Published online June 29, 2009
PEDIATRICS Vol. 124 No. 1 July 2009, pp. 302-309 (doi:10.1542/peds.2008-2004)

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ARTICLE

Elevated Cerebral Pressure Passivity Is Associated With Prematurity-Related Intracranial Hemorrhage

Heather O'Leary, BSc^a, Matthew C. Gregas, PhD^b, Catherine Limperopoulos, PhD^a,c, Irina Zaretskaya, BSc^a, Haim Bassan, MD^a, Janet S. Soul, MD^a, Donald N. Di Salvo, MD^d, Adré J. du Plessis, MBChB, MPH^a

^a Fetal-Neonatal Neurology Research Group, Department of Neurology
^b Clinical Research Program, and Children's Hospital Boston
^d Department of Radiology, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts
^c Department of Neurology and Neurosurgery and School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada

OBJECTIVES: Cerebral pressure passivity is common in sick premature infants and may predispose to germinal matrix/intraventricular hemorrhage (GM/IVH), a lesion with potentially serious consequences. We studied the association between the magnitude of cerebral pressure passivity and GM/IVH.

PATIENTS AND METHODS: We enrolled infants <32 weeks' gestational age with indwelling mean arterial pressure (MAP) monitoring and excluded infants with known congenital syndromes or antenatal brain injury. We recorded continuous MAP and cerebral near-infrared spectroscopy hemoglobin difference (HbD) signals at 2 Hz for up to 12 hours/day and up to 5 days. Coherence and transfer function analysis between MAP and HbD signals was performed in 3 frequency bands (0.05–0.25, 0.25–0.5, and 0.5–1.0 Hz). Using MAP-HbD gain and clinical variables (including chorioamnionitis, Apgar scores, gestational age, birth weight, neonatal sepsis, and Score for Neonatal Acute Physiology II), we built a logistic regression model that best predicts cranial ultrasound abnormalities.

RESULTS: In 88 infants (median gestational age: 26 weeks [range 23–30 weeks]), early cranial ultrasound showed GM/IVH in 31 (37%) and parenchymal echodensities in 10 (12%) infants; late cranial ultrasound showed parenchymal abnormalities in 19 (30%) infants. Low-frequency MAP-HbD gain (highest quartile mean) was significantly associated with early GM/IVH but not other ultrasound findings. The most parsimonious model associated with early GM/IVH included only gestational age and MAP-HbD gain.

CONCLUSIONS: This novel cerebrovascular monitoring technique allows quantification of cerebral pressure passivity as MAP-HbD gain in premature infants. High MAP-HbD gain is significantly associated with GM/IVH. Precise temporal and causal relationship between MAP-HbD gain and GM/IVH awaits further study.

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Key Words: prematurity • intraventricular hemorrhage • cerebral pressure passivity • transfer function analysis • cerebral autoregulation

Abbreviations: GM/IVH—germinal matrix/intraventricular hemorrhage • HbD—hemoglobin difference • NIRS—near-infrared spectroscopy • MAP—mean arterial pressure • PSD—power spectral density • HQM—highest quartile mean

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Accepted Nov 11, 2008.

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Frequency Domain Analysis to Assess Association between Cerebral Pressure Passivity and IVH

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Pediatrics Online, 15 Oct 2009 [Full text]