My husband was diagnosed with diffuse alveolar hemorrhage (DAH) and ARDS but what is the difference between the two conditions?

Question: January, 2022

Crystal A., family member of an ARDS survivor, asks:

Also, why do ARDS patients often suffer an acute kidney injury/kidney failure, and how does CRRT/dialysis not only treat the kidneys, but also helps the patient recover from ARDS?

Doctor Response:

Ask the docotrDAH is caused by a lot of bleeding into the lungs. This is sometimes caused by inflammation from a vasculitis, as granulomatosis with angiitis. This is a different process than in most other causes of ARDS. On the other hand, we think some DAH is precipitated by an infection.  ARDS from most other causes has relatively little bleeding into the lungs, whereas in DAH there is a lot of bleeding.

ARDS is frequently caused by a severe infection that causes sepsis, which means some noxious substances from the infection and from the patient’s immune response are circulating in the blood. These substances sometimes injure the kidneys. Also, sepsis sometimes causes shock, with low blood pressure and poor blood flow to various organs. Kidneys are very sensitive to poor blood flow.

CRRT/dialysis cleans the blood of substances normally cleared by kidneys, and CRRT/dialysis can be used to remove excess fluid (water) from the body. It does not really treat the kidneys. It substitutes for the failed kidneys until the failed kidneys can recover, which they frequently can do. CRRT can help patients recover from ARDS by removing excess fluid from the body, which can get into the lungs and worsen the edema problem of ARDS.p;

Roy Bower

Roy Bower MD
Professor of Medicine –
Pulmonary and Critical Care Medicine  –
Johns Hopkins University School of Medicine


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By | 2022-01-16T11:59:51-06:00 January 16th, 2022|Ask The Doctor, News, Uncategorized|Comments Off on My husband was diagnosed with diffuse alveolar hemorrhage (DAH) and ARDS but what is the difference between the two conditions?