Predicting outcome after cardiac surgery: comparison of global haemodynamic and tonometric variables

To compare how outcome can be predicted from global haemodynamic compared with regional perfusion-related variables (gastric intramucosal pH (pHi) and intramucosal-arterial PCO2 difference (Delta PCO2)), we measured global haemodynamics, gastric pHi and Delta PCO2 in 68 haemodynamically compromised patients after cardiac surgery on admission to the intensive care unit (ICU) and 12 h later. Overall mortality rate in the ICU was 19.1%. In non-survivors, mean arterial pressure on admission (P = 0.03) and at 12 h (P = 0.02) was lower, and mean pulmonary artery pressure on admission (P = 0.006) and at 12 h (P = 0.004) was higher than in survivors. Gastric pHi on admission and at 12 h did not differ between non-survivors and survivors (7.37 (SD 0.1) vs 7.39 (0.09), and 7.37 (0.1) vs 7.41 (0.09), respectively). Delta PCO2 on admission and at 12 h did not differ between non-survivors and survivors (0.52 (0.52) kPa vs 0.47 (1.01) kPa and 0.59 (0.7) kPa vs 0.62 (0.9) kPa, respectively). Our data showed that global, routinely monitored, haemodynamic variables are better early predictors of outcome after cardiac surgery than regional, tonometric variables. This conclusion does not support hypoperfusion of the gastrointestinal tract as an early determinant of outcome after cardiac surgery.