Ventilatory responsiveness to progressive asphyxia during sleep in newborn lambs: effects of maternal anemia during pregnancy.
Our aim was to determine the effects of intrauterine compromise, induced by maternal anemia, on ventilatory responsiveness of the sleeping newborn to progressive asphyxia. We induced anemia in 6 sheep for the final third of pregnancy and studied their offspring for 2-3 weeks after birth. Lambs from anemic ewes were growth-restricted at birth; they and 6 control lambs were chronically instrumented soon after birth and underwent studies during which we determined ventilatory and arousal responsiveness to a progressive asphyxic stimulus during sleep. During quiet wakefulness, active sleep and quiet sleep, lambs from anemic ewes had elevated end-tidal CO2 levels (FECO2,%) compared to controls. Ventilatory responsiveness (i.e., gradient of relationship between minute ventilation and FECO2) was greater in quiet sleep than in active sleep for both groups of lambs but did not differ between the two groups in either active or quiet sleep. Lambs from anemic ewes had significantly higher FECO2 values than controls before arousing from either active or quiet sleep. Other indices of arousability (time to arousal, percent hemoglobin saturation at arousal) were not different between the two groups. Our results indicate that prenatal exposure to maternal anemia induces fetal growth restriction and elevates the CO2 'set-point' for normal ventilation. It does not, however, produce significant abnormalities in ventilatory responsiveness to progressive asphyxia during sleep.
Moss
T J
TJ
Department of Physiology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia. tmoss@cyllene.uwa.edu.au
Harding
R
R
D000740:Anemia / Q000378:metabolism; D000818:Animals; D001238:Asphyxia Neonatorum / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D002245:Carbon Dioxide / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D010092:Oximetry; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000378:metabolism; D011297:Prenatal Exposure Delayed Effects; D012121:Respiration, Artificial; D012756:Sheep; D013398:Sudden Infant Death / Q000209:etiology*
D002245:Carbon Dioxide