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

Abstract

SUMMARY 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.Lower respiratory tract infection (LRTI) is a common cause of hospital admission in children aged under 1 year. Apnoea has been noted in infants with severe respiratory tract infections' and also, in a retrospective survey, in those less severely affected.2 Apnoea in babies with LRTI may also be relevant in the sudden infant death syndrome. Upper and lower respiratory tract infection, not generally sufficiently severe to explain death, have been found at necropsy in infants found dead at home,3 4 and it has been suggested that minor respiratory illness may trigger sudden apnoea.5 6 We studied 3 groups of children; 1 group with LRTI, 1 group with upper respiratory tract infection (URTI), and 1 control group without respiratory disease to determine the incidence of apnoea. We aimed to establish whether apnoea occurred more frequently during severe illness, whether it was associated with bradycardia, and whether bradycardia occurred alone. Patients and methods Electrocardiographic tracings (ECG) and respiration were recorded over 24 hours on 101 infants. The LRTI group comprised 60 infants aged (mean ± SD) 16-3 ± 10.4 weeks and birthweight (mean ± SD) 2.9 + 0.7 kg. We did not distinguish between bronchitis, bronchiolitis, or bronchopneumonia.7 The URTI group comprised 20 infants aged (mean ± SD) 12.1 ± 6.2 weeks and birthweight (mean ± SD) 3.2 ± 0.5 kg. The 21 control infants studied were aged (mean ± SD) 12-1 ± 6.2 weeks and birthweight (mean ± SD) 2.9 ± 0 5 kg. In all cases a full history was obtained from parents and chest x-ray films were taken. In all the LRTI and URTI patients nasopharyngeal secretions were collected for bacterial culture and in 60% of these infants secretions were taken for viral studies.Impedance pneumography was used to monitor respiration. Changes in transthoracic electrical impedance produced a reliable record of respiration.8 9 In all infants respiration signals were obtained from 2 electrodes placed on opposite sides ofthe chest wall, and ECG from the same 2 electrodes and a reference electrode. The monitor system was a Healthdyne infant monitor fitted with a Medilog cassette recorder (Oxford Medical Systems). Two channels of the recording system were used for the respiration and ECG signal and a third channel for timing. The recordings on the patients with URTI and LRTI were taken when the illness was severe and the tapes were stored for analysis.

Sudden Infant Death Syndrome

“…As mentioned in the section on pathology respiratory syncytial virus, influenza and parainfluenza viruses have been isolated in significant numbers from SIDS infants. These viruses are recognized as being responsible for precipitating apnoeic attacks in infants (24). However as there is no evidence of viral infection in many SIDS infants, in particular the younger ones, viral induced apnoea does not appear to be the only mode of death of these infants.…”