KEY CONCEPTS IN ACUTE PAIN MANAGEMENT - 2 SURGERY RESIDENTS Nov. 15, 2011

1. KEY CONCEPTS IN ACUTE PAIN MANAGEMENT - 2SURGERY RESIDENTS Nov. 15, 2011 John Penning MD FRCPC Director Acute Pain Service The Ottawa Hospital

2. Objectives • Review the “new” acute pain ladder • When step # 3 on the ladder isn’t working? • Pronociception, glial activation?? • Role of anti-hyperalgesic drugs • Fundamentals of IV PCA • What is an epidural anyway? • Epidural pitfalls for the surgeon • Review principles discussed by case presentation • Opioid tolerance, conversion from IV to PO • When, how to use naloxone • Assessing the hypotensive epidural patient

3. Tramadol Foundational

4. Multi-modal Analgesia Orders • Celecoxib 100 – 200 mg PO Q12H or • Naproxen 250 – 375 mg PO Q8H Available OTC as “Aleve” 220 mg • Acetaminophen 650 mg PO Q4H • Tramadol 25 – 50 – 75 mg PO Q4H prn • Hydromorphone 1 – 2 mg POQ4H prn To supplement Tramadol if required

5. Case Problem:32 yr. Male with multiple ribs # Patient previously healthy, MVA with no other injuries. In Trauma Unit, c/o 9/10 pain. Difficultly breathing due to severe splinting. Analgesic orders are: Hydromorphone 2 – 4 mg PO Q4H prn or 1 – 2 mg SC Q4H prn Nurse just gave 1 mg S/C one hour ago and now won’t give anything for 3 hours! What do you do?

6. Case Problem:32 yr. Male with multiple ribs # Review of PHx reveals no drug use. Patient has received total of 3 mg hydromorphone sc in the 6 hours since admission.

7. Case Problem:32 yr. Male with multiple ribs # Acetaminophen 650 mg PO Q4H W/A Ketorolac 30 mg IV stat followed by 10 mg IV Q4H. Tramadol 50 – 75 mg PO Q4H Hydromorphone 1 – 2 mg s.c. Q2H prn Hydromorphone 0.5 - 1 mg IV Q1H prn

8. Case Problem:32 yr. Male with multiple ribs # • You are at the top of the analgesic ladder and the patient still has inadequate control of acute pain. • With more pain is more opioid always the answer? • NO! Why?? • The problem likely is HYPERALGESIA

9. A New Dawn in Analgesia

10. Scientific American Nov 2009. Pg. 54. Douglas Fields

11. E = MC2

12. Hyperalgesia Pro-nociceptive modulation Nociceptive Stimulus Pain Anti-nociceptive modulation Analgesia

13. Analgesic Drugs that act by Nociceptive Modulation • Pro-antinociceptive • Augments inhibitory modulation of nociception i.e opioids • Anti-pronociceptive • Inhibits the facilitatory modulation of nociception i.e. ketamine, gabapentin and pregabalin New New

15. Grande et al. Anesth and Analg Oct 08

16. NMDA Receptor Antagonists -To prevent or reverse “pathological” acute pain • Ketamine, Dextromethorphan • Ketamine is widely known as a dissociative “general anesthetic” - 3 mg/Kg IV bolus • Ketamine 2.5 - 5.0 mg IV bolus for analgesia in post-op patient - • Ketamine as co-analgesic - combined 0.5:1 with hydromorphone IV PCA. Better analgesia, less S/E • Dextromethorphan 30 mg PO Q8H available OTC as Benylin DM, 3 mg/ml.

17. Case Problem:32 yr. Male with multiple ribs # IV PCA with hydromorphone / ketamine Ketorolac changed to naproxen when eating. 250 mg PO Q8H Or Celecoxib 200 mg PO Q12H for 5 days then 100 mg Q12H until no longer needed.

18. Case Problem:32 yr. Male with multiple ribs # On day three patient is doing well and planning for D/C tomorrow. Convert to PO hydromorphone. Daily IV PCA use is 20 mg per day. Equals about 40 mg per day orally. Order about 50% as long acting. 9 mg HM Contin Q12H and 2 – 4 mg PO Q4H prn.

19. Case Problem:32 yr. Male with multiple ribs # Weaning instructions: As daily “breakthough” hydromorphone requirements decrease, reduce the HM Contin dose by 25% increments. The NSAID or coxib is D/C after the opioids D/C Acetaminophen is last to be D/C

20. Analgesic Drugs that act by Nociceptive Modulation • Anti-pronociceptive • Inhibits the facilitatory modulation of nociception i.e. ketamine, gabapentin and pregabalin, lidocaine New New

22. Pregabalin for acute pain? • Acute pain is “off-label” use • Be cautious of Over-sedation • Sleep deprivation • Elderly • Patient already has significant opioids

23. Pregabalin: The Good, The Bad and the Ugly • The Good • Chronic pain in region of surgery, when pronociceptive mechanisms play a role such as joint arthroplasty, bowel surgery in IBD patients, chronic limb ischemic pain, opioid tolerant patients • The Bad • Mild pain when simple analgesics like acetaminophen, NSAIDs or low dose opioid or tramadol suffice. • The Ugly • Too large a dose in sleep deprived patient already in state of “morphine-failure”

24. Pregabalin dosage • This is NOT a one size fits all. • Drugs binding to receptors have considerable patient to patient variability in dose:response • Alpha-2 delta sub-unit of Voltage-Gated Calcium Channel • 75 mg PO 2 hours pre-op (50 – 150) • 50 mg PO Q8H for 3 to 5 days (25 – 75)

25. The New Challenges in Managing Acute Pain after Surgery and Trauma • The Opioid Tolerant Patient • The greatest change in practice/attitudes in the last 10 years is the now wide spread acceptance of the use of opioids for CHRONIC NON-MALIGNANT PAIN • Renders the “usual” standard “box” orders totally inadequate in these patients • Get a pre-op Anesthesia/APS consult • The Brief Pain Inventory – “BPI”

26. Eipe and Penning 2009

27. Opioid Conversions – total daily ORAL dose equivalents • Tramadol 500 mg • Tapentadol 250 mg • Morphine 100 mg • Oxycodone 50 mg • Hydromorphone 20 mg • Fentanyl patch 25 mcg/hr

28. The surgeon and IV PCA? • Hydromorphone opioid of choice • (0.5 mg/ml) • Less active metabolites than morphine • Better tolerated in renal insufficiency/elderly • Safety? In setting of having both available it is better to be more familiar with HM (substitution errors) i.e. want to avoid giving HM at the morphine dose!

29. The surgeon and IV PCA? • Loading dose required • HM: 0.03 mg/kg, 2 mg in 70 kg • Bolus dose • HM: 0.2 mg (0.1 – 0.4) • Lock-out interval – 6 minutes • Continuous infusion • Not always required: (0 – 0.2 mg/hr) • One hour limit - ( 1.6 mg)

30. Naloxone, a two-edged sword! • Is there a down side to the administration of naloxone, 0.4 mg IV in the post-op patient where opioid induced respiratory depression is suspected? • Severe acute pain, sympathetic response, pulmonary edema, MI, dysrhythmias

31. Case Presentation:Somnolence and hypoxemia while on IV PCA hydromorphone • 65 yr. Female with large ventral hernia repair on IV PCA hydromorphone • PMHx: Angioplasty 9 yr. ago, MI, CHF in past • Moderate COPD, NIDDM • Doing well day 1, but day 2 found to be somewhat confused, somnolent and SaO2 remains in high 80s despite Oxygen by N/P • Is Narcan Indicated? Urgently?

32. Case Presentation:Somnolence and hypoxemia while on IV PCA Hydromorphone • Further patient evaluation • Patient arousable, RR 8-16, pupils slightly constricted, BP 130/70, pulse 90 and reg. • Chest: A/E fair bil. And some mild basilar creps • ABG: pH 7.46 pCO2 50 pO2 55 BiCarb 36 FiO2 > .50 • Chest X-ray: Extensive bilateral, diffuse, interstitial infiltrate consistent with ARDS • Naloxone would probably have had a serious adverse effect on this patient. Hypoxemia despite supplemental O2 in a breathing patient. Look beyond the Opioids!

33. Case Presentation:Somnolence and hypoxemia while on IV PCA Hydromorphone • Management of suspected opioid induced respiratory depression • Support A/W • Simulate breathing • Supply supplemental oxygen • Assess SaO2, BP, Pulse • Naloxone titration, IF INDICATED • 0.04 mg Q5 min. X 3 as needed • Hypoxemia is a medical emergency • Hypercarbia is NOT

34. Opioids Issue With parenteral opioids the patient may experience intolerable side effects before adequate analgesia is attained

35. CONCEPT Targeted regional administration of opioid results in enhancement of the therapeutic index (ratio of analgesia/side effects) Opioids

36. Neuraxial Opioids – the good • Intrathecal morphine • simple technique • potent analgesia for 12 -16 hrs. • highly effective for pain in lower abdomen and lower limbs

37. Neuraxial Opioids – adverse effects • Risk of delayed onset of respiratory depression, peaks at 6 hours • Urinary retention >50% for 16 hours • Pruritus, is not an allergy

39. What is an “EPIDURAL”? • Anatomical • Location of the catheter, C7 – L5 • Cervical, thoracic and lumbar epidurals • Segmental Blockade • Drugs • Opioids(hydrophillic vs. lipophillic) • morphine, hydromorphone, demerol, fentanyl • Hydrophillic drugs migrate rostrally and also yield greater spinal selectivity

40. What is an “EPIDURAL”? • Drugs • Local Anesthetics : • Lidocaine, bupivacaine, ropivacaine Varying concentrations/drug mass produces “Differential Blockade” sympathetics > somatosensory > motor • Adjuncts: epinephrine • Mode of Drug Delivery • Intermittent bolus vs. continuous infusions

41. True or False? • Epidural analgesia impairs the resolution of post-operative ileus i.e. it “slows down the gut” delaying return of normal bowel function.

43. Epidural analgesia and recovery of bowel motililty?? • Thoracic placement of epidural with the administration of local anesthesic and minimal opioid will promote bowelrecovery via sympathetic blockade • If the primary mode of epidural analgesia is via potent opioid, recovery of motility may be delayed.

44. True or False? • Epidural analgesia necessitates a foley catheter until the epidural is removed.

45. What about epidurals and the foley catheter?? • Less Urinary Tract Infection by Earlier Removal of Bladder Catheter in Surgical Patients Receiving Thoracic Epidural Analgesia. Zaouter C, Kaneva P, Carli F (McGill) Regional Anesthesia and Pain Medicine Nov-Dec 2009 pp. 542-552.

46. Epidural Pit-falls for the Surgeon • Epidural hematoma • > 50 reported cases in USA in patients treated with LMWH • Epidural insertion andremoval of the catheter • Risk factors: Elderly, low body weight, twice daily dosing, anti-coagulation vs. prophylactic dose range • The decision to fully anti-coagulate a patient with an epidural in-situ should be made in consultation with anesthesia and thrombosis medicine

47. Epidural Pit-falls for the Surgeon • More epidural hematoma risks!! • Heparin 5000 units s.c. Q8H for thromboprophyllaxis?? This is full clinical anti-coagulation for some patients! • Once daily LMWH at thromboprophyllactic dose is safer.

48. What about anti-platelet agents? • Plavix • ASRA guidelines state no neuraxial anesthesia or epidural catheters implemented until D/C for 7 days – • Plavix may be started 12 – 24 hour after neuraxial block or catheter removal • concensus only, speculative • Obviously risk is much lower than with heparin/coumadin since reports are extremely rare • New agents on horizon??

49. Epidural Pit-falls for the Surgeon • “Masked-Mischief” • The potential high efficacy of the modality could block pain related to complications • Peritonitis; anastomosis dehiscence • Wound infection, wound hematoma • Limb ischemia, compartment syndrome • Delay in appropriate therapy, diagnosis • Neurological problems inappropriately attributed to the epidural i.e. anterior spinal artery syndrome • Hypovolemia

50. The “Hypotensive” Patient with an Epidural 64 yr. female, 48 kg, with no Hx of CVS problems, had an esophagectomy for cancer with combined GA/epidural anesthesia. Later that evening you are called because the patient’s BP is 85/50. Epidural at T5/6 and running hydromorphone 10 µg/ml in 0.1% bupivacaine with epinephrine 2 mcg/ml at 8 ml/hr