To explore the prediction value of lactic acid (LAC) combined with interleukin-9 (IL-9) in acute respiratory distress syndrome (ARDS).

From Aug. 2015 to Jul. 2016, 44 ARDS patients were enrolled and divided into moderate ARDS group (24 cases) and severe ARDS group (20 cases) according to Berlin ARDS criterion. Forty healthy volunteers were enrolled in the control group. Using double antibody sandwich enzyme-linked immunosorbent assay for peripheral venous IL-9 and LAC examination in both groups. All patients were followed up for at least 30 days and then divided into survival group (23 cases) and non-survival group (21 cases). The prediction value of combining these two parameters was analyzed by ROC curve.

The levels of IL-9 and LAC in ARDS group were higher than those in control group [(4.31±1.86) pg/ml vs (2.31±0.81) pg/ml, (8.5±4.0) mmol/L vs (2.1±2.7) mmol/L] at the first day, the difference was statistically significant (t=6.31, 7.42, all P<0.05). There was no significant difference in IL-9 and LAC levels between moderate ARDS patients and severe ARDS patients at the first day (all P>0.05); the LAC and IL-9 levels in moderate group were lower than those in severe group at the third day [(3.21±1.07) pg/ml vs (4.37±1.01) pg/ml, (7.1±1.0) mmol/L vs (8.0±1.5) mmol/L], the difference was statistically significant (t=-3.67, -3.42, all P<0.05). There was no difference in IL-9 level between survival group and non-survival group at the first day (P>0.05), but lactate level in the same day between these two groups are different [(6.2±1.4) mmol/L vs (8.4±1.9) mmol/L], the difference was statistically significant (t=-4.48, P<0.05). The levels of LAC and IL-9 in non-survival group were significantly higher than those in survival group at the third day [(3.02±0.97) pg/ml vs (4.11±0.54) pg/ml, (5.0±1.3) mmol/L vs (7.2±1.8) mmol/L], the difference was statistically significant (t=-3.99, -3.67, P<0.05). In ROC curve, the sensitivity of prediction value for these two combined parameters was 95.65% and the specificity was 90.48%, which meant combination of these two parameters were better than separate use either of them.

Combined determination of LAC and IL-9 in patients with acute respiratory distress syndrome is helpful to predict the prognosis in these patients.