Background The ratio of central venous-to-arterial carbon dioxide content difference to arterial-to-venous oxygen content difference (Cv-aCO2/Ca-vO2) and central venous-to-arterial carbon dioxide tension difference (Pv-aCO2) are indicators for monitoring anaerobic metabolism and tissue perfusion in shock. We hypothesized that significant differences in patient outcomes exist across different Cv-aCO2/Ca-vO2 and Pv-aCO2 groups during the early stages of shock resuscitation and that these two indicators reflect microcirculatory perfusion in septic shock patients. Methods This single-center, prospective, observational, cohort, exploratory, pilot study involved newly diagnosed patients with septic shock admitted to intensive care unit (ICU) between May 2023 and August 2024. We classified patients into four groups based on their Cv-aCO2/Ca-vO2 and Pv-aCO2 levels at 6 h post-ICU admission (T6), monitored sublingual microcirculation, and followed them for 28 days. The grouping is as follows: Group A is Cv-aCO2/Ca-vO2 ≤ 1 and Pv-aCO2 < 6 mmHg; Group B is Cv-aCO2/Ca-vO2 ≤ 1 and Pv-aCO2 ≥ 6 mmHg; Group C is Cv-aCO2/Ca-vO2 > 1 and Pv-aCO2 < 6 mmHg; and Group D is Cv-aCO2/Ca-vO2 > 1 and Pv-aCO2 ≥ 6 mmHg. Results 105 patients were included in the study. The 28-day mortality differed significantly among the four groups of patients (A:8.3%, B:19%, C:30%, and D:46.7%, p < 0.05). The Kaplan–Meier curves for the four groups revealed significant differences in the 28-day survival probabilities. (p = 0.014). Multivariate Cox regression revealed that the independent risk factors for 28-day mortality were age [hazard ratio (HR) = 1.05, 95% confidence interval (95% CI) = 1.02–1.09, p = 0.001], Cv-aCO2/Ca-vO2 (HR = 1.67, 95% CI = 1.03–2.69, p = 0.036), and Pv-aCO2 (HR = 1.13, 95% CI = 1.00–1.27, p = 0.043). There were significant differences among the four groups in terms of the proportion of perfused vessels for all (PPV), proportion of perfused vessels for d < 20 μm (sPPV), microvascular flow index (MFI), and heterogeneity index (HI) values (p < 0.001); correlations were observed for Cv-aCO2/Ca-vO2, Pv-aCO2, and sPPV (r = −0.49, p < 0.001, R2 = 0.19; r = −0.22, p = 0.028, R2 = 0.08). Conclusions The combined assessment of Cv-aCO2/Ca-vO2 and Pv-aCO2 during the early stages of resuscitation demonstrates a significant association with mortality in septic shock patients. This combination could potentially serve as a resuscitation target and reflect microcirculatory perfusion in septic shock patients.

Combination of C_v-aCO₂/C_a-vO₂ and P_v-aCO₂ as markers of resuscitation or microcirculation in patients with septic shock: a pilot study

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2025年6月17日

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Luping Cheng,
Wenxin Wang,
Xia Hu,
Chuanliang Pan

摘要

Background

The ratio of central venous-to-arterial carbon dioxide content difference to arterial-to-venous oxygen content difference (C_v-aCO₂/C_a-vO₂) and central venous-to-arterial carbon dioxide tension difference (P_v-aCO₂) are indicators for monitoring anaerobic metabolism and tissue perfusion in shock. We hypothesized that significant differences in patient outcomes exist across different C_v-aCO₂/C_a-vO₂ and P_v-aCO₂ groups during the early stages of shock resuscitation and that these two indicators reflect microcirculatory perfusion in septic shock patients.

Methods

This single-center, prospective, observational, cohort, exploratory, pilot study involved newly diagnosed patients with septic shock admitted to intensive care unit (ICU) between May 2023 and August 2024. We classified patients into four groups based on their C_v-aCO₂/C_a-vO₂ and P_v-aCO₂ levels at 6 h post-ICU admission (T6), monitored sublingual microcirculation, and followed them for 28 days. The grouping is as follows: Group A is C_v-aCO₂/C_a-vO₂ ≤ 1 and P_v-aCO₂ < 6 mmHg; Group B is C_v-aCO₂/C_a-vO₂ ≤ 1 and P_v-aCO₂ ≥ 6 mmHg; Group C is C_v-aCO₂/C_a-vO₂ > 1 and P_v-aCO₂ < 6 mmHg; and Group D is C_v-aCO₂/C_a-vO₂ > 1 and P_v-aCO₂ ≥ 6 mmHg.

Results

105 patients were included in the study. The 28-day mortality differed significantly among the four groups of patients (A:8.3%, B:19%, C:30%, and D:46.7%, p < 0.05). The Kaplan–Meier curves for the four groups revealed significant differences in the 28-day survival probabilities. (p = 0.014). Multivariate Cox regression revealed that the independent risk factors for 28-day mortality were age [hazard ratio (HR) = 1.05, 95% confidence interval (95% CI) = 1.02–1.09, p = 0.001], C_v-aCO₂/C_a-vO₂ (HR = 1.67, 95% CI = 1.03–2.69, p = 0.036), and P_v-aCO₂ (HR = 1.13, 95% CI = 1.00–1.27, p = 0.043). There were significant differences among the four groups in terms of the proportion of perfused vessels for all (PPV), proportion of perfused vessels for d < 20 μm (sPPV), microvascular flow index (MFI), and heterogeneity index (HI) values (p < 0.001); correlations were observed for C_v-aCO₂/C_a-vO₂, P_v-aCO₂, and sPPV (r = −0.49, p < 0.001, R² = 0.19; r = −0.22, p = 0.028, R² = 0.08).

Conclusions

The combined assessment of C_v-aCO₂/C_a-vO₂ and P_v-aCO₂ during the early stages of resuscitation demonstrates a significant association with mortality in septic shock patients. This combination could potentially serve as a resuscitation target and reflect microcirculatory perfusion in septic shock patients.

Combination of Cv-aCO2/Ca-vO2 and Pv-aCO2 as markers of resuscitation or microcirculation in patients with septic shock: a pilot study

摘要

Combination of C_v-aCO₂/C_a-vO₂ and P_v-aCO₂ as markers of resuscitation or microcirculation in patients with septic shock: a pilot study