery. These effects were consistent in 27 of the 29 cases, but in two, periodic breathing levels during infection exceeded the 90th percentile in age-matched controls and were reduced after recovery. Measurements made after recovery tended to conform more closely to values in the control infants. None of the 29 infants studied subsequently died or suffered chronic respiratory problems. This study suggests that prolonged apneic pauses or increased numbers of short pauses are not usually a consequence of respiratory tract infection in normal infants.