Post-operative Pain Control Flashcards
What causes post-op pain?
Inflammation
- reaction of vascularised living tissue to local injury
- injury may be caused by microbial infection, physical agents, chemicals, necrotic tissue
- contain and isolate injury, destroy invading micro-organisms and inactivate toxins
What are the signs of acute inflammation?
Heat, redness, edema, pain and loss of function
Describe the surgical/clinical factors causing post-op pain
1) difficulty of procedure
- deep impaction, bulbous roots, texture of bone, amount of bone removal required, size of flap raised
2) presence of inflammation or infection present at time of procedure
Describe the operator factors causing post-op pain
- Experience and competence
- Duration of operation
- Handling of tissue
Describe patient factors that cause post-op pain
- Subjective
- Depends on past experiences, emotional, cultural and social factors
- Compliance with post-op instructions, medication intake
- Individual response to analgesics (pharmacokinetics)
How to achieve pain relief?
- Patient factors
- Surgical factors (good LA)
- Medications
How to achieve effective pain relief with LA?
- good technique
- articaine (concentration of LA)
- Long acting LA on completion (bupivacaine)
Name the 3 types of medications for pain relief
- Simple analgesics
- NSAIDs (non-selective COX inhibitors and selective COX-2 inhibitors)
- Narcotics
Describe acetaminophen
Aka tylenol/ paracetemol
- mild to moderate pain
- effective anti-pyretic agent
- weak prostaglandins inhibitor
- no anti-inflammatory effect
- metabolised by liver
- symptoms include dizziness, excitement, disorientation (large doses)
- 15g toxic amount (fatal due to hepatic toxicity symptoms - diarrhoea, vomiting, abdominal pain)
List NSAIDs (non-selective and selective COX-2 inhibitors)
Non-selective: (common)
- ketorolac
- mefenamic acid
- ibuprofen
- naproxen
- Indomethacin -> joint pain (less common)
- Diclofenac
- aspirin (used more for anti-platelet effect than analgesic)
Selective:
- Celecoxib (common)
- Etoricoxib
Describe the action and effects of NSAIDs
- inhibit synthesis of prostaglandins in the endo peroxide pathway
- side effects: dyspepsia (indigestion), gastric mucosal damage, increased bleeding
*prostaglandins helps to maintain renal blood flow, gastric mucin production, mucosa protection and maintenance of platelet function BUT causes pain, inflammation, fever
Describe the characteristics of Aspirin
- analgesic
- anti-inflammatory
- antipyretic
- anti-thrombosis
- mild to moderate pain
- non selective COX inhibitor -> COX-1 inhibition undesirable (not used for post-op analgesic)
Describe the characteristics of ibuprofen
- Analgesic
- Anti-inflammatory
- Anti-pyretic
- Non selective COX inhibitor (peripheral prostaglandin inhibition)
- Mild to moderate pain
- 400mg every 4-6 hourly
- may combine with narcotics drug for severe pain
Describe the characteristics of naproxen
- Analgesic
- Anti-pyretic
- Non-selective COX inhibitor
- Mild to moderate pain
- Propionic derivatives
- Extended half life (10-20h)
- Dosage 550mg twice daily
Describe the characteristics of ketorolac
- Analgesic
- Antipyretic
- Pain control comparable to morphine but without side effects
- Parental dose: 30mg IV, 60mg IM (healthy patients 50kg and above)
- Repeat dose every 6h, max dose should NOT exceed 120mg
- Follow up with oral dose 20mg, then 10mg 4-6h after, max dose 40mg
Describe the characteristics of Etoricoxib
- COX-2 inhibitor
- Take every 24h
- Avoid pregnancy, nursing
- Avoid those in risk of thrombotic events
- Avoid in patients taking ACE inhibitors (cause high BP)
- Can result in high BP, fluid retention, peripheral edema
Describe the characteristics of Celecoxib
- COX-2 inhibitor
- 200mg twice daily,
- Same precautions as etorizoxib- avoid use of those with known sulfonamide allergy
- increases risk of heart attack and stroke
Describe the characteristics of narcotics
- Act on opioid receptors, mu, kappa and delta
- activation of opioid receptors - inhibition of pain transmission
- Opiod mu receptors activated by codeine, hydrocodone, tramadol and morphine
- Drugs and neurotransmitters that act on receptors and may cause biological effects
- mu receptors have analgesic effects and respiratory depression
Describe the characteristics of Tramadol
- type of opioid
- central acting analgesia
- used in patients with NSAID allergy
- low levels of dependence
- side effects: headache, nausea, sweating, drowsiness
- 400mg/day MAX dose
What are the side effects of opioids?
- Sedation
- Nausea
- Vomiting
- Constipation
- Mood alteration
- Respiratory depression
List 3 commonly used oral narcotic analgesics (dosage and frequency)
1) codeine (30-60mg twice daily) -> max 360mg daily
2) tramadol (50-100mg twice daily) -> 400mg daily
3) Panadeine (2 tab twice daily) -> do not give when patient allergic to paracetemol
Which is most effective? NSAIDs, paracetemol, or opioids in reducing post-op pain?
Combination!!!
No clear difference between NSAIDS and paracetemol
What are the patient factors determining the choice of analgesic?
1) MH
- G6PD/asthma/renal failure
- renal failure: use paracetamol, DO NOT use NSAIDs when NOT on dialysis, NSAIDs safe to use when on dialysis
2) Drug allergy
3) Pregnancy
- DO NOT use aspirin (causes vascular disruption)
- NSAIDs used in late trimester can increase risk of premature diurnal closure
- DO NOT use opioids
- Opiods in late pregnancy with long term use may cause neonatal withdrawal syndrome
4) Nursing mother
- use paracetemol
- NSAIDs mostly safe
- DO NOT use opiods
Which steroid can be used to control pain?
Dexamethasone reduces pain and swelling after extraction of wisdom teeth
