Intestinal obstruction in palliative care

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• always worth performing a rectal examination to rule out constipation before confirming a diagnosis of intestinal obstruction
• development of malignant bowel obstruction can be a slow and insidious process with episodes of paralytic ileus and mechanical obstruction over days to weeks
• careful assessment of the clinical symptoms/signs is essential for the most appropriate management
• paralytic ileus (e.g. electrolyte disturbance or autonomic dysfunction) may mimic intestinal obstruction but is potentially reversible. Colic is usually not a feature in such patients and clinical examination may reveal absence of or reduced bowel sounds
• mechanical intestinal obstruction (e.g. as a result of adhesions or tumour) will usually present with colic and clinical examination may reveal increased bowel sounds. This can generally be divided into:-
  • subacute or partial obstruction (intermittent symptoms of colicky abdominal pain, nausea and vomiting, reduced frequency of passing flatus and opening bowels) which may resolve for a limited time
  • complete obstruction (sustained symptoms of colicky abdominal pain, nausea and vomiting and absence of flatus and stool) which is irreversible
• surgical intervention or stenting may be helpful for a small number of patients. A palliative bypass with or without stoma formation may be indicated if there is single level obstruction. Diffuse intra-abdominal disease or ascites are contraindications for palliative surgery

The principles of management of intestinal obstruction in palliative care are outlined (1):

• main principles of management are to control nausea, colic and other abdominal pain using drugs shown below
• it is possible to keep a patient's symptoms controlled with subcutaneous medications given via a syringe driver. Some patients may prefer occasional vomits (as long as nausea is well controlled) to avoid naso- gastric tube (NGT) insertion. Other patients with obstruction and large volume vomiting may prefer NGT insertion to avoid persistent vomiting
• thirst can be managed with regular oral care and ice cubes to suck and may avoid the need for intravenous or subcutaneous saline infusion
• if symptoms are thought to be primarily due to paralytic ileus rather than mechanical obstruction the combination below can be effective in restoring bowel function:-
  • symptoms are thought to be due to ileus rather than mechanical obstruction, a combination of metoclopramide and dexamethasone can be effective in restoring function.
  • do not use metoclopramide or 5HT3 antagonists in patients with intestinal colic
• when complete intestinal obstruction occurs, prokinetic agents and bulk-forming or stimulant laxatives are contra- indicated
• patients may be able to tolerate small amounts of food and drink, if the nausea is well controlled. A low residue diet may be better tolerated (soft low fibre foods)

• it can be possible to keep a patient's symptoms controlled (although vomiting may still occur), by s.c. medications given via syringe driver, avoiding nasogastric and i.v. infusion
• patients my wish to take small amounts of food and drink, if the nausea is well controlled
• occasional vomits, if not accompanied by persistent nausea, may be an acceptable price to pay for the freedom from the discomfort of a nasogastric tube
• in small bowel obstruction with large volume vomits, a naosgastric tube may be of value
• thirst can be manageed with regular oral care and ice cubes to suck. Effective oral care may avoid the need for i.v. or s.c. saline infusion for persistent thirst
• some patients may benefit from corticosteroids
• as a general rule it is advisable not to combine more than two drugs in a syringe driver, so two syringe drivers are sometimes required. However there are combinations of drugs whicare are well established in intestinal obstruction:  
  • diamorphine, haloperidol and hyoscine butylbromide may be mixed together
  • diamorphine, haloperidol and cyclizine may be mixed together
  • diamorphine and octreotide can be mixed

Reference:

1. West Midlands Palliative Care Physicians (2003). Palliative care - guidelines for the use of drugs in symptom control.
2. West Midlands Palliative Care Physicians (2007). Palliative care - guidelines for the use of drugs in symptom control.
3. West Midlands Palliative Care Physicians (2012). Palliative care - guidelines for the use of drugs in symptom control