1. Acute Pain Management

2. Objectives/Discussion Topics
Appropriate assessment of acute pain
Concept of multi-modal analgesia
Indications and side effects of analgesics
How to rationally prescribe opioids
side effects and complications of opioids
Special populations ie elderly, opioid tolerant
Neuraxial/regional analgesia
side effects and complications of neuraxial analgesia
interaction of various anticoagulant medications and neuraxial analgesia

3. Goal
To provide patients with a level of pain control that allows them to actively participate in recovery
This level will be individual to each patient
To minimize nausea and vomiting
To minimize other side effects of analgesics
Sedation
Ileus
Weakness
Hypotension

4. Why all the fuss? Pain is a miserable experience
Pain increases sympathetic output
Increases myocardial oxygen demand
Increases BP, HR
Pain limits mobility
Increases risk for DVT/PE
Increases risk for pneumonia, atelectasis secondary to splinting

5. Assessment Intensity Location Onset Duration Radiation Exacerbation
Alleviation

6. How do we do it?
Multimodal analgesia: Several analgesics with different mechanisms of action, each working at different sites in the nervous system
Acetaminophen
Non-steroidal anti-inflammatory drugs (NSAIDs)
Opioids
Anticonvulsants
Antidepressants
Local anaesthetics
NMDA Antagonists
Non-pharmacologic methods

7. OPIOIDS Efficacy is limited by Side-Effects
The harder we “push” with single mode analgesia, the greater the degree of side-effects
Side-effects
There is no single silver bullet. With many patients, especially knee arthroplasty and shoulder repairs, it is not possible to achieve satisfactory analgesia devoid of side-effects that both pose a risk to the patient and also slow down the recovery process, ie. Sedation, slow progress in rehab.
Analgesia

8. Multimodal Analgesia Side-effects Analgesia
Lower doses of each drug can be used therefore minimizing side effects
With the multimodal analgesic approach there is additive or even synergistic analgesia, while the side-effects profiles are different and of small degree (Pasero & Stannard, 2012).
There is no single silver bullet. The concept here is to administer more than one agent, each alone being inadequate for effective analgesia but combined effective analgesia is attained, yet with the avoidance of problematic side-effects. It is NOT to give a maximal dose of everything, so that the patient has NO pain and potential side-effects from several agents.
Side-effects
Analgesia

9. Systemic Analgesia Opioids Potent analgesics
Drug of choice for moderate to severe pain
Unfortunately, they are often the only drug ordered
Side effects:
Sedation, nausea, decreased bowel motility, urinary retention, pruritis, respiratory depression, etc.

10. Opioids 10 fold variability between patients
All opioids have same side effects but efficacy:side effect ratio is different for everyone
Stick with what works and keep it simple
Always by mouth if possible
Avoid pro-drugs ie. codeine
Avoid combo preparations

11. ~ 60-100mg (4-fold variability)
Equianalgesia
Opioid PO
Parenteral (IV/SC)
Morphine
10 mg
5 mg
Codeine
~ mg (4-fold variability)
N/A
Hydromorphone
2 mg
1 mg
Oxycodone

12. NALOXONE (Narcan) Mu opioid antagonist
Dilute 1 mL of naloxone 0.4 mg/mL (ie. one vial) with 9 mL of NS for a total of 10 mL of solution and a final concentration of mg/mL
Administer 0.04 mg at a time until reversal of respiratory depression has been achieved, ie. when they’re sitting up awake and talking to you!

13. NALOXONE (Narcan)
REMEMBER: the half-life of naloxone is only 30 minutes, while the half-life of opioid is 2-3 hr so you may have to repeat dosing OR place pt on naloxone infusion until all opioid has been metabolized to prevent further respiratory depression

14. Elderly Patient Pronounced effect therefore, lower doses
Cognitive dysfunction is a major issue
Organ dysfunction/insufficiency affects metabolism
Interaction with other medications, increased incidence of polypharmacy

15. Addiction
Primary, chronic, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations.
Characterized by behaviors that include one or more of the following:
impaired control over drug use
compulsive use
continued use despite harm
craving
Definitions Related to the Use of Opioids for the Treatment of Pain. American Academy
of Pain Medicine; American Pain Society; American Society of Addiction Medicine

16. Physical Dependence
State of adaptation that is manifested by a drug class-specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist

17. Tolerance The body's physical adaptation to a drug:
Greater amounts of the drug are required over time to achieve the initial effect as the body adapts to the intake

18. Pseudo Addiction
Term used to describe patient behaviors that may occur when pain is undertreated
May become focused on obtaining medications, "clock watch," seem inappropriately "drug seeking."
Illicit drug use and deception can occur in the patient's efforts to obtain relief
Distinguished from true addiction in that the behaviors resolve when pain is effectively treated.

19. NSAIDS
Work at site of tissue injury to prevent the formation of the nociceptive mediators Prostaglandins
Can decrease opioid use ~30% therefore decreasing opioid-related side effects
Minor surgeries can use NSAIDs instead of opioids to completely eliminate opioid-associated side effects
Side effects:
GI upset, gastric ulcers, decrease renal medullary blood flow, reversible inhibition of platelet function

20. NSAIDS
Newer NSAIDS selectively (primarily) inhibit cyclooxygenase-2 (COX-2) which is induced by surgical trauma with minimal effect on COX-1 which is responsible for GI and platelet side effects
Celecoxib (Celebrex)

21. Neuraxial Techniques Who Gets Them?
Patient factors:
Low pain tolerance, opioid tolerance
Sleep apnea
Narcolepsy
Obesity
COPD
Cardiac disease
Elderly – those at risk for post-operative cognitive dysfunction

22. …….

