Document Detail

Hypoxemic reperfusion exacerbates the neurological injury sustained during neonatal deep hypothermic circulatory arrest: a model of cyanotic surgical repair.
MedLine Citation:
PMID:  17331738     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Deep hypothermic circulatory arrest (DHCA) is frequently used in infants undergoing the Norwood procedure. These infants are necessarily hypoxemic after separation from CPB. Considerable energy has been spent characterizing the physiological and histological consequences of DHCA, but these have largely focused on a normoxemic period of reperfusion. Furthermore, evidence has accumulated to suggest that the cerebral vascular autoregulatory mechanisms are dysfunctional following DHCA. In particular, the vasodilatation that elevates cerebral blood flow (CBF) in response to hypoxemia is absent. This study therefore aimed to investigate whether post-CPB hypoxemia exacerbates brain injury resulting from DHCA. METHODS: Twelve neonatal piglets were subjected to 2h DHCA and then separated from CPB. They were then randomized to either: Group 1, normoxic ventilation (n=5); or Group 2, hypoxemia (n=7), in which the arterial PaO(2) was reduced to 40-50 mmHg for the duration of reperfusion. Following a 20 h period of warm reperfusion, the animals were perfusion fixed and the brain analyzed for histological evidence of injury. Nine additional animals were studied in one of three control groups. RESULTS: All animals survived the protocol. Post-operative parameters - including mean arterial pressure, acid-base status, inotrope requirements and arterial PaCO(2) - were similar. None of the control animals had any evidence of ischemia. Group 1 animals had moderate injury (total score 7.4+/-1.6). In Group 2, three animals sustained irretrievable brain injury evidenced by gross edema and early liquefactive necrosis. The remaining four had severe ischemic histological changes (score 14.5+/-1.6, p<0.03). CONCLUSIONS: Hypoxemic reperfusion after prolonged DHCA results in increased neuronal loss. The use of DHCA for staged palliation may confer disproportionately greater cerebral risk than other patient groups. Alternatively, methods to augment oxygen delivery - such as by ECMO - may be of particular benefit in the early re-perfusion window.
Edward J Hickey; Xiaomang You; Vassil Kaimaktchiev; Ross M Ungerleider
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-02-28
Journal Detail:
Title:  European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery     Volume:  31     ISSN:  1010-7940     ISO Abbreviation:  Eur J Cardiothorac Surg     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-04-09     Completed Date:  2007-07-19     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8804069     Medline TA:  Eur J Cardiothorac Surg     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  906-14     Citation Subset:  IM    
Oregon Health Science University, Portland, Oregon, USA.
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MeSH Terms
Animals, Newborn
Anoxia / pathology,  physiopathology*
Brain / pathology,  physiopathology
Brain Ischemia / etiology,  pathology,  physiopathology*
Cardiopulmonary Bypass / methods*
Cerebrovascular Circulation / physiology
Circulatory Arrest, Deep Hypothermia Induced / adverse effects*,  methods
Disease Models, Animal
Microscopy, Fluorescence / methods
Myocardial Reperfusion / adverse effects

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