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Fact file: A guide to managing constipation: part two

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VOL: 103, ISSUE: 19, PAGE NO: 42

Gaye Kyle BA, DipEd, RGN, is senior lecturer, Faculty of Health and Human Sciences, Thames Valley University, Slough.

Kyle, G. (2007) A guide to managing constipation: part two. Nursing Times; 103: 19, 42-43.

In the first article in this three-part series, Gaye Kyle discussed the causes and assessment of constipation. This second article discusses the management of the condition.

If there are no underlying conditions causing constipation, a stepped approach should be used in its management (Bayliss et al, 2000). The first step should be appropriate dietary and lifestyle advice, and the second is the use of laxatives.

Dietary and lifestyle advice

Mobility

All patients experiencing constipation should be encouraged to exercise and increase their mobility, especially if housebound, as immobility is thought to be a contributory risk factor in constipation (Campbell et al, 1993). Bed rest or a period of immobility results in a weakening of the abdominal wall muscles, leading to difficulty in raising the intra-abdominal pressure sufficiently for defecation. Kinnunen (1991) found an increased risk of constipation for people walking less than 0.5km daily, while Ross (1995) found that both mobility and diet play a greater role in changes to bowel elimination in older people than in middle-aged patients.

As well as encouraging mobility and exercise, nurses should ascertain that patients are sitting correctly on the lavatory in order to raise their intra-abdominal pressure during defecation. Footstools can help patients who have raised lavatory seats or who are wheeled on a commode over the lavatory to sit in the correct position.

Dietary fibre

The link between bowel movement frequency and dietary fibre is well established (Maestri-Banks and Burns, 1996). During stool formation, fluids are drawn from the colon into the stool by insoluble fibre particles, and can swell up to 20 times their original size, resulting in bulky stools that can move easily through the colon.

Taylor (1990) stated that dietary fibre comes from plant food and is intimately related to starch as it is composed of long complex chains of polysaccharides. These chains cannot be broken down; instead they maintain their bulk and, in doing so, stretch the bowel wall and stimulate peristalsis. A high-fibre diet containing about 30g of fibre per day should therefore be encouraged.

While the effects may be seen within a few days, such a diet should be tried for at least a month before its effects are determined. The daily fibre intake should be consumed in three to four regular meals during the day.

Fluid intake

A high-fibre diet will require adequate fluid intake in order for the fibre to swell and bulk up the faeces. While there is no consensus on the adequate quantity of fluid required to prevent constipation, inadequate fluid intake is thought to be a risk factor for constipation (Maestri-Banks and Burns, 1996). Fluid intake is controlled by thirst, which signals the need for more fluid. Older people are at greater risk of dehydration due to an impaired thirst mechanism (Reedy, 1988), especially those with severe cognitive impairment (Hoffman, 1991). It is also possible that some older people may drink less in an attempt to avoid urinary incontinence.

Klauser et al (1990) found that a fluid reduction changed bowel frequency and stool weight significantly in healthy young men, and hypothesised that a low fluid intake might be a risk factor for constipation in some patients, and that increasing fluids might be a reasonable way of treating it. However, Chung et al (1999) studied the effect of increased fluid on stool output in healthy adults and found that increased fluid intake did not produce a significant change in stool weight. While fluid deprivation may decrease stool output and lead to constipation, it is not yet clear whether there is an optimum intake of fluid beyond which there is no further increase in stool output.

Although daily fluid intake will vary from one patient to another, there appears to be a consensus in the literature that 1.5L per day is required to maintain good health (Morrison, 2000; Norton, 1996), which equates to about eight cups or mugs of fluid. However, excessively hot weather, alcohol consumption and pyrexia all indicate a need to increase fluid requirements.

Nurses can suggest foods that contain large quantities of water in order to increase fluid intake such as jelly, yoghurt, soup, mousses, whipped puddings, rice pudding and other milky puddings and sauces. Finally, they could suggest that patients drink coffee instead of tea, as coffee (not caffeine) appears to stimulate colonic activity (Brown et al, 1990), whereas tea in large quantities may lead to constipation (Hojgaard et al, 1981). However, there is a lack of robust research to confirm these observations.

Laxatives

A recent audit demonstrated that bowel care problems can be linked to ineffective and/or inappropriate prescribing of laxatives (Addison et al, 2003). Comments from the audit show that many patients are receiving a combination of laxative regimens, which are suggestive of poor treatment plans and a failure to follow treatment guidelines for constipation.

In order to ensure laxatives are used as recommended, nurses need to understand the mode of action of laxatives prescribed.

Laxatives are the most commonly prescribed pharmacological intervention for the management of constipation. There are four main types used regularly in practice: bulk-forming; stimulant; osmotic; and stool softeners.

Bulk-forming laxatives

These are the least harmful laxatives and can be used in conjunction with the lifestyle advice of increasing fibre in the diet. The most commonly used preparations are from the ispaghula husk (Fybogel) and sterculia (Normacol). These should be taken with plenty of water and not immediately before going to bed.

Stimulant laxatives

These stimulate an increase in colonic motility and mucus. The most commonly used are anthraquinones (senna and dantron) and diphenylmethane cathartics (bisacodyl). Senna is the most powerful of the anthraquinones. It is an effective short-term remedy for acute constipation, is usually effective within 6-12 hours and is therefore best given at bedtime (Ross, 1998). Dantron-containing laxatives are subject to licence limitations (patients with terminal illness).

Bisacodyl may be given in suppository form and may be effective within 15-60 minutes. Glycerine suppositories may also act as a rectal stimulant by virtue of the mildly irritant action of glycerol. They must be moistened before insertion and, like all bowel care suppositories, placed alongside the bowel wall so that body heat causes them to dissolve. If suppositories are placed in the middle of faecal matter they will remain intact and useless.

Osmotic laxatives

These include mixed electrolyte solutions containing polyethylene glycol and non-absorbable sugars such as lactulose and sorbitol. Their action is to retain fluid in the bowel by osmosis. Lactulose may take up to 2-3 days to have an effect and is therefore not suitable for the rapid relief of constipation, and osmotics are not appropriate where gut motility is impaired (Abrams et al, 1995).

Macrogols

(Movicol and Idrolax) are relatively new laxatives; they are inert polymers of ethylene glycol. Movicol is the only laxative currently recommended for faecal impaction.

Rectal preparations such as phosphate enemas and micro enemas are useful for bowel clearance; however, there is a lack of evidence in the published literature to support the use of phosphate enemas in the management of constipation. Indeed, nurses should be aware of the risks involved with the use of phosphate enemas and conversant with evidence-based alternative treatments.

Stool softeners

These act by lowering surface tension of faecal matter, thereby allowing penetration of hardened faeces by water and fats. The most commonly used is docusate sodium, which also has weak stimulant properties. Liquid paraffin is a stool softener/lubricant but can cause anal seepage and irritation, lipoid pneumonia (rarely) and malabsorption of lipid-soluble vitamins, and is not recommended for use in clinical practice.

Retention enemas containing arachis oil both lubricate and soften impacted faeces. Arachis oil enema should be warmed to body temperature before use and if possible given last thing at night. Patients should be asked if they have a nut allergy as arachis oil contains nut oils.

Risk assessment

A major theme in much of the literature is the importance of assessing patients to identify those who might be at risk of developing constipation. This was further endorsed by Potter et al (2002) who stated that the identification of risk factors for constipation in older patients is critical to achieving effective management of the condition.

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