Tips for Managing Acute Pain

Transcription

1 Tips for Managing Acute Pain Daniel Johnson, MD, FAAHPM Kaiser Permanente University of Colorado Session Outline 1. Pseudoaddiction 2. Opioid Selection 3. PCA Titration 4. Co-Analgesics 5. Breakthrough Dosing Pain Management: Meet Mr. J a 69 y/o retired engineer with CAD, HTN, BPH, and spinal stenosis who is admitted with severe back pain Agitated, sweating, markedly uncomfortable Claims to have lost prescription Records show: Hasn t seen PCP in 9 months Taking oxycodone for 3 yrs, chronic back pain Frequent opioid refills, most recent 1 wk ago Drug seeking addict?

2 Misunderstanding Addiction Addiction is common, BUT un- or undertreated pain is even more common Addiction feared and misunderstood by patients, families and professionals Fears can lead to delays in diagnosis and optimal pain control Learn how to recognize and talk about addiction and related terms Fast Facts, EPERC ( Addiction Dependence or Tolerance Features of addiction: Psychological dependence w/ compulsive drug seeking Using drugs for reasons other than pain Continued use of drugs despite known harm Social consequences and negative life effects Physical dependence: Abrupt stoppage withdrawal symptoms If wean: reduce dose by 50% every 2-3 days Tolerance: reduced analgesic effect of a given dose with time (usually months) From End-of-Life Education Resource Center (EPERC, Pseudoaddiction What I found helpful was lying to the doctor. All the time. Instead of since 4:00, it was since yesterday that the pain increased. And then I would get results. KEY CONCEPT: Pseudoaddiction = drug-seeking behaviors resulting from un- or under-treated pain Kimberlin et al. J Pain Symptom Manage, 2004

3 When Pain and Substance Abuse Coexist Recognize both diagnoses! Address each, independent of one another Example: a patient taking methadone for chronic pain who abuses crack cocaine Analogy: a clinician would not withdraw insulin therapy if a diabetic patient fails to adhere to anti-hypertensive medications Very challenging! Basu et al. J Sub Abuse Treat, Vogl D et al. J Pain Symptom Management, Back to Mr. J Assessment reveals worsening back pain x months, excruciating in last 2 w, now 11/10 Patient avoiding MD visits don t like doctors Typical 4 tabs oxycodone/ day not helping Weight loss (30 lb in 6 m), oral intake x wks Spine MRI: T12 mass, fracture, no compression Labs: Cr. 2.3 (base 1.1), PSA 22, normal LFTs Admitted for pain PCA, CA work-up PCA drug and orders? Starting Opioids: WHO 3-Step Ladder 3 Severe 1 Mild ASA Acetaminophen NSAIDs ± Adjuvants 2 Moderate A/Codeine A/Hydrocodone A/Oxycodone Tramadol ± Adjuvants Morphine Hydromorphone Methadone Fentanyl Oxycodone ± Adjuvants

4 Don t Choose the Wrong Opioid KEY CONCEPT: Avoid morphine in patients with a GFR < 30 Due to drug and active metabolites Fentanyl and hydromorphone better, but suggest reducing doses for all opioids Methadone OK 90% cleared fecally Other cautions: Morphine safe in liver dz, but T1/2 doubled Don t use meperidine or propoxyphene! Codeine: 10% persons cannot activate Davis et al. Drugs Aging, 2003 Patient Controlled Analgesia (PCA) Rapid pain control for appropriate patients Most commonly morphine or hydromorphine, but also fentanyl and methadone PCA settings: Basal: set based on chronic outpatient dose, often no basal rate if not on chronic opioids Demand dose: typically % of basal rate Lockout: 8-10 minutes (time to peak effect) Nurse bolus: additional breakthrough Weissman, David. Fast Fact #72, End-of-Life Physicians Education Resources Center Back to Mr. J Fluids started to treat dehydration, ARF Hydromorphome PCA started No initial basal rate, demand = 0.5 mg, lockout = 10 m (+ RN bolus Q30 m prn) After 45 minutes: pain still at 9/10 despite four demand (0.5/ dose) + 2 mg bolus Total dose (ER + PCA) over 4 hrs = 7 mg Next adjustments to PCA?

5 Principles Guiding Titration Titration interval = peak effect time Peak effect IV: 8-12 minutes Peak effect PO: minutes Adjust long-acting PO agents no more than every 24 hrs; fentanyl patch Q3 d When titrating doses: Mild to moderate pain: 25-50% Moderate to severe pain: % Davis et al. Drugs Aging, 2003; Fast Facts, EPERC ( Beware: Too Rapid Basal Increases KEY CONCEPT: Avoid changing a PCA basal rate more often than every 6-8 hrs TIPS for PCA adjustments: Titrate DEMAND dose initially to achieve relief Change basal rate no > than every 8 hrs (typical minimum time to steady state for opioid infusion) Be prepared to adjust basal as crises wanes Recognize that adjustments to basal rate assume dose needed now AND in the future Weissman, David. Fast Fact #72, End-of-Life Physicians Education Resources Center Dynamic Nature of Pain Crises 10 Crisis Pain Level 5? Basal or long-acting Time

6 Back to Mr. J Demand dose increased to 1 mg Relief over next 2 hours w/ regular dosing then decreased use in subsequent hours Basal rate adjusted at 12 hours based on use over preceding 2 hours Work-up reveal Stage IV prostate CA Mets at T12, probable femur, lung nodule Oncologist recommends Tx: Leuprolide (Lupron) and bicalutamide (Casodex) Co-Analgesics or therapies? Co-Analgesics for Bone Pain KEY CONCEPT: First-line co-analgesics for bone pain are NSAIDs, steroids, bisphosphonates and radiotherapy NSAIDs: increased risk in elderly Steroids: dexamethasone 4 mg PO QD/BID Bisphosphonates: multiple myeloma, breast CA and other solid tumors External beam radiation: helpful for most malignant bone pain, single fraction option Radioisotopes: useful for widespread mets Bisphosphonates for Bone Mets Inhibits osteoclast activity Breast CA and MM > lung, GI, prostate CAs Options: pamidronate 90mg IV over 2 hours or Zoledronic acid 4 mg IV over 15 minutes Most patients (50-70%) achieve a 30% reduction in pain within one week Mean duration pain relief = 12 weeks If no 1 week, can re-treat Contraindicated in acute renal failure Fast Facts, EPERC (

7 Radiation for Bone Mets External Beam (XRT) or radionuclide therapy: 1. XRT pain relief in over 75% of patients Relief may begin after first few treatments Peak relief four wks post-therapy Single fraction XRT recommended for palliation 2. Radionuclide therapy (e.g., Strontium, Samarium) Indicated for multiple sites (often breast, prostate) Peak analgesic effect: 3-6 weeks post-therapy May see transient pain flare (Tx: dexamethasone) Dy SM et al. J Clin Oncol, Hird A. et al. Clinical Oncology, Co-Analgesics for Neuropathic Pain Best studied: diabetic peripheral neuropathy, postherpetic neuralgia, trigeminal neuralgia First line drugs: TCAs and gabapentin Other common agents: Lidocaine patches, pregabalin, duloxetine Opioids: decrease neuropathic pain with quicker onset than most other agents Gilron IC, CMAJ, Sindrup SH, Jensen TS. Pain Wiffen PJ. Cochrane Database Syst Rev Rowbotham MC et al. Pain Saarto T. Number Needed to Treat (NNT)* DRUG INITIAL DOSE DPN NNT PHN TRIAL PERIOD TCA mg QHS wks Gabapentin mg QHS wks Opioids Variable wk Tramadol 25 mg BID/TID wk Pregabalin 75 mg BID wk Duloxetine 20 mg QD 5-6 N/A 1-2 wks Lidocaine 1 Patch Q12 N/A wks * NNT for one patient to have moderate pain relief

8 Cochrane Review: Antidepressants for Neuropathic Pain (2010) Review of 61 RCTs of 31 antidepressants TCAs and venlafaxine effective and have a number needed to treat (NNT) of ~ 3. SSRIs may be effective, but insufficient numbers to calculate robust NNTs. Lacking data: St. John s Wort, L-Tryptophan Not yet clear whether antidepressants can prevent the development of neuropathic pain Saarto T et al. J Neurol Neurosurg Psychiatry, Other Drugs for Neuropathic Pain Carbamazepine: trigeminal neuralgia Other anti-seizure drugs (examples): phenytoin, valproic acid, levetiracetam (Keppra), topiramate (Topomax), lamotrigine (Lamictal) NMDA antagonists: ketamine, methadone (?) Others: Capsaicin, baclofen, clonidine IV lidocaine and mexiletine: hospice Gilron IC et al. CMAJ, Guay DR. Am J Ger Pharm, 2003.Argoff CE et al. J Pain Symptom Mng, Back to Mr. J Pain controlled on hydromorphone 0.4 mg/h Single fraction radiation to T12, dex 8 mg QD Plan for discharge to home in next 24 hr Plan: convert to oral regimen (Cr at baseline (1.1), NKDA) Recommendations? (Hint In addition to a dexamethasone taper, Mr. J will need 3 prescriptions)

9 Converting Opioids 1) Calculate total 24 hr dose of IV opioid 2) Convert to equivalent 24 hr oral dose of desired opioid 3) Adjust for incomplete cross-tolerance (if applicable): reduce dose by 1/3 4) Divide dose based on duration of action (i.e. MS Contin = split dose BID) Common Conversion Pitfalls 1. Misreading conversion charts 2. Math mistakes don t go it alone! 3. Incomplete cross-tolerance Variability in tolerance (receptor specificity) when switching amongst opioids Reduce dose by 33% where appropriate: Prior stable dose new drug High dose conversions Might ignore correction in uncontrolled pain Back to Mr. J 1) Total 24 hr dose = 0.4 mg/hr x 24 hrs = 9.6 mg/d IV hydromorphone 2) Conversion ratio = 20:1 (20 mg oral MSO4 = 1 mg IV hydromorphone). Therefore: 9.6 mg/day IV x 20 = 192 mg/ day oral MSO4 3) Adjust for incomplete cross-tolerance (reduce dose by 1/3): 2/3 x 192 = 128 mg/d oral MSO4 4) Morphine LA (e.g., MSContin) dosed twice/ day. Therefore: MSContin 60 mg PO BID

10 Breakthrough Dosing KEY CONCEPT: Appropriate breakthrough dosing = 10% of total 24 hr given every 2 hours as needed for pain Common error: dose too small, too infrequent Guidelines: Breakthrough dose = 10% of total 24-hr dose Interval: (w/ normal liver/kidney, compliant): dose Q2 hrs prn based on time to peak effect (60-90 m) Inform patients to call with > 2 repeated doses For Mr. J: 10% of 120 mg/day = 12 mg MSO4 Sig: MSIR 15 mg tabs, 1 tab PO Q2 hr prn Don t Mismanage the Bowels! NO tolerance to constipation with time Docusate (Colace) is not enough! Fiber may worsen opioid constipation Use stimulants and titrate to QD or QOD bowel movement: Senna: 1-2 tabs PO QD/BID Biscodyl (Dulcolax): 5-10 mg PO QD Methylnaltrexone: refractory constipation Fast Facts, EPERC ( Questions and Comments