Pain management Flashcards
Define pain
Unpleasant sensory and emotional experience associated with actual or potential tissue damage
What are the side effects of opioids?
-Respiratory depression
-Nausea/vomiting
-Constipation
-Urinary retentaion
Chronic use
-Hypogonadism
-Immunosuppression
-Withdrawal
What is the pain pathway?
Pain is tramsmitted via fast A-delta fibers (sharp pain) and slower C fibers (dull pain) to lateral spinothalamic tract and then to thalamus
What is patient controlled analgesia?
-Syringe pump connected IV to allow patient to self-administer boluses of morphine
-Overdosage is avoided by limiting size of bolus and frequency of administration
-Lock out time is set within which pressing the button again will not result in a bolus of analgesia
-One way valve preventing backflow of opiates into the infusion chamber which may lead to overdose when redelivered
What is normal dose of morphine pca?
0.5-2mg bolus
What are the disadvantages of a PCA?
-Patient has to be alert and orientated to use it
-Can break down, run out of battery
-Sleep disturbance
-Limits patient mobility
What are the complications of pain?
CVS
-Increased HR, BP, myocardial consumption –> increased risk of MI
-DVT from immobility
GIT
-delayed gastric emptying
-Reduced bowel motility
-Paralytic ileus
Respiratory
-Limits chest movements leading to atelectasis, retained secretions, pneumonia
How would you manage patient in post op pain?
-A-E assessment
-Assess severity with pain scale
-Give analgesics according to WHO ladder with regular assessment
Non pharmacological methods:
–> cold or heat
–> Immobilisation of injured limbs
–> TENS`
Give examples of opioids in common use. Which are synthetic and which are non synthetic?
-Non synthetic: morphine, codeine (10% metabolised to morphine)
-Semi-synthetic: diamorphine, dihydrocodeine
-Synthetic: pethidine, fentanyl
Why is codeine bad?
-Drowsiness, constipation, orthostatic hypotension
-CYP2D6 enzyme converts codeine into morphine in the liver
-Some patients have high levels of this enzyme, resulting in rapid metabolisation to morphine, causing over-intoxication which can cause respiratory depression
-Some patients have less of this enzyme and therefore lose analgesic affect while still suffering side effects
What is the mechanism of action of paracetamol?
-Mechanism poorly understood
-Generally considered to be weak inhibitor of prostaglandin production
-In vivo effects similar to COX 2 inhibitors
How would you manage paracetamol toxicity?
-Activated charcoal 30mins-2 hrs ingestion
-Acetylcysteine: antidote replenishing body stores of antioxidant glutathione
-Liver transplant in acute liver failure
What different pain scoring systems are there?
-Verbal numerical rating scale 0-10
-Visual anaglogue scale (mark on 10cm line no pain to worst imaginable)
-Wong-baker FACES (children)
What are the advantages and disadvantages of NJ tube over NG tube?
Bypass stomach
–> less liability to pneumonia
–> avoids gastric phase of timulation
–> doesn’t stimulate pancreatic secretions
–> feed delivered directly to the intestine, thus maintaining mucosal integrity
Disadvantages:
–> needs endoscopic guidance for placement
–> smaller in diameter (more prone to kinking)
Risk factors for refeeding syndrome
2 vs 1of:
-Low BMI (<18.5)/<16.5
-Unintentional weight loss >10% 3-6 months/15%
-Little nutritional intake 5 days/10 days
1 of
-Electrolyte disturbance (hypokalaemia, hypophosphatemia/hypomagnaesemia preior to starting feeding
