Ventilatory and arousal responses to respiratory stimuli of full term, intrauterine growth restricted lambs

We aimed to determine the effect of intrauterine growth restriction (IUGR) on the control of breathing and arousal in sleeping postnatal animals. We measured ventilatory and arousal responses to respiratory challenges during sleep in normally grown (birthweight 5.17 +/- 0.48 kg) and IUGR (2.64 +/- 0.19 kg) full term lambs. During wakefulness, IUGR lambs had significantly lower arterial pH and higher Pa-CO2 levels. During quiet sleep, but not active sleep, end tidal CO2 was elevated in IUGR lambs (P = 0.08). During active and quiet sleep, minute ventilation (per kg body weight) was significantly higher in IUGR lambs than controls. Ventilatory responses to hypercapnia and/or hypoxia were not different between control and IUGR lambs during active and quiet sleep but end tidal CO2 at arousal was consistently higher in IUGR lambs; other indices of arousal were not affected by IUGR. Our findings suggest IUGR lambs require an elevated level of ventilation to maintain respiratory homeostasis and that alterations in lung function are likely consequences of IUGR. (C) 2001 Elsevier Science B.V. All rights reserved.