Background: The characteristics, incidence and risk factors for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) may depend on definitions and geography.
Methods: A prospective, 3-day point-prevalence study was performed by a survey of all intensive care units (ICU) in the Netherlands (n=96). Thirty-six ICU's responded (37%), reporting on 266 patients, of whom 151 were mechanically ventilated. The questionnaire included criteria and potential risk factors for ALI/ARDS, according to the North American-European Consensus Conference (NAECC) or the lung injury score (LIS>or=2.5).
Results: Agreement between definitions was fair (kappa 0.31-0.42, P=0.001). ALI/ARDS was characterized, regardless of definition, by radiographic densities, low oxygenation ratios, high inspiratory O(2) and airway pressure requirements. Depending on definitions, ALI and ARDS accounted for about 12-33% and 7-9% of ICU admissions per year, respectively, constituting 21-58% (ALI) and 13-16% (ARDS) of all mechanically ventilated patients. The annual incidences of ALI and ARDS are 29.3 (95%CI 18.4-40.1) and 24.0 (95%CI 14.2-33.8) by NAECC, respectively, and are, respectively, 83.6 (95%CI 65.3-101.9) and 20.9 (95%CI 11.7-30.1) by LIS per 100,000. Risk factors for ALI/ARDS were aspiration, pneumonia, sepsis and chronic alcohol abuse (the latter only by NAECC).
Conclusion: The effect of definitions of ALI/ARDS on mechanical ventilation in the Netherlands is small. Nevertheless, the incidence of ALI/ARDS may be higher than in other European countries but lower than in the USA, and the incidence of ALI by LIS may overestimate compared to that by NAECC. Aspiration, pneumonia, sepsis and chronic alcohol abuse are major risk factors, largely independent of definitions.