Alpha-stat capnography for the Sorin Monolyth oxygenator.

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Respiratory Physiology

Background:

• Accurate control of arterial carbon dioxide tension (paCO2) is crucial during cardiopulmonary bypass (CPB).
• Current methods for monitoring paCO2 can be invasive or delayed.
• Oxygenator exhaust gas monitoring presents a potential non-invasive alternative.

Purpose of the Study:

• To evaluate the efficacy of monitoring oxygenator exhaust carbon dioxide (p exCO2) for predicting paCO2 during CPB.
• To establish a statistical relationship between p exCO2, arterial blood temperature (ABT), and paCO2.
• To introduce the concept of a unique
• regression signature
• for oxygenator ventilation control.

Main Methods:

• Continuous monitoring of p exCO2 from the oxygenator's capnograph port during CPB.
• Simultaneous recording of ABT and p exCO2 at the time of arterial blood gas sampling.
• Statistical analysis to determine the relationship between p exCO2, ABT, and paCO2, employing alpha-stat ventilation.

Main Results:

• An exponential regression with a correlation coefficient of 0.98 was found between p exCO2, ABT, and paCO2.
• This relationship, termed the
• regression signature
• , is unique to each oxygenator manufacturer.
• No statistical difference in paCO2 was observed across different arterial blood temperature groups.

Conclusions:

• Monitoring oxygenator exhaust CO2 is an inexpensive and accurate method for predicting and controlling paCO2 during CPB.
• The established
• regression signature
• can be utilized by perfusionists to enhance ventilation management.
• This technique offers a valuable tool for optimizing patient respiratory status during CPB.