Patient directed bypass: cooling for aortic surgery--a preliminary concept

Area of Science:

• Cardiovascular Surgery
• Hypothermia Research
• Cerebral Protection Strategies

Background:

• Aortic arch surgery lacks consensus on optimal cooling temperatures during cardiopulmonary bypass.
• Current cerebral protection methods include circulatory arrest and cerebral perfusion, but patient-specific variations are not considered.

Purpose of the Study:

• To investigate the temperature at which metabolic activity ceases in patients undergoing aortic arch surgery.
• To identify potential for optimizing cooling protocols and reducing cardiopulmonary bypass time.

Main Methods:

• Retrospective analysis of 10 patients undergoing aortic arch surgery using an electronic perfusion database.
• Monitoring mixed venous saturations during cooling to determine the point of no oxygen extraction.
• Variables uploaded to www.perfsort.net for analysis.

Main Results:

• Significant variation observed in the temperature at which metabolic activity ceased, ranging from 17-25 degrees Celsius.
• On average, patients were cooled 6 degrees Celsius below the cessation of oxygen extraction.
• This suggests an average of 111 minutes of potentially unnecessary bypass time.

Conclusions:

• Excessive cooling may be occurring in some patients undergoing aortic arch surgery.
• Patient-directed cooling protocols could minimize morbidity associated with hypothermia.
• This preliminary work suggests a move away from a one-size-fits-all approach in clinical practice.