Predictors of electrocerebral inactivity with deep hypothermia

Area of Science:

• Cardiovascular Surgery
• Neuroscience
• Critical Care Medicine

Background:

• Deep hypothermic circulatory arrest (DHCA) is used in thoracic aortic operations.
• Electrocerebral inactivity (ECI) via electroencephalography (EEG) is the gold standard for organ protection during DHCA.
• Predicting ECI without EEG is crucial for guiding cooling protocols.

Purpose of the Study:

• To identify predictors of ECI during DHCA.
• To guide cooling strategies when EEG monitoring is unavailable.

Main Methods:

• Retrospective analysis of 325 patients undergoing thoracic aortic operations with DHCA and EEG monitoring (July 2005-July 2011).
• Multivariable linear regression to assess predictors of nasopharyngeal temperature and cooling time to ECI.
• EEG used to guide cooling in elective and available non-elective cases.

Main Results:

• ECI achieved in >95% of patients at a nasopharyngeal temperature of 12.7°C or after 97 minutes.
• Only 7% and 11% reached ECI by 18°C or 50 minutes, respectively.
• Body surface area, white race, and starting temperature predicted cooling time, but no factors predicted temperature at ECI.
• Low complication rates: stroke (1.5%), paraplegia (1.5%), dialysis (2.2%), mortality (4.3%).

Conclusions:

• Cooling to 12.7°C or 97 minutes achieved ECI in most patients.
• Patient-specific factors were poor predictors of temperature or time to ECI.
• EEG monitoring remains essential for precise ECI detection during DHCA.