Diarrhea

Published on 26/03/2015 by admin

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25 Diarrhea

Diarrhea is one of the most common abnormal manifestations of gastrointestinal (GI) dysfunction in the intensive care unit (ICU); the reported incidence is between 2% and 63%.1 Diarrhea is best defined as bowel movements that, owing to increased frequency, abnormal consistency, or increased volume, cause discomfort to the patient or the caregiver. This definition demonstrates the subjectivity in diagnosing diarrhea, a fact that complicates interpretation of the literature and limits applicability of guidelines. The impact of diarrhea on patient care in the ICU, including its cost in morbidity and mortality, is unknown. However, it is undeniable that diarrhea remains a persistent problem in many ICUs.

image Pathophysiology

Bowel movements with normal physiologic volume, consistency, and frequency are the result of a GI tract that integrates motility, secretion, and absorption of fluids and adapts to the quality of the food bolus given. The result is a fecal bolus that is produced once or twice every 24 hours and has consistency and fluidity within the boundaries of normal.

Diarrhea results when there is a disorder of GI physiology or when GI tract function is incapable of handling the food bolus. There are several classifications of diarrhea, suggesting that no classification is ideal at helping the clinician plan for patient care. Perhaps the most useful approach is to classify diarrhea according to alterations of physiologic events:

1 Increased fluid secretion that overwhelms absorption. On average, up to 9 liters of fluid is secreted into the GI lumen in addition to the normal oral intake. Less than 1% of that fluid is contained in stool, owing to the amazingly large absorptive capacity of the small and large bowel. Within the intestinal mucosa, passive and active transport of sodium determines the amount of water that is absorbed. Stimulation of the active secretion of fluids into the GI lumen occurs when intracellular levels of the second messenger, cyclic adenosine monophosphate (cAMP), increase within enterocytes. Increased intracellular cAMP concentration promotes chloride secretion.3 Thus, diarrhea caused by excessive secretion of fluids is called secretory diarrhea. Secretory diarrhea characteristically contains large amounts of fluid and is described as watery. Secretory diarrhea is observed in certain infectious diseases such as cholera or infections with rotavirus. Secretory diarrhea also can be observed in endocrine disturbances associated with carcinoid syndrome or vasoactive intestinal peptide (VIP)-secreting tumors.
4 Diarrhea due to increased osmotic load. Many substances that are taken orally and are not fully absorbed can exert a significant osmotic force, overwhelming the physiologic absorptive capacity of the GI tract. A significant number of patients with diarrhea in the ICU fall into this category.

b Incomplete digestion and malabsorption. The incidence of malabsorption in the ICU is unknown. However, there are many instances where malabsorption should be considered as a cause of diarrhea in the critically ill patient. These include:

iv Excessive dietary load. Diarrhea due to excessive load (overfeeding) of any of the main dietary components (protein, carbohydrate, or fat) can be observed in the ICU. Iatrogenic overfeeding occurs in up to 33% of patients in the ICU, and is a result of inappropriate estimations of caloric and protein needs or inadequate metabolic surveillance.9 Excessive loads of protein, carbohydrate, or fat also occur with “specialized” formulas that contain altered amounts of one or more of these components. For example, certain diets may contain high amounts of fat, overwhelming digestive and absorptive processes.

image Diagnosis

Careful and complete evaluation of diarrhea is necessary for good patient care. Unfortunately, diarrhea is often ignored or hastily “treated” while clinicians pay more attention to other organ systems. Diagnostic laboratory tests often do not exist, making it ever more difficult to identify and treat the patient. We propose the following approach:

image Treatment

Treatment is dependent on identification of the underlying cause. One or several reasons for the presence of diarrhea generally can be identified. Once identified, the causes of diarrhea should be eliminated, modified, or treated. In particular, iatrogenic causes of diarrhea should be identified and corrected whenever feasible. For example, prolonged courses of prophylactic antibiotics are no better than short courses for the prevention of surgical site infections; therefore, adherence to current guidelines to limit antibiotics is important.12,13

Modification of the diet may be important if the GI tract is being overwhelmed with high quantities of a particular nutrient. This is particularly important for patients receiving formulas that deliver excessive fat loads.

