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Constipation in palliative care |
Constipation is an extremely common encounter in the palliative care patient. It is defined as difficulty in passing stools or incomplete or infrequent passage of hard stools. Although it may be a minor discomfort for a well patient, constipation in a palliative care patient can cause severe symptoms ranging from pain, nausea and vomiting, confusion, urinary retention, faecal impaction and bowel obstruction.
Causes
1. General
Inactivity, dehydration, poor nutrition, weakness, hypercalcaemia, inability to reach toilet with urge to defaecate, painful perianal region.
2. Drugs
Opioids, non-opioids: anticholinergics, antihistamines, tricyclics, phenothiazines, antacids, haloperidol, anti-diarrhoeals, diuretics, 5HT antagonists.
In this patient group the cause of constipation is usually multifactorial but it is worth running through the above checklist as some causes are reversible and some drugs can be reduced or stopped.
In the management of constipation 1) the history will clinch the diagnosis and 2) examination will clinch the management plan.
Points in the history
When was the last time the bowels were opened?
What was the stool like, eg. hard pellets = constipation; watery stool/faecal incontinence = overflow?; ribbon stool = impending obstruction?
Was it difficult to pass?
When was the time before that?
What is normal for the patient?
Nutrition/fluid intake.
Laxative history.
Patients ability to independently go to toilet.
Points on the examination
- On abdominal examination a faecal mass may be palpable, usually on the left side of the abdomen. Faecal masses indent and move with time, whereas tumour masses do not.
- PR empty and dilated = high constipation or faecal impaction.
- Is the rectum full?
- Is the faeces soft or hard?
- Is the anal tone normal?
An abdominal x-ray should be considered to exclude obstruction or to identify the level of faecal impaction and faecal loading.
Management
The primary goal is always prevention.
1. Prophylaxis
Consider reversible causes (as above) eg. encourage adequate fluid intake, use raised toilet seat, handrails, commodes, etc. Laxatives will usually be required and “Coloxyl with Senna” is a very common and useful choice. The coloxyl component is a softener and the senna component is a stimulant. Maximum dose is 2 tds.
If the stools remain hard add a softener, eg. plain coloxyl or agarol (liquid paraffin). If the stools are infrequent add a stimulant, eg. senna or bisacodyl.
A PRN bowel cocktail is a useful addition when the above measures have failed, i.e. 2-4 teaspoons of Senokot granules, 30mls Agarol and warm milk to taste taken at night.
The aim of laxative treatment is to ease defaecation not necessarily to achieve a daily bowel action. It is also to try and make the patient/carer confident in titrating the laxative dose according to the response. In this way a bowel chart in hospital or bowel diary at home can be a useful record for patient and carer alike.
2. Established constipation
If bowels have not been open for three days or more, a suppository or micro enema may be necessary. Rectal agents are used when laxatives fail or are not tolerated.
a) Full rectum
Soft faeces x 2 bisacodyl suppositories
Hard faeces x 1 glycerin x 1 bisacodyl suppository
NB. Make sure suppository is in contact with wall mucosa.
No result – olive oil retention enema.
Next day – high coloxyl enema.
b) Empty rectum (impacted higher up)
Overnight - olive oil retention enema
Next day - high coloxyl enema
Cautionary notes
1. Faecal impaction may present as diarrhoea and therefore the diagnosis is missed. It can present with a history of prolonged constipation, small liquid faeces, faecal leak, pain (colic, tenesmus or both). Digital removal of impacted faeces may be necessary under sedation.
2. Bulk-forming laxatives, eg Metamucil, Fibogel, Normacol, and fibre supplements are usually unsuitable for debilitated patients, as the patients are unable to drink the corresponding increased amount of fluid to enable the laxatives to work and subsequently risk becoming severely constipated.
3. Osmotic laxatives such as Epsom salts, Milk of Magnesia, lactulose and
sorbitol draw fluid into the bowel by osmosis and thereby softening the stool, eg 15mls lactulose draws in 500-600mls of water into the bowel. In the debilitated patient this can produce dehydration and electrolyte imbalance.
4. Agarol no longer contains phenolphthalein and therefore acts as a faecal softener (liquid paraffin) and no longer has a stimulant component.
Joanne Doran (jdoran@nor.com.au) is the area medical director for palliative care. She can be contacted at St Vincent’s Hospital, Lismore, NSW, Australia.
Further reading:
1. Palliative Medicine, Roger Woodruff
2. Symptom Management in Advanced Cancer, Robert Twycross
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