47 PROGNOSTIC VALUE OF CEREBRO-VASCULAR CO2-REACTIVITY IN PREMATURE INFANTS

Abstract

Studies in animals and human adults have shown that ischemic brain lesions are associated with dysregulation of cerebral blood flow (CBF) and loss of pCO2-reactivity. We measured CBF by means of the iv Xe-133 method in 60 premature babies at days 1, 3 and 7, and asked whether (i) changes in arterial pCO2 might influence CBF, and (ii) whether periventricular leukomalacia (PVL) might impair CO2-reactivity. Patients: birthweight 1072 ± 156 g, gestational age 29.1± 2.1 wk. US was normal in 17 (28%), 14 (23%) had subependymal (SEH), and 11 (18%) intraventricular (IVH) hemorrhage; 10 (17%) had increased parenchymal echodensities (IPE), and 8 (13%) cystic PVL. In normal babies and those with SEH/IVH only, a positive correlation between pCO2 and CBF was found on day 3 (r = 0. 49, p<0.01, n=29); multiple regression showed that the influence of pCO2 was significant and independent of Hkt, MABP and [HbF] at all days. The CO2-reactivity (Δ %CBF/ΔmmHg pCO2) was measured in 12 infants of this US-group. Mean: +3.47%/mmHg. In infants with IPE/PVL, CBF was not correlated with pCO2 and mean CO2-reactivity significantly reduced to -0.85% (p < 0.0001). Thus, normal babies and those with SEH/IVH only, have a CO2-reactivity comparable to normal adults. Infants with IPE/PVL show dysregulation of CBF with loss of CO2-reactivity before brain lesions can be visualized by means of US, Supp: NF 3.894.