Abstract
The cardio-respiratory response to hypoxia is the subject of intense research in human infants, but is mostly limited to noninvasive studies. Animal investigation is an attractive alternative, but most animal studies have involved anesthetized or non-intact preparations, which may not reflect human physiology. The cardio-respiratory responses to hypoxia are not well documented in unanesthetized intact newborn animals. In particular, there is little information on the periodic breathing (PB) response to hypoxia and, hence, on the practicality of an animal model for PB.
We studied heart rate (HR) and respiratory responses during quiet sleep to 17% FlO2 in unanesthetized full-term newborns of five species; lamb, piglet, puppy, kitten, and rabbit (N=31). ECG, HR and respirogram monitoring was used. There was no significant change in mean HR and respiratory rate (RR) with hypoxia for any species. Brief apneas >5 sec. were frequent(5–8/hr) both in 21% and 17% O2, but only in lambs and puppies. No sustained periodic breathing was induced by hypoxia; although in three species, there was one brief episode.
We conclude that mild hypoxia has little effect on HR and RR in these unanesthetized newborns. Respiratory patterns showed some apneas in only two species, but these were not significantly affected by hypoxia. Periodic breathing was not frequent enough to make an animal model practicable. This may indicate considerable maturity of respiratory control in full-term newborns of these species.
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Finley, J., Kelly, C. & Goldbloom, R. 259 HEART BATE AND RESPIRATORY RESPONSES TO HYPOXIA IN UNANESTHETIZED NEWBORN MAMMALS. Pediatr Res 19, 154 (1985). https://doi.org/10.1203/00006450-198504000-00289
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DOI: https://doi.org/10.1203/00006450-198504000-00289