Hypercapnia: An Added Culprit in Gray Matter Injury in Preterm Neonates

Abstract

Over the last decade, there has been increased recognition of diverse forms of primary gray matter injury (GMI) in postpreterm neonates. In this study, we aimed to assess whether early neonatal hypercapnia in the preterm infant was associated with GMI on magnetic resonance imaging (MRI) at term equivalent age (TEA). All blood gases taken during the first 2 weeks of life were analyzed for hypercapnia. MRI was performed at TEA postpreterm infants using a unique neonatal MRI 1T scanner. The neonatal MRI scans were assessed using a standardized scoring system, the Kidokoro scoring system, a method used to assess abnormal brain metrics and the presence and severity of brain abnormalities. Subscores are assigned for different regions of the brain. Twenty-nine infants were studied, about half of whom had evidence of some gray matter abnormality. Fifteen of the infants were hypercapnic. The hypercapnic infants had significantly higher deep gray matter abnormality readings as compared with the nonhypercapnic infants (12 [11; 12] vs. 10 [8; 11], respectively; p = 0.0106). Correlations were observed between peak pCO₂ over the first 2 weeks of life and the overall gray matter abnormality score (GMAS) at TEA, and between the percentage of hypercapnic blood gases during the first 2 weeks of life and the GMAS. All of the infants in our population who had severe GMI at TEA were hypercapnic in the first 2 weeks of life. In conclusion, our data show a correlation between early hypercapnia in preterm neonates and GMI at TEA.

Keywords

gray matter injury - hypercapnia - preterm neonates

Note

The images used in this study were acquired from MRI scans that were funded by Aspect Imaging Ltd. for another study. The sponsor had no further involvement in the current study. Data collection, analysis and interpretation, writing, and submitting the manuscript for publication were made by the authors. No honorarium, grant, or other forms of payment was given to anyone to produce the manuscript. The authors have no financial relationships relevant to this article to disclose.

Author Contributions

A.B.N, C.H., and Y.K. contributed substantially to the conception and design of the study, analysis and interpretation of the data, drafted the initial manuscript, and revision of the article for important intellectual content. E.B.D. contributed substantially to the conception and design of the study, analyzing, and scoring of the MRIs and revision of the article for important intellectual content. I.S. contributed substantially to data collection, analysis and interpretation of the data, and revision of the article for important intellectual content. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

^* These authors contributed equally to this work as first authors.

Publication History

Received: 05 July 2021

Accepted: 29 December 2021

Accepted Manuscript online:
04 January 2022

Article published online:
02 March 2022

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