Background: 

The incidence of hyperlactatemia due to hypoperfusion during cardiopulmonary bypass (CPB) increases morbidity. Carbon dioxide production during CPB is one of the lactate production markers, in addition to other markers such as delivery oxygen (DO₂), oxygen consumption (VO₂), mixed vein oxygen saturation (SvO₂), and oxygen extraction ratio (O₂ER).

Method: 

This observational analytic study was conducted on 40 adult cardiac surgery patients using a CPB machine. Initial lactate is taken when entering CPB and final lactate is examined 15 min after coming off bypass. The values of DO₂, VO₂, SvO₂, VCO₂, respiratory quotient (RQ), DO₂/VCO₂, PvCO₂ × Ve/Q were calculated from the results of blood and venous gas analysis 1 h after entering CPB in the nadir of core temperature and lowest pump flow.

Result: 

The multivariate test showed that the value of PvCO₂ × Ve/Q was more effective than other oxygenation and carbon dioxide parameters in predicting an increase in the percentage of lactate. Each increase of 1 mmHg PvCO₂ ×× Ve/Q can predict a final lactate increase of 29% from the initial lactate. The high PvCO₂ × Ve/Q value is also the strongest correlation factor for the incidence of hyperlactatemia after CPB (final lactate >3 mmol/L). The cutoff value of this marker is >19.3 mmHg, which has a sensitivity of 100% and a specificity of 55.6% with a strong correlation value.

Conclusion: 

The PvCO₂ × Ve/Q value proved to be one of the significant markers in predicting hyperlactatemia during cardiac surgery using CPB.