perioperative pain management
TRANSCRIPT
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 healingPsychological:
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 appendicitisChronic Pain
ie. Chronic back painAcute 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 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 Intolerances
Nausea / 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 Effects
Nausea / 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)
OpioidsCodeine
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 OralMorphine 10 mg 20-30 mg 2-10 mg
q4h5-20 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
GabapentinAnti-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 EffectsNausea / Vomiting
Ondansetron (Zofran)Dimenhydrinate (Gravol)Metoclopramide (Maxeran)Changing medication(s) / ↓ dose
PruritusDiphenhydramine (Benadryl)Changing medication(s) / ↓ dose
Regional Anesthesia
Regional AnesthesiaInvolves 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 AnesthesiaPeripheral Nerve Blocks
Upper 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