The document discusses acute perioperative pain management. It emphasizes the importance of treating pain to improve patient outcomes and recovery. A multimodal approach using pharmacological and non-pharmacological methods is recommended, including acetaminophen, NSAIDs, opioids, regional anesthesia techniques, and consulting an acute pain service for complex cases. Proper pain assessment and multimodal analgesia can provide superior pain relief while reducing side effects and length of hospital stay.

1. Acute Perioperative
Pain Management
AHMED HAMDY
Staff Anesthesiologist
St. Michael’s Hospital

2. Outline
Introduction
Why Treat pain?
Pain Assessment
Methods to Treat Pain
Management of Opiate Overdose
Acute Pain Service

3. Introduction
What is Pain?
An unpleasant sensory and emotional experience
associated with actual or potential tissue damage or
described in terms of such damage.
IASP Pain Definition (1994, 2008)

4. Introduction
Classification of Pain
Acute or Chronic
Nociceptive or Neuropathic

5. Introduction
Pain Signal Processing:
Pain perception is a complex phenomenon involving
sophisticated transmission pathways in the nervous
system
 With many pain signal transmission points, there exists
opportunity!

6. Why Treat Pain?

7. Why Treat Pain?
Basic human right!
↓ pain and suffering
↓ complications – next slide
↓ likelihood of chronic pain development
↑ patient satisfaction
↑ speed of recovery → ↓ length of stay → ↓ cost
↑ productivity and quality of life

8. Adverse Effects of Poor Pain
Control
CVS: MI, dysrhythmias
Resp: atelectasis, pneumonia
GI: ileus, anastomotic failure
Endocrine: “stress hormones”
Hypercoagulable state: DVT, PE
Impaired immunological state
Infection, cancer, wound healing
Psychological:
Anxiety, Depression, Fatigue
Chronic Post-surgery/trauma Pain

9. “… it remains a common misconception amongst
clinicians that acute postoperative pain is a transient
condition involving physiological nociceptive
stimulation, with a variable affective component, that
differs markedly in its pathophysiological basis from
chronic pain syndromes.”
Cousins MJ, Power I, and Smith G.
Regional Analgesia and Pain Medicine, 25 (2000) 6-21
Adverse Effects of Poor Pain
Control

10. Pain Assessment

11. Pain Assessment
Pain History
O – Onset
P – Provoking / Palliating factors
Q – Quality / Quantity
R – Radiation
S – Severity
T – Timing

12. Pain Assessment
Origin of Pain
Acute Pain
ie. Incisional pain, acute appendicitis
Chronic Pain
ie. Chronic back pain
Acute on Chronic Pain
Acute and chronic causes may or may not be related to each
other

13. Pain Assessment
Visual Analogue Scale

14. Pain Assessment
Current Pain Medications
Accuracy and detail are very important!
Name, dose, frequency, route
ie. Oxycontin 10mg PO TID
Don’t forget to re-order or factor in patient’s pre-existing
pain Rx usage when writing orders
Conflicts with HPI / PMH
Renal disease → avoid morphine, NSAID’s
Vomiting → avoid oral forms of medication
Short gut/high output stomas → avoid CR formulations

15. Pain Assessment
Allergies / Intolerances
Drug allergies
Document drug, adverse reaction and severity
Intolerances
Nausea / vomiting, hallucinations, disorientation, etc.
Very important to differentiate between an allergy and an
intolerance!

16. Methods to Treat Pain

17. Methods to Treat Pain
Pharmacologic
 Medications (po, iv, im, sc, pr, transdermal)
Acetaminophen
NSAIDs
Opioids
Gabapentin
NMDA antagonists
Alpha-2 agonists
 Procedures
Regional Anesthesia
LA infiltration at incision site
Surgical Intervention
Non-Pharmacologic / Non-Surgical

18. WHO Analgesic Ladder

19. Multimodal Analgesia
Using more than one drug for pain control
Different drugs with different mechanisms/sites of action
along pain pathway
Each with a lower dose than if used alone
Can provide additive or synergistic effects
Provides better analgesia with less side effects (mainly
opiate related S/E)
Always consider multimodal analgesia when treating pain

20. Acetaminophen
First-line treatment if no contraindication
Mechanism: thought to inhibit prostaglandin synthesis
in CNS → analgesia, antipyretic
Only available in po form in Canada
Typical dose: 650 to 1000 mg PO Q6H
Max dose: 4 g / 24 hrs from all sources
Warning: ↓ dose / avoid in those with liver damage

21. NSAIDs
Also, first-line treatment
Mechanism
Block cyclooxygenase (COX) enzyme → ↓ prostaglandin
synthesis
COX-2 → Prostaglandins → pain, inflammation, fever
COX-1 → Prostaglandins → gastric protection,
hemostasis

22. NSAIDs
Warnings: ↓dose / avoid if
GI ulceration
Bleeding disorders / Coagulopathy
Renal dysfunction
High cardiac risk – COXII inhibitors
Asthma
Allergy
?Avoid celecoxib if allergic to Sulpha
Concern for anastomotic leaks?

23. Opioids
Dilaudid 1-4mg PO/IM/IV/SC Q3H PRN
Any concerns?

24. Opioids
Key Points:
Centrally acting on opioid receptors
No ceiling effect
High dose/response variability in non-opiate users
Previous dependence creates a challenge in acute on
chronic pain management cases
Balancing safety and efficacy can be difficult (OSA patients)
Side effects may limit reaching effective dose

25. Opioids
Side Effects
Nausea / Vomiting
Sedation
Respiratory Depression
Pruritus
Constipation
Urinary Retention
Ileus
Tolerance

26. Opioids
Morphine
Most commonly prescribed opioid in hospital
Metabolism:
Conjugation with glucuronic acid in liver and kidney
 Morphine-3-glucuronide (inactive)
 Morphine-6-glucuronide (active)
Impaired morphine glucuronide elimination in renal failure
 Prolonged respiratory depression with small doses
 Due to metabolite build-up (morphine-6-glucuronide)

27. Opioids
Hydromorphone (Dilaudid)
Better tolerated by elderly, better S/E profile
Preferred over morphine for renal disease patients
Low cost, IV and PO forms available
Oxycodone
Good S/E profile, but $$
PO form only
Percocet (oxycodone + acetaminophen)

28. Opioids
Codeine
 1/10th
Potency of morphine
 Metabolized into morphine by body
 Ineffective in 10% of Caucasian patents
 Challenge with combination formulations
Meperidine (Demerol)
 Not very potent
 Decreases seizure threshold, dystonic reactions
 Neurotoxic metabolite (normeperidine)
 Avoid in renal disease

29. Opioids - Formulations
Short acting forms
Need to be dosed frequently to maintain consistent
analgesia
Controlled Release forms
Provides more consistent steady state level
Helpful for severe pain or chronic pain situations
Never crush / split / chew controlled release pills

30. Opioid Equianalgesic Table
Drug Equianalgesic Dose Initial Adult Dose
(>50kg)
IV/SC/IM Oral IV/SC/IM Oral
Morphine 10 mg 20-30 mg 2-10 mg q4h 5-20 mg q4h
Hydromorphon
e
1.5 mg 4-7.5 mg 0.5-2 mg q4h 1-4 mg q4h
Oxycodone N/A 10-20 mg N/A 5-10 mg q4h

31. Opioids – PCA

32. Opioids – PCA
Allows patient to reach their own minimum effective
analgesic concentration (MEAC)
Rapid titration (Morphine 1mg IV every 5 min)
Better analgesia and less side effects than IM prn

33. Gabapentin
Anti-epileptic drug, also useful in:
Neuropathic pain, Postherpetic neuralgia, CRPS
Blocks voltage-gated Ca channels in CNS
Additive effect with NSAIDs
Reduces opioid consumption by 16-67%
Reduces opioid related side effects
Drowsiness if dose increased too fast

34. Management of Side Effects
Nausea / Vomiting
Ondansetron (Zofran)
Dimenhydrinate (Gravol)
Metoclopramide (Maxeran)
Changing medication(s) / ↓ dose
Pruritus
Diphenhydramine (Benadryl)
Changing medication(s) / ↓ dose

35. Regional Anesthesia

36. Regional Anesthesia
Involves blockade of nerve impulses using local
anesthetics (LA)
LA bind sodium channels preventing propagation of
action potentials along nerves
Wide variety of LA with different characteristics:
ie. Lidocaine – fast onset, short duration of action
ie. Bupivacaine (Marcaine) – slow onset, longer duration

37. Regional Anesthesia
Peripheral Nerve Blocks
Upper Limb: Brachial plexus
Lower Limb: Femoral, sciatic, popliteal, ankle
Abdomen: TAP blocks
Thoracic: Paravertebral, intercostal blocks
Use of Ultrasound Imaging has revolutionized
peripheral nerve blockade
Safety?
Accuracy / Improved Success
Efficiency

38. Regional Anesthesia
Neuraxial Techniques
Spinal (subarachnoid) anesthesia
Epidural anesthesia (lumbar and thoracic)

39. Benefits of
Epidural Analgesia
 Superior analgesia to IV PCA in open abdominal procedures &
specifically in colorectal surgery
 Reduce incidence of paralytic ileus
 Blunt surgical stress response
 Improves dynamic pain relief
 Reduces systemic opiate requirements
 Facilitates early oral intake, mobilization and return of bowel fx
when part of fast track protocols

40. Epidural Analgesia
 Recommended as part of ERAS/fast track protocols for
colon/colorectal surgery
 Increased incidence of hypotension and urinary retention
 Management of postoperative hypotension?

41. Contraindications to
Neuraxial Blockade
Absolute:
 Pt refusal or allergy to LA
 Uncorrected hypovolemia
 Infection at insertion site
 Raised ICP
 ? Coagulopathy
Relative:
 Uncooperative patient
 Fixed cardiac output states
 Systemic infection/sepsis
 Unstable neurological disease
 Significant spine abnormalities or surgery

42. Management of
Opioid Overdose

43. Management of
Opioid Overdose
For ↓LOC, somnolent patient:
Stimulate patient
Vitals/Monitors/Lines
Airway
Breathing
Circulation
CODE BLUE? CCRT? ICU? APS

44. Opioid Overdose
Management
Opioid Reversal
Naloxone - opioid antagonist
Reverses effects of opioid overdose (for 30-45min)
MUST BE diluted before use:
0.4mg ampule
Dilute: 1mL Naloxone + 9mL Saline = 0.04 mg/mL
Give 0.04 to 0.08 mg (1 to 2 mL) IV q3-5 minutes
If no change after 0.2mg, consider other causes

45. Opioid Overdose
Management
Ddx:
Seizure, stroke
Hypoxia, Hypercarbia
Hypotension
Other medication effect
Severe electrolyte or acid base abnormalities
MI
Sepsis
…..etc.

46. Acute Pain Service
Consult service for complex / specialized pain
management
Anesthesia Staff + Advanced Practice Nurses
Many post-op patients will be followed by APS
If APS involved, APS must write all pain Rx
Call for:
Advice
Difficult to manage cases

47. Summary
Accurate pain assessment
Make sure to continue or account for patient’s pre-
hospital pain regimen
Use Multimodal pain management
Discharge pain management plan
Acute Pain Service available 24 hrs/day

48. Summary
Superior analgesia, ↓ side effects means:
Improved patient satisfaction
Better rehabilitation
Earlier functional return
Earlier discharge from hospital
↓ likelihood of chronic pain
Reduced health care costs