Management of Acute Postoperative Pain

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Management of Acute Postoperative Pain

• Dr Alice Man
• Department of Anaesthesia Intensive Care
• The Chinese University of Hong Kong
• Prince of Wales Hospital

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Case scenario

• You are a houseman in an acute hospital

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• By any reasonable code, freedom from pain should
  be a basic human right, limited only by our
  knowledge to achieve it
• - Liebeskind JC Melzack R
•  

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IASP definition of Pain

• An unpleasant sensory and emotional experience
  associated with actual or potential tissue
  damage, or described in terms of such damage.
•  

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Why should we treat postoperative pain?
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Principles of postop pain Mx
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Factors affecting postop pain

• A. Surgical factors
• 1. site of incision and nature of the surgery
• upper abdomen gt thoracotomy gt lower abdomen gt
  limbs
• 2. complications, eg wound infection,
  intraabdominal sepsis, distension
• B. Patient factors
• Psychology, genetic, hx of substance abuse, hx
  of chronic pain

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Causes of postop pain

• 1. Incisional- skin and subcutaneous tissue
• 2. Deep- cutting, coagulation, trauma
• 3. Positional- bed sore, nerve compression
  traction
• 4. IV site- needle trauma, extravasation, venous
  irritation
• 5. Tubes- drains, nasogastric tube, ETT
• 6. Respiratory- from ETT, coughing, deep
  breathing
• 7. Rehab- physiotherapy, movement, ambulation
• 8. Surgical- complication of surgery
• 9. Others- cast, dressing too tight, urinary
  retention

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Acute pain service

• 1.     Education
• 2.     introduction and supervision of more
  advanced analgesic techniques e.g. iv PCA
• 3.     improvement of traditional analgesic Tx
• 4.     standardization of equipment, standing
  order, guidelines, protocol
• 5.     24-hr availability of pain service
  personnel
• 6.     collaboration and communication with other
  medical staff
• 7.     audit of pain service
• 8.     research
•  

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How can we assess pain?
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Pharmacology

• What drug to give?

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Analgesic

• 1. Simple analgesic
• Paracetamol-for mild pain, caution with liver
  impairment
• Dologesic- paracetamolpropoxyphene- mild to
  moderate pain

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• 2. NSAID
• -         Mild and moderate pain
• -         Opioid sparing
• -         SE peptic ulcer and bleeding, platelet
  aggregation inhibition, bronchospasm, renal
  impairment, allergy
• -         CI bleeding, hypovolaemia, GIB,
  pregnancy, breast feeding, hypersensitivity,
  renal impairment, asthma

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• 3. Opioid
• e.g. morphine, pethidine, fentanyl , codeine
  phosphate, methadone, dextro-propoxyphene
• Desirable effects Analgesia, Sedation
• Adverse effects Over sedation, Respiratory
  depression, Nausea vomiting, Pruritus, Urinary
  retention, Constipation, Dysphoria,
  hallucination, Addiction

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• 4. Local anaesthetics
• e.g. bupivacaine (marcain), lignocaine
• used in epidural and regional analgesia
• features of LA toxicity perioral numbness,
  dizziness, tinnitis, diplopia, drowsiness,
  convulsion coma, respiratory depression, CVS
  depression

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How to give?
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Methods of postop analgesia

• 1. Oral/ PR
• 2. Intramuscular
• 3. intravenous-intermittent bolus, continuous
  infusion

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4. Epidural analgesia
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5. Spinal
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6. Regional block-brachial plexus block
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Patient controlled analgesia
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Non-pharmacological

• 1. Psychotherapy distraction,  information 
• 2. Behavioral therapy modification
• 3. Physical therapy TENS, acupuncture,
  cryoanalgesia, heat therapy

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Postop Nausea vomiting
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Consequence of PONV

• Delayed in oral intake, dehydration, e imbalance
• Tachycardia, arrhythmia, salivation, pallor
• Oesophageal tear, disruption of surgical
  anstomosis, wound dishiscence, increased ICP,
  IOP, haematoma
• Aspiration pneumonia
• Delayed in discharge, unplanned hospital
  admission

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Case scenario

• You are a houseman in an acute hospital

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Case 1

• While u are having dinner in the canteen, a ward
  nurse call u, Mrs Chan came back from OT just
  now and her recent blood pressure is 70/40. She
  has an epidural.
• What are u going to do?
• What is the definition of shock?
• Any investigation?

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Hypotension

• Epidural analgesia- sympathetic blockade, iv PCA
• Ddx hypovolaemia, cardiogenic, distributive,
  obstructive
• Mx
• 1.     Assess patient, recheck BP
• 2.     ABC
• 3.     give O2
• 4.     stop epidural infusion, iv PCA
• 5.     iv fluid challenge, vasopressor
• 6.     exclude other causes e.g. haemorrhage

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Case 2

• Mr Chan, 50yr old gentleman, postop D2, on iv PCA
  LOC
• What will u do?
• What are the differential diagnosis?
• What is the management for opioid overdose?

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Opioid overdose

• Causes human error, equipment malfunction,
  patient risk factors,
• Presentation Altered conscious state, slow RR,
  desaturation, small pupil
• Ddx stroke, electrolyte disturbance, hypoxaemia,
  hypercarbia, hypotension 

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Mx

• 1.     ABC
• 2.     ? drowsy, rousable
• 3.     stop PCA/ Continuous infusion
• 4.     give O2 via mask, ambu bag
• 5.     monitor closely
• 6.     inform APS
• 7.     give 0.1mg naloxone iv and repeat 3-5min
  as necessary 

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Case 3

• 60 years old female
• morbidly obese
• evidence of obstructive sleep apnoea
• on DVT prophylaxis - fraxiparine
• require anterior resection
• You are an anaesthetist, what mode of postop
  analgesia would you choose?
• Any precautions concerning the postop analgesia?

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Choice of analgesic modality

• 1.     Patient factors physical conditions, age,
  cognitive ability, previous experience,
  psychological state, oral diet, drug interaction
• 2.     Surgical factors type and extent of
  surgery, surgical complication
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• 3.     Anaesthetic factors anasthetic technique,
  expertise, available resource, ward nurse training

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Considerations

• abdominal surgery
• adverse effect of pain to heart
• effect of systemic opioid
• effect of anti-coagulant
• technical difficulty on epidural insertion

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Options

• Options
• opioid - IV PCA
• epidural - PCA Pethidine
• epidural infusion - LA fentanyl
• Note
• anticoagulant and epidural

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Case 4

• Miss J, a 20 yr old patient just had a
  laparoscopy performed and asked u, Can I get
  some antiemetic?
• What would u do?
• What are the risk factors for postop nausea
  vomiting?
• Any treatment?

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High risk of PONV

• Patient young, F, early preg, previous hx of
  PONV, motion sickness, anxiety
• Increased gastric vol obesity, blood in stomach
• Anaesthetic technique RA vs GA, N2O, opioid
• Surgical duration, laparoscopy, eye, ear
  operation
• Post op pain, movement, hypotension, forced oral
  fluid

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Mx

• Ensure pain control, adequate hydration,
  oxygenstion, slow and deep breath, stable BP,
  gentle handling of pt

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Pharmacological

• -Anticholinergic scopolamine
• -Phenothiazine prochlorperazine, promethazine
• -Butyrophenones droperidol
• -Benzamides metoclopramide
• -Antihistamine cyclizine, diphenhydramine
• -Corticosteroid dexamethasone, betamethasone
• -5-HT antagonist ondansetron, topisetron

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Non-pharmacological

• NGT?
• Acupuncture

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Thank you.