[Prognostic significance of early lactate clearance rate for severe acute respiratory failure patients on extracorporeal membrane oxygenation].

OBJECTIVE

To investigate the prognostic significance of early lactate clearance rate for severe acute respiratory failure patients on extracorporeal membrane oxygenation (ECMO).

METHODS

Forty-three patients with severe acute respiratory failure supported by venous-venous (v-v) ECMO were enrolled from January 2007 to January 2013. Arterial blood lactate at pre-ECMO support(0 h) and at post-ECMO 6 hours (6 h) were measured and then 6 h lactate clearance rate was calculated. The acute physiology and chronic health evaluation II (APACHEII) score was evaluated on the first day of ECMO support. Survival at 90 d after admission was the study endpoint. Patients were divided into the survival group (n = 24) and the death group (n = 19) . The 0 h blood lactate, 6 h lactate clearance rate and APACHE II score were compared between groups. The value of 0 h blood lactate, 6 h lactate clearance rate and APACHE II score for predicting death was evaluated by receiver operating characteristic (ROC) curves. The surviving curve was drawn using the Kaplan-Meier method, and the survival of the patients was analyzed by the Log-rank test. Factors influencing the prognosis were analyzed by the multiple logistic regression analysis.

RESULTS

(1) The 0 h blood lactate and APACHE II score were lower in survivors than in nonsurvivors [(3.8 ± 2.1) mmol/L vs. (5.9 ± 2.3) mmol/L, (18 ± 7) vs. (25 ± 7) , t = 7.924, 8.446, respectively, both P < 0.05], while the 6 h lactate clearance rate was higher in survivors than in nonsurvivors [(35.7 ± 20.4) % vs. (10.7 ± 18.2) %, t = 8.607, P < 0.05]. (2) The areas under the ROC curve of 0 h blood lactate, 6 h lactate clearance rate and APACHE II score for predicting death were 0.699 ± 0.083 (95%CI:0.567∼0.892, P < 0.05) , 0.871 ± 0.119 (95%CI:0.724∼0.980, P < 0.05) and 0.836 ± 0.063 (95%CI: 0.713∼0.958, P < 0.05) . The best cutoff point was 17.5% for 6 h lactate clearance with a sensitivity of 87.5% and specificity of 84.2%. (3) Kaplan-Meier survival analysis showed that 90 d survival rate of the high lactate clearance rate group and the low lactate clearance rate group were 78.3% and 30%, with significant difference between the two groups (χ² = 10.103, P < 0.05). (4) Multivariate logistic regression analysis showed that 0 h blood lactate (OR = 1.318, 95%CI:1.159∼6.882, P < 0.05) , 6 h lactate clearance rate (OR = 6.921, 95%CI:4.469∼15.036, P < 0.05) and APACHEII score (OR = 4.417, 95%CI:3.058∼10.356, P < 0.05) were independent risk factors associated with mortality of patients on ECMO.

CONCLUSION

Early lactate clearance rate could be used as an important variable for evaluating the prognosis of severe acute respiratory failure patients on ECMO.