Acute mucosal ulceration

Peptic ulcers may recur during critical illness. However, other forms of acute ulceration of the gastroduodenal mucosa are more commonly encountered in critically ill patients without actual association with peptic ulcer disease. This mucosal injury is often referred to as a stress ulcer. However, the pathological anatomical definition of this lesion is an erosion (a superficial lesion not penetrating the mucosa). In contrast, an ulcer by definition penetrates at least down to the muscular layer.

Stress ulceration may be found in critically ill patients, usually as multiple superficial erosions on top of the gastric ridges in the acid-producing part of the stomach. The clinical manifestation of stress ulceration is acute gastrointestinal hemorrhage. This is less common today than 10 to 20 years ago, but an incidence of 1 to 3 per cent in critically ill patients has recently been reported. Bleeding is less likely to occur if the pH of the gastric contents can be kept normal or close to normal. Endoscopic examination of the stomach within the first 24 h of severe injury has revealed that almost all patients develop mucosal injury. Several risk factors for hemorrhage have been identified, including sepsis, shock, acidosis, and other coexisting components of the multiple organ failure syndrome. Impaired mucosal oxygenation has been demonstrated to be an important pathophysiological factor for the development of bleeding stress ulcers. The most important preventative factor is recognized to be optimal intensive care, providing adequate oxygenation of the peripheral tissues.

A special form of acute ulceration is the Curling ulcer seen in major burn injury. Burn patients often have single ulcers which may penetrate quite deep into the gastric or upper duodenal wall and, in contrast with stress ulcers, may even cause perforation. Cushing ulcers, which are seen in patients with neurological injury, fall between the two other acute ulcer forms. For completeness, a fourth type of acute mucosal ulceration caused by drugs, mainly non-steroidal anti-inflammatory drugs (NSAIDs), should be noted. There are often multiple erosions combined with deeper ulcers. Characteristically, these acute ulcerations are most often found in the gastric mucosa while peptic ulcers are most often seen in the duodenum. The pathogenesis of NSAID-induced ulcers is complex but is probably related to inhibition of prostaglandin synthesis by a non-selective inhibition of the enzyme cyclo-oxygenase.

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