Received on February 18, 2007
Accepted on October 8, 2007

Proteomics and Protein Markers

Adrenomedullin Blood Concentrations in Infants Subjected to Cardiopulmonary Bypass: Correlation with Monitoring Parameters and Prediction of Poor Neurological Outcome

¹ Department of Pediatrics, Obstetrics, and Reproductive Medicine, University of Siena, Siena, Italy
² Department of Cardiac Surgery, S. Donato Milanese University Hospital, S. Donato Milanese, Italy
³ Laboratory of Perinatal Medicine and Molecular Biology and Department of Internal Medicine, University "La Sapienza", Rome, Italy
⁴ Department of Pediatric Intensive Care, Hesperia Hospital, Modena, Italy
⁵ Department of Pediatrics and Neuroscience, G. Gaslini Children’s Hospital, University of Genoa, Genoa, Italy; and Department of Fetal, Maternal, and Neonatal Health, G. Garibaldi Hospital, Catania, Italy

^* To whom correspondence should be addressed. E-mail: dgazzolo{at}hotmail.com.

BACKGROUND: Brain injury is a major adverse event after cardiac surgery, especially when extracorporeal circuits are used. We evaluated whether cardiopulmonary bypass (CPB) affects cerebrovascular resistance and plasma concentrations of adrenomedullin (AM), a vasoactive peptide regulating cerebral blood flow.

METHODS: We evaluated 50 infants (age <1 year) with congenital heart defects, matched according to a 2-year follow-up; 40 infants had no overt neurological injury, and 10 had brain damage. Blood samples were taken before surgery, during surgery before CPB, at the end of CPB, at the end of surgery, and at 12 h after surgery. Neurological outcome was evaluated before surgery, on postoperative day 7, and 2 years after surgery. We measured AM concentrations and used Doppler velocimetry to measure middle cerebral artery (MCA) pulsatility index (PI).

RESULTS: The highest MCA PI values and lowest AM concentrations occurred at the end of CPB and of the surgical procedure. Infants who developed abnormal neurologic sequelae had significantly (P <0.001 for both) higher MCA PI values and lower AM concentrations than patients with normal neurologic outcome at the end of CPB and after surgery. As single markers for predicting neurological abnormalities, AM (cutoff: 17.4 ng/L) achieved a sensitivity of 100% and a specificity of 73.0% and MCA PI (cutoff value: 1.8) a sensitivity of 100% and a specificity of 56.8%,.

CONCLUSIONS: AM concentrations and MCA PI patterns change during CPB, mainly in infants with brain damage, and may be useful for early identification of infants at risk for brain damage.