Pain Management Dilemmas. Five Pain Dilemmas. Barriers: Meet Loretta. Daniel Johnson, MD, FAAHPM

Transcription

1 Pain Management Dilemmas Daniel Johnson, MD, FAAHPM Kaiser Permanente University of Colorado Five Pain Dilemmas 1. Barriers to Pain Management 2. Selecting and Titrating Opioids 3. Managing PCAs 4. Using Co-Analgesics 5. Converting Opioids Barriers: Meet Loretta a 52 y/o mother with scleroderma and painful (10/10) contractures Treatments include: steroids, fentanyl patch (50 mcg/hr), oxycodone/apap, and baclofen Distant history of alcohol use (none x 10 yrs) No sleep x 2 days. Plan: admit, PCA HD #1: patient reluctant to use PCA Sister: I m afraid she s been lying about her pills. Patient: I m worried am I becoming an addict?

2 Pain Management Dilemma #1 What is addiction? What are strategies to overcome patients, families and providers fears of addiction? 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. Kimberlin et al. J Pain Symptom Manage, 2004

3 Back to Loretta Inquiry: What does that mean to you? Patient fears: Worried about the worsening pain (am I dying?) Anxious that the drug might stop working Family fears: She will become hooked on drugs, a zombie Shared story of the patient s junkie uncle Process led to reassurances, lower initial dose, adjuvant agents, sedation management, and frequent check-ins Selecting Opioids: Meet Ms. T a 74 y/o grandmother w/ breast CA, osteoporosis, anorexia admitted with severe back pain At home: 2 tabs/d oxycodone/ APAP (5/325) + ibuprofen at home, POs x 2 days ED: Dx = fracture, 2 mg + 4 mg IV MSO4 Ward: 4 mg IV x 3 over 8 hrs, some relief Morphine LA PO 15 mg started at 12 hrs Evening: agitated delirium, workup ensues Pain Management Dilemma #2 What principles guide opioid selection and titration for acute pain?

4 WHO 3-step Ladder 1 Mild ASA Acetaminophen NSAIDs ± Adjuvants 2 Moderate A/Codeine A/Hydrocodone A/Oxycodone Tramadol ± Adjuvants 3 Severe Morphine Hydromorphone Methadone Fentanyl Oxycodone ± Adjuvants Don t Choose the Wrong Opioid Renal failure: avoid morphine, codeine Due to drug and active metabolites Fentanyl and hydromorphone better, but suggest reducing doses for all opioids Methadone cleared through fecal waste 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; Fast Facts, EPERC ( Principles Guiding Titration Titration interval = peak effect time Peak effect IV: 8-12 minutes Peak effect PO: minutes If no relief, then safe to provide more Effects prolonged in renal disease WHO titration guidelines: Mild to moderate pain: 25-50% Moderate to severe pain: %

5 Back to Ms. T Workup reveals likely delirium etiology = morphine toxicity in context of ARF (Cr=1.8) Morphine initially held, IV hydration Bone scan indicates new metastasis (but no evidence for cord compression on MRI) Radiation therapy and bisphosphonate Oxycodone 5 mg TID started day 3 (Cr=0.7) Patient leaves with low dose opioid and minimal pain on day 4 Managing PCAs: Mr. Lee a 64 y/o manager of a dry cleaning store with DM, CAP with pleural effusions and an empyema S/p chest tube placement, severe pain Morphine PCA started: 0.5 mg/hr basal, 1 mg demand dose, 10 minute lockout After 1 hour: patient has used additional five demand doses + one-time bolus of 5 mg Pain remains at 8 to 9/10, mostly constant Nurse inquires: new orders for PCA? Pain Management Dilemma #3 What principles guide the adjustment of PCA parameters to achieve safe and effective pain relief?

6 Dynamic Nature of Pain Crises 10 Pain Level 5 Time PCA Management Tips PCA settings: Basal: set based on chronic outpatient dose Demand dose: typically % of basal rate Lockout: 8-10 minutes (time to peak effect) Concentration Cmax Tmax ~ 8-12 min ~ min Time Weissman, David. Fast Fact #72, End-of-Life Physicians Education Resources Center Beware: Too Rapid Basal Increases Repeated early adjustments in basal rate may result in overshooting relief Steady state: typically no sooner than 6-8 h Consider the time course of the pain crises; adjust basal based on course and demand Tips for PCA adjustments: Titrate DEMAND dose initially to achieve relief Change basal rate no > than every 8 hrs Be prepared to adjust basal as crises wanes Weissman, David. Fast Fact #72, End-of-Life Physicians Education Resources Center

7 Back to Mr. Lee Additional 5 mg bolus x % increase in PCA demand dose (2mg) Use of demand dosing over next 3 hours due to relief (4/10) and mild sedation At 10 hours, basal = 0.5 mg, demand = 2 mg (using ~ 1 push each hour), improved Basal increased to 1.0 mg, good relief with rare demand doses by 24 hrs Chest tube removed at day 3, rapid wean Co-Analgesics: Ms. K an 87 y/o church choir director who develops unrelenting chest wall pain due to post-herpetic neuralgia Requires hospital admission: anorexia, frailty, insomnia and FFT x 3 days Pain: burning, constant (7/10) w/ flairs (10/10) Just make it end ; on sertraline 100 mg Hydrocodone/APAP (5/325) 6-8 tabs/d providing minimal relief Pain Management Dilemma #4 What pharmacologic agents are most effective for neuropathic pain?

8 Co-Analgesics for Neuropathic Pain Best studied: diabetic peripheral neuropathy, postherpetic neuralgia, trigeminal neuralgia First line: TCAs and gabapentin Other prominent 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 NNT DPN 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 Other Drugs for Neuropathic Pain Carbamazepine: trigeminal neuralgia SNRIs: Venlafaxine (not SSRIs) 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, 2004.

9 Back to Ms. K Hydromorphone PCA started (demand only) Lidocaine patch Q12 hrs Gabapentin 100 mg QHS well-tolerated; to 300 mg QHS by day 3 Sertraline continued (due to preference, $$) Discharged from hospital at day 3, pain and sleep much improved, participating in PT Able to wean to low dose opioids by 3 wks Opioid Conversions: Mr. J a 76 y/o retired engineer with CAD, HTN, and a chronic infected hip who is admitted with severe pain Prior oxycodone/apap 5/325 mg (180 tabs/m) Debridement, hydromorphone for severe pain Final basal rate: 0.6 mg/hr IV hydromorphone Pain well controlled with rare demand dose Goal: home with oral morphine regimen (longacting and breakthrough regimen) Pain Management Dilemma #5 What are key steps when converting amongst opioids?

10 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 May ignore correction in uncontrolled pain Back to Mr. J 1) Total 24 hr dose = 0.6 mg/hr x 24 hrs = 14.4 mg/d IV hydromorphone 2) Conversion ratio = 20:1 (20 mg oral MSO4 = 1 mg IV hydromorphone). Therefore: 14.4 mg/day IV x 20 = 288 mg/ day oral MSO4 3) Adjust for incomplete cross-tolerance (reduce dose by 1/3): 2/3 x 288 = 192 mg/d oral MSO4 4) Morphine LA (e.g., MSContin) dosed twice/ day. Therefore: MSContin 100 mg PO BID

11 Breakthrough Dosing Providers often give too small a dose at too large a time interval (e.g., Q4-6 hr) Guidelines: Breakthrough dose =10% of total 24-hour dose Interval: (normal liver/kidney, compliant): dose Q2 hrs prn based on time to peak effect (60-90 m) Inform patients to call with > 2 doses For Mr. J: 10% of 200 mg/day = 20 mg MSO4 Dose as Roxanol (20 mg/cc), 1 cc Q2 hrs prn or MSIR 15 mg tabs, 1 tab PO Q2 hrs prn Questions and Comments