To assess the predictive value of peripheral perfusion index (PI) combined with central venous-arterial carbon dioxide tension to arterial-venous oxygen content ratio (Pv-aCO₂/Ca-vO₂) for prognosis after 3 h of initial resuscitation of septic shock.

This was a rospective study in which elderly patients with septic shock admitted to the Emergency Intensive Care Unit of Harison International Peace Hospital of Hebei Medical University from October 2019 to October 2023 were selected. After 3 h of initial resuscitation, PI was monitored and Pv-aCO₂/Ca-vO₂ was calculated by central vein and arterial blood gas analysis. The patients were divided into either a survival group or a death group according to the 28-d survival status, and the differences in demographics and clinical data were compared between the two groups. Binary logistic regression analysis was used to screen out the independent predictors of 28-d death. Receiver operating characteristic (ROC) curve analysis of PI, Pv-aCO₂/Ca-vO₂, and their combination was performed, and MedCalc software was used to compare the diagnostic efficacy of PI and Pv-aCO₂/Ca-vSO₂, either alone or in combination, for the prognosis at 28 d.

A total of 70 patients were included in the study, including 34 patients in the survival group and 36 in the death group. There was no significant difference in general data at admission between the two groups (P>0.05 for all), and the 28-d fatality rate was 51.43%. After 3 h of initial resuscitation, PI (1.56±0.50 vs 0.72±0.32) was significantly higher and Pv-aCO₂/Ca-vO₂ (1.58±0.56 vs 2.32±0.78) was significantly lower in the survival group than in the death group (P<0.001). Binary logistic regression analysis demonstrated that PI (odds ratio [OR]=0.004, 95% confidence interval [CI]: 0~0.079, P<0.001) and Pv-aCO₂/Ca-vO₂ (OR=11.520, 95%CI: 2.199~60.344, P=0.004) were independent predictors of death at 28 d after septic shock. ROC analysis showed that the area under ROC curve (AUC) values of PI, Pv-aCO₂/Ca-vO₂, and their combination in the prediction of 28-d death in septic shock patients were 0.901, 0.783, and 0.951, respectively, with sensitivities of 97.2%, 80.6%, and 91.7%, and specificities of 71.6%, 67.6%, and 88.2%, respectively.The comparison of AUC values showed that PI and Pv-aCO₂/Ca-vO₂ had no significant difference in the prediction of 28-d death (P=0.095), but their combination was superior to either of them alone (P=0.043 and 0.002, respectively).

PI and Pv-aCO₂/Ca-vO₂ are independent predictors of 28-d mortality in patients with septic shock after 3 h of initial resuscitation, and PI combined with Pv-aCO₂/Ca-vO₂ could more accurately predict 28-d mortality risk than either of them alone.