Management of Post-Op Pain

Question 1

Patient factors

Answer 1

Past experiences
Emotions
Certain ethnic groups
Compliance, medication intake
Individual PK to analgesics

Question 2

Surgical/clinical factors

Answer 2

Degree of difficulty of extraction = greater trauma
Inflammation/infection at time of procedure

Question 3

Operator factors

Answer 3

Level of experience/competence
Duration of operation
Tissue handling

Question 4

How to control factors causing pain?

Answer 4

Patient factors: hard to control, depends on individual. Can use verbal communication to reassure and distract, make patient more receptive to medication

Surgical factors: Hard to control, generally try to reduce trauma

Medications

Alternative methods like adjuncts to pain (ice pack, massage etc)

Question 5

What types of analgesics are used?

Answer 5

Non narcotic analgesics (Simple analgesics, NSAIDs, coxibs)
Narcotics

Question 6

Acetaminophen / Paracetamol

Answer 6

First line for mild to moderate pain
Weak prostaglandin inhibitor
No antiinflammatory effect
Antipyretic, analgesic
Metab by liver, so overdose can be fatal due to hepatic toxicity
Large doses can cause dizziness, excitement, disorientation

Question 7

Common NSAIDs

Answer 7

Esp used when pt is allergic to paracetamol, for mild to moderate pain

Non-selective COX inhibitors:
- Indomethacin (joint pain like TMD and arthritic pain)
- Ketorolac (severe pain)
- Mefenamic acid (very common)
- Ibuprofen
- Naproxen
- Aspirin (now defunct for analgesia, but used as antiplatelet)

COX-2 inhibitors
- Celecoxib
- Etoricoxib (arcoxia)

Question 8

How do NSAIDs work

Answer 8

Inhibit prostaglandin synthesis by COX enzymes, which have both beneficial and detrimental physiologic effects

Prostaglandins maintain renal blood flow, gastric mucin production and protection, and maintain platelet function.
However, they also cause pain, inflammation, fever, bronchial constriction and decreased blood flow

Question 9

Aspirin

Answer 9

Not impt as j used as antiplatelet nowadays

Analgesic, antiinflammatory, antithrombotic and antipyretic agent
Nonselective COX inhibitor

Question 10

Ibuprofen

Answer 10

Antiinflammatory, antipyretic, analgesic
Non selective COX inhibitor (peripheral PG inhibition)
400mg every 4-6hrs, can combine w narcotics for severe pain

Question 11

Naproxen

Answer 11

Analgesic, antipyretic
Non selective COX inhibitor
Extended half life of 10-20h
550mg twice a day (bd)
More costly than ibuprofen and paracetamol

Question 12

Ketorolac

Answer 12

Analgesic, antipyretic
Pain control better, comparable to morphine
Parenteral 30mg IV or 60mg IM for healthy individual of >50kg
Can repeat 6hrly, max 120mg
Can combine with oral dose of 20mg then 10mg 4-6hrly, max 40mg

Question 13

Coxib functions

Answer 13

Blocks COX2 but maintains the cytoprotective effects of COX1
COX2 is released after tissue injury in macrophages, monocytes, synovial cells, leukocytes and fibroblasts
Extended half life, can have lowered dosing frequency for better compliance, but more expensive

Question 14

Arcoxia

Answer 14

Etoricoxib
60mg, 90mg, 120mg for acute pain, <8 days
Contraindicated in those at risk of thrombotic events, pregnancy, nursing, pts taking ACE inhibitors, ACE receptor antagonists as it can increase BP, causing fluid retention and peripheral oedema

Question 15

Celebrex

Answer 15

Celecoxib
200mg twice a day (bd), stat 400mg
Contraindicated in those at risk of thrombotic events, pregnancy, nursing, pts taking ACE inhibitors, ACE receptor antagonists as it can increase BP, causing fluid retention and peripheral oedema
Also contraindicated in pts with sulfonamide allergy
Can increase risk of heart attack and stroke

Question 16

Narcotic functions

Answer 16

Act on mu, kappa and delta opioid receptors, activating them to inhibit pain transmission

Mu receptors activated by codeine, hydrocodeine, oxycodone, hydrocodone, tramadol and morphine, causing analgesia and respiratory depression

Can cause dizziness, sleepiness, tolerance and dependence

Contraindicated with alcohol usage

Used when allergic to paracetamol and NSAIDs

Question 17

Tramadol

Answer 17

Central acting analgesic
Low levels of dependence
Can cause headaches, nausea, sweating, drowsiness
50mg-100mg tds, 400mg/day max

Question 18

Codeine

Answer 18

30mg tds (three times a day) typically
30-60mg tds, max 360mg/day

Question 19

Panadeine

Answer 19

2 tablets tds
Codeine + paracetamol

Question 20

Opioids and NSAIDs?

Answer 20

Can be given together if pain control is not effective, combining opioids with NSAIDs like Arcoxia

Question 21

Choice of analgesics

Answer 21

Severity of pain
> mild pain - NSAIDs, paracetamol
> moderate pain - weak opioids, can have other analgesics and adjuvants
> severe and persistent pain - strong opioids, can have other analgesics and adjuvants

Patient factors (medical history of G6PD/asthma/renal failure etc, drug allergy, pregnancy/nursing, age)
> avoid strong NSAIDs in asthma/renal failure
> safest for pregnancy/nursing is paracetamol
> higher age = more likely to have kidney/liver failure

Clinical setting (can give IM/IV?)

Cost
> if cost is not a factor give COX-2 for NSAIDs

Question 22

Analgesia for pregnant pts

Answer 22

Aspirin causes vascular disruption
NSAIDs in third trimester causes increased risk of premature ductus arteriosus closure
Long term opioid usage in late pregnancy can result in neonatal withdrawal syndrome

Use paracetamol!

Question 23

Analgesia for nursing mothers

Answer 23

Use paracetamol!
NSAIDs also generally safe
Avoid opioids

Question 24

Analgesia for pts with chronic renal failure

Answer 24

Use paracetamol!
Pt not on dialysis - avoid NSAIDs

Question 25

Steroids?

Answer 25

Help to reduce inflammation and associated pain
May not be required, maybe dexamethasone following extractions