Differences between arterial and expired pump carbon dioxide during robotic cardiac surgery

Area of Science:

• Cardiovascular Surgery
• Anesthesiology
• Medical Device Monitoring

Background:

• Accurate monitoring of arterial carbon dioxide (PaCO(2)) is crucial during cardiopulmonary bypass (CPB).
• Expired pump carbon dioxide (PepCO(2)) has been proposed as a non-invasive alternative monitoring method.
• Robotic cardiac surgery presents unique physiological challenges during CPB.

Purpose of the Study:

• To evaluate the efficacy of PepCO(2) as a continuous monitor for PaCO(2) during CPB.
• To compare PepCO(2) monitoring with standard PaCO(2) measurements in patients undergoing robotic cardiac surgery.
• To assess the reliability of PepCO(2) across different phases of CPB (cooling, hypothermia, rewarming).

Main Methods:

• Prospective control study conducted in a single university institution.
• Sixty patients undergoing cardiac surgery were included.
• PepCO(2) was measured from the oxygenator exhaust, alongside simultaneous arterial blood gas analysis for PaCO(2) during CPB.

Main Results:

• Significant differences were observed between temperature-uncorrected PaCO(2) and PepCO(2) during cooling and stable hypothermia (p < 0.001).
• No significant differences were found between temperature-corrected PaCO(2) and PepCO(2) during cooling and rewarming phases (p > 0.122).
• Significant discrepancies highlight temperature-dependent variations and limitations of PepCO(2) monitoring.

Conclusions:

• Expired pump carbon dioxide (PepCO(2)) is not suitable for continuous monitoring of arterial carbon dioxide (PaCO(2)) during CPB in robotic cardiac surgery.
• The observed discrepancies, particularly during cooling and hypothermia, limit its clinical utility.
• Further research may be needed to explore alternative non-invasive monitoring techniques for CO(2) during CPB.