1. Acute Pain management in the Opioid dependent patient
Siva Raghavan MD FRCA FFPMRCA FRCPC

3. Outline
Acute pain management in opioid dependent patients can be very challenging
Universal agreement is lacking
Recent APS post-operative pain management guidelines
Chronic post surgical Pain and strategies to minimize it
Opioid prescription and crisis in the community

4. Acute pain management: Scientific evidence 4th edition (ANZCA and FPM Australia)

5. Clinician’s concerns:
OPIOID DEPENDENT PATIENT COMING FOR SURGERY
Patient’s fears:
Fear of withdrawal symptoms
Fear of under-treatment due to prejudice
Fear of being perceived as “manipulative”
Clinician’s concerns:
Pain management can be very challenging
Analgesic requirements can be high due to opioid tolerance and opioid induced hyperalgesia
Inadequate pain control:  RS/ CVS complications and hospital stay
Concern about overtreatment of pain and respiratory depression
Reports of pain may be fabricated
Diversion of prescription opioids

6. Opioid dependence vs Addiction
Tolerance and withdrawal is not addiction. They are features of opioid dependence
Addiction (Opioid use disorder): (Psychological dependence)
Strong desire to take the drug
Difficulty in controlling its use
Persistent use despite being aware of harmful consequences
High priority given to drug use than to other activities
Most of the chronic pain patients are opioid dependent but not addicts

7. Common misconceptions
Maintenance opioid therapy provides adequate analgesia X
Maintenance opioids need to be continued to prevent withdrawal
Additional opioids are needed to manage acute pain.
These patients need more opioids than opioid naive patients due to tolerance and opioid induced hyperalgesia
Additional opioids for analgesia cause addiction relapse X
- Unrelieved pain is a risk factor for relapse of addiction

8. Common misconceptions
Additional opioids cause respiratory and CNS depression X
- Opioid dependent patients have tolerance to respiratory and
CNS depression
PCA is inadequate in opioid tolerant patients X
Besides regional anesthesia, PCA is the best option for
opioid-tolerant patients.
Long acting opioids give better pain control X
- Long acting opioids have higher incidence of unintentional overdose and are not recommended in opioid naïve patients.

9. Peri-operative opioid dosing
Example 1: 59 year old man with chronic arthritic pains, on Morphine sulphate 90 mg q 12h coming for a total knee replacement Allow MST 90 mg PO q 12h to prevent withdrawal. Use short acting morphine/hydromorphone/oxycodone for acute pain

10. Peri-operative opioid dosing
Example 2:
59 year old man with gastric cancer and chronic arthritic pains, on Morphine sulphate 90 mg q 12h coming for Total gastrectomy. Patient refuses epidural analgesia.

11. OPIOID CONVERSION

12. Peri-operative opioid dosing
Example 2: IV PCA will be a good choice for this patient 180 mg PO morphine = 60 mg iv morphine 60 mg iv morphine= 12 mg iv hydromorphone Partial cross tolerance allows 50% reduction in dose when switching opioids. Hence 180 mg/d PO morphine = 6 mg/d iv hydromorphone Run a PCA background infusion of 0.25 mg/hr to prevent withdrawal Program bolus (0.2 to 0.4mg) with lock out interval (5-10 min) for acute pain

13. Peri-operative opioid dosing
Example 3: 59 year old man with previous H/O substance use disorder, currently on methadone 80mg/d. Methadone conversion is challenging due to long half life and high inter-patient variability in pharmacokinetics. Use conversion tables to guide you (conversion is complicated) ALWAYS USE LOWER DOSES AND TITRATE

14. Peri-operative opioid dosing
Example 3:
If able to take oral meds- continue Methadone 80 mg/d PO and give short acting opioid for acute pain
If unable to take oral meds:
Oral methadone to iv morphine conversion is approx 2:1
IV morphine equivalent= 40mg/d
50% dose reduction mg/d morphine
Program PCA morphine with 1mg/h background infusion (24mg/d)
PCA bolus 1mg with 5 minute lockout interval for acute pain

15. Peri-operative opioid dosing
Example 4: Patient on buprenorphine / suboxone Problems: Partial μ agonist and κ antagonist Ceiling effect with analgesia High affinity to opioid receptors κ-receptor antagonism interferes with other opioids Broad inter-patient half life variability (24-60 h)

16. Peri-operative opioid dosing
Example 4: Patient on buprenorphine / suboxone
If on a low dose and severe pain is not anticipated, continue maintenance buprenorphine dose and use short acting opioid for acute pain
For major elective surgery, convert to oral morphine or methadone pre-op. Discontinue buprenorphine at least 72h prior to surgery. Use opioid sparing adjuncts
For emergency surgery, use PCA morphine with background infusion (high doses may be needed).Use Opioid sparing adjuncts. Will need to be in a monitored setting (ICU)

17. Guidelines Education:
Preoperative education- Patient and family- centered, individually tailored education
Parents and adult-caregivers should be educated about developmentally appropriate methods to assess pain and pain management options
Education to patients and primary caregivers on pain treatment plan and medication tapering after discharge

18. Patient education: Establish Clear goals
Managing pain appropriately does not mean having “zero pain”
Some ongoing pain is normal. Encourage mobility
Talk about expected duration of use of opioids after surgery.
Talk about “opioid sparing” pain relief strategies

19. Guidelines Assessment:
Conduct pre-op evaluation of medical and psychiatric comorbidities, medications, history of chronic pain, substance abuse, previous response to analgesics
Use a validated pain assessment tool to track responses and adjust treatment plans.
Do not rely solely on “objective” measures like vital signs or pain-related behaviors
Adjust the pain management plan on the basis of adequacy of pain relief and presence of adverse events

20. Chronic post surgical pain (CPSP)
Crombie IK, Davies HT, Macrae WA
Cut and thrust: antecedent surgery and trauma among patients attending a chronic pain clinic. Pain. 1998;76(1-2):167-71
5130 patients, 10 outpatient clinics in North Britain
Surgery contributed to pain in 22.5% of patients
Macrae WA, Davies HTO. Chronic postsurgical pain. In: Crombie IK, Linton S, Croft P, Von Korff M, editors. Epidemiology of pain. Seattle: IASP Press; p. 125–42.
Definition of CPSP
Pain after a surgical procedure that lasts for at least two months and other causes of pain have been excluded (eg, continuing malignancy, chronic infection)

21. 2017- IASP Global year against pain after surgery
Current definition of CPSP
Pain after a surgical procedure or increased after the surgical procedure
At least 3 months’ duration with significant negative effect on QOL
Pain is a continuation of acute post-op pain or may develop after an asymptomatic period
Pain is localized to the surgical field or to a referred area (dermatome)
Other possible causes have been excluded (eg, infection, cancer recurrence)
Patricia Lavand’homme, PAIN 158(2017): S50-S54

22. Chronic Post Surgical Pain

23. PATHOGENESIS OF CHRONIC POST-SURGICAL PAIN

24. Functional MRI – Neuroanatomy of pain processing
Irene Tracey, BJA 101(1): 32-9 (2008)

25. Risk factors for CPSP

26. Strategies to reduce Chronic post-surgical pain
Consider the indications for surgery
Minimally invasive surgical techniques
Good treatment of acute pain
Regional anesthesia (epidurals, spinals, nerve blocks, local infiltration)
Drugs affecting central sensitization- ketamine, gabapentin, pregabalin
(2 weeks’ perioperative treatment with pregabalin reduced neuropathic
pain 3 months and 6 mths after TKR from 9% and 5% respectively to 0)
Buvanendran et al, Anesth Analg 2010

27. Multimodal “opioid sparing” analgesia (APS guidelines)
Acetaminophen and NSAIDs if there are no contraindications
Gabapentin / pregabalin
iv ketamine ( mg/kg bolus, mg/kg/h infusion)
iv lidocaine (5mg/kg infusion over 1 h)
Subcutaneous/ intra-articular infiltration of local anesthetic
Peripheral nerve blocks, continuous perineural LA infusions
Neuraxial techniques: Spinal, epidural, combined spinal epidural
Intrathecal and epidural opioids
Clonidine as adjuvant in regional anesthetic techniques
Oral opioids preferred over iv in people who can use the oral route
Long acting opioids not recommended unless patient is already on long acting opioids before surgery

28. Remember there is a problem with opioids in the community
Treat acute pain aggressively
BUT
Remember there is a problem with opioids in the community

29. Problems with long term opioids
Patients who used opioids for at least 90 days were more than 60% likely to still be on chronic opioids in 5 years (Martin et al. J Gen Intern Med 2011;26:1450-7)
Receiving one week supply of >2 opioid prescriptions after an acute back sprain is associated with a doubling of the patients’ risk for long term disability (Franklin et al. Spine 2008;33: )
The goal of opioid therapy is to prescribe the briefest, least invasive and lowest dose regimen that minimizes pain and avoids dangerous side effects (Hegmann et al. J Occup Environ Med 2014;56:e143-59; Bates et al. J Urol 2011;185:551-5)

31. Source of abused prescription pain killer CDC 2011

33. Excessive post-op opioid prescription
Opioid consumption following outpatient upper extremity surgery.
Rodgers J, Cunningham K, Fitzgerald K, Finnerty E
J Hand Surg Am Apr;37(4):645-50
67% of pills unused
Prescription Opioid Analgesics Commonly Unused After Surgery: A Systematic Review.
Bicket MC, Long JJ, Pronovost PJ, Alexander GC, Wu CL
JAMA Surg Nov 1;152(11):
42% to 71% of prescribed opioids went unused
In 2 studies examining storage safety, 73% to 77% of patients reported that their prescription opioids were not stored in locked containers

34. ACUTE PAIN MANAGEMENT IN THE OPIOID DEPENDENT PATIENT
SUMMARY
Identify opioid user and abuser. Do not be judgmental
Consider comorbidities
Ensure baseline opioid requirements to prevent withdrawal
Provide effective analgesia and treat acute pain aggressively
Use multimodal analgesia
Prefer local and regional analgesia when suitable
Use strategies to minimize Chronic post-surgical pain
Do not induce weaning in the immediate perioperative period
Be mindful of the consequences of excessive opioid prescription