• Xueting Wang, Xuehua Gao, Wen Cao, Yin Guan, Yannian Luo, Foyan Lian, Nannan He, and Peijie Li.
• Department of Critical Care Medicine, Lanzhou University Second Hospital, Lanzhou 730030, Gansu, China. Corresponding author: Li Peijie, Email: lipeijielanzhou@hotmail.com.
• Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2020 Jan 1; 32 (1): 39-43.

ObjectiveTo evaluate the prognostic value of arterial lactate (Lac) combined with central venous-to-arterial carbon dioxide difference to arterial-to-central venous oxygen content difference ratio (Pcv-aCO2/Ca-cvO2) in patients with septic shock following early fluid resuscitation.MethodsA total of 97 patients with septic shock admitted to intensive care unit (ICU) of Lanzhou University Second Hospital from January 2017 to December 2019 were enrolled. The Pcv-aCO2/Ca-cvO2 ratio was calculated from blood gas analysis of radial artery and superior vena cava which was performed before resuscitation and at 6 hours of resuscitation at the same time. The patients were divided into death group and survival group according to the 28-day prognosis. The baseline data, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure score (SOFA), clinical therapy, lactate clearance rate (LCR) at 6 hours, the length of ICU stay, hemodynamics and oxygen metabolism parameters before and after resuscitation were compared between the two groups. Risk factors were analyzed by multivariate Cox regression for 28-day mortality of patients with septic shock. The receiver operating characteristic (ROC) curve was plotted to assess the prognostic values of these factors for 28-day mortality.Results(1) Compared with the survival group, the patients in the death group showed significantly higher levels of APACHE II score (23.96±4.31 vs. 17.70±3.92) and SOFA score (12.74±2.80 vs. 9.23±2.43, both P < 0.01), significantly higher proportions of mechanical ventilation [85.2% (23/27) vs. 50.0% (35/70)] and continuous renal replacement therapy [CRRT; 51.9% (14/27) vs. 25.7% (18/70), both P < 0.05], a significantly more fluid replacement at 6 hours (L: 2.92±0.24 vs. 2.63±0.25, P < 0.01), a significantly lower level of LCR at 6 hours [(11.61±7.76)% vs. (27.67±13.71)%, P < 0.01], and a shorter length of ICU stay (days: 6.37±2.70 vs. 7.67±2.31, P < 0.05). (2) Compared with the survival group, the patients before resuscitation in the death group showed a significantly lower level of mean arterial pressure [MAP (mmHg, 1 mmHg = 0.133 kPa): 52.63±4.35 vs. 55.74±3.01, P < 0.01], significantly higher levels of Lac and Pcv-aCO2/Ca-cvO2 ratio [Lac (mmol/L): 7.13±1.75 vs. 5.22±1.36, Pcv-aCO2/Ca-cvO2 ratio: 1.67±0.29 vs. 1.48±0.22, both P < 0.01]; and the patients at 6 hours of resuscitation in the death group showed a significantly lower level of MAP (mmHg: 62.59±4.80 vs. 66.71±3.91, P < 0.01), significantly higher levels of central venous pressure (CVP), Lac, Pcv-aCO2 and Pcv-aCO2/Ca-cvO2 ratio [CVP (mmHg): 10.74±1.40 vs. 8.80±0.75, Lac (mmol/L): 6.36±1.86 vs. 3.90±1.95, Pcv-aCO2 (mmHg): 7.59±2.02 vs. 4.34±1.37, Pcv-aCO2/Ca-cvO2 ratio: 1.87±0.51 vs. 1.03±0.27, all P < 0.01]. (3) Multivariate Cox regression analysis showed that the independent risk factors for 28-day mortality in patients with septic shock were Lac and Pcv-aCO2/Ca-cvO2 ratio whether before or at 6 hours of resuscitation [Lac before resuscitation: relative risk (RR) = 1.434, 95% confidence interval (95%CI) was 1.070-1.922, P = 0.016; Lac at 6 hours of resuscitation: RR = 1.564, 95%CI was 1.202-2.035, P = 0.001; Pcv-aCO2/Ca-cvO2 ratio before resuscitation: RR = 2.828, 95%CI was 1.108-4.207, P = 0.038; Pcv-aCO2/Ca-cvO2 ratio at 6 hours of resuscitation: RR = 4.386, 95%CI was 2.842-5.730, P = 0.000]. (4) ROC curve analysis showed that Lac and Pcv-aCO2/Ca-cvO2 ratio at 6 hours of resuscitation had predictive value for the prognosis of patients with septic shock, the area under ROC curve (AUC) was 0.849 (95%CI was 0.762-0.914) and 0.905 (95%CI was 0.828-0.955), respectively. However, the predictive value of Lac combined with Pcv-aCO2/Ca-cvO2 ratio in patients with septic shock was significantly higher than Lac [AUC (95%CI): 0.976 (0.923-0.996) vs. 0.849 (0.762-0.914), Z = 3.354, P = 0.001], the sensitivity was 97.14%, and the specificity was 88.89%.ConclusionsLac and Pcv-aCO2/Ca-cvO2 ratio are independent risk factors for predicting 28-day mortality in patients with septic shock. Lac combined with Pcv-aCO2/Ca-cvO2 ratio can assess the prognosis of patients with septic shock more accurately.

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