Hypocarbia during the First 24 Postnatal Hours and White Matter Echolucencies in Newborns ≤28 Weeks Gestation

Abstract

The purpose of the present study was to test the hypothesis that newborns Յ28 wk gestation who have a Pco 2 measurement in the lowest gestational age-specific quartile (hypocarbia) on the first day of life are not at increased risk for ultrasonographic white matter echolucency (EL) after adjustment for confounders. The sample consisted of 799 infants Յ28 wk gestation born during 1991-1993. Forty-eight infants with EL were classified as cases and compared with 751 controls, i.e. those without EL. We performed univariable comparisons, stratified analyses, and multivariable logistic regression. In the univariable analyses, hypocarbia on the first day of life was associated with an increased EL risk. The odds ratios for the hypocarbia-EL relationship were prominently elevated in the strata of infants who did not have other major risk factors for EL (e.g. gestational age 26 -28 wk, normothyroxinemia, no characteristics of antenatal infection). In the multivariable analyses, the association diminished after adjustment with a hypocarbia propensity score (odds ratio ϭ 1.7; 95% confidence interval, 0.8 -3.2) or with potential confounders. White matter EL predicts spastic cerebral palsy among preterm very-low-birth-weight infants (1-3). Among the risk factors we previously found for EL are subnormal neonatal thyroid hormone levels (4), absence of antenatal exposure to corticosteroid (5), and inflammation of the fetal vessels in the chorionic plate or umbilical cord (fetal vasculitis) (6). Although hypoxia-ischemia is a causative factor in controlled experimental settings (7,8), its role as a risk factor for EL in preterm infants is less clear (9).Extremely low carbon dioxide levels appear to be associated with an increased risk for ultrasound-defined WMD (10 -15) and cerebral palsy (16,17). Many of these studies, however, suffer from small numbers and/or the lack of adjustment for potential confounders in multivariable analyses. In the present study, we compared the occurrence of hypocarbia among 48 infants with ultrasonographic EL to that among 751 infants who did not have EL. Our study has the advantages of large size (n ϭ 799), detailed high-quality data about outcome and many antecedents, and the use of a propensity score to adjust for antecedents of hypocarbia. METHODSPermission. The present study was approved by the Institutional Review Boards of all participating centers. Written informed consent was obtained before enrollment of an infant was initiated.Sample. The multicenter cohort that provided the study population for these analyses enrolled 1607 very-low-birthweight infants (500 -1500 g) born January 1, 1991 through December 31, 1993 at five medical centers in the cities of

Hypocapnia and Other Ventilation-Related Risk Factors for Cerebral Palsy in Low Birth Weight Infants

“…In none of these studies were cohorts larger than 300 infants studied. In the only large cohort study to date, Damman et al (32) found among 799 Ͻ28-wk infants that first-day PaCO 2 values in the lowest quartile were predictive of white matter echolucencies, although multivariate significance was not attained.…”

Periventricular leucomalacia: a review

“…Vasoconstriction induced by hypocarbia would have a similar effect. Although the effect of hypocarbia on brain damage has been confirmed in clinical studies, such an association has not been shown in the case of hypotension [10,14,16].…”

Timing of Neutrophil Depletion Influences Long-Term Neuroprotection in Neonatal Rat Hypoxic-Ischemic Brain Injury

“…Mice deficient in key adhesion molecules are protected from ischemic injury (61,62). Dammann and Leviton (63) have proposed that proinflammatory cytokines might be the link between prenatal intrauterine infection and neonatal brain damage, although there is also strong support of an ischemic component to the pathogenesis of PVL (58,64). We speculate that activated neutrophil-endothelial interactions could be enhanced by both components, linking inflammatory cytokines with hypoperfusion mechanistically in a common pathway toward "vascular failure" in the pathogenesis of PVL.…”