The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [191]
From the ileocaecal sphincter to the anus, the colon is approximately 1.5–1.8 m in length. Its main function is to eliminate the waste products of digestion by the propulsion of faeces towards the anus. In addition, it produces mucus to lubricate the faecal mass, thus aiding its expulsion. Other functions include the absorption of fluid and electrolytes, including sodium and potassium, the storage of faeces and the synthesis of vitamins B and K by bacterial flora (Thibodeau and Patton 2007a, Tortora and Derrickson 2009).
Faeces consist of the unabsorbed end-products of digestion, bile pigments, cellulose, bacteria, epithelial cells, mucus and some inorganic material. They are normally semi-solid in consistency and contain about 70% water (Tortora and Derrickson 2009). The colon absorbs about 2 litres of water in 24 hours, so if faeces are not expelled they will gradually become hard due to dehydration and more difficult to expel. If there is insufficient roughage (fibre) in the faeces, colonic stasis occurs, which leads to continued water absorption and further hardening of the faeces. The movement of faeces through the colon towards the anus is by mass peristalsis, a gastrocolic reflex initiated by the presence of food in the stomach, which begins at the middle of the transverse colon and quickly drives the colonic contents into the rectum. This mass peristaltic movement generally occurs 3–5 times a day (Perdue 2005). In response to this stimulus, faeces move into the rectum (Norton 1996b, Taylor 1997, Tortora and Derrickson 2009).
Diarrhoea
Definition
The term diarrhoea originates from the Greek for ‘to flow through’ (Bell 2004) and can be characterized according to its onset and duration (acute or chronic) or by type (e.g. secretory, osmotic or malabsorptive). Diarrhoea can also be defined in terms of stool frequency, consistency, volume or weight (Metcalf 2007).
Related theory
Diarrhoea is a serious global public health problem, in particularly in low-income and middle-income countries. The World Health Organization 2003 believes that over 3 million episodes happen each year, with many people dying. The disease pathogens are most commonly transmitted via the faecal–oral route (Ejemot et al. 2008).
Acute diarrhoea
Acute diarrhoea is very common, usually self-limiting, lasts less than 2 weeks and often requires no investigation or treatment (Shepherd 2000). Causes of acute diarrhoea include:
dietary indiscretion (eating too much fruit, alcohol misuse)
allergy to food constituents
infective:
— travel associated
— viral
— bacterial (usually associated with food)
— antibiotic related.
Chronic diarrhoea
Chronic diarrhoea generally lasts longer than 2–4 weeks (Metcalf 2007) and may have more complex origins. Chronic causes can be divided as follows (Thomas et al. 2003).
Colonic: colonic neoplasia, ulcerative colitis and Crohn’s disease, microscopic colitis.
Small bowel: small bowel bacterial overgrowth, coeliac disease, Crohn’s disease, Whipple’s disease, bile acid malabsorption, disaccharidase deficiency, mesenteric ischaemia, radiation enteritis, lymphoma, giardiasis.
Pancreatic: chronic pancreatitis, pancreatic carcinoma, cystic fibrosis.
Endocrine: hyperthyroidism, diabetes, hypoparathyroidism, Addison’s disease, hormone-secreting tumours.
Other causes: laxative misuse, drugs, alcohol, autonomic neuropathy, small bowel resection or intestinal fistulas, radiation enteritis.
Preprocedural considerations
Assessment
The cause of diarrhoea needs to be identified before effective treatment can be instigated. This may include clinical investigations such as stool cultures for bacterial, fungal and viral pathogens or a more formal medical evaluation of the gastrointestinal tract