Diarrhoea

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• Antibiotics
• Additives eg sorbitol
• Pulmonary - theophylline
• GI
  • magnesium antacids
  • H2 blockers
  • misoprostol
  • sulfasalazine
• Anti-neoplastic agents
• Anti-arrhythmics
  • quinidine
  • procainamide
  • digoxin
• Anti-hypertensives
  • beta blockers
  • ACE inhibitors
  • hydralazine
  • guanethidine
  • diuretics
• Cholesterol medications
  • lovastatin
  • gemfibrozil
  • probucol
• Thyroxine

Accounts for only 20% of cases of diarrhoea in enterally fed patients in ICU. Osmotic diarrhoea. Typically produces a stool with an osmotic gap of > 100 mOsm/kg. Thought to be the result of malabsorption, the cause of which is not known. Possible that malabsorption is due to malnutrition, or antibiotic therapy.
Catabolic state results in flattening of intestinal villi, crypt atrophy, reduced levels of mucosal digestive proteins and decreased production of gut hormones (eg gastrin, cholecystokinin). Also possible that mucosal changes result from luminal nutritional deprivation rather than overall nutritional state as the same changes occur in patients fed intravenously.

Impairment of colonic fermentation of carbohydrates possibly the most important factor in antibiotic induced diarrhoea in enterally fed patients. Unabsorbed carbohydrates are usually fermented by colonic bacteria to short chain fatty acids. These are a major stimulus to sodium and water absorption in the large intestine so the problem caused by the osmotic load of the unfermented carbohydrates is compounded by decreased colonic salt and water absorption

- Clostridium difficile (see below)
- Salmonella, Shigella, Campylobacter and Yersinia (rare in ICU setting)
- E coli 0157:H7 serotype. May also be associated with haemolytic uraemic syndrome or thrombotic thrombocytopaenic purpura

- any cause of diarrhoea eg faecal impaction, ischaemic bowel

Assessment

History

• Duration and speed of onset

• Stool characteristics: watery, bloody, mucous, purulent, greasy etc

• Frequency of bowel opening and quantity of stool

• Symptoms of dysentery: fever, tenesmus, blood or pus in stools

• Symptoms of volume depletion: thirst, tachycardia, postural faintness, decreased urination, lethargy

• Associated symptoms: nausea, vomiting, abdominal pain, cramps, headache, myalgia

• Epidemiological risk factors:

  • Travel

  • Attendance or employment in day care facility

  • Consumption of unsafe foods eg raw meats, eggs, shellfish, unpasteurized milk

  • Swimming in or drinking untreated fresh surface water from, for example, a lake or stream

  • Contact with animals

  • Contact with patient with diarrhoea

• Past medical history. Conditions which predispose to infectious diarrhoea include:

  • AIDS

  • Immunosuppression

  • Gastrectomy

  • Medication

• Sexual preferences

  • Receptive anal intercourse

  • Oral-anal contact

• Employment as food handler or caregiver

Frequency of clinical features varies according to aetiological agent although there is considerable overlap:

STEC = Shiga toxin producing E. coli

Examination

• Signs of dehydration

• Abdominal examination

  • Abdominal tenderness

  • Rectal examination

Investigations

• Stool electrolytes. Calculate osmolar gap based on assumption that stool osmolality is 290 mOsm/kg as measurement of stool osmolality is difficult for technical reasons. Osmolar gap = 290 - 2(Na + K). Gap > 100 mOsm/kg is indicative of osmotic diarrhoea which is most likely to be due either to drugs or to malabsorption of enteral feed

• If diarrhoea is osmotic and there is no drug which is likely to be responsible try changing patient to peptide based diet (peptides absorbed more effectively than amino acids during disease states associated with impaired small bowel absorption). If diarrhoea persists stop and consider changing to IV feeding. Little evidence that fibre supplements, change in feed osmolarity, temperature or fat content or use of aseptic technique is useful.

• If diarrhoea is not osmotic then by far the most likely cause is C. difficile colitis. Treatment of choice is enteral vancomycin 125 mg qds. Metronidazole is an alternative in less seriously ill patients

• Routine examination of stool for enteric pathogens is of low yield unless diarrhoea was present within 24-48 h of admission to ICU

Suspected infectious diarrhoea

• Presence of inflammation suggestive of invasive colitis with Salmonella, Shigella or Campylobacter or more severe C. difficile colitis or inflammatory bowel disease

Treatment

Suspected infectious diarrhoea

Consider empirical treatment for:

• Giardiasis in patients with diarrhoea that lasts more than 10-14 days if other evaluations are negative and if the patient’s history of travel or water exposure is suggestive

• Patients with febrile diarrhoeal illnesses, particularly those thought to have moderate or severe invasive disease. Quinolones are drugs of choice although Campylobacter and Salmonella resistance to quinolones is increasing

• Shiga toxin-producing E. coli (STEC) infections

• Avoid anti-motility agents

• Treatment of STEC O157 infections with antimicrobial agents does not ameliorate the diarrhoea and may increase the risk of developing haemolytic uraemic syndrome

©Charles Gomersall, August, 2008 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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