Acute Perioperative
Pain Management
AHMED HAMDY
Staff Anesthesiologist
St. Michael’s Hospital
Outline
 Introduction
 Why Treat pain?
 Pain Assessment
 Methods to Treat Pain
 Management of Opiate Overdose
 Acute Pain Service
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)
Introduction
Classification of Pain
 Acute or Chronic
 Nociceptive or Neuropathic
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!
Why Treat Pain?
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
Adverse Effects of Poor Pain
Control
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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
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
Pain Assessment
Pain Assessment
Pain History
 O – Onset
 P – Provoking / Palliating factors
 Q – Quality / Quantity
 R – Radiation
 S – Severity
 T – Timing
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
Pain Assessment
Visual Analogue Scale
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
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!
Methods to Treat Pain
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
WHO Analgesic Ladder
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
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
NSAIDs
 Also, first-line treatment
 Mechanism
 Block cyclooxygenase (COX) enzyme → ↓ prostaglandin
synthesis
 COX-2 → Prostaglandins → pain, inflammation, fever
 COX-1 → Prostaglandins → gastric protection,
hemostasis
NSAIDs
 Warnings: ↓dose / avoid if
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GI ulceration
Bleeding disorders / Coagulopathy
Renal dysfunction
High cardiac risk – COXII inhibitors
Asthma
Allergy
 ?Avoid celecoxib if allergic to Sulpha
Concern for anastomotic leaks?
Opioids
Dilaudid 1-4mg PO/IM/IV/SC Q3H PRN
Any concerns?
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
Opioids
Side Effects
 Nausea / Vomiting
 Sedation
 Respiratory Depression
 Pruritus
 Constipation
 Urinary Retention
 Ileus
 Tolerance
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)
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)
Opioids
 Codeine
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1/10th Potency of morphine
Metabolized into morphine by body
Ineffective in 10% of Caucasian patents
Challenge with combination formulations
 Meperidine (Demerol)
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Not very potent
Decreases seizure threshold, dystonic reactions
Neurotoxic metabolite (normeperidine)
Avoid in renal disease
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
Opioid Equianalgesic Table
Drug
Equianalgesic Dose
Initial Adult Dose (>50kg)
IV/SC/IM
Oral
IV/SC/IM
Oral
10 mg
20-30 mg
2-10 mg q4h
5-20 mg q4h
Hydromorphon 1.5 mg
e
4-7.5 mg
0.5-2 mg q4h
1-4 mg q4h
Oxycodone
10-20 mg
N/A
5-10 mg q4h
Morphine
N/A
Opioids – PCA
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
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
Management of Side Effects
 Nausea / Vomiting
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Ondansetron (Zofran)
Dimenhydrinate (Gravol)
Metoclopramide (Maxeran)
Changing medication(s) / ↓ dose
 Pruritus
 Diphenhydramine (Benadryl)
 Changing medication(s) / ↓ dose
Regional Anesthesia
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
Regional Anesthesia
 Peripheral Nerve Blocks
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Upper Limb:
Lower Limb:
Abdomen:
Thoracic:
Brachial plexus
Femoral, sciatic, popliteal, ankle
TAP blocks
Paravertebral, intercostal blocks
 Use of Ultrasound Imaging has revolutionized
peripheral nerve blockade
 Safety?
 Accuracy / Improved Success
 Efficiency
Regional Anesthesia
 Neuraxial Techniques
 Spinal (subarachnoid) anesthesia
 Epidural anesthesia (lumbar and thoracic)
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
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?
Contraindications to
Neuraxial Blockade
 Absolute:
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Pt refusal or allergy to LA
Uncorrected hypovolemia
Infection at insertion site
Raised ICP
? Coagulopathy
 Relative:
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Uncooperative patient
Fixed cardiac output states
Systemic infection/sepsis
Unstable neurological disease
Significant spine abnormalities or surgery
Management of
Opioid Overdose
Management of
Opioid Overdose
 For ↓LOC, somnolent patient:
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Stimulate patient
Vitals/Monitors/Lines
Airway
Breathing
Circulation
CODE BLUE? CCRT? ICU? APS
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
Opioid Overdose
Management
 Ddx:
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Seizure, stroke
Hypoxia, Hypercarbia
Hypotension
Other medication effect
Severe electrolyte or acid base abnormalities
MI
Sepsis
…..etc.
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
Summary
 Accurate pain assessment
 Make sure to continue or account for patient’s prehospital pain regimen
 Use Multimodal pain management
 Discharge pain management plan
 Acute Pain Service available 24 hrs/day
Summary
 Superior analgesia, ↓ side effects means:
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Improved patient satisfaction
Better rehabilitation
Earlier functional return
Earlier discharge from hospital
↓ likelihood of chronic pain
Reduced health care costs