kEY cONCEPTS iN pOST-OPERATIVE pAIN mANAGEMENT

Dr Pranav BansalAssociate ProfessorDept of Anaesthesiology

BPS Govt. Medical College for Women, Khanpur Kalan, Sonepat

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)

According to Katz and Melzack, pain is a personal and subjective experience that can only be felt by the sufferer.

It is easier to find men who will volunteer to die, than to find those who are willing to endure pain with patience. Julius Caesar

What is Pain?

ACUTE PAINCUTANEOUS PAINDEEP SOMATIC PAINVISCERAL PAINCHRONIC PAINREFERRED PAINNEUROPATHIC PAINPHANTOM PAIN

TYPES OF PAIN

Pain Assessment Visual Analogue Scale

Why Treat Pain?

Basic human right!Moral responsiblity ↓ suffering and post operative complications↓ likelihood of chronic pain development↑ patient satisfaction

Consequences of poorly managed acute post-operative pain

The Patient may suffer from:CVS: Tachycardias, dysrhythmias, IschaemiaResp: atelectasis, pneumoniaGI: ileus, anastamosis failureHypercoagulable state: DVTImpaired immunological state:

Delayed wound healing

Psychological:Anxiety, Depression, Fatigue, Sleep

DeprivationChronic Post-surgery Pain

ForThe Healthcare professional:Low MoraleComplaints to/towards/against InstituteLitigation

Consequences of poorly managed acute post-operative pain

CAUSES OF VARIATION IN ANALGESIC REQUIREMENTS

Site and type of surgeryAge, gender Psychological factors Pharmacokinetic variabilityPharmacodynamic variability

Surgical pain

Mild Intensity PainHerniotomyVaricose veinGynecological laparotomy

Moderate Intensity PainHip replacementHysterectomyMaxillofacial

Severe Intensity PainThoracotomyMajor abdominal surgeryKnee surgery

Paracetamol /NSIADs / weak opiodsWound infiltrationRegional block analgesiaAdd weak opioid or rescue analgesia

Paracetamol /NSIADs +Wound infiltrationPeripheral nerve blockSystemic opioidsPCA

Paracetamol /NSIADs+ Wound infiltration Epidural anesthesia Systemic opioidsPCA

Treatment modality

Surgical procedure

WHO Analgesic Ladder

WHO analgesic guidelinesOral medications whenever possibleDose “by the clock” – but always have “as

needed”medications for breakthrough painTitrate the doseUse appropriate dosing intervalsBe aware of relative potenciesTreat side effects

Multimodal (Balanced) AnalgesiaUsing 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 aloneCan provide additive or synergistic effectsProvides better analgesia with less side effects

(mainly opiate related S/E)

Always consider multimodal analgesia when treating pain

The administration of analgesic agents prior to an injury in order to prevent development of central nervous system hyperexcitability or sensitization

Preemptive analgesia

Methods to Treat Postoperative PainPharmacologic (Medications (PO/IV/PR)

Acetaminophen (Paracetamol)NSAIDsOpioidsAlpha-2 agonists

ProceduresRegional Anesthesia LA infiltration at incision site

Nonpharmacologic ApproachesMusic and AudioanalgesiaTranscutaneous electrical nerve stimulation (TENS)

Site of Action of Analgesics

Acetaminophen (Paracetamol)First-line treatment if no contraindicationMechanism: thought to inhibit prostaglandin

synthesis in CNS → analgesia, antipyreticTypical dose: 650 to 1000 mg PO every 6HMax dose: 4 g / 24 hrs from all sourcesWarning: ↓ dose / avoid in those with liver

damage

NSAIDsFirst-line treatmentMechanism

Block cyclooxygenase (COX) enzyme → ↓ prostaglandin synthesis

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

hemostasis

No physical dependenceNo toleranceCeiling effect

NSAIDDrug Dosage Maximum daily

doseDiclofenacPiroxicamIbuprofen Ketorolac

Ketoprofen

50 mg PO bd/tds20 mg OD200-800 mg q 6 hr.3 x 30-40 mg/day (only IV form)4 x 50 mg/day

200 mg40 mg

3200 mg

Cox-2 inhibitorCelecoxib Parecoxib

100-200 mg PO bid40 mg followed by 1-2 x 40 mg/day (IV form)

400 mg

NSAIDsWarnings: ↓dose / avoid if

GI ulceration Bleeding disorders / CoagulopathyRenal dysfunctionHigh cardiac risk – COXII inhibitorsAsthmaAllergy

TramadolMultiple mechanism

Weak µ-receptor agonistInhibit serotonin & NE reuptake

Application : Mild to Moderate Post-op pain

Dose : 50-100 mg PO q 4-6 hr.Max. 400 mg/dSide effect: Nausea and Vomitting

OpioidsEssential element of pain managementMechanism

Action on opioid receptorLocated mainly in spinal cord & brain stem, some

in peripheral tissue

Opioids receptorsReceptorsMu (μ or OP3)

μ1μ2

Kappa (κ or OP2)Delta (δ orOP1)Sigma(σ)

Clinical effect

Analgesia, sedation, euphoriaResp. depression, physical dependenceSpinal analgesia, resp. depressionAnalgesia, resp. depressionDysphoria, hallucination, tachycardiahypertension

Opioids

1.Agonists : stimulate receptor : no ceiling effect ( no limit mg/kg)

: moderate to severe pain : Codiene, morphine, pethidine,

fentanyl, methadone

Opioids2. Partial agonists

: ceiling effects eg. Buprenorphine

Opioids3. Agonists-antagonists

: agonist-κ or σ receptor but antagonist to μ receptor

: can used in mild to moderate pain : ceiling effects

: precipitate withdrawal in opioids dependent

E.g: Pentazocine, Nalbuphine, Nalorphine

Side Effects include:Nausea / Vomiting, Pruritus, Constipation, Urinary Retention,

Ileus, Sedation, Respiratory Depression, Tolerance

Opioid OverdoseManifests as Somnilence, respiratory depression, bradycardia, miosis.

Management: Stimulate patient Attach Monitors/ IV Lines and record VitalsAirway, Breathing, Circulation Shift to ICU

Opioids

Opioid OverdoseOpioid Reversal

Naloxone - Pure antagonist at all the Opioid receptors

Reverses effects of opioid overdose (for 30-45min)0.4mg ampuoleDilute: 1mL Naloxone + 9mL

Saline = 0.04 mg/mL conc.Give 0.04 to 0.08 mg (1 to 2

mL) IV every 3-5 minutes till condition improves

Local Anaesthetics

LA bind sodium channels preventing propagation of action potentials along nerves

Wide variety of LA with different characteristics:Lidocaine (Lox) – fast onset, short duration of

actionBupivacaine (Sensorcaine) – slow onset, longer

duration Ropivacaine: longer duration, less cardiotoxic

AgentsLidocaine-infiltration-epidural-plexus or nerveBupivacaine-infiltrate-epidural-plexus or nerve

% solution

0.5-11-2

0.75-1.5

0.125-0.25

0.25-0.750.25-0.5

Duration(h)

1-21-21-3

1.5-61.5-68-24+

Max dose

7mg/kg

3 mg/kg

Local Anaesthetics

Potential side effects of Local anesthetics- Residual motor weakness- Peripheral nerve irritation- Cardiac arrhythmias- Allergic reactions-Sympathomimetic effects (due to vasoconstrictors)

Regional Anesthesia techniques in PostOperative Pain Management

Peripheral nerve blocksIlioinguinal/hypogastric : herniorrhaphyBrachial plexus : arm, handThoracic: Intrapleural Regional Anaesthesia (IPRA), Paravertebral, intercostal blocksPenile : circumcisionIntercostal/paravertebral : breastLower Limb: Femoral, sciatic, popliteal, ankleParacervical : F&C, D&C, cone biopsyAbdomen:TAP blocks

Epidural AnalgesiaEpidural Catheter placed in lumbar or thoracic

segments. LA+ Opioids given via bolus dosing, Infusion pump or

Patient Controlled Analgesia pump•Superior analgesia compared to Intravenous drugs in thoracic/ abdominal procedures•Reduced systemic opiate requirements•Improves GI blood supply

Patient Controlled Analgesia Pump

Regime for using IV Morphine in PCA pump

Regime for using Epidural Opioids with LA in PCA pump

Advantages of PCA:Allows patient participation and gives

them autonomy in their treatmentRapid titrationPrecise Analgesic calculations for

scientific studiesReduced analgesic requirementsReduced incidence of breakthrough painLess staffing and monitoring concerns

A model for organizing postoperative pain management unit

A model for organizing postoperative pain management

.......In a Nutshell Excellent Post Operative analgesia means:

Improved patient satisfaction and Doctor-Patient relationship.

Better rehabilitationEarlier discharge from hospital & return to

function↓ likelihood of chronic painReduced health care costs