description of various methods of perioperative pain managment has note on pre emptitive analgesia

1. Acute Perioperative Pain
Management

2. Introduction
What is Pain?
• Pain is an unpleasant sensory and emotional
experience associated with actual or
potential tissue damage, or described in
terms of such damage
IASP – International Association for the Study of Pain 2011

3. Introduction
Classification of Pain
– Acute or Chronic
– Nociceptive or Neuropathic

4. 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!

5. Why Treat Pain?

6. 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

7. 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

8. “… 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

9. Pain Assessment

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

11. 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

12. Pain Assessment
Visual Analogue Scale

13. Current Pain Medications
– Accuracy and detail are very important!
• Name, dose, frequency, route
– Don’t forget to re-order or factor in patient’s pre-
existing pain Rx usage when writing orders
Conflicts
– Renal disease → avoid morphine, NSAID’s
– Vomiting → avoid oral forms of medication
– Short gut/high output stomas → avoid controlled
release formulations

14. 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!

15. Methods to Treat Pain

16. 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

17. WHO Analgesic Ladder

18. 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. Pre-emptive analgesia
• Formulated by Crile and Wolf started animal studies
• It is a antinociceptive treatment that prevents
establishment of altered processing of afferent input,
which amplifies postoperative pain
• It has the potential to be more effective than a
similar analgesic treatment initiated after surgery

21. Preemptive analgesia has been defined as
treatment that:
 Starts before surgery;
 Prevents the establishment of central
sensitization caused by incisional injury
(covers only the period of surgery);
 Prevents the establishment of central
sensitization caused by incisional and
inflammatory injuries (covers the period of
surgery and the initial postoperative
period).

22. • When preemptive analgesia was studied by
comparing preincisional versus postincisional
treatment groups, many authors found no
difference in the pain outcome
• However, some of the previous positive clinical
studies in combination with basic science
results are probably sufficient to indicate that
preemptive analgesia is a valid phenomenon
• Preemptive analgesia continues to have
promise for the effective treatment of
postoperative pain

23. 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

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

25. 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?

26. 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

27. Side Effects
– Nausea / Vomiting
– Sedation
– Respiratory Depression
– Pruritus
– Constipation
– Urinary Retention
– Ileus
– Tolerance

28. 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)

29. • 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 costly
– PO form only
– Percocet (oxycodone + acetaminophen)

30. • 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

31. 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

32. 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

33. Opioids – PCA
• Patient-controlled analgesia
• 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

34. Opioids – PCA

35. 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

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

37. Regional Anesthesia

38. 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

39. 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

40. • Neuraxial Techniques
– Spinal (subarachnoid) anesthesia
– Epidural anesthesia (lumbar and thoracic)

41. 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

42. 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?

43. 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

44. Management of
Opioid Overdose

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

46. • 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

47. • Ddx:
– Seizure, stroke
– Hypoxia, Hypercarbia
– Hypotension
– Other medication effect
– Severe electrolyte or acid base abnormalities
– MI
– Sepsis

48. 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