Permissive Hypercapnia and Risk for Brain Injury and Developmental Impairment

Abstract

Objective-Permissive hypercapnia is a respiratory care strategy used to reduce the risk of lung injury. The goal of this study was to evaluate whether permissive hypercapnia is associated with higher risk for intraventricular hemorrhage (IVH) and early childhood behavioral and functional problems than normocapnia among very low birthweight (VLBW) infants.Patients and Methods-VLBW infants from a statewide cohort were eligible for this study if they were born <32 weeks gestational age and survived at least 24 hours. Infants were classified as receiving a permissive hypercapnia (N=122), normocapnia (N=235), or unclassifiable (N=791) respiratory strategy during the first 24 hours after birth according to an algorithm based on PCO 2 values and respiratory treatment decisions abstracted from medical records. IVH diagnosis was also abstracted from the medical record. Behavioral and functional outcomes were assessed by parent interview at 2-3 years. Logistic regression was used to evaluate the relationship between IVH and respiratory strategy; ordinary linear regression was used to evaluate differences in behavior and function scores between children by respiratory strategy.Results-Infants who received a permissive hypercapnia strategy were not more likely to have IVH than those with normocapnia (odds ratio=1.0, 95% confidence interval: 0.59, 1.8). There were no differences in any of the behavioral or functional scores between children by respiratory strategy. There was a significant interaction between care strategy and one-minute Apgar score, indicating that infants with lower Apgar scores may be at higher risk for IVH with permissive hypercapnia.Conclusion-This study suggests permissive hypercapnia does not increase risk for brain injury and impairment among VLBW children. The interaction between respiratory strategy and Apgar score is a potential worrisome exception to this conclusion. Future research should further evaluate the effect of elevated PCO 2 levels among those sickest at birth. KeywordsPermissive hypercapnia; developmental follow-up; intraventricular hemorrhage; VLBW-very low birthweight Very low birthweight (VLBW, <1500g) infants are often premature with incompletely developed respiratory systems, and most require respiratory assistance for survival. Despite the suggested benefit of permissive hypercapnia for decreasing risk of BPD, it is not well understood whether it is associated with risk of brain injury, such as intraventricular hemorrhage (IVH), and subsequent developmental impairment. IVH was evaluated as a secondary outcome in two clinical trials of permissive hypercapnia. 5,6 Neither trial found any relationship between permissive hypercapnia and risk of IVH, but the first 5 had a small sample size (n=49) and the second 6 was terminated early with a smaller than planned sample (n=220). A trial that targeted even higher PaCO 2 levels found that, at 18-22 months, children in this minimal ventilation group had worse scores on the Bayley mental developmental index than children randomized t...

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Permissive Hypercapnia in the Management of Congenital Diaphragmatic Hernia: Our Institutional Experience

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Newborn blood gas derangements of children born extremely preterm and neurocognitive dysfunctions at age 10 years

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