Metabolic acidosis rather than hypo/hypercapnia in the first 72 hours of life associated with intraventricular hemorrhage in preterm neonates

Abstract

Aim

Safe limits of arterial partial pressure of carbon dioxide (PaCO₂) and acidosis in premature infants are not well defined. Both respiratory and systemic illness along with center-specific ventilation strategies contribute to PaCO₂ fluctuations and acid–base imbalances during the critical time period of first 72 h of life. This study evaluated the association between early blood gas parameters and intraventricular hemorrhage (IVH) in preterm infants.

Methods

This retrospective observational study included neonates with a gestational age (GA) of ≤29 wks, who had at least 7 blood gas analysis done within the first 72 h of life. By adjusting for known variables that predispose to IVH, multivariable logistic regression analysis was used to study the association of PaCO₂ and acid–base measures with the risk of IVH.

Results

Between 2013–2016, among 272 neonates who met inclusion criteria and were assessed for IVH on cranial ultrasound within first week of life, 101 neonates [mean GA of 25 ± 1.5 wks] had IVH and 171 neonates [mean GA of 25 ± 1.6 wks] had normal scans. After adjustment for confounding variables, higher values of maximum lactate (OR = 1.18, 95% CI = 1.1–1.3, p < .0001) and maximum base deficit (OR = 1.19, 95% CI = 1.1–1.2, p < .0001) within 72 h of life increased the likelihood of any grade of IVH. However, time-weighted average PaCO₂, maximum and minimum PaCO₂ had no statistically significant effect on the risk of IVH. The relationship remained unchanged even when moderate–severe IVH was considered as the primary outcome.

Conclusion

Severe metabolic acidosis rather than hypo/hypercapnia during the first 72 h of life was associated with higher odds of IVH in infants born at ≤29 wks of gestation. Future studies determining levels of PaCO₂ that is safe for premature brain would need to control for the metabolic component of acidosis.

Keywords:

• Acute brain injury
• blood gas
• carbon dioxide
• extreme prematurity
• intraventricular hemorrhage
• metabolic acidosis

Disclosure statement

No potential conflict of interest was reported by the authors.