Predictors of mortality in ARDS patients referred to a tertiary care centre: a pilot study

Abstract

Background and objective: In order to identify parameters predicting intensive care unit mortality in patients transferred to a specialized tertiary centre because of progressive acute respiratory distress syndrome, an observational pilot study was carried out involving 94 patients.

Methods and results: Forty-one patients (43.6%) died. Survival was defined as intensive care unit discharge. Survivors were younger (32.0 +/- 11.8 vs. 39.1 +/- 12.4 yr, P = 0.008), at admission they had a lower acute physiology and chronic health evaluation (APACHE) II score (21.7 +/- 5.4 vs. 25.4 +/- 5.2, P = 0.0009), higher PaO2/FiO2 (122 +/- 79 vs. 79 +/- 42 mmHg, P = 0.002), lower positive end-expiratory pressure (10.6 +/- 3.1 vs. 12.5 +/- 3.7 cmH2O, P = 0.02) and a lower Murray score (2.8 +/- 0.63 vs. 3.0 +/- 0.62, P = 0.04). No differences were observed for tidal volumes and peak inspiratory pressures. Days of hospitalization and mechanical ventilation prior to transferral were not related to survival. Multivariate analysis of variables assessed on admission detected only differences for age (P = 0.014) and APACHE II (P = 0.005). Odds ratio was 1.06 (95% confidence interval (CI): 1.013-1.119) for age and 1.21 (CI: 1.059-1.381) for APACHE II. Multivariate analysis of changes in respiratory parameters, APACHE II and Murray score during the first 3 days after transferral revealed a significant difference only for positive end-expiratory pressure (P < 0.008). Corresponding odds ratio was 2.40 (CI: 1.25-4.58) for an increase of 1 cmH2O/24 h.

Conclusion: Age-related mortality in this small, but highly selected group of patients with established ARDS increased early in life even in a population with an overall mean age of 35.1 yr. APACHE II was the only clinical predictor for mortality on admission. The need for a substantial increase in positive end-expiratory pressure after transferral markedly reduced the chance to survive.