Managing Pain (effectively!)

1. Managing Pain (effectively!) Alec Price-Forbes Consultant Rheumatologist December 15th 2010

2. Mrs W • OA, Inflammatory arthritis • April 2010 unwell anaemic, APR raised • July 2010 presumed osteomyelitis right ankle • September 2010 Staph sepsis • Cervical discitis • ? SBE

3. Mrs W • 3/12 IV antibiotics • November 2010 - septic - CCU for inotropes - drowsy • On fentanyl 175mcg/hr • What is PRN dose • What dose of diamorphine would you convert to?

4. Aims • To consider general aspects of pain relief What is pain? • To consider issues around assessing and diagnosing pain • To understand the principles of choosing an analgesic • To understand the use of morphine and appropriate dose calculations

5. What is pain? • How would you describe and define pain? - please share thoughts with your neighbour

6. The background

7. What is pain? • Pain is perceived along a spectrum from peripheral pain receptors to the cerebral cortex and is modified at every step along its travel • Pain is an unpleasant, complex, sensory and emotional experience • Pain is a distressing experience for the patient • Pain is what the patient says it is

8. Reasons Belief that pain is inevitable Inaccurate diagnosis of the cause Lack of understanding of analgesics Unrealistic objectives Infrequent review Insufficient attention to mood and morale Consequences Unnecessary pain Inappropriate Rx Use of inappropriate, insufficient or infrequent analgesics Dissatisfaction with Rx Rejection of Rx by patient Lowered pain threshold Adapted from Twycross Update 1972 Causes of failure to relieve pain

9. Total Pain Spiritual Physical Total Pain Social Psychological Saunders 1964

10. Chronic pain is different…

11. Ms. Unhappy Why can’t you fix my back and fxxk off

12. Ms. Unhappy 33 year old woman, accident at work “lifted something heavy and felt a click at the back” MRI: unremarkable Nociception

13. Ms. Unhappy She felt so bad that she cannot sleep, cannot eat, and became irritable Affect

14. Ms. Unhappy She cannot work, cannot go out, cannot do housework, cannot…. Social

15. Ms. Unhappy She insisted to use a walking aid, visited 4 doctors for the “right diagnosis”, alcohol to “knock me off the pain” Behavior

16. Pain in cancer and non-cancer diseases What % approximates the correct amount of distressing pain in the following conditions? 10%, 30%, 60%, 80% • Cancer • MND/Neurological disease • End-stage cardiac disease • AIDS

17. Acute (eg fracture) Obviously in pain Complains of pain Understands why they have pain Primarily affects patient Chronic (eg neuralgia) May only seem depressed May only complain of discomfort May see pain as never-ending/meaningless Pain overflows to affect others Acute versus chronic pain

18. Definitions • Nociception • Pain threshold versus pain tolerance • Allodynia • Analgesia • Dysasthesia

19. CLASSIFICATION OF PAIN Nociceptive – associated with tissue distortion or injury Caused by tissue damage injury – information carried to the brain via normal nerves

20. CLASSIFICATION OF PAIN Neuropathic – associated with nerve compression or injury The nerves carrying the information to the brain are abnormal and are associated with abnormal sensations Nerve compression Nerve crushing/destruction Nerve being cut

21. Issues in assessing pain • Where is it? • What is it like? • How long has it been present? • How severe is it? • Does it spread anywhere else • How is it affecting functioning? • What are the goals for the pain?

22. Managing Pain • Take a good history and examine the patient • Think about the cause or type of pain • Somatic • Visceral • Neuropathic • Establish patient’s expectations, priorities • Choose appropriate medication • Set realistic goals, negotiate a plan

23. Problems in assessing pain Think about TWO problems that could make it difficult to assess someone’s pain?

24. Common mistakes in pain management • Forgetting there may be more than one pain • Reluctance to prescribe morphine • Failure to explore holistically • Failure to educate patient about dose, timing, side effects and deal with their fears • Reducing the interval instead of increasing the dose

25. Problems in assessing pain • The number of different pains (50% of patients have 3 or more different pains) • Not all pains respond to morphine • Patients underplaying their pain • Patients reacting markedly to their pain (usually anxiety, anger or depression are present) • Staff or partners assessing a patient’s pain • The patient with poor or absent communication

26. Help with assessing pain • Ask the patient highly accurate • Ask the partner subject to bias • Body chart involves patient • VAS some patients stuggle with the concept • Pain diary qualitative research • Pain questionnaire

27. Diagnosing Pain • Bone metastases produce pain worsened with movement • Muscle pain produces pain on active movement • Chest infection causes pain worse on inspiration • Constipation causes pain at rest in the abdomen which is periodic • Neuropathic pain causes an unpleasant sensory change at rest, sometimes with pain on touching

28. Pain behaviours/signs where communication impaired • Expressive: grimacing, clenched teeth, shut eyes, wide open eyes • Adaptive: rubbing or holding area, keeping still, reduced or absent function • Distractive: rocking, pacing, biting, clenched fists • Postural: increased muscle tension, limping • Autonomic: sympathetic, parasympathetic

29. Analgesic Mantra By the Ladder Attention to detail Individualised Treatment By the Mouth By the Clock

30. Types of analgesic Primary • Non-opioids eg paracetamol • Weak opioid agonists eg codeine, DF118 • Strong opioid agonists eg morphine, diamorphine, fentanyl, oxycodone • Opioid partial agonist/antagonists eg buprenorphine • NSAIDs • NMDA antagonists eg ketamine, methadone • Nitrous oxide

31. Types of analgesic Secondary analgesics • Adrenergic pathway modifiers eg clonidine • Antibiotics • Anticonvulsants eg CMZ, gabapentin • Antidepressants eg amitriptyline • Antispasmodics eg hyoscine • Antispastics eg Baclofen • Corticosteroids • Membrane stabilising drugs eg flecanide, lidocaine • NSAIDs

32. WHO Pain Ladder Consider nerve block

33. WHO Analgesic staircase • Use non-opioids, weak opioids and strong opioids as the 3 steps • However, not all pain opioid responsive (eg colic, neuropathic pain) • Consider adjuvants for each patient • Different pains need different analgesics

34. Opioids • Agonists at opioid receptors (mu, kappa, delta) in spinal cord and brain • Differences between opioids relate to differences in receptor affinity • Morphine is the strong opioid of choice- cost, effectiveness, no ceiling effect

35. Morphine given Orally Regularly Prevents pain Haloperidol treats nausea Injections are unnecessary No addiction is seen and Early use is best Morphine is still the gold standard opioid: It has more evidence for its use and safety No evidence that other opioids are better 30 years use Wide safety margin Well tolerated in most people Opioid choice

36. Starting Opioids • What concerns might patients have about starting morphine?

37. Dependence and Addiction • Dependence- state in which an abstinence syndrome may occur following abrupt opioid withdrawal or administration of opioid antagonist. • Addiction - characterised by psychological dependence

38. Morphine dose timing • For continuous pain analgesia should be continuous • Regular administration should enable good pain control and prevent it returning • Do not rely on PRN PRN = ‘PAIN RELIEF NIL’

39. Indications for injections • Inability to tolerate other routes (eg nausea and vomiting) But NOT because of poor pain control: • Giving injections means need less drug to have same effect • But it cannot be more effective because it’s the same drug

40. Metabolism • Morphine is absorbed from small bowel, metabolised in liver to active metabolite (morphine 6-glucuronide, M6G) which is renally excreted • Liver impairment has little effect; kidney impairment does affect handling • Other metabolites (eg M3G) also renally excreted and can accumulate

41. Strong Opioids • Immediate release (peak concentration after 1h, duration of action 1-4 hours) • Oramorph, Sevredol, OxyNorm • Modified release (peak concentration after 2-6 hours, duration 12-24h depending on formulation) • MST, MXL, Oxycontin

42. Starting morphine (5mg – 10mg) 4hrly + 30mins prn (& laxative) (2.5 mg 4hrly if previously on non-opioid) 4hrly dose plus prn dose over 24hrs=TDD (total daily dose) TDD/2= 12 hourly (bd) dose TDD/6= prn dose

43. Calculate breakthrough dose for MST 30mg bd MST 60mg bd MST 120 mg bd MST 1500 mg bd MST 3000 mg bd

44. Dose titration 12 hourly dose & total prn use= new TDD New TDD/2= new 12 hourly dose New TDD/6= new prn dose

45. Calculate new MST dose and breakthrough dose for MST 10mg bd and 4 doses of oramorph 2.5 mg MST 120 mg bd and 2 doses of oramorph 40mg MST 600 mg and 6 doses of oramorph 200mg

46. Changing the route of administration po morphine > sc morphine po morphine > sc diamorphine po morphine > sc oxycodone po oxycodone > sc oxycodone 1/2 1/3 1/4 1/2

47. STRONG OPIOIDS Morphine – global strong oral opioid of choice Morphine – s/c if unable to take oral morphine. (When changing to Morphine (s/c) from morphine (oral) give 1/2 of the PO morphine dose) Fentanyl – transdermal patch or sublingual

48. Alternative Strong Opioids

49. Alternative OpioidsFentanyl Patches • Adhesive patch delivering a constant amount of fentanyl per unit time: e.g. 25 micrograms/hour • Less constipation, sedation and nausea • Preferable in serious renal impairment • Change every 72 hours • Takes up to 24 hours to start or stop acting • For controlled pain • Need to supply breakthrough morphine or oxycodone

50. Equivalent doses of fentanyl