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 nasogastric tube may be of value
• thirst can be managed 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 which are 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 Guidance (2024). Palliative care - guidelines for symptom control.