Objective: Central venous oxygen saturation (ScvO2) is a useful therapeutic target in septic shock and high-risk postoperative patients. We tested the hypothesis that central venous-to-arterial carbon dioxide difference (ΔPCO(2)) combine with ScvO2 to guide shock resuscitation is better than ScvO2 only.
Methods: A retrospective study was conducted for 93 septic shock and high-risk postoperative patients. They underwent resuscitation through early goal-directed therapy. We calculate whether there were correlations between the ΔPCO(2) and tissue perfusion index or blood flow index, including the beginning of resuscitation (T0) and after 6 hour resuscitation (T6). They were divided into 4 groups according to ΔPCO(2) and ScvO2. Then the clearance of lactate was compared between the groups.
Results: No correlation existed between ΔPCO(2) and tissue perfusion index. But there was some correlation between ΔPCO(2) and the indices of blood flow such as CO, ScvO2 and clearance of lactate. At T0, the correlation (r) between ΔPCO(2) and cardiac index was -0.858 (P = 0.029) and the correlation between ΔPCO(2) and ScvO2 -0.403 (P = 0.000). At T6, the correlation (r) between ΔPCO(2) and ScvO2 was -0.363 (P = 0.000) and the correlation between ΔPCO(2) and clearance of lactate -0.314 (P = 0.002). After continuous 6-hour resuscitation, there was significant difference in clearance of lactate between the groups. The clearance of lactate was the highest in the group of patients achieving the goals of both ScvO2 > 70% and ΔPCO(2) < 6 mm Hg. We further analysis the ΔPCO(2) < 6 mm Hg and ScvO2 > 70% subgroup and found that the 6 h lactate clearance rate were statistically significant difference.
Conclusion: The combination of ΔPCO(2) and ScvO2 may guide the shock resuscitation. It helps identify the inadequately resuscitated when the ScvO2 goal is reached.