Chapter 48- Cancer Pain

Question 1

What are components of cancer pain?

Answer 1

Sensory, affective and psyschological.

Tissue damage may be associated with somatic or visceral involvement.

Neuropathic pain due to invasion/compression

Question 2

What is the WHO stepladder approach to cancer pain management?

Answer 2

1) Nonopioid +/- adjuvent for pain
2) opoiod for mild-moderate pain– nonopoid +/- adjuvent
3) opioid for mod-severe pain + nonopioid +/- adjuvent

Question 3

What is the difference between morphine and other synthetic opioids?

Answer 3

Morphine is present in opium and undergoes chemical modification for drug preparation. It releases histamine.

Synthetic opioids are made by drug synthetic, not modification; no histamine release.

Question 4

Describe the role of methadone in cancer treatment.

Answer 4

Oral and rectal administration possible. Synthetic opioid with NDMA antagonist helpful for neuropathic pain. Low cost.

Question 5

What is the mechanism of action of opioids?

Answer 5

Opioids act at opioid receptors that are usually activated by endophins. By binding to the opioid receptor it INHIBITS adenylate cyclase activity and causes hyperpolarization of the nurson which causes suppression of evoked potenials. It also interferes with release of some neurotransmitters such as acetylcholine, substance P, dopamine.

Question 6

Dysphoric reaction of opioids is from activation of which receptor?

Answer 6

Kappa receptor

Question 7

Nausea and vomiting from opioids is from stimulation of what?

Answer 7

chemoreceptor trigger zone

Question 8

How can you treat opioid-induced constipation?

Answer 8

Methylnaltrexone is a peripheral mu opioid receptor antagonist with limited ability to cross BBB.

Question 9

What is opioid rotation?

Answer 9

Sequential trial of changing from one opioid to another after poor responsiveness develops.

Question 10

How would go about testing to see if a celiac plexus block would be beneficial for your patient?

Answer 10

Performed with local anesthetic, assess response to test.

Question 11

How do you perform a celiac pelus neurolysis.

Answer 11

Use alcohol (more painful than phenol) or phenol with CT or fluoro guidance

Question 12

What are complications of celiac plexus block?

Answer 12

Hypotension
Increased gastric motility
Subarrachnoid or epidural injection– long lasting parastesias
Artery of adamkiewicz injection- paraplegia
Kidney injury resulting in hematuria
pneumothorax