Digestive enzymes such as pancreatic enzymes or bile substitutes should be supplemented when the disease process (or treatment) is associated with decreased production of these enzymes.

Agents that inhibit GI motility, such as loperamide, should be used with caution. These drugs are often ordered empirically and may worsen underlying pathology, especially when the causative agent is infectious.

Bulk-forming agents are sometimes given to patients to improve the consistency of the fecal bolus. These agents have to be used in the appropriate amount, since they can also be a cause of diarrhea.14

Antibiotics to treat infectious diarrhea also should be used with caution. If the diarrhea is causing minimal discomfort and is of no physiologic consequence, waiting for arrival of results of tests for C. difficile may be advised.15

Restoring normal colonic flora has become an increasingly frequent practice in the ICU. Provision of prebiotics and probiotics in different presentations is now being suggested, but the implications of such therapies are not clear and require further investigation.11,16 Soluble fiber may have a role in restoring normal colonic function and flora.

Stopping or decreasing the rate of enteral nutrition is often done; however, this is only advocated if the patient is being overfed or exhibits intolerance to the diet. Only under exceptional circumstances should stopping oral intake and giving total parenteral nutrition be advocated as a treatment for diarrhea.

References

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2 Wiesen P, van Gossum A, Presier JC. Diarrhoea in the critically ill. Curr Opin Crit Care. 2006 Apr;12(2):149-154.

3 Krishnan S, Ramakrishna BS, Binder HJ. Stimulation of sodium chloride absorption from secreting rat colon by short-chain fatty acids. Dig Dis Sci. 1999;44:1924-1930.

4 Cunha BA. Nosocomial diarrhea. Crit Care Clin. 1998;14:329-338.

5 Hyams JS. Sorbitol intolerance: an unappreciated cause of functional gastrointestinal complaints. Gastroenterology. 1983;84:30-33.

6 Pilotto A, Franceshi M, Vitale D, Zaninelli A, DiMario F, Seripa D, et al. The prevalence of diarrhea and its association with drug use in elderly outpatients: a multicenter study. FIRI; SOFIA Project Investigators. Am J Gastroenterol. 2008 Nov;103(11):2816-2823.

7 Leonard J, Marshall JK, Moayyedi P. Systematic review of the risk of enteric infection in patients taking acid suppression. Am J Gastroenterol. 2007 Sep;102(9):2047-2056.

8 Fernandez-Banares F, Esteve M, Viver JM. Fructose-sorbitol malabsorption. Curr Gastroenterol Rep. 2009 Oct;11(5):368-374.

9 Edes TE. Nutrition support of critically ill patients. Guidelines for optimal management. Postgrad Med. 1991;89:193-198. 200

10 OKeefe SJD. Tube feeding, the microbiota, and Clostridium difficile infection. World J Gastroenterol. 2010 Jan 14;16(2):139-142.

11 Morrow LE. Probiotics in the intensive care unit. Curr Opin Crit Care. 2009 Apr;15(2):144-148.

12 Wistrom J, Norrby SR, Myhre EB, et al. Frequency of antibiotic-associated diarrhoea in 2462 antibiotic-treated hospitalized patients: a prospective study. J Antimicrob Chemother. 2001;47:43-50.

13 Nelson RL, Glenny AM, Song F. Antimicrobial prophylaxis for colorectal surgery. Cochrane Database Syst Rev 2009 Jan 21;(1):CD001181.

14 Nakao M, Ogura Y, Satake S, et al. Usefulness of soluble dietary fiber for the treatment of diarrhea during enteral nutrition in elderly patients. Nutrition. 2002;18:35-39.

15 Dallal RM, Harbrecht BG, Boujoukas AJ, et al. Fulminant Clostridium difficile: an underappreciated and increasing cause of death and complications. Ann Surg. 2002;235:363-372.

16 Meier R, Burri E, Steuerwald M. The role of nutrition in diarrhoea syndromes. Curr Opin Clin Nutr Metab Care. 2003;6:563-567.