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Published on: November 20, 2015
Permissive hypercapnia and risk for brain injury and developmental impairment
Erika W Hagen1, Mona Sadek-Badawi, David P Carlton
1University of Wisconsin, Department of Population Health Sciences, School of Medicine and Public Health, 610 Walnut St, WARF 662, Madison, WI 53726, USA. ewarkentien@wisc.edu
Insights
Permissive hypercapnia did not increase the risk of brain injury or behavioral issues in very low birth weight infants. However, infants with lower Apgar scores may face higher intraventricular hemorrhage risks with this respiratory strategy.
Area of Science:
- Neonatal care
- Pediatric neurology
- Respiratory medicine
Background:
- Permissive hypercapnia is a respiratory strategy to mitigate lung injury risk in premature infants.
- Intraventricular hemorrhage (IVH) and neurodevelopmental outcomes are critical concerns for very low birth weight (VLBW) infants.
Purpose of the Study:
- To investigate the association between permissive hypercapnia and the risk of IVH in VLBW infants.
- To assess the impact of permissive hypercapnia on early childhood behavioral and functional outcomes compared to normocapnia.
Main Methods:
- A statewide cohort of VLBW infants (<32 weeks gestational age) surviving >24 hours was analyzed.
- Infants were categorized by respiratory strategy (permissive hypercapnia, normocapnia) in the first 24 hours.
- IVH and parent-reported behavioral/functional outcomes at 2-3 years were assessed using medical records and interviews.
Main Results:
- Permissive hypercapnia was not associated with a higher likelihood of IVH compared to normocapnia.
- No significant differences in behavioral or functional scores were observed between the respiratory strategy groups.
- A significant interaction between respiratory strategy and 1-minute Apgar score suggested increased IVH risk in infants with lower Apgar scores under permissive hypercapnia.
Conclusions:
- Permissive hypercapnia appears safe regarding brain injury and impairment in VLBW infants.
- The interaction with Apgar score warrants further investigation, particularly for the sickest infants.
- Elevated PCO2 levels require continued study in critically ill newborns.
Objective:
Permissive hypercapnia is a respiratory-care strategy that is used to reduce the risk for lung injury. The goal of this study was to evaluate whether permissive hypercapnia is associated with higher risk for intraventricular hemorrhage and early childhood behavioral and functional problems than normocapnia among very low birth weight infants.
Methods:
Very low birth weight infants from a statewide cohort were eligible for this study when they were born at <32 weeks' gestational age and survived at least 24 hours. Infants were classified as receiving a permissive hypercapnia, normocapnia, or unclassifiable respiratory strategy during the first 24 hours after birth according to an algorithm based on Pco(2) values and respiratory-treatment decisions that were abstracted from medical charts. Intraventricular hemorrhage diagnosis was also abstracted from the medical chart. Behavioral and functional outcomes were assessed by parent interview at 2 to 3 years. Logistic regression was used to evaluate the relationship between intraventricular hemorrhage 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 intraventricular hemorrhage than those with normocapnia. There were no differences in any of the behavioral or functional scores among children according to respiratory strategy. There was a significant interaction between care strategy and 1-minute Apgar score, indicating that infants with lower Apgar scores may be at higher risk for intraventricular hemorrhage with permissive hypercapnia.
Conclusions:
This study suggests that permissive hypercapnia does not increase risk for brain injury and impairment among very low birth weight 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 who are sickest at birth.
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