Pain Flashcards
Risk factors for poor outcomes in back pain
fear avoidance
Catastrophising
Anxiety - psychological vulnerability
Difference between nocebo and placebo
Placebo leads to positive outcome.
Nocebo leads to negative outcome
What reduces CPSP in breast surgery
PVB, local infiltrartion, IV lignocaine
Can gabapentinoids prevent CPSP
Pregabalin reduces incidence of chronic post surgical neuropathic pain only.
Gabapentin no demonstrated effect
Does alcohol consumption increase the risk of paracetamol toxicity
no, hepatotoxicity is very rare.
Which NSAIDs have shown to increase bleeding risk
Aspirin in adults and children.
Ketoralac only in adults
How does rofecoxib increase CV adverse events like myocardial infarction?
Selective blocking of COX-2, reducing prostaglandin production but preserves thromboxane A2, which is a vasoconstrictor and stimulus of platelet aggregation
Is parecoxib used in cardiac surgery
no, increases incidence of CV and cerebrovascular effects
Which NSAIDs increase the risk of anastomotic leak?
Non-selective NSAIDs
Not coxib
What drugs have evidence as pre-emptive analgesia?
Paracetamol and epidural
What drugs have evidence as preventive analgesia
Epidural, regional, systemic LA for CPSP
Ketamine
Does pre-op education in analgesia lead to a reduction in analgesic requirements?
no, but it reduces pre-op and post-op anxiety
What are the options to attenuate remifentanil hyperalgesia?
Propofol, ketamine, pregabalin, nitrous oxide use
Gradual tapering of Remi dose.
Options to treat opioid-induced pruritus?
naloxone, naltrexone, droperidol, nalbuphine, ondansetron
what is the more reliable way to detecting early opioid-induced ventilatory impairment?
assessment of sedation
What is the ceiling dose of intrathecal morphine?
300microg
Any more = increase risk of respiratory depression
What’s the evidence of IV lignocaine in breast surgery?
Does not improve pain score
Lower acute opioid consumption, less CPSP at 3 and 6 months.
what are the rare but serious side effects of nitrous oxide?
Neurotoxicity: spinal cord degneration, myelopathy, demyelinating polyneuropathy
Anaemia from B12 inactivation
Pharmacological options for neuropathic pain
TCA, SNRI, SSRI
Gabapentinoids
Atypical opioids
What are the different types of CRPS?
Type 1, accounts for 90% of cases, no evidence of neural damage
Type 2, evidence of neural damage
Describe the Budapest criteria for CRPS
- Continued pain disproportional to injury
- Display 1, in 3 out of 4 categories, both for self-reporting symptom, and objective examined signs.
–> Sensory (allodynia, hyperalgesia)
–> vasomotor (temperature asymmetry, skin colour change)
–> Sudomotor (oedema, sweating)
–> Motor or trophic (nail/hair growth change, decrease range of motor function, motor weakness). - Exclude other causes
Pharmacological treatments of CRPS?
Methylpred 100mg/d, reducing by 25mg/d every week
Bisphosphonate for 8 weeks
Ketamine, lignocaine, capsaicin, A2 agonist
Benefit of opioid PCA vs. conventional regimen
Downside?
Higher patient satisfaction
Better analgesia
Aside from below, no diff in other opioid related SE.
Higher opioid consumption, higher incidence of pruritus.
Downside of adding a background opioid infusion to PCA?
increases OIVI
does not improve pain relief or sleep or reduce the number of PCA demands
What’s the most common problem related to PCA?
operator error
Does continuous regional catheter prevent phantom limb pain?
No preventive effect on phantom limb pain.
It provides post-op analgesia.
Which drugs reduce phantom limb pain?
Morphine, gabapentin, ketamine
Calcitonin when used acutely <7 days post amputation
Non-pharmacological treatments of phantom limb pain?
Mirror therapy, sensory discrimination training, motor imagery - aiming at cortical reorganisation.
what are the four operations associated with higher risk of CPSP
Thoracotomy, breast, hysterectomy, herniotomy
Typical dose of dexmedetomidine?
0.5mic/kg bolus, over 10 mins, followed by 0.5mic/kg/hr
When would surgical fixation be indicated in rib fractures?
≥3 fractured ribs
surgical management decreases incidence of pneumonia, need for tracheotomy, reduce duration of ventilation, ICU and hospital stay
what drugs reduce the incidence of sickle cell vase-occlusive crisis?
hydroxyurea, zinc
Treatment of tension type headache?
Acupuncture
Paracetamol + ibuprofen
Metoclopramide, chlorpromazine
Caffeine/aspirin
How does sumatriptan work?
inhibition of vasoactive neuropeptides -> vasoconstriction
Treatment of pain for Guillain-Barré syndrome?
Plasma exchange
Carbamazepine and gabapentin
Paracetamol, ibuprofen
Ketamine to reduce opioid doses
Why do patients with OSA have an increased risk of post-op respiratory complications?
- Increased upper airway collapsibility and obstruction
- Decreased central drive to hypoxaemia and hypercarbia
- Increased sensitivity to opioid and heightened pain sensitivity
What’s the indication of naltrexone in opioid tolerance?
Prevention of relapse
It does not prevent withdrawal, like methadone or buprenorphine
When should you stop naltrexone before surgery?
24 hours at least, but ideally 72 hours.
What’s a validated opioid withdrawal scale?
COWS - clinical opioid withdrawal scale
Total scoring range of 0-48
>36 = severe withdrawal
Components include pulse rate, sweating, pupil size, restlessness, tremor, GI upset… .
IV dexamethasone - what’s the evidence of its use in children undergoing tonsillectomy
Reduction of pain post surgery
Does not increase overall risk of bleeding post tonsillectomy but increases the risk of reoperation for bleeding
