Management of Acute
Postoperative Pain
Dr Alice Man
Department of Anaesthesia & Intensive
Care
The Chinese University of Hong Kong
Prince of Wales Hospital
Case scenario
You are a houseman in an acute
hospital
• “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
IASP definition of Pain
• An unpleasant sensory and emotional
experience associated with actual or
potential tissue damage, or described in
terms of such damage.
Why should we treat
postoperative pain?
Principles of postop pain Mx
Factors affecting postop pain
• A. Surgical factors:
• 1. site of incision and nature of the surgery
• upper abdomen > thoracotomy > lower abdomen
> limbs
• 2. complications, eg wound infection,
intraabdominal sepsis, distension
• B. Patient factors:
• Psychology, genetic, hx of substance abuse, hx
of chronic pain
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
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
How can we assess pain?
Pharmacology
What drug to give?
Analgesic
• 1. Simple analgesic
• Paracetamol-for mild pain, caution with
liver impairment
• Dologesic- paracetamol+propoxyphenemild 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
• 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
How to give?
Methods of postop analgesia
• 1. Oral/ PR
• 2. Intramuscular
• 3. intravenous-intermittent bolus,
continuous infusion
4. Epidural analgesia
5. Spinal
6. Regional block-brachial
plexus block
Patient controlled analgesia
Non-pharmacological
• 1. Psychotherapy:
distraction, information
• 2. Behavioral therapy: modification
• 3. Physical therapy: TENS, acupuncture,
cryoanalgesia, heat therapy
Postop Nausea & vomiting
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
Case scenario
You are a houseman in an acute
hospital
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?
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
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?
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
Mx
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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
Case 3
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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?
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
Considerations
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abdominal surgery
adverse effect of pain to heart
effect of systemic opioid
effect of anti-coagulant
technical difficulty on epidural insertion
Options:
• Options
– opioid - IV PCA
– epidural - PCA Pethidine
– epidural infusion - LA + fentanyl
• Note
– anticoagulant and epidural
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?
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
Mx
• Ensure pain control, adequate hydration,
oxygenstion, slow and deep breath, stable
BP, gentle handling of pt
Pharmacological
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-Anticholinergic: scopolamine
-Phenothiazine: prochlorperazine, promethazine
-Butyrophenones: droperidol
-Benzamides: metoclopramide
-Antihistamine: cyclizine, diphenhydramine
-Corticosteroid: dexamethasone, betamethasone
-5-HT antagonist: ondansetron, topisetron
Non-pharmacological
• NGT?
• Acupuncture
Thank you.