Article Text
Abstract
Aims: To test the hypothesis that apnoea of infancy (AOI) is due to a deficit in chemoreception.
Methods: Tests were performed on 112 infants: 43 healthy control infants, 28 infants with periodic breathing or central apnoea (PBCA), and 41 infants with obstructive apnoea (OA) on overnight polysomnography. Chemoreceptor responses to hypercapnia (4% and 6% CO2 in air) for 6–8 minutes and hyperoxia (100% O2) for 60 seconds were expressed in terms of response strength and reaction time. Age at birth (gestational week 37–41) and age at test (2–34 postnatal weeks) were comparable across groups (median, min–max value). A total of 70 CO2 and 71 O2 tests were analysed.
Results: The strongest and fastest CO2 responders were control infants: their median increase in ventilation was 291%/kPaCO2 and their reaction time 16 breaths. In infants with PBCA and OA, the increase in ventilation was 41% and 130%/kPaCO2, and reaction time 64 and 54 breaths, respectively. There was a significant negative correlation between CO2 response strength and response time. In response to hyperoxia there was a comparable decrease in ventilation in all infants (12–20%), but a significantly longer response time in infants with apnoea (20 v 12 breaths). There was no correlation between the response strength and response time to O2 and CO2.
Conclusion: An inappropriate central control of respiration is an important mechanism in the pathogenesis of apnoea of infancy.
- ALTE, apparent life threatening event
- AOI, apnoea of infancy
- CA, central apnoea
- OSA, obstructive sleep apnoea
- PB, periodic breathing
- PBCA, periodic breathing and central apnoea