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At the heart of general practice since 1960

Trend for GPwSIs is threat to valuable generalist role

Dr Papiya Biswas gives practical advice on a

common problem in palliative care patients

Many people with palliative care needs suffer with constipation. About 50 per cent of patients with cancer who are admitted to hospices specifically complain of constipation and around 80 per cent of cancer patients require laxatives. Even anorexic patients should have some bowel movements to evacuate normal gastrointestinal secretions and bowel mucosa renewal.

The usual aim of treatment in this population is to ensure comfortable defecation which occurs often enough to prevent abdominal or rectal discomfort, rather than a specific frequency.

Why do terminally-ill patients become constipated?

Debilitated patients are at risk of constipation Weakness, inactivity and poor fluid intake can contribute. An inability to reach the toilet or embarrassment related to dependency on others for toileting or painful toileting can result in stool withholding and eventual non-voluntary constipation.

Medication is the commonest cause of constipation in this population Opioids in particular, but also anticholinergic drugs (antispasmodics, antidepressants, neuroleptics) can affect bowel smooth muscle and slow transit time. Others are listed in the box, right.

Cancer effects can cause constipation specifically hypercalcaemia, peritoneal or pelvic disease which may compress the bowel, spinal cord compression which affects nerve-related peristaltic function of the bowel.

Opioid-induced constipation is a particular problem for terminally-ill patients. Opioids cause constipation by suppressing peristalsis, increasing ileocecal valve and anal sphincter tone and reducing the response mechanism to rectal distension. The resulting prolonged bowel transit time causes excess water absorption from the stool via the colon, resulting in hard faeces.

So opioid-induced constipation is best treated with both softening and stimulant laxatives in combination, and all patients on opioids should have access to laxatives, as is recommended in the Scottish National Guidelines.

Assessment

History and examination aims to establish:

·Diagnosis: mainly to distinguish constipation from obstruction/subacute obstruction, and diarrhoea from faecal impaction and overflow

·Cause of the constipation: consider stopping unnecessary medication, treat hypercalcaemia etc

·Nature of constipation: is the stool hard/ soft/high in the intestine (cannot be reached with rectal administration)? Is peristalsis impaired (may have soft stool in colon but no bowel motions)?

Lifestyle treatments

Increasing dietary fibre, oral fluid intake, and general activity are an important first step in the general population, but often inappropriate or not possible in a debilitated, anorexic palliative care patient.

Discussion about a low residue diet and good oral fluid intake is important for patients with bowel narrowing and propensity for bowel obstruction. Widely-publicised healthy eating information emphasises a fibrous diet; patients may need diet sheets to help them choose an 'unhealthy' low-residue diet.

Addressing toileting arrangements may also help.

Laxatives

Laxatives are usually thought of as:

·Mainly softening

·Mainly peristalsis-stimulating

·Combination of the two

It is useful to choose a laxative based on the predominant mechanism of action. However, softeners have weak stimulating actions and stimulators can soften stool by promoting intestinal fluid secretion. Combination therapy is recommended for those on opioids.

Combination

Both of the following laxatives contain danthron which is genotoxic and potentially carcinogenic. They should therefore be used only in those with a shortened life expectancy. Danthron can cause skin sloughing after prolonged contact and so is not recommended in incontinent patients or those with no sensation of defecation.

Patients should be warned that these laxatives colour urine red, to prevent them phoning you in alarm about haematuria. They are often a good first choice in the palliative care population.

Co-danthramer

Comprises poloxamer (softener) + stimulant (danthron)

The 'strong' formulation contains five times the poloxamer dose and three times the danthron dose as standard strength. Typically started as 10ml daily of standard strength increased to 10ml tds, and changed to the strong preparation if necessary.

Co-danthrusate

Contains docusate and danthron. Start at two capsules nocte up to tds.

Osmotic laxatives

These retain water in the bowel by osmosis or change the water distribution of stools. Oral fluid should be increased. Movicol and Idrolax are administered with this fluid. They may cause abdominal discomfort.

Movicol can be given up to three times a day, and is often used when co-danthramer has failed to produce results.

·Its large volume (125ml/sachet) limits use in this population

·Licensed for faecal impaction, eight sachets are given once a day for three days

·Rarely tolerated by terminally-ill patients

·Contains electrolytes that can lead to disordered blood biochemistry when given regularly.

Idrolax

·Taken as a smaller volume than Movicol, so is better tolerated

·It is not used for impaction, and less associated with electrolyte changes.

Lactulose has a long onset of action (two to three days), should be taken with increased fluid, is sweetly unpalatable and causes abdominal colic, bloating and flatulence, all of which can make it an unpopular choice with patients, and possibly their relatives.

Softening

Sodium docusate (100-200mg up to three times daily) reduces surface tension and allows the stool to absorb more water. It is a good choice for patients with bowel constriction, especially those with colic.

·Lactulose is predominantly softening.

·Liquid paraffin can be irritant and is no longer recommended.

Stimulating

Although long-term use can cause atonic bowel and hyperkalaemia and should be approached with caution in the general population, this is often less of an issue with palliative care patients. There is a risk of colic by stimulating peristalsis.

·Bisacodyl 10mg can be given orally or rectally. In a patient unsuitable for

co-danthramer, it can be used in combination with docusate.

·Senna is also a mild stimulant; its large tablets can deter patient compliance.

·Metoclopramide, the anti-emetic, is a prokinetic so can worsen diarrhoea, or cause colic in susceptible patients.

Bulking agents These include Fybogel and methylcellulose. The increased faecal mass stimulates peristalsis but oral fluid should be about two litres a day or obstruction may ensue. The risk of obstruction rises with opioids, so while a good choice for other populations, these are usually unsuitable for the terminally-ill.

Rectal treatment

Similar principles apply. Suppositories work for constipation with rectally palpable stool. Use softening suppositories for hard stool (glycerin, docusate), stimulating ones for soft stool with a lax rectum and enemas for a stronger result. Microlette enemas are gentler than phosphate enemas.

If the stool is very hard, use an arachis oil enema (based on peanut oil, so avoid in nut allergy sufferers), which can be followed the next day with a phosphate enema to aid evacuation.

A high-phosphate enema is administered high in the bowel using a foley catheter. Maintenance is usually with oral laxatives once the bowel is cleared.

A word for the weary...

Thankfully, nurses get much more undergraduate training on this distressing and sometimes complex symptom than we GPs do, and putting your head together with your district nurse can often produce results. Your local palliative care team will be happy to discuss patients with difficult or resistant constipation.

Some drugs that

cause constipation

·Antacids

·Amiodarone

·Anticholinergics

·Antidiarrhoeal agents

·Anti-Parkinsonian agents

·Calcium channel blockers

·Calcium supplements

·Clonidine

·Cyclizine

·Disopyramide

·Diuretics

·Iron preparations

·Lithium

·Non-steroidal anti-inflammatories

·Ondansetron (very constipating)

·Opioids

From Prodigy Guidance on constipation (website)

Useful websites

www.prodigy.nhs.uk/guidance

.asp?gt=Constipation

www.ncpc.org.uk

www.medicines.org.uk

Papiya Biswas is staff grade physician and clinical research fellow in palliative medicine, Marie Curie Hospice, Edinburgh

Marie Curie Cancer Care provides high-quality nursing, totally free, to give terminally-ill people the choice of dying at home supported by their families. This unique service complements the 10 Marie Curie hospices across the UK, which actively promote quality of life for people with cancer and provide support for their families, completely free.

For more information on Marie Curie Cancer Care:

phone: 0800 716 146

e-mail: info@mariecurie.org.uk

website www.mariecurie.org.uk

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