Management of postoperative pain Dr B Brandner Consultant in Anaesthesia and Pain Management

Definition 1 Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. IASP 1986

Acute Pain 1Cause is known 2Temporary (< 6 weeks) 3Located in area of trauma 4Resolves spontaneously

Sensitisation Peripheral and central sensitisation

Wind up Increased excitation/reduced inhibition

Wind up - 3 Mg 2+ Glutamate binding site Ion channel blocked by magnesium ion NMDA receptor

Anatomical reorganisation Allodynia / Central sensitisation

I II III IV V VI To dorsal columns C AA AA Primary sensory neurone termination in the dorsal horn

Mechanism Peripheral and central sensitisation Peripheral and central sensitisation Wind-up Wind-up Recruitment of receptive fields Recruitment of receptive fields Longterm potentiation Longterm potentiation Immediate early gene expression Immediate early gene expression

The Acute Pain Team Report of the Joint Working Party on Pain after Surgery (1993): Need for designated team if new techniques are used. Report of the Joint Working Party on Pain after Surgery (1993): Need for designated team if new techniques are used. Adequate equipment Adequate equipment HDU/ITU HDU/ITU

Multidisciplinary Approach Acute Pain Team Pharmacist Nurse Anaesthetist Physiotherapist Psychologist Surgeon

Principles Of Pain Management

WHO

Analgesic ladder

Acute Pain Analgesic Staircase Stage 1:Immediately post-operative Strong opioid eg morphine sc,im,iv or PCA or epidural opioid/ local anaesthetic infusion +/- non-opioid analgesic Stage 1:Immediately post-operative Strong opioid eg morphine sc,im,iv or PCA or epidural opioid/ local anaesthetic infusion +/- non-opioid analgesic Stage 2: Oral opioid for moderate to strong pain +/- non-opioid analgesic( NSAID) Stage 2: Oral opioid for moderate to strong pain +/- non-opioid analgesic( NSAID) Stage 3: Prior to discharge Non-opioid analgesic Stage 3: Prior to discharge Non-opioid analgesic

What Endpoint Should Be Achieved? Patient awake and not nauseated Patient awake and not nauseated Ability to mobilise, cooperate with physiotherapy, eg coughing, deep breathing Ability to mobilise, cooperate with physiotherapy, eg coughing, deep breathing VAS of below 30mm on a scale of 0-100mm seen as adequate VAS of below 30mm on a scale of 0-100mm seen as adequate

Non-opioid Analgesics Paracetamol: Acetaminophen centrally acting 1g 6h or mg/kg for children Paracetamol: Acetaminophen centrally acting 1g 6h or mg/kg for children Diclofenac sodium: 50mg TDS orally Diclofenac sodium: 50mg TDS orally NSAIDs: Analgesic, antipyretic,antiinflammatory Opioid sparing SE: Prostaglandin and prostacyclin effect Ibuprofen, diclofenac, naproxen, piroxicam COX 1 and COX 2

Compound Analgesics Co-Proxamol: Paracetamol 325mg, Dextropropoxyphene 32.5mg Co-Proxamol: Paracetamol 325mg, Dextropropoxyphene 32.5mg Co-Dydramol: Paracetamol 500mg, Dihydrocodeine 10mg Co-Dydramol: Paracetamol 500mg, Dihydrocodeine 10mg Co-Codamol: Paracetamol 500mg, Codeine phosphate 8mg Co-Codamol: Paracetamol 500mg, Codeine phosphate 8mg Aspav:Aspirin 500mg and opium alkaloids Aspav:Aspirin 500mg and opium alkaloids

Weak opioids Dihydrocodeine 30mg 4 hrly po Dihydrocodeine 30mg 4 hrly po Tramadol weak iv,po agonist mg Tramadol weak iv,po agonist mg Buprenorphine mcg sl 4-6h Buprenorphine mcg sl 4-6h Codeine phosphate mg 4h Codeine phosphate mg 4h Strong opioids Morphine Fentanyl Diamorphine Pethidine: max 1.2g daily

PCA Patient Controlled Analgesia Advantages Advantages Safe, effective, good analgesia, reduces delay, saves nursing time, high patient satisfaction, few complications Disadvantages Disadvantages Respiratory depression, nausea and vomiting, programming errors, costs

Patient controlled analgesia

PCA

Outcome PCA does not alter outcome, but good quality of pain relief

Mr Jones will undergo a thoracotomy. What would be your analgesia of choice?

Local Anaesthetic Techniques Local anaesthetics are either esters or amides Local anaesthetics are either esters or amides Influence action potential along the nerve Influence action potential along the nerve Local infiltration Local infiltration Nerve block/ Plexus block Nerve block/ Plexus block Caudal/ epidural/spinal analgesia Caudal/ epidural/spinal analgesia

Epidural analgesia

Promises of epidural analgesia Mortality Mortality Morbidity Morbidity Cardiovascular Cardiovascular Respiratory Respiratory Coagulation Coagulation Major infections Major infections Quality of pain relief Quality of pain relief Hospital costs Hospital costs

NNT NNT to prevent one episode of respiratory failure with epidural analgesia is 15 NNT to achieve 50% reduction in moderate to severe pain with ibuprofen 200mg is 2

Problems Dural puncture Dural puncture Epidural haematoma Epidural haematoma Epidural abscess Epidural abscess Failure of technique Failure of technique Training Training Resource restraint Resource restraint

Mr Jones Your consultant has decided to discontinue the epidural analgesia. What are the appropriate next steps?

Step down analgesia Aim: To discharge the patient on non-opioid analgesic medication, often simple analgesics such as paracetamol 1g QDS is enough! Aim: To discharge the patient on non-opioid analgesic medication, often simple analgesics such as paracetamol 1g QDS is enough! If the patient is discharged on strong opioids the GP is informed and a reduction plan advised. If the patient is discharged on strong opioids the GP is informed and a reduction plan advised.

Julie 4yrs old is scheduled for a fixation of her fractured femur.

CHILDREN Difficult assessment Opioid sensitive Opioid sensitive PCA/NCA PCA/NCA Simple analgesics very useful Simple analgesics very useful Regional analgesia Regional analgesia Drugs Not many drugs licensed in paediatric use

The Elderly patient Slow circulation time Associated diseases Respiratory recovery important Early mobilisation

Ken, 23 admitted with severe pain in his right leg after injecting inadvertently into his artery

Chronic pain after surgery: Phantom limb pain

Summary Every patient has got individual needs. Every patient has got individual needs. Pain is best treated in a multimodal fashion Pain is best treated in a multimodal fashion Balanced analgesia with opioids, reduced peripheral stimulus (NSAID’s), interrupted pain pathways, eg nerve block and alteration of emotional and behavioural response Balanced analgesia with opioids, reduced peripheral stimulus (NSAID’s), interrupted pain pathways, eg nerve block and alteration of emotional and behavioural response Careful monitoring of cardiovascular and respiratory functions in the postoperative patient Careful monitoring of cardiovascular and respiratory functions in the postoperative patient Evidence that good pain relief will reduce the incidence of ongoing pain Evidence that good pain relief will reduce the incidence of ongoing pain