Abstract:
Continuous monitoring and control of arterial carbon dioxide tension (PaCO2) during cardiopulmonary bypass (CPB) is essential. A reliable, accurate, and inexpensive system is not currently available. This study was undertaken to assess whether the continuous monitoring of oxygenator exhaust carbon dioxide tension (PexCO2) can be used to reflect P aCO2 during CPB. A total of 33 patients undergoing CPB for cardiac surgery were included in the study. During normothermia (37°C) and stable hypothermia (31°C), the values of PexCO2 from the oxygenator exhaust outlet were monitored and compared simultaneously with the PaCO2 values. Regression and agreement analysis were performed between PexCO2 and temperature corrected-P aCO2 and temperature uncorrected-PaCO 2. At normothermia, a significant correlation was obtained between PexCO2 and PaCO2 (r = 0.79; p andlt; 0.05); there was also a strong agreement between PexCO2 and PaCO 2 with a gradient of 3.4 ± 1.9 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature corrected-PaCO2 (r = 0.78; p andlt; 0.05); also, there was a strong agreement between PexCO2 and temperature corrected-PaCO2 with a gradient of 2.8 ± 2.0 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature uncorrected-P aCO2 (r = 0.61; p andlt; 0.05); however, there was a poor agreement between PexCO2 and the temperature uncorrected-P aCO2 with a gradient of 13.2 ± 3.8 mmHg. Oxygenator exhaust capnography could be used as a mean for continuously monitoring P aCO2 during normothermic phase of cardiopulmonary bypass as well as the temperature-corrected PaCO2 during the stable hypothermic phase of CPB.