Acute respiratory distress syndrome: Frequency, clinical course, and costsof care

Objective: To define the occurrence rate of acute respiratory distress synd rome (ARDS) using established criteria in a well defined general patient po pulation, to study the clinical course of ARDS when patients were ventilate d using a "lung-protective" strategy, and to define the total costs of care . Design: A 3-yr (1993 through 1995) retrospective descriptive analysis of al l patients with ARDS treated in Kuopio University Hospital. Setting: Intensive care unit in the university hospital. Patients: Fifty-nine patients fulfilled the definition of ARDS: Pao(2)/Fio( 2) < 200 mm Hg (33.3 kPa) during mechanical ventilation and bilateral infil trates on chest radiograph. Interventions: None. Measurements and Main Results: With a patient data management system, the d ay-by-day data of hemodynamics, ventilation, respiratory mechanics, gas exc hange, and organ failures were collected during the period that Pao(2)/Fio( 2) ratio was <200 mm Hg (33.3 kPa). The frequency of ARDS was 4.9 cases/100 ,000 inhabitants/yr. Pneumonia and sepsis were the most common causes of AR DS. Mean age was 43 +/- 2 yrs. At the time of lowest Pao(2)/Fio(2), the non survivors had lower arterial and venous oxygen saturations and higher arter ial lactate than survivors, whereas there were no differences between the g roups in other parameters. Multiple organ dysfunction preceded the worst ox ygenation in both the survivors and nonsurvivors. The intensive care mortal ity was 37%; hospital mortality and mortality after a minimum 8 months of f ollow-up was 42%. The most frequent cause of death was multiple organ failu re. The effective costs of intensive care per survivor were US $73,000. Conclusions: The outcome of ARDS is unpredictable at the time of onset and also at the time of the worst oxygenation. Keeping the inspiratory pressure s low (30-35 cm H2O [2.94 to 3.43 kPa]) reduces the frequency of pneumothor ax, and might lower the mortality. Most patients are young, and therefore t he costs per saved year of life are low.