Ventilatory responses preceding hypoxia-induced arousal in infants: effects of sleep-state.
Augmented ventilation and/or arousal in response to hypoxia are important protective mechanisms during sleep. We aimed to quantify ventilatory responses preceding hypoxia-induced arousal in infants and determine the effects of sleep-state. Fifteen term infants were studied at 2-4 weeks, 2-3 and 5-6 months of age. Ventilatory responses to 15% oxygen inhalation were expressed as breath-by-breath changes from normoxic levels and averaged over 5, 10 and 15 breaths preceding arousal. Minute ventilation preceding arousal significantly increased above normoxic levels only in AS at 5-6 months. There were no sleep-state related differences in minute ventilation, oxygen saturation or carbon dioxide levels (expressed as changes from normoxic values) at 5, 10 or 15 breaths preceding arousal. However, the rate of oxygen desaturation during hypoxia in AS was two to four times faster than in QS at each age. We conclude that the ventilatory responses preceding hypoxia-induced arousal do not differ between sleep-states and that arousal occurs at similar levels of desaturation in both states.
Parslow
Peter M
PM
Department of Paediatrics, Ritchie Centre for Baby Health Research, Monash University, Level 4, Monash Medical Centre, 246 Clayton Road, 3168, Vic., Clayton, Australia.
Harding
Richard
R
Cranage
Susan M
SM
Adamson
T Michael
TM
Horne
Rosemary S C
RS
D000375:Aging; D001143:Arousal / Q000502:physiology*; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000378:metabolism; D004569:Electroencephalography; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000502:physiology; D010313:Partial Pressure; D017286:Polysomnography / Q000379:methods; D011659:Pulmonary Gas Exchange; D011930:Reaction Time; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen