Published online February 29, 2008
PEDIATRICS Vol. 121 No. 3 March 2008, pp. 654 (doi:10.1542/peds.2007-3602)

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LETTER TO THE EDITOR

Hypotension and Brain Injury in Premature Infants

Richard W. Hall, MD
Department of Pediatrics
Section of Neonatology
University of Arkansas for Medical Sciences
Little Rock, AR 72205

Jeffrey R. Kaiser, MD, MA
Departments of Pediatrics and Obstetrics and Gynecology
Section of Neonatology
University of Arkansas for Medical Sciences
Little Rock, AR 72202

To the Editor.—

We read the article by Limperopoulos et al¹ with great interest. The authors reported that hypotension, as characterized by the 3 most widely used definitions,^2–4 was unrelated to early brain injury in high-risk premature infants of 30 weeks' gestation. Instead of using their favorite hypotension definition, they should be commended for evaluating all of the blood pressure (BP) thresholds for a possible association with germinal matrix-intraventricular hemorrhage (GM-IVH). The analysis was further strengthened by their use of continuous BP monitoring as well as their evaluation of BP variability.

Because BP measurements were only evaluated for 15 hours during the first 72 hours of life, we agree with the authors that "injurious" hypotensive episodes could have been missed. In addition, 40% of the infants did not have their BP evaluated during the first 12 hours of life, a time during which important hemodynamic changes occur. Moreover, given the liberal use of volume expanders and vasopressors in >70% of their infants as well as the high incidence of early brain injury, we question the generalizability of these results. It is possible that the early and aggressive use of treatment may have prevented (or even caused) brain injury. On the other hand, because there were no early cranial ultrasound studies performed, one cannot say whether the brain lesions were preexisting or acquired, so conclusions regarding cause and effect are problematic. Finally, given that all grades of GM-IVH were grouped in the analysis, was there a relationship between hypotension and severe IVH (grade III and parenchymal echodensities)?

The authors appropriately state that the pathophysiology of GM-IVH is complex, and that an investigation of an association between BP and brain injury may be too simplistic without also considering cerebral autoregulation. They quoted one of their recent studies that observed that pressure passivity (impaired autoregulation) occurred during both normal and low BP⁵ and that some other factor may affect autoregulation. We agree, because we have shown previously that increasing PaCO₂ in premature infants is associated with progressively impaired autoregulation.⁶

Neonatologists desperately need to know whether treatment for hypotension can ameliorate GM-IVH in premature infants. This study, ¹ which used actual BP (treated or not) did not address this major issue faced by practicing neonatologists. There is sufficient equipoise to perform a properly controlled trial to evaluate whether treatment for hypotension is beneficial or harmful for this vulnerable group of infants; this would not be an exercise in futility.

ACKNOWLEDGMENTS

The authors were supported by National Institutes of Health grants 1K23 NS43185 and RR20146.

REFERENCES

1. Limperopoulos C, Bassan H, Kalish LA, et al. Current definitions of hypotension do not predict abnormal cranial ultrasound findings in preterm infants. Pediatrics.2007; 120 (5):966 –977[Abstract/Free Full Text]
2. Joint Working Group of the British Association of Perinatal Medicine and the Research Unit of the Royal College of Physicians. Development of audit measures and guidelines for good practice in the management of neonatal respiratory distress syndrome. Arch Dis Child.1992; 67 (10 Spec No):1221 –1227[Free Full Text]
3. Nuntnarumit P, Yang W, Bada-Ellzey HS. Blood pressure measurements in the newborn. Clin Perinatol.1999; 26 (4):981 –996[Web of Science][Medline]
4. Watkins AM, West CR, Cooke RW. Blood pressure and cerebral haemorrhage and ischaemia in very low birthweight infants. Early Hum Dev.1989; 19 (2):103 –110[CrossRef][Web of Science][Medline]
5. Soul JS, Hammer PE, Tsuji M, et al. Fluctuating pressure-passivity is common in the cerebral circulation of sick premature infants. Pediatr Res.2007; 61 (4):467 –473[CrossRef][Web of Science][Medline]
6. Kaiser JR, Gauss CH, Williams DK. The effects of hypercapnia on cerebral autoregulation in ventilated very low birth weight infants. Pediatr Res.2005; 58 (5):931 –935[CrossRef][Web of Science][Medline]

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PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics

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This Article Extract Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services E-mail this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Add to My File Cabinet Download to citation manager Request Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Hall, R. W. Articles by Kaiser, J. R. Search for Related Content PubMed PubMed Citation Articles by Hall, R. W. Articles by Kaiser, J. R. Related Collections Heart & Blood Vessels Social Bookmarking                         What's this?