25. Epidural Infusions
Used for major surgery ie. oncologic TAH BSO, thoracotomy
Ideally placed pre-operatively and used in combination with a GA for surgery and continued ~ 2 days
Usually patient is tolerating diet and ambulation to chair when epidural is D/C

26. Ideal Epidural Infusions
When placed at the level of the incision and with a constant infusion of LA and opioid:
Minimal or no pain at all, particularly with movement
No motor block
Can ambulate
Speedier return of bowel function
With more LA and less opioid –Cochrane review 2003
Less nausea
Less sedation
Less delerium
Do not require supplemental IV opioids and associated side effects
Less pulmonary complications
Quicker extubation, better oxygen saturation, less pneumonia

27. Side Effects of Epidural Infusions
Hypotension
LA causes a sympathectomy which leads to vasodilatation
Mild volume depletion, which can normally be compensated for with vasoconstriction, will be unmasked with an epidural
Pts require adequate volume status with an epidural

28. Side Effects Hypotension
Pts will initially c/o dizzyness, lightheadedness and nausea when sitting up or standing
Can document orthostatic hypotension
Will then progress to supine hypotension if not corrected
Major problem POD #1 when 3rd spacing still occurring, minimal IV fluids infusing and pt NPO

29. Side Effects Leg weakness or numbness
Can occur if catheter is too low (low thoracic or lumbar) or if it is one-sided
Inhibits ambulation and distressing to pt therefore must be fixed
Infusion can be adjusted or catheter pulled back
Must be addressed as this is the first sign of epidural hematoma leading to permanent paralysis

30. Complications Post dural puncture headache 1:100 Infection
Only if dura is unintentionally punctured
More likely in younger people
Infection
Some reports of epidural abscess as high as 1:1900
Usually just superficial skin infections
Increased risk in immunosuppressed

31. Complications Epidural hematoma Most feared complication
Incidence of 1: – 1:
Increased with heparin, age, gender, ASA, NSAIDs, traumatic placement, spinal stenosis
Leg weakness, numbness and bladder/bowel disturbance are first signs
If not evacuated within 8-12 hours, usually leads to permanent paralysis

32. Complications Epidural Hematoma Risks Abnormal coagulation Elderly
Female
Debilitated patients
Traumatic insertion
Unknown spinal pathology

33. Complications Anticoagulation and Epidurals: ASA – OK NSAIDS – OK
UFH 5000 sc bid – OK if no other antiplatelets
UFH 5000 sc tid – sort of OK, but not really (according to ASRA)
LMWH (Dalteparin)– increased risk – not really OK
IV heparin – not OK
Clopidigrel, ticlodipine – not OK
Coumadin – not OK

34. Ideal Patient Care Surgeons, APMS, nursing all working for same goal
Pre-operative optimization
Intra-operative care
Post-operative
Ambulation, pain, bowels, voiding
Improved patient recovery

35. Addiction – proposed mechanisms
Incentive sensitization
Casual use sensitizes reward system
high motivation to repeat rewarding behaviour for pleasurable experience
Hedonic allostasis
Chronic exposure and production of stress factors and negative emotional state, withdrawal and anxiety
Use to avoid negative-affect state
Mesocorticolimbic dopamine system
Wand, G. (2010). The influence of stress on the transition from drug use to addiction. National institute on alcohol abuse and alcoholism: National Institute of Health.

36. Addiction – proposed mechanisms
Positive reward
Reward system responds – corticotropic releasing factors and stress factors reduced
End of drug salience
Dopamine reward threshold increases, pleasure decreases
Drug use based on negative affect and stress
Modulation of withdrawal, stress and anxiety
S&S of withdrawal:
Psychological symptoms: cravings, insomnia, fatigue
Flu-like physical symptoms: myalgias, chills, nausea, diarrhea
Agitation, restlessness
Tearing, yawning, running nose
Vomiting
Sweating, goose bumps
Tachycardia, HTN
Management:
NSAIDs for myalgias, HA, fever
Dimenhydrinate
Loperamide
Benzos
Trazodone
Fluids
Clonidine for managing autonomic symptoms of opioid withdrawal
CAMH. Opioid Advice: Detection and Management of Acute Opioid Withdrawal in Non-Pregnant Patients Prescribed Opioids for Chronic Pain. retrieved Oct 2012 from
Wand, G. (2010). The influence of stress on the transition from drug use to addiction. National institute on alcohol abuse and alcoholism: National Institute of Health.

37. Dependence and Tolerance
Opioids bind to Mu receptor [all are Mu agonists]
Dopamine release into Nucleus Accumbens

38. Dependence and Tolerance
Repeated use – Mu receptors become downregulated
Same mechanism as end of drug salience – tolerance

39. Dependence and Tolerance
More receptors created to accommodate chronic use = more that become unbound when brain/blood levels decrease
Excessive norepinephrine release & low dopamine levels
Withdrawal occurs
Kosten, T., George T. (2001). The neurobiology of opioid dependence: implications for treatment. Science & Practice Perspectives, 1,

40. Acute Pain Management Service (APMS)
Consulting service, mostly post-op patients
PCAs, non-labour epidurals, regional techiques
Don’t need to co-sign our orders
Can’t order any analgesics, anti-emetics, antihistamines, neuropathic pain agents, or sedatives while patient being followed by APMS
“Suggest Orders” once APMS signs off DO need to be co-signed