Issues of Palliative Care - N/V, Bowel Obstruction

Question 1

What causes nausea via the CTZ pathway (dopamine receptor and serotonin receptor)?

Answer 1

○ Drugs: chemotherapy agent, anaesthetic agents, opioids, Abx, antidepressants
○ Toxins: sepsis, tumours
- Biochemistry: hypercalcaemia, uraemia, ammonia, hyponatraemia

Question 2

What causes nausea via the GI pathway?

Answer 2

• mechanoreceptors and chemoreceptor that activates the vagus nerve:
• obstruction
• gastroenteritis
• gastroparesis (e.g. DM, post op, malignancy can cause ascites cause distension and compression and tumour cells in peritoneal cavity and invade gut wall causing direct bowel dysfunction)

Question 3

What central or higher functions lead to nausea?

Answer 3

○ Raised ICP

- Psychological: anticipatory nausea

Question 4

What are the pathways that lead into the vomiting centre?

Answer 4

Vestibular, CTZ, Vagus, Higher centres

Question 5

What is the first line anti-emetics?

Answer 5

metoclopramide - always use first except: Parkinson’s (use Domperidone instead), bowel obstruction

Question 6

What are the second line anti-emetics?

Answer 6

haloperidol if CTZ related (drug related, tumour)

Question 7

What anti-emetics should be used for constipation or opioid induced nausea?

Answer 7

use metoclopramide or domperidone - increases GI motility

Question 8

What anti-emetics should be used for medication or biochemical disorder (hyperCa) induced nausea?

Answer 8

use metoclopramide , haloperidol - acts on CTZ

Question 9

What anti-emetics should be used for positional induced nausea?

Answer 9

Promethazine, antihistamine

Question 10

Anxiety or anticipatory nausea

Answer 10

Benzo

Question 11

Chemo or radio induced

Answer 11

Use odansetron PLUS dexamethasone

Question 12

Raised ICP

Answer 12

Dexamethasone

Question 13

Which anti emetics must be avoided in bowel obstruction?

Answer 13

• Avoid antiemetics that increase GI motility such as metoclopramide and domperidone if due to bowel obstruction
• Do not use odansetron in pall care situation, can add to constipation and head ache
Reassess laxative use for constipation

Question 14

What anti-emetics should be used for bowel obstruction in palliative care?

Answer 14

Haliperidol
Second line is cyclizine as it slows motility
Anti-secretory: hyoscine butylbromide may relieve colicky pain as well; ranitidine

Question 15

What is the first line management of constipation?

Answer 15

Coloxyl and Senna

Question 16

What are the mechanisms of action of Coloxyl and Senna?

Answer 16

Coloxyl (stool softener) + Senna (stimulant laxative)

Question 17

What is the second line management of constipatino?

Answer 17

If ineffective, consider adding lactulose or macrogol laxative e.g. Movicol, the osmotic laxatives

Question 18

How do we manage faecal impaction?

Answer 18

If faecal impaction (found on Px, therefore if prolonged constipation then must do PR) : use suppositories, enema; or last resort is manual evacuation