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Cerebral oxygen supply and utilization during infant cardiac surgery
A J du Plessis1, J Newburger, R A Jonas
1Department of Neurology, Children's Hospital, Harvard Medical School, Boston, MA, USA.
Annals of Neurology
|April 1, 1995
Summary
Infant heart surgery can cause brain injury due to impaired mitochondrial oxygenation, especially in older infants. This study highlights a dissociation between blood and brain tissue oxygen levels during surgery.
Area of Science:
- Cardiology
- Neurology
- Biomedical Engineering
Background:
- Infant survival after congenital heart defect surgery has improved.
- Neurological injury remains a significant complication, linked to hypoxia-ischemia/reperfusion during surgery.
- Deep hypothermia, cardiopulmonary bypass, and circulatory arrest are standard surgical procedures.
Purpose of the Study:
- To investigate the relationship between cerebral intravascular and mitochondrial oxygenation in infants undergoing cardiac surgery.
- To assess the impact of postnatal age on these oxygenation changes.
- To identify mechanisms of brain injury during infant cardiac surgery.
Main Methods:
- Near-infrared spectroscopy (NIRS) was used to monitor cerebral oxygenation in 63 infants (1 day to 9 months old).
- Measurements included intravascular hemoglobin (oxyhemoglobin) and mitochondrial (cytochrome aa3) oxygenation.
- Data were collected throughout the intraoperative period, including deep hypothermic cardiopulmonary bypass and circulatory arrest.
Main Results:
- Cerebral oxidized cytochrome aa3 decreased during hypothermic cardiopulmonary bypass, despite increased oxyhemoglobin.
- Infants older than 2 weeks showed a greater decrease in oxidized cytochrome aa3 compared to younger infants.
- Recovery of oxidized cytochrome aa3 was delayed after circulatory arrest, with only 46% returning to baseline after rewarming.
Conclusions:
- A paradoxical dissociation exists between intravascular and mitochondrial oxygenation during infant cardiac surgery.
- Mitochondrial oxygenation is impaired during hypothermia induction and recovery is delayed after circulatory arrest.
- These effects are more pronounced in older infants, suggesting impaired mitochondrial function or oxygen delivery influenced by cerebral maturation.