Central venous to arterial pCO₂ difference in cardiogenic shock

In normal circumstances central venous to arterial pCO₂ difference is approximately 1 kPa (7.5 mmHg). In shock states it is usually increased. We sought to evaluate the agreement between admission central venous to arterial pCO₂ difference and mortality in patients with acute myocardial infarction and cardiogenic shock. We hypothesized that patients with higher central venous to arterial pCO₂ difference on admission would have higher mortality. We retrospectively included 30 patients with acute myocardial infarction and cardiogenic shock (mean age 67 ± 10 years, 73 % men), of which 20 (67 %) died. Nonsignificant differences between survivors and nonsurvivors were observed in age, gender, admission mean blood pressure, heart rate, lactate, hemoglobin, peak troponin I, cardiopulmonary resuscitation, use of therapeutic hypothermia, vasopressors, inotropes, intraaortic balloon pump, and mechanical ventilation. A significant difference between survivors and nonsurvivors was observed in admission central venous to arterial pCO₂ difference (1.35 ± 0.49 kPa vs. 0.83 ± 0.36 kPa, p = 0.003). In patients with admission central venous oxygen saturation over 70 %, we observed a significant difference in central venous to arterial pCO₂ difference between survivors and nonsurvivors (1.33 ± 0.51 kPa vs. 0.7 ± 0.3 kPa, p = 0.003) and a nonsignificant difference between survivors and nonsurvivors in patients with admission central venous oxygen saturation under 70 % (1.38 ± 0.53 kPa vs. 1.25 ± 0.33 kPa, p = 0.37). Patients with decreased central venous to arterial pCO₂ difference on admission seem to be at increased risk of dying even with admission central venous oxygen saturation over 70 %.