[Predictive values of different critical scoring systems for mortality in patients with severe acute respiratory failure supported by extracorporeal membrane oxygenation].

OBJECTIVE: To investigate the predictive values of different critical scoring systems for mortality in patients with severe acute respiratory failure (ARF) supported by venovenous extracorporeal membrane oxygenation (VV-ECMO).

METHODS: Forty-two patients with severe ARF supported by VV-ECMO were enrolled from November 2009 to July 2015.There were 25 males and 17 females. The mean age was (44±18) years (rang 18-69 years). Acute Physiology and Chronic Health Evaluation (APACHE) Ⅱ, Ⅲ, Ⅳ, Simplified Acute Physiology Score Ⅱ (SAPS) Ⅱ, Sequential Organ Failure Assessment (SOFA), ECMO net, PRedicting dEath for SEvere ARDS on VVECMO (PRESERVE), and Respiratory ECMO Survival Prediction (RESP) scores were collected within 6 hours before VV-ECMO support. The patients were divided into the survivors group (n=17) and the nonsurvivors group (n=25) by survival at 180 d after receiving VV-ECMO. The patient clinical characteristics and aforementioned scoring systems were compared between groups. Scoring systems for predicting prognosis were assessed using the area under the receiver-operating characteristic (ROC) curve. The Kaplan-Meier method was used to draw the surviving curve, and the survival of the patients was analyzed by the Log-rank test. The risk factors were assessed for prognosis by multiple logistic regression analysis.

RESULTS: (1) Positive end expiratory pressure (PEEP) 6 hours prior to VV-ECMO support in the survivors group [(9.7±5.0)cmH2O, (1 cmH2O=0.098 kPa)] was lower than that in the nonsurvivors group [(13.2±5.4)cmH2O, t=-2.134, P=0.039]. VV-ECMO combination with continuous renal replacement therapy(CRRT) in the nonsurvivors group (32%) was used more than in the survivors group (6%, χ(2)=4.100, P=0.043). Duration of VV-ECMO support in the nonsurvivors group [(15±13) d] was longer than that in the survivors group [(12±11)d, t=-2.123, P=0.041]. APACHE Ⅱ, APACHE Ⅲ, APACHE Ⅳ, ECMO net, PRESERVE, and RESP scores in the survivors group were superior to the nonsurvivors group (all P<0.05). (2) The areas under the ROC curve of APACHE Ⅳ score for predicting death were largest (0.792±0.076, 95%CI: 0.643-0.940, P<0.05). The best cutoff point was 48 for APACHE Ⅳ score with a sensitivity of 92.0%, specificity of 64.7%, and overall accuracy of 81%. (3) Kaplan-Meier survival analysis showed that 180 d survival rate of the low APACHE Ⅳ score group was higher than the high APACHE Ⅳ score group (χ(2)=11.331, P<0.05). (4) Multiple logistic regression analysis showed that PEEP (OR=1.555, 95%CI: 1.097-2.204, P<0.05), APACHE Ⅳ score (OR=1.152, 95%CI: 1.021-1.301, P<0.05), and PRESERVE score (OR=4.984, 95%CI: 1.531-16.227, P<0.05) were independent risk factors associated with mortality of patients supported by VV-ECMO.

CONCLUSION: The critical scoring systems proved to have good prognostic ability in predicting hospital mortality for severe ARF patients supported by VV-ECMO. Compared to other scoring systems, APACHE Ⅳ score system predicted more accurately, while specific scoring systems in predicting hospital mortality showed no advantage.