If partial obstruction without colic is present, metoclopramide, 80-120 mg over 24 hours sc, may stimulate effective bowel motility. This can be combined with high-dose dexamethasone, 16 mg/24 hours, to reduce peri-tumour oedema and to also serve as an antiemetic. As vomiting is controlled, introduce oral laxatives as tolerated.
If obstruction is complete or if colic is present, cyclizine, 100150 mg/24 hours sc, is given with buscopan. Haloperidol, 5-15 mg/ 24 hours, is a suitable alternative. Haloperidol, cyclizine, and hyoscine are all miscible with diamorphine in a driver syringe.
Methotrimeprazine is a highly specific 5HT2 antagonist and has inhibitory effects on other emetic pathway receptors. It is a useful alternative to the aforementioned antiemetics and is also miscible with diamorphine. If vomiting persists then octreotide, 300-600 mg/ 24 hrs via continuous sc infusion—a somatostatin analogue—can be used. This drug is antisecretory and promotes reabsorption of electrolytes and, hence, water from the bowel. Effectively this decompresses the dilated bowel.
In difficult cases a nasogastric tube should be considered for short-term use. If all else fails to control the vomiting and it is distressing to the patient, then a venting gastrostomy must be considered, taking into account the patient's prognosis, current condition, and, above all, their own wishes. With a gastrostomy in situ, the patient can take oral liquids which can be drawn off via the gastrostomy, as needed.
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