management of post op pain Flashcards
post op pain is due to
inflammation
what is the purpose of inflammation
contains and isolates injury
destroy invading microorganisms
inactivate toxins
healing and repair
5 cardinal signs of inflammation
calor (heat) rubor (redness) dolor (pain) tumor (swelling) functio laesa
what happens to arachidonic acid
Broken down by 5-lipoxygenase to form leukotriene
Broken down by cyclooxygenase to form prostaglandins, prostacyclins, thromboxane
effect/function of prostaglandin
vasodilation (inflammation) fever increase vascular permeability (edema) pain maintain renal blood flow gastric mucin production bronchial constriction decreased blood flow
what is pain transduction
from peripheral nervous system to central nervous system
what blocks pain transduction
local anaesthesia
capsaicin
NSAIDS
SSRI
what is pain transmission
from central nervous system to thalamus
what blocks pain transmission
LA, opioids, a2 agonists
what is pain modulation
limitation of flow of pain information
what drugs can modulate pain
SSRI
SNRI
TCA
which pain pathways can opioids affect
pain transmission and pain perception
which pain pathways can LA affect
pain transduction and pain transmission
extent of post op pain affected by what factors
- patient factors (pain is sbujective, compliance with post op instructions, individual pharmacokinetics)
- operator factors eg competence
- surgical factors eg degree of difficulty, amount of bone required to remove, presence of inflammation during procedure (reduce LA effectiveness)
pain VAS score grading
mild 1-3
moderate 4-6
severe 7-10
articaine duration of action
1 hour
bupivacaine duration of action
4-8 hours
mepivacaine duration of action
2-3 hours
How long does it take to start feeling the effect of oral analgesics
30min
mode of action of acetaminophen/paracetamol
prostaglandin cox inhibitor
no antiinflamamtory effect
effective anti pyretic
why should tylenol not be given with anarex
result in OD as both contain paracetamol
maximum dose of paracetamol
15g can cause hepatic toxicity (diarrhea, vomiting, abdominal pain)
mode of action of NSAIDS
inhibit cyclooxygenase, inhibiting synthesis of prostaglandins via endoperoxide pathway (cascade inhibited)
adverse effect of nsaids
dyspepsia
gastric mucosal bleeding
increased bleeding
anaphylactoid reactions
contraindications to NSAIDS
- third trimester pregnancy due to premature closure of ductus arteriosus
- aspirin induced asthma
- gastric ulcers, gastrointestinal inflammatory disease, acute gastritis
- significant renal disease
- anti coagulants
- anti neoplastic doses of methatrexate
- alcohol
use of ibuprofen for post op pain
may combine with narcotics for severe pain
mild to moderate pain
400mg every 4-6 hourly
non selective cox inhibitor
what analgesic can you give for a patient in severe pain
ketorolac – pain control cpmparable to morphine
6hrly dose, max dose 120mg
arcoxia mechanism
cox 2 selective inhibitor
Arcoxia given for
Acute pain ie last less than 8 days
Arcoxia should not be given to patients
with risk of thrombotic events
who are pregnant or nursing
who are taking ace inhibitors/ace receptor antagonists as raise bp and cause acute renal failure, peripheral edema
celecoxib cannot be given to patients with
sulfonamide allergy
what are the opioud receptors
mu, kappa, delta
which pain pathway does opioid inhibit
pain transmission ie cns to thalamus/higher centres
mu receptors result in
analgesia and respiratory depression
side effects of opioids
antitussive (cough suppressant) sedation nausea constipation mood alteration (euphoria/dysphoria) miosis (except meperidine) physical dependence respiratory depression (mu)
contraindications for use of opioids
concurrent alcohol use
inflammatory bowel disease
chronic respiratory disease (mu)
long term use in late pregnancy (neonatal withdrawal syndrome)
if allergy to opioids –> can use synthetic opioid meperidine, or pentazocine
what type of drug is tramadol
opioid
name 3 opioids
tramadol, codeine, fentanyl, morphone, oxycodone
