Page 181 - Critical Care Notes

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Acute Gastrointestinal Bleeding
Causes of upper GI (UGI) bleeding include:
■ Gastric or duodenal ulcers including stress-related ulceration; nonsteroidal
anti-inflammatory drugs (NSAIDs)–related peptic ulcer disease, erosive or
hemorrhagic gastritis, or esophagitis
■ Esophagogastric varices
■ Mallory-Weiss tear from ↑ abdominal pressure (coughing, vomiting) →
esophageal wall rupture
■ Neoplasms
■ Liver disorders
Causes of lower GI bleeding include:
■ Diverticulitis
■ Infectious colitis, Crohn’s disease
■ Bowel disease or trauma, ischemic bowel
■ Eroding aortic aneurysm
■ Neoplasms and polyps
■ Hemorrhoids or anorectal disorders
Pathophysiology
■ Constriction of peripheral arteries →↓ blood flow to skin and kidneys
→ renal failure; ↓ blood flow to GI tract → mesenteric insufficiency → bowel
infarction and liver necrosis; ↓ blood flow to coronary arteries → myocardial
infarction (MI), pulmonary edema, heart failure, and dysrhythmias;
↓ blood flow to brain → confusion, anxiety, restlessness, stupor, and coma.
■ Acute massive GI bleeding →↓ blood volume →↓ venous return, ↓ cardiac
output →↓ BP, ↑ HR → hypovolemic shock and multiple organ dysfunction.
■ Metabolic acidosis and lactic acid accumulation → anoxia and respiratory
failure.
Clinical Presentation
■ Hematemesis: Bright red or brown, coffee-ground emesis or NG tube
drainage
■ Melena: black, tarry stools
■ Hematochezia: Maroon stools or bright red blood from rectum
■ Hypotension: May be orthostatic, lightheadedness, fainting. Orthostatic
changes: ↓ BP >10 mm Hg with ↑ HR 20 bpm sitting or standing indicating
volume depletion of 15% or more

GI