ICU Chest Films > Fluid in the Chest > Adult Respiratory Distress Syndrome > ARDS vs. CHF

ARDS versus Congestive Heart Failure

While it is not always easy, it is often possible to radiographically distinguish between pulmonary edema caused by congestive heart failure (CHF) and ARDS. Indeed, both may coexist. Although both entities may share the x-ray finding of bilateral airspace opacification or "white out", ARDS is not associated with cardiomegaly or with cephalization of pulmonary vasculature. However, cephalization may not be visible in the midst of "white out"and CHF can exist without cardiomegaly. Both of these findings may be difficult to discern in the supine patient. The patient with ARDs could also have preexistant cardiomegaly or be fluid overloaded because of sepsis.

Features that are helpful in distinguishing CHF from ARDS include the following: While cardiogenic pulmonary edema typically begins centrally in the bilateral perihilar areas, ARDS usually causes more uniform opacification. Pleural effusions are not typical of ARDS but often present in CHF. Kerley B lines are common in CHF but not in ARDS, while air bronchograms can be found in both.

Temporally, radiographic abnormalities usually closely parallel cardiogenic pulmonary edema, while the chest radiograph in ARDS may remain unremarkable for up to twelve hours and usually stabilize after the first thirty-six hours. While radiographic findings in cardiogenic edema may clear rapidly, ARDS typically clears slowly. Unlike cardiogenic edema, which, once resolved, does not leave behind permanent pulmonary changes, a percentage of ARDS cases will result in some degree of permanent pulmonary fibrosis, characterized by increased intersitital markings depending on the severity and length of time the patient was in ARDS.