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

Acute Perioperative Pain Management

AHMED HAMDYStaff AnesthesiologistSt. Michael’s Hospital

OutlineIntroduction

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 PainAcute or ChronicNociceptive 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

CVS: MI, dysrhythmiasResp: atelectasis, pneumoniaGI: ileus, anastomotic failureEndocrine: “stress hormones”Hypercoagulable state: DVT, PEImpaired immunological state

Infection, cancer, wound healing

Psychological:Anxiety, Depression, Fatigue

Chronic Post-surgery/trauma Pain

“… 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

Pain Assessment

Pain Assessment

Pain HistoryO – Onset P – Provoking / Palliating factorsQ – Quality / QuantityR – RadiationS – Severity T – Timing

Pain Assessment

Origin of PainAcute Pain

ie. Incisional pain, acute appendicitis

Chronic Painie. Chronic back pain

Acute on Chronic PainAcute and chronic causes may or may not be related to each

other

Pain Assessment Visual Analogue Scale

Pain Assessment

Current Pain MedicationsAccuracy and detail are very important!

Name, dose, frequency, routeie. 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 / PMHRenal disease → avoid morphine, NSAID’sVomiting → avoid oral forms of medicationShort gut/high output stomas → avoid CR formulations

Pain Assessment

Allergies / IntolerancesDrug allergies

Document drug, adverse reaction and severity

IntolerancesNausea / vomiting, hallucinations, disorientation, etc.

Very important to differentiate between an allergy and an intolerance!

Methods to Treat Pain

Methods to Treat PainPharmacologic

Medications (po, iv, im, sc, pr, transdermal)AcetaminophenNSAIDsOpioidsGabapentinNMDA antagonistsAlpha-2 agonists

ProceduresRegional AnesthesiaLA infiltration at incision site

Surgical Intervention

Non-Pharmacologic / Non-Surgical

WHO Analgesic Ladder

Multimodal Analgesia

Using more than one drug for pain controlDifferent drugs with different mechanisms/sites of action

along pain pathwayEach with a lower dose than if used aloneCan provide additive or synergistic effectsProvides better analgesia with less side effects (mainly

opiate related S/E)

Always consider multimodal analgesia when treating pain

AcetaminophenFirst-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

MechanismBlock cyclooxygenase (COX) enzyme → ↓ prostaglandin

synthesisCOX-2 → Prostaglandins → pain, inflammation, feverCOX-1 → Prostaglandins → gastric protection,

hemostasis

NSAIDs

Warnings: ↓dose / avoid ifGI ulceration Bleeding disorders / CoagulopathyRenal dysfunctionHigh cardiac risk – COXII inhibitorsAsthmaAllergy

?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 receptorsNo ceiling effectHigh dose/response variability in non-opiate usersPrevious dependence creates a challenge in acute on chronic pain management casesBalancing safety and efficacy can be difficult (OSA patients)Side effects may limit reaching effective dose

Opioids

Side EffectsNausea / VomitingSedationRespiratory DepressionPruritusConstipationUrinary Retention IleusTolerance

Opioids

MorphineMost commonly prescribed opioid in hospitalMetabolism:

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 profilePreferred over morphine for renal disease patientsLow cost, IV and PO forms available

OxycodoneGood S/E profile, but $$PO form onlyPercocet (oxycodone + acetaminophen)

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

Opioids - Formulations

Short acting formsNeed to be dosed frequently to maintain consistent

analgesia

Controlled Release formsProvides more consistent steady state levelHelpful for severe pain or chronic pain situationsNever crush / split / chew controlled release pills

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

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

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 / VomitingOndansetron (Zofran)Dimenhydrinate (Gravol)Metoclopramide (Maxeran)Changing medication(s) / ↓ dose

PruritusDiphenhydramine (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 BlocksUpper Limb: Brachial plexusLower Limb: Femoral, sciatic, popliteal, ankleAbdomen: TAP blocksThoracic: Paravertebral, intercostal blocks

Use of Ultrasound Imaging has revolutionized peripheral nerve blockadeSafety?Accuracy / Improved SuccessEfficiency

Regional Anesthesia

Neuraxial TechniquesSpinal (subarachnoid) anesthesiaEpidural 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: 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

Management of Opioid Overdose

Management of Opioid Overdose

For ↓LOC, somnolent patient:Stimulate patient Vitals/Monitors/LinesAirway BreathingCirculation CODE BLUE? CCRT? ICU? APS

Opioid Overdose Management

Opioid Reversal Naloxone - opioid antagonistReverses effects of opioid overdose (for 30-45min)MUST BE diluted before use:

0.4mg ampuleDilute: 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:Seizure, strokeHypoxia, HypercarbiaHypotensionOther medication effectSevere electrolyte or acid base abnormalitiesMISepsis…..etc.

Acute Pain ServiceConsult 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:AdviceDifficult to manage cases

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

Summary

Superior analgesia, ↓ side effects means: Improved patient satisfactionBetter rehabilitationEarlier functional returnEarlier discharge from hospital↓ likelihood of chronic painReduced health care costs