Stress ulcer prophylaxis has always involved a tradeoff.
Critically ill patients can develop stress-related mucosal injury and clinically important upper gastrointestinal bleeding. Acid suppression can reduce that risk.
But PPIs have also raised concerns about pneumonia, C. difficile infection, unnecessary continuation, and overuse in low-risk patients.
The physiology begins with mucosal vulnerability.
Shock, mechanical ventilation, coagulopathy, renal failure, hepatic dysfunction, and severe inflammation can impair mucosal blood flow and protective barriers. Acid exposure then increases the risk of clinically important bleeding.