Evaluation of the Progress and Prognosis of Adult Respiratory Distress Syndrome

In our study of 14 patients with adult respiratory distress syndrome (ARDS), we measured A-aDO 2 , Vd/Vt, arterial-to-end tidal Pco 2 difference (a-etPco 2 ), effective dynamic compliance, and pulmonary vascular resistance on a daily basis. At the onset of ARDS, all patients showed bilateral interstitial edema on the chest x-ray films, P(A-a)O 2 of more than 500 mm Hg, marked decrease in effective dynamic compliance, a moderate increase in Vd/Vt, and a normal value of a-etPco 2 . Pulmonary vascular resistance was low. After seven days, all of those who subsequently died had developed persistent elevation of P(A-a)O 2 , significant increase in Vd/Vt, a-etPco 2 and pulmonary vascular resistance, and significant decrease in effective dynamic compliance compared to the values at the onset of ARDS. Those abnormalities diverged significantly from the findings in those who survived. By evaluating sequential changes of those parameters, we might be able to predict an accurate prognosis of ARDS.