Introduction: ARDS is associated with high morbidity and mortality; despite its importance to intensivists, the true incidence of ARDS has not been determined. The aim of our study was to determine the incidence and outcome (mortality and ventilator-free days) in patients with ARDS in Olmsted County, MN, and the effect of tidal volumes (VT) and steroids on outcome. METHODS: We conducted a retrospective analysis of the medical records of 293 patients who had been prospectively identified by reviewing daily blood gas reports. We tabulated the names of patients with PaO2/FiO2 ratios < 300 mmHg over a 4-year period (1995-1999). Ninety-nine patients, a age 18 who did not object to having their medical records reviewed, were identified. ARDS was defined as 1) PaO2/FiO2 ratios ≤ 200 mmHg on arterial blood gas, 2) bilateral infiltrates on chest radiograph as determined by review of the radiologist's report, 3) pulmonary capillary wedge pressure < 18 mmHg, and for those patients without a pulmonary artery catheter, myocardial dysfunction was ruled out based on echocardiography or clinical history. RESULTS: The female to male ratio was 38/61, the mean age was 63.3 years (range 19-91). The annual incidence of ARDS, adjusted to the 1990 U.S. total population, was 29/100,000 person per year (95% confidence interval: 23-35/100,000). Mortality was significantly associated with increased age (p = 0.016, 2 sample t-test). Medical patients had higher mortality (46%) than surgical patients (26%) (p = 0.048). Ventilator-free days during the first 30 days post-diagnosis were a median of 16 days (X:13.8 ± 12 days [SD]). Initial VT were 9.3 ± 2.1 mL/kg (range 4.6-15.0) with no association with mortality (p = 0.89). Only 29 patients received steroids (NS). CONCLUSION: The lack of an association of mortality with tidal volume is not surprising given the sample size. Our mortality rate in patients with ARDS of 38% is in keeping with observations of a decreasing mortality rate for ARDS. The incidence of ARDS hi a well-defined population is 29/100,000, approximately 4-6 times higher than previously reported (1,2).
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine