Epidemiology and outcome of acute lung injury in European intensive care units

To re-examine the epidemiology of acute lung injury (ALI) in European intensive care units (ICUs).

A 2-month inception cohort study in 78 ICUs of 10 European countries.

All patients admitted for more than 4 h were screened for ALI and followed up to 2 months.

Acute lung injury occurred in 463 (7.1%) of 6,522 admissions and 16.1% of all mechanically ventilated patients; 65.4% cases occurred on ICU admission. Among 136 patients initially presenting with “mild ALI” (200< PaO₂/FiO₂ ≤300), 74 (55%) evolved to acute respiratory distress syndrome (ARDS) within 3 days. Sixty-two patients (13.4%) remained with mild ALI and 401 had ARDS. The crude ICU and hospital mortalities were 22.6% and 32.7% (p<0.001), and 49.4% and 57.9% (p=0.0005), respectively, for mild ALI and ARDS. ARDS patients initially received a mean tidal volume of 8.3±1.9 ml/kg and a mean PEEP of 7.7±3.6 cmH₂O; air leaks occurred in 15.9%. After multivariate analysis, mortality was associated with age (odds ratio (OR) =1.2 per 10 years; 95% confidence interval (CI): 1.05–1.36), immuno-incompetence (OR: 2.88; Cl: 1.57–5.28), the severity scores SAPS II (OR: 1.16 per 10% expected mortality; Cl: 1.02–1.31) and logistic organ dysfunction (OR: 1.25 per point; Cl: 1.13–1.37), a pH less than 7.30 (OR: 1.88; Cl: 1.11–3.18) and early air leak (OR: 3.16; Cl: 1.59–6.28).

Acute lung injury was frequent in our sample of European ICUs (7.1%); one third of patients presented with mild ALI, but more than half rapidly evolved to ARDS. While the mortality of ARDS remains high, that of mild ALI is twice as low, confirming the grading of severity between the two forms of the syndrome.