The Relationship between Arterial Carbon Dioxide Tension and Oxygenator Exhausted Carbon Dioxide Tension during Cardiopulmonary Bypass

ABSTRACT

BACKGROUND: The neurologic deficit is one of the most serious complications after cardiopulmonary bypass (CPB). This complication has reported to be closely associated with arterial partial pressure of carbon dioxide tension (PaCO2). The traditional way to measure PaCO2 is by intermittent arterial gas analysis during CPB. We tested the relationship between PaCO2 and CPB exhausted partial pressure of carbon dioxide tension (exPCO2) which can be monitored continuously during CPB. METHODS: The total 46 patients who underwent cardiac surgery under CPB were studied. Capnography sampling line was connected to CPB exhausted port to monitor exPCO2. We sampled arterial blood from CPB for gas analysis at cooling, stable hypothermia, and rewarming phase and recorded exPCO2 simultaneously at each phase. RESULTS: We found out that exPCO2 was associated with temperature corrected PaCO2 (cPaCO2) at all 3 phases(r = 0.73, 0.70, 0.84, P < 0.05) and with temperature uncorrected PaCO2 (ucPaCO2) at cooling (r = 0.64, P < 0.05) and rewarming phases (r = 0.81, P < 0.05). CONCLUSIONS: We concluded that exPCO2 could be used to monitor either ucPaCO2 or cPaCO2 at cooling and rewarming phase and cPaCO2 at hypothermia during CPB.