What is the optimal NIRS saturation during deep hypothermic circulatory arrest (DHCA)?

The optimal Near Infrared Spectroscopy (NIRS) saturation during deep hypothermic circulatory arrest (DHCA) should be within 20% of baseline values, with a target of ideally being greater than 50%. This is important because maintaining NIRS saturation at this level indicates that the cerebral oxygen delivery is sufficient during the period of hypothermic circulatory arrest.

During DHCA, the body's metabolic demands decrease significantly due to the profound drop in temperature, which reduces neuronal activity and oxygen consumption. However, adequate cerebral perfusion is still critical to protect the brain from injury during this period. If NIRS saturation drops significantly below the threshold of 50%, it may suggest inadequate brain oxygenation, raising the risk of neurological injury upon rewarming.

Maintaining NIRS saturation within 20% of baseline allows clinicians to monitor the effectiveness of circulatory support and the brain's oxygenation status while ensuring that it does not fall to dangerous levels that could compromise cerebral protection. Monitoring NIRS saturation in this manner is vital for the safe and effective performance of procedures involving DHCA.