Principles of Acute Pain Management

1. Principles of Acute Pain Management 29.9.10 Rik Kapila

2. What this talk isn’t…. • A pharmacology lecture • A physiology lecture • Comprehensive

3. What this talk is ( I hope!)…. • An overview • Relevant • Enlightening • Interesting • An opportunity

4. What is pain? • “An unpleasant sensory and emotional experience arising from actual or potential tissue damage or described in terms of such damage”. International Association for the Study of Pain

5. Perhaps more usefully… • “whatever the experiencing person says it is, existing whenever he says it does." Margo McCaffrey 1968

6. Epictetus (55-135 A.D) • ‘It is not death or pain that is to be dreaded but the fear of pain or death’

7. Lance Armstrong (1971- present) • ‘pain is temporary – quitting lasts forever’

8. Saint Augustine of Hippo (354-430) • ‘the greatest evil is physical pain’

9. Does pain matter?

10. Cardiovascular • Tachycardia • Hypertension • Increased myocardial oxygen consumption • Myocardial ischaemia

11. Respiratory • Decreased lung volume • Atelectasis • Decreased cough • Sputum retention • Infection • Hypoxia

12. Gastrointestinal • Decreased gastric motility • Decreased bowel motility • Ileus

13. Genitourinary • Urinary retention

14. Metabolic • Increased catabolic hormones • Cortisol • Glucagon • Growth hormone • Reduced anabolic hormones • Insulin • Testosterone

15. Psychological • Anxiety • Fear • Sleep disturbance • Depression • Distressing for patient, family and staff

16. Chronic Pain after Surgery • Not fully understood • Worse after some surgery than others • Aggressive acute management may reduce incidence of chronic problems • But more of that later….

17. This is why pain matters

18. Endogenous morphine • 1975 endorphin • enkephalin • Dynorphin • synthesised in pituitary • Receptors in the • peri-aqueductal gray matter

19. Endogenous morphine • Responsible for “hedonistic tone” • Increase descending inhibition in spinal cord • Increased release in: • happiness • touch / massage • sex • exercise • hypnosis / relaxation • placebo effect -anticipation of the above

20. Endogenous morphine • Increased release in: • happiness • Increase descending inhibition in spinal cord • touch / massage • sex • exercise • hypnosis / relaxation • placebo effect -anticipation of the above • Reversed by naloxone

21. How does this link in with the anatomy? • On the way up… • Aδ - fast - instant reaction • C - slow - throbbing after-pains / chronic pain • Aβ - non-pain but inhibit Aδ and C when stimulated • Rubbing / massage / TENS • Local anaesthetics - block • NSAIDS and ketamine - modulate • Pain to cortex via spino-thalamic tract

22. How does this link in with the anatomy? • In the central processor… • Augment the endorphin system • placebo • opioids • Psychological • Self-hypnosis / relaxation

23. How does this link in with the anatomy? • On the way down… • Noradrenergic pathways - inhibitory • adrenaline in spinals? • Serotonin pathways - facilitate • Block with ondansetron!

25. How can we manage pain? • Multimodal • Multi disciplinary

26. Analgesic ladder • WHO • Simple analgesics first • Moderate opioids next • Strong opioids last

27. Paracetamol • Is fantastic!

28. Paracetamol • Paracetamol in acute postoperative pain • Clinical bottom line • Paracetamol is an effective analgesic. • A single dose of 1000 mg paracetamol had an NNT of 3.8 (3.4-4.4) for at least 50% pain relief over 4-6 hours in patients with moderate or severe pain compared with placebo based on information from 2,759 patients. • Paracetamol is not associated with increased adverse effects in single dose administration.

29. NSAIDS • Non-selective eg. Diclofenac, ibuprofen • Selective eg. Parecoxib, celecoxib

30. Good Part of multimodal analgesia Bone pain Opioid sparing Bad Gastric Renal Asthma Bleeding GRAB NSAIDS

31. Codeine • Oral codeine in acute postoperative pain • Clinical bottom line: • Codeine 60 mg orally is not an effective analgesic for postoperative pain. • A 60 mg oral dose of codeine had an NNT of 16.7 (11-48) for at least 50% pain relief over 4 to 6 hours compared with placebo in pain of moderate to severe intensity.

32. Tramadol • Oral tramadol in postoperative pain • Clinical bottom line: Tramadol is an effective analgesic in postoperative pain. A single 100 mg oral dose of tramadol is equivalent to 1000 mg paracetamol. A dose of 100 mg had an NNT of 4.6 (3.6-6.4) for at least 50% pain relief over 4-6 hours in patients with moderate to severe pain compared with placebo. • At doses of 50 and 100 mg incidence of adverse effects (headache, nausea, vomiting, dizziness, somnolence) was similar to comparator drugs. In dental trials there was increased incidence of vomiting, nausea, dizziness and somnolence.

33. Morphine • The standard against which others are measured • Effective • May have side effects • Cheap

34. Oxycodone • Synthetic opioid • Developed in 1916 in Germany

35. Why use oxycodone? • Subjectively • Better tolerated • Feel less ‘weird’ • Objectively • Less hallucinations

36. Lets use it all the time! • Expensive • MST 20mg 18p • Oxycontin 10mg 47p • Better but not perfect • Still have side effects • Second line to morphine in cancer pain • Br J Cancer 84(5);587-593

37. MST (regular) Oral morphine solution (prn) 20mg orally Oxycodone MR (reg) Oxycontin Oxycodone IR (prn) Oxynorm 10mg orally Morphine – Oxycodone relationship

38. How do regular and PRN work together • Regular Px? • Having lots of prn? • Is the prn dose enough? • Increase the regular dose

39. Opioid problems • Respiratory depression • Sedation • Constipation • Nausea and vomiting • Ileus • Urinary retention • Etc, etc, etc…..

40. Nausea and vomiting • All of them can cause it • Morphine is especially good at it • Changing analgesic may help • If someone is vomiting give the antiemetics intravenously!

41. Itching • Opioids can cause itching • Especially with neuraxial administration • Difficult to treat • Ondansetron can help • Low dose naloxone can help • Chlorpheniramine less so

42. City Campus Single nurse administration Used lots and lots Predictable Oral opioid of choice Queens Campus 2 nurses needed Used much less Alternatives used instead Sevredol, tramadol, DHC Oramorph

43. Why? • I have absolutely no idea!

44. Abuse and addiction • Its is a potential problem • Don’t let that stop you treating pain

45. Routes of administration • Oral • Subcut • Intramuscular • Intravenous • Transdermal • Epidural • Intrathecal

46. Local Anaesthetics • Lots of uses • But you may see them cropping up in the following places:

47. Epidurals • Used in surgical patients • The significance of the little girl?

48. Spinals • Intra and post op analgesia • Can have opiate added to them • Need to watch for respiratory depression • Should have PCA obs even if they don’t have a PCA

49. But it still hurts…..

50. Take a critical look at the drug card • What have they got? • Regular or PRN? • How much? • How often? • Are they actually taking it? • Is the route appropriate?