EVALUATION OF DEFINITIONS FOR ADULT-RESPIRATORY-DISTRESS-SYNDROME

We conducted a cohort study of 423 intensive care unit (ICU) admission s with a primary clinical diagnosis of acute respiratory failure, a Pa -O2/Fl(O2) on ICU admission of < 300 mm Hg, and an ICD-9 discharge dia gnosis of adult respiratory distress syndrome (ARDS) (518.5 or 518.82) drawn from a nationally representative database of 17,440 ICU admissi ons to evaluate current and proposed revisions for definitions of ARDS . A variety of nonpulmonary physiologic risk factors, from shock to el evated serum bilirubin measurements, were significant (p < 0.01) for h ospital mortality. Multivariable analysis using the admission APACHE I II score, primary ICU admission diagnosis, and treatment location befo re ICU admission provided greater accuracy in prediction (ROC = 0.80) than the individual Pa-O2/Fl(O2) (ROC = 0.68). Patients were given an individual risk of hospital mortality based on their admission APACHE III score, treatment location before ICU admission, and ICU admitting diagnosis. Dividing the patient population into groups using a Pa-O2/F l(O2) less than or equal to 150 resulted in a wide range of individual risk for hospital mortality, from < 10 to > 90% in both groups. We co nclude that ARDS is a complex clinical entity with a variety of pulmon ary and nonpulmonary risk factors for both its development and its pro gnosis. Current and proposed categorical definitions based on the seve rity of hypoxemia result in a wide distribution of individual patient risks. Use of these findings in the design and conduct of future clini cal trials would improve the evaluation of new therapies.