The prognostic value of transcutaneous oximetry for patients with septic shock

Abstract

Objective To evaluate the prognostic value of transcutaneous oximetry in patients with septic shock. Methods Fifty-three patients with septic shock were enrolled prospectively from January 2013 to December 2015. Transcutaneous oximetry were used to determine the results of 10 min oxygen challenge tests (OCT) carried out at beginning(0 h) and at 6 h after fluid resuscitation respectively. The 10-min OCT value (10 min OCT) and oxygen challenge index(OCI) were calculated. The APACHE Ⅱ and SOFA score, hemodynamic variables, oxygen metabolism indexes, dose of vasoactive agents, 10 min OCT, and OCI at 0 h and at 6 h were recorded. Patients were assigned into survival group and death group according to the 28 d survival. The differences in demographics and clinical data were compared between groups. The role of 10 min OCT and OCI in predicting death was evaluated by receiver operating characteristic curves(ROC). The Kaplan-Meier surviving curve was created and the survival of the patients was analyzed by the Log-rank test. Risk factors associated with the prognosis were analyzed using the multiple logistic regression analysis. Results There were 29 patients in the survival group and 24 patients in the death group. Compared with death group, 10 min OCT[(77.55±18.48)mmHg vs. (51.30±21.60)mmHg] and OCI [(0.78±0.13) vs. (0.59±0.15)] at 6 h in survival group were significantly higher(P<0.05), while APACHEⅡ [(12.48±5.69) vs. (17.25±8.79)] and SOFA [(5.79±1.72) vs. (10.10±2.52)] in survival group were significantly lower than those in death group(P<0.01). The area under the ROC curve of 10 min OCT at 6 h and OCI at 6 h for predicting 28 d death were 0.86±0.05(95%CI:0.76-0.87,P<0.01) and 0.79±0.08(95%CI:0.64-0.95,P<0.01), respectively. The optimal cutoff point for 10 min OCT at 6 h was 72.00 mmHg with the sensitivity of 76.84% and specificity of 85.03%. The optimal cutoff point for OCI at 6 h was 0.76 with the sensitivity of 76.84% and specificity of 77.47%. Kaplan-Meier survival analysis showed that 28 d survival rate in high level of 10 min OCT at 6 h and high level of OCI at 6 h were significantly higher than that in low level of 10 min OCT at 6 h(70.86% vs. 31.82%, χ2=7.96, P<0.01) and low level of OCI at 6 h (75.00% vs. 32.00%, χ2=9.86, P<0.01). Multivariate logistic regression analysis showed that both 10 min OCT at 6 h (OR=0.92,95%CI:0.88-0.96,P<0.05) and OCI at 6 h (OR=0.01,95%CI:0.001-0.023,P<0.05) were independent risk factors associated with 28 d mortality of patients with septic shock. Conclusions The 10 min OCT and OCI were reliable predictors for the prognosis of patients with septic shock. Key words: Transcutaneous oximetry; Oxygen challenge test; Septic shock; Prognosis