Management of Pain

Question 1

Define acute pain

Answer 1

Response to injury, with tissue damage

Rapid onset, duration < 3 months, regresses and remits on healing, adequately treated with analgesics

Question 2

Define chronic pain

Answer 2

Onset maybe slower, duration > 6 months no regression, inadequate response to analgesics

Question 3

22 yo. caucasian female –acute injury to her left knee during a basketball match
Cause of pain ?
Therapeutic options ?
Rx diclofenac 37.5 mg IV

Within 20 mins develops uritcaria, SOB with wheeze ++,
HR. 114/min. reg.; BP 115/60 mmHg
What is occurring and why ?

How could this clinical scenario have been avoided?

Answer 3

Anaphylactoid
aspirin-induced asthma

NSAIDs ==> blocking Cox1, Cox2 –> unopposed leukotriene action

Question 4

22 yo. caucasian female –acute injury to her left knee during a basketball match
Cause of pain ?
Therapeutic options ?
Rx diclofenac 37.5 mg IV

Within 20 mins develops uritcaria, SOB with wheeze ++,
HR. 114/min. reg.; BP 115/60 mmHg
What is occurring and why ?

How could this clinical scenario have been avoided?

Answer 4

Anaphylactoid
aspirin-induced asthma

NSAIDs ==> blocking Cox1, Cox2 –> unopposed leukotriene action

Question 5

52 yo. Caucasian female undergoes axillary LN dissection and wide excision for melanoma on her left arm

C/O sharp stabbing pain down medial aspect of her upper arm,
often severe and worse at night

OTC analgesics (APAP/ibuprofen/naproxen) –> little relief

Seen by PCP: Rx codeine/APAP –> little benefit

How best could this patients symptoms be managed?

Answer 5

one of the few people who doesn’t metabolize codeine
(deficient in Cyp2D6) == no morphine, no adequate analgesic

Instead give hydromorphone

Question 6

43 yo medical school professor presented acutely one morning having noted he could not pass urine, nor stand up to get out of bed. His wife mentions he was “ a bit weak and unsteady on his feet” for 1-2 days. Had intermittent lower back pain worse with movement for ~ 3-4 weeks

1. Clinical examination focus and diagnosis?
2. Confirmatory investigations?
3. Best therapy?

Post-operative course
Requires analgesia
Given PCA morphine – 4 mg bolus, with maintenance infusion of 0.5 mg/hr and a lockout interval of 6 minutes

Questions
Why this regimen from a pharmacologic perspective?
What side effects are likely problematic here?
Why is PCA the best option?

Post-operative course
First day post-operatively he required a total of 80 mg of morphine via PCA. By the second day he required 25 mg during 12 h
Path report: AdenoCa. Further investigation - reveals adenocarcinoma of unknown primary but suspicious for prostate carcinoma. Bone scan reveals metastatic lesions in axial and appendicular skeleton
End of second day post-op, he is tolerating oral fluids and some food - starts oral morphine sulfate 10 mg 4 hourly

Develops severe back pain during the night.
Issues
Why is he in so much pain?

How to convert from IV to oral morphine dosing regimen?

What additional therapy should be considered at this point?

Post-operative course
Day 5: better analgesia morphine PO dose-100 mg /day
Oral naproxen helped
Narcotic bowel orders effective
Day 6: noted to have a sustained sinus tachycardia of 110-120 /min for which no obvious cause could be identified. Started on metoprolol 100 mg bid for this.
Day 7: transferred to hospice
Over next 36 hours becomes confused, obtunded and is found unconscious, with a respiratory rate of 4/min and pin point pupils

Why did this happen?

Answer 6

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E.