Post-op analgesia

Question 1

What are the medications in step 1 of the WHO pain management ladder?

Answer 1

Non-opioid NSAIDs (paracetamol, ibuprofen), +/- adjunct (antidepressants, anticonvulsants, corticosteroids)

Question 2

What are the medications in step 2 of the WHO pain management ladder?

Answer 2

Weak opioid (codeine, tramadol), +/- non-opioid +/- adjunct

Question 3

What are the medications in step 3 of the WHO pain management ladder?

Answer 3

Strong opioids (oxycodone, morphine, fentanyl) +/- non-opioid +/- adjunct

Question 4

Opioid MOA?

Answer 4

Binds to mu, kappa and delta opioid receptors, inhibiting adenylyl cyclase and reducing intracellular cAMP, hyperpolarising cells.

This decreases ascending pain signals to the dorsal horn.

Question 5

What medications do you have to prescribe together with the opioid?

Answer 5

1. Laxatives

2. Anti-emetics/N&V medications

Question 6

Side effects of opioids?

Answer 6

Respiratory depression, sedation, immunosuppression, constipation, nausea & vomiting, addiction, urinary retention, miosis

Question 7

What is the function of COX-1?

Answer 7

1. Synthesises prostaglandins needed for gastric mucosa protection (production of bicarbonate, mucosal blood flow maintenance)
2. Platelet aggregation and platelet plug formation through thromboxane A2

Question 8

What is the function of COX-2?

Answer 8

Release of cytokines (IL-1, IL-6 and TNF-⍺) resulting in inflammatory response, pain and increase in hypothalamus thermostat (fever).

Question 9

Give some examples of NSAIDs.

Answer 9

Diclofenac, Celecoxib, Ibuprofen, Aspirin, Naproxen

Question 10

What are some side effects of NSAIDs?

Answer 10

• GI upset: dyspepsia, PUD, GI bleeding
• Renal: acute renal failure due to afferent vasoconstriction
• CVS: bleeding and dilation of efferent arteriole
• Bronchospasm
• Steven Johnson syndrome

Question 11

Ondansetron MOA?

Answer 11

5HT-3 receptor antagonist, acting centrally on the chemoreceptor trigger zone in the medulla oblongata, altering the vomiting centre.

Question 12

Side effects of morphine based on different opioid receptors?

Answer 12

All of them have analgesic effect and respiratory depression.

• Mu: constipation, addiction, miosis, euphoria, bradycardia
• Delta: euphoria, immunosuppression
• Kappa: miosis, dysphoria, sedation

Question 13

What happens in NSAID overdose?

Answer 13

Signs & symptoms:
Nausea & vomiting, drowsiness, blurred vision, dizziness, hypotension, cardiovascular collapse, hypothermia

Test:
Increased anion gap, acute renal failure