Abstract
Background:
Abnormal PCO2 is common in infants with hypoxic ischemic encephalopathy (HIE). The objective was to determine whether hypocapnia was independently associated with unfavorable outcome (death or severe neurodevelopmental disability at 18 mo) in infants with moderate-to-severe HIE.
Methods:
This was a post hoc analysis of the CoolCap Study in which infants were randomized to head cooling or standard care. Blood gases were measured at prespecified times after randomization. PCO2 and follow-up data were available for 196 of 234 infants. Analyses were performed to investigate the relationship between hypocapnia in the first 72 h after randomization and unfavorable outcome.
Results:
After adjusting for pH, amplitude-integrated electroencephalogram background and seizures, birth weight, Apgar score at 5 min, cooling status, and Sarnat stage, PCO2 was inversely associated with unfavorable outcome (P < 0.001). The probability of unfavorable outcome was 0.20 ± 0.1 (point estimate ± SE), 0.53 ± 0.23 and 0.89 ± 0.16 for a PCO2 of 40, 30, and 20 mm Hg respectively and was greater in infants with severe HIE than with moderate HIE.
Conclusions:
Hypocapnia in infants with moderate-to-severe HIE was independently associated with unfavorable outcome. Future studies of controlled normocapnia will be important.
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Acknowledgements
We thank the many technicians, nurses, physicians, and scientists in the participant sites who contributed to the development and implementation of the CoolCap Study, and the parents who consented to enrollment of their infants in the trial who trusted in us under conditions of great stress and anxiety. We thank the many charities and research funding agencies who supported the preliminary research necessary for the study. The original study was designed by and was the responsibility of the Scientific Advisory Committee (SAC), who had full access to the trial data, and after reading and editing this manuscript, approved the final draft for submission.
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Lingappan, K., Kaiser, J., Srinivasan, C. et al. Relationship between PCO2 and unfavorable outcome in infants with moderate-to-severe hypoxic ischemic encephalopathy. Pediatr Res 80, 204–208 (2016). https://doi.org/10.1038/pr.2016.62
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DOI: https://doi.org/10.1038/pr.2016.62
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