analgesia

Question 1

nociceptive pain

Answer 1

1. somatic nociceptive pain is from skin, mucosal surfaces, bone joints. It is localised and described as sharp, stabbing, shooting, throbbing e.g. minor burns, wounds, minor surgery, trauma respond well to NSAIDS
2. visceral nociceptive pain originated from the organs such as the liver and pancreas. Describes as aching, nagging, cramping and may be associated with nausea and emesis and responds well to OPIODS
3. muscle spasm nociceptive pain originates from skeletal or smooth muscle and is medicated by prostaglandins. It is worse on movement or when smooth muscle is stretched. Responds well to NSAIDS and MUSCLE RELAXANTS

Question 2

acute pain

Answer 2

• anything acute that is short and sharp. non-steroidal anti-inflammatory drugs and opiates are commonly used

step 1: paracetamol and/or NSAIDS
step 2: add a weak opioid for mild to moderate pain e.g. codeine, tramadol
step 3: change to a strong opioid for moderate to severe pain e.g. morphine, fentanyl, methadone

Question 3

chronic pain

Answer 3

• alongside analgesics and opioids other options include nerve stabbing stabilisers in the antidepressants and anticonvulsant groups

Question 4

NSAIDS

Answer 4

• used for self medication e.g. ibuprofen, nurofen, paracetamol
• inhibit the enzyme cyclo-oxygenase (COX-1 and COX-2)
• Reduces pain, inflammation and fever from COX-2 but can also remove GI protection, decrease platelet aggregation and impair renal function from COX 1 which may not be wanted

Question 5

effects of opioids on the CNS and PNS

Answer 5

CNS
- analgesia
- cough suppression
- sedation and sleep
- nausea and vomiting
- hypotension and bradycardia
- hallucinations

PNS
- decreased GI motility and increased tone in smooth muscle; severe constipation
- spasms of sphincter muscles- delayed gastric emptying, urinary retention
- suppression of some spinal reflexes
- itching

Question 6

points to remember

Answer 6

1. opiates can change the brain stem which controls autonomic body functions and depresses breathing
2. opiates block pain messages transmitted via the spinal cord from the body
3. opiates can change the limbic system which controls emotion to increase feelings of pleasure
4. non-selective antagonists such as naloxone can block all of these (1,2,3) effects

Question 7

acute and chronic effects of opioids

Answer 7

acute- respiratory depression fixed by nalaxone, constipation fixed by laxsol, nausea treated by anti-nausea medication
chronic- dependance intolerance- methadone as treatment

Question 8

fentanyl (CNS)

Answer 8

• highly potent, short half life
• constant infusion at low level is affected
• can cause respiratory depression, bradycardia and possibly asystole
• high risk of overdose because it crosses straight over to CNS