Relationship Analysis of Central Venous-to-arterial Carbon Dioxide Difference and Cardiac Index for Septic Shock

To analyze the relationship of the central venous-to-arterial carbon dioxide difference ( p (cv-a)CO 2 ) and cardiac index (CI) in patients with septic shock, an observational study was conducted in intensive care unit (ICU). 66 consecutive patients with septic shock and central venous oxygen saturation (ScvO 2 ) ≥ 70% were included after early fluid resuscitation. Measurements were taken at a 6 h interval (T0, T6, T12, T18, T24) during first 24 h after their admission into ICU, including heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), p (cv-a)CO 2 , cardiac index(CI, L/(min•m 2 )) and ScvO 2 . Patients were divided into low p (cv-a)CO 2 group (n = 35) and high p (cv-a)CO 2 group (n = 31) according to a threshold of 6 mmHg for p (cv-a)CO 2 at T0. As a result, at T0, T6, T12, T18 and T24, there were respectively significant differences between low and high p (cv-a)CO 2 groups for CI (4.1 ± 1.4 vs 2.4 ± 0.6, 4.4 ± 0.9 vs 2.8 ± 0.7, 4.1 ± 1.3 vs 2.9 ± 0.6, 4.0 ± 1.3 vs 2.7 ± 0.8, 4.2 ± 1.4 vs 2.9 ± 0.8, p 0.05), there were significant differences for p (cv-a)CO 2 ( p 0.05). CI was inversely correlated with p (cv-a)CO 2 value ( r = −0.804, p 0.05). Receiver operating characteristic curve analysis confirmed the correlation of p (cv-a)CO 2 with CI (AUC: 0.782; p