Chronic pain

Background

  • Chronic pain is defined as pain lasting >3 months or beyond expected tissue healing time[1]
  • Affects approximately 50 million US adults; ~20 million experience "high-impact" chronic pain that limits daily activities[1]
  • Pain is the chief complaint in up to 70% of all ED visits[2]
  • Subacute pain (1-3 months) represents a critical window for prevention of chronification
  • Emergency physicians are not the primary drivers of chronic opioid prescriptions, but ED visits represent an important touchpoint for intervention[3]
  • 1-5% of opioid-naive patients prescribed opioids in the ED may develop prolonged use[3]

Classification

Common Chronic Pain Presentations

Evaluation

  • Rule out dangerous etiologies masquerading as chronic pain exacerbations (the primary role of the EP)
  • Identify new or worsening pathology requiring urgent intervention
  • Assess functional status and current treatment regimen
  • Screen for opioid use disorder and substance misuse

History

  • Onset, character, location, radiation, severity, aggravating/alleviating factors
  • Prior workup and diagnoses
  • Current pain management regimen — ask specifically about:
    • Prescribed medications (opioids, gabapentinoids, muscle relaxants, antidepressants)
    • OTC medications (acetaminophen, NSAIDs)
    • Non-prescribed substances (kratom, tianeptine, cannabis, illicit opioids)
    • Non-pharmacologic treatments (PT, injections, neurostimulation)
  • Functional impact: work, sleep, ADLs
  • History of substance use disorder
  • Who manages their pain (PCP, pain specialist)

Red Flags

Workup

  • Imaging and labs should be guided by clinical concern for acute pathology, NOT routinely obtained for chronic pain exacerbations
  • Check PDMP (Prescription Drug Monitoring Program) — recommended before prescribing opioids[1]
  • Consider EKG if on QT-prolonging medications (methadone, certain antidepressants)

Management

  • Set realistic expectations — the goal is improved function and symptom management, not elimination of pain
  • Use multimodal analgesia whenever possible
  • Non-opioid therapies are preferred for chronic pain exacerbations in the ED[3]
  • Do not routinely prescribe opioids to treat an acute exacerbation of non-cancer chronic pain for patients discharged from the ED (ACEP Level C recommendation)[3]
  • Do not abruptly discontinue or taper a patient's home chronic opioid regimen from the ED
  • Do not co-prescribe opioids + benzodiazepines for pain (ACEP consensus recommendation)[3]

Non-Pharmacologic Therapies

  • Heat/ice application
  • Positioning and splinting
  • Referral to physical therapy
  • Brief counseling on activity modification and self-management strategies

Pharmacologic Therapies — Non-Opioid (First Line)

Acetaminophen

  • 1000 mg PO/IV q6-8h (max 3-4 g/day; 2 g/day if hepatic impairment or chronic alcohol use)
  • Safe and effective for many pain types; often underutilized
  • IV formulation available but costly; PO equivalent in efficacy for most indications

NSAIDs

  • Ibuprofen 400-800 mg PO q6-8h
  • Ketorolac 15-30 mg IV/IM (not to exceed 5 days total course; avoid in renal disease, GI bleed risk, elderly, pregnancy)
  • Naproxen 250-500 mg PO q12h
  • Avoid in CKD, GI bleed risk, CHF, third trimester pregnancy
  • Effective for MSK pain, renal colic, headache

Ketamine (Subdissociative Dose)

  • IV: 0.1-0.3 mg/kg over 15 minutes[4]
    • Lower end (0.1 mg/kg) preferred in elderly and obese patients
    • Short infusion over 15 min reduces psychoperceptual side effects vs. IV push
  • Intranasal: 0.5-1 mg/kg via atomizer
  • Nebulized: 0.75 mg/kg via breath-actuated nebulizer[5]
  • Continuous infusion: 0.15-0.2 mg/kg/hr, titrated q30 min[4]
  • Particularly useful in opioid-tolerant patients, central sensitization, and as opioid-sparing adjunct
  • Common side effects: dizziness, nausea, feeling of unreality (transient, typically <30 min)
  • Avoid in patients with active psychosis; safe in controlled hypertension and elevated ICP (previously disproven concern)
  • No respiratory monitoring required at subdissociative doses

Gabapentinoids

  • Useful for neuropathic pain
  • Generally best initiated by PCP/pain specialist rather than ED
  • Use caution when combined with opioids (risk of respiratory depression)

Lidocaine

  • IV lidocaine: 1-1.5 mg/kg over 10-15 min — mixed evidence; may consider for refractory pain
  • Topical lidocaine patches for localized MSK or neuropathic pain

Muscle Relaxants

  • Cyclobenzaprine 5-10 mg PO — for acute MSK spasm
  • Methocarbamol 750-1500 mg PO — less sedating alternative
  • Baclofen — avoid initiating from ED (complex dosing, withdrawal risk)
  • Avoid carisoprodol (high abuse potential)
  • Avoid co-prescribing with opioids or benzodiazepines

Trigger Point Injections

  • Effective for myofascial pain with identifiable trigger points
  • Use lidocaine or bupivacaine ± small volume of corticosteroid
  • Can be performed in the ED for low back pain, neck pain, and shoulder girdle pain

Opioids

  • Acute exacerbation of cancer-related pain
  • Sickle cell vaso-occlusive crisis (disease-specific protocols apply)
  • Severe acute-on-chronic pain after non-opioid therapies have been maximized or are contraindicated
  • Short-term bridge while awaiting definitive intervention (e.g., surgical repair)
  • If prescribing opioids
    • Use immediate-release formulations only (never initiate ER/LA from the ED)[1]
    • Prescribe the lowest effective dose for the shortest feasible duration (≤3-7 days)[1]
    • Check the PDMP before prescribing[1]
    • Avoid co-prescribing with benzodiazepines or other sedative-hypnotics[3]
    • Counsel on risks, safe storage, and disposal
    • Consider co-prescribing naloxone if risk factors for overdose are present[1]

Special Population: Patients on Buprenorphine/Methadone Maintenance

  • Do NOT discontinue buprenorphine or methadone in the setting of acute pain[6]
  • The maintenance dose does NOT provide adequate analgesia (analgesic duration 4-8 hours vs. withdrawal suppression 24-48 hours)[6]
  • These patients are opioid-tolerant and may require higher than typical doses of short-acting full-agonist opioids for acute pain[6]
  • Multimodal analgesia is essential: maximize NSAIDs, acetaminophen, ketamine, nerve blocks
  • For patients on buprenorphine:
    • Continue home buprenorphine dose
    • Can administer additional full-agonist opioids on top (buprenorphine's "ceiling effect" is for euphoria/respiratory depression, NOT for blocking analgesia from added full agonists in most clinical scenarios)
    • Consider splitting buprenorphine into q8h dosing for added analgesic benefit
  • For patients on methadone:
    • Verify dose with the methadone clinic
    • Continue home dose; add short-acting opioids PRN for acute pain
    • Think of methadone as "basal insulin" — patients still need "bolus" analgesia for acute pain
  • Consult addiction medicine if available; notify outpatient provider of ED visit and any medication changes

Special Population: Patients on Naltrexone

  • Oral naltrexone: effective opioid blockade for 24-72 hours
  • Extended-release injectable naltrexone (Vivitrol): blockade for up to 30 days
  • Opioids will have reduced or absent analgesic effect while naltrexone is active
  • Management strategy: maximize non-opioid multimodal analgesia (ketamine, NSAIDs, nerve blocks, regional anesthesia)
  • For severe pain requiring opioids: may need very high doses to overcome blockade (risk of respiratory depression when blockade wears off — discuss with toxicology/pain)

Disposition

  • Most chronic pain exacerbations can be safely discharged with adequate analgesia and follow-up
  • Discharge with:
    • Appropriate short-term analgesic prescriptions (prefer non-opioids)
    • Clear follow-up plan with PCP or pain specialist (within 