Management of Acute Postoperative Pain

1. Management of Acute Postoperative Pain Dr Alice Man Department of Anaesthesia & Intensive Care The Chinese University of Hong Kong Prince of Wales Hospital

2. Case scenario You are a houseman in an acute hospital

3. “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

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

6. Why should we treat postoperative pain?

8. Principles of postop pain Mx

10. 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

11. 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

12. 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

13. How can we assess pain?

17. Pharmacology What drug to give?

19. Analgesic • 1. Simple analgesic • Paracetamol-for mild pain, caution with liver impairment • Dologesic- paracetamol+propoxyphene- mild to moderate pain

20. 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

21. 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

22. 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

23. How to give?

24. Methods of postop analgesia • 1. Oral/ PR • 2. Intramuscular • 3. intravenous-intermittent bolus, continuous infusion

25. 4. Epidural analgesia

27. 5. Spinal

28. 6. Regional block-brachial plexus block

29. Patient controlled analgesia

32. Non-pharmacological • 1. Psychotherapy: distraction,  information • 2. Behavioral therapy: modification • 3. Physical therapy: TENS, acupuncture, cryoanalgesia, heat therapy

33. Postop Nausea & vomiting

35. 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

37. Case scenario You are a houseman in an acute hospital

38. 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?

39. 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

40. 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?

41. 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 

42. 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 

43. 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?

44. 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 • 3.     Anaesthetic factors: anasthetic technique, expertise, available resource, ward nurse training

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

46. Options: • Options • opioid - IV PCA • epidural - PCA Pethidine • epidural infusion - LA + fentanyl • Note • anticoagulant and epidural

47. 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?

48. 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

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

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