Perioperative Pain Management

1
Acute Perioperative Pain Management
AHMED HAMDY Staff Anesthesiologist St. Michaels
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
Adverse Effects of Poor Pain Control

• 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

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
• Dont forget to re-order or factor in patients
  pre-existing pain Rx usage when writing orders
• Conflicts with HPI / PMH
• Renal disease ? avoid morphine, NSAIDs
• 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 Equianalgesic Dose Initial Adult Dose (gt50kg) Initial Adult Dose (gt50kg)
IV/SC/IM Oral IV/SC/IM Oral
Morphine 10 mg 20-30 mg 2-10 mg q4h 5-20 mg q4h
Hydromorphone 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 patients
  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