Chapter 040. Diarrhea and Constipation (Part 7)

ACUTE DIARRHEA: TREATMENT Fluid and electrolyte replacement are of central importance to all forms of acute diarrhea. Fluid replacement alone may suffice for mild cases. Oral sugarelectrolyte solutions (sport drinks or designed formulations) should be instituted promptly with severe diarrhea to limit dehydration, which is the major cause of death. Profoundly dehydrated patients, especially infants and the elderly, require IV rehydration.In moderately severe nonfebrile and nonbloody diarrhea, antimotility and antisecretory agents such as loperamide can be useful adjuncts to control symptoms. Such agents should be avoided with febrile dysentery, which may beexacerbated or prolonged by them. Bismuth subsalicylate may...
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Chapter 040. Diarrhea and Constipation (Part 7) Chapter 040. Diarrhea and Constipation (Part 7) ACUTE DIARRHEA: TREATMENT Fluid and electrolyte replacement are of central importance to all forms ofacute diarrhea. Fluid replacement alone may suffice for mild cases. Oral sugar-electrolyte solutions (sport drinks or designed formulations) should be institutedpromptly with severe diarrhea to limit dehydration, which is the major cause ofdeath. Profoundly dehydrated patients, especially infants and the elderly, requireIV rehydration. In moderately severe nonfebrile and nonbloody diarrhea, antimotility andantisecretory agents such as loperamide can be useful adjuncts to controlsymptoms. Such agents should be avoided with febrile dysentery, which may beexacerbated or prolonged by them. Bismuth subsalicylate may reduce symptomsof vomiting and diarrhea but should not be used to treat immunocompromisedpatients or those with renal impairment because of the risk of bismuthencephalopathy. Judicious use of antibiotics is appropriate in selected instances of acutediarrhea and may reduce its severity and duration (Fig. 40-2). Many physicianstreat moderately to severely ill patients with febrile dysentery empirically withoutdiagnostic evaluation using a quinolone, such as ciprofloxacin (500 mg bid for 3–5 d). Empirical treatment can also be considered for suspected giardiasis withmetronidazole (250 mg qid for 7 d). Selection of antibiotics and dosage regimensare otherwise dictated by specific pathogens, geographic patterns of resistance,and conditions found (Chaps. 122, 143, 146, 147, 148, 149, 150, 151, and 152).Antibiotic coverage is indicated whether or not a causative organism is discoveredin patients who are immunocompromised, have mechanical heart valves or recentvascular grafts, or are elderly. Antibiotic prophylaxis is indicated for certainpatients traveling to high-risk countries in whom the likelihood or seriousness ofacquired diarrhea would be especially high, including those withimmunocompromise, IBD, hemochromatosis, or gastric achlorhydria. Use oftrimethoprim/sulfamethoxazole, ciprofloxacin, or rifaximin may reduce bacterialdiarrhea in such travelers by 90%, though rifaximin may not be suitable forinvasive disease. Finally, physicians should be vigilant to identify if an outbreakof diarrheal illness is occurring and to alert the public health authorities promptly.This may reduce the ultimate size of the affected population. Chronic Diarrhea Diarrhea lasting >4 weeks warrants evaluation to exclude seriousunderlying pathology. In contrast to acute diarrhea, most of the causes of chronicdiarrhea are noninfectious. The classification of chronic diarrhea bypathophysiologic mechanism facilitates a rational approach to management,though many diseases cause diarrhea by more than one mechanism (Table 40-3). Table 40-3 Major Causes of Chronic Diarrhea According toPredominant Pathophysiologic Mechanism Secretory causes Inflammatory causes Exogenous stimulant laxatives Idiopathic inflammatory bowel disease (Crohns, chronic ulcerative Chronic ethanol ingestion colitis) Other drugs and toxins Lymphocytic and collagenous Endogenous laxatives colitis(dihydroxy bile acids) Immune-related mucosal disease Idiopathic secretory diarrhea (1° or 2° immunodeficiencies, food allergy, eosinophilic gastroenteritis, Certain bacterial infections graft-vs-host disease) Bowel resection, disease, or Infections (invasive bacteria,fistula (absorption) viruses, and parasites, Brainerd diarrhea) Partial bowel obstruction or Radiation injuryfecal impaction Gastrointestinal malignancies Hormone-producing tumors(carcinoid, VIPoma, medullary cancer Dysmotile causesof thyroid, mastocytosis, gastrinoma, Irritable bowel syndromecolorectal villous adenoma) Addisons disease (including post-infectious IBS) Congenital electrolyte Visceral neuromyopathiesabsorpti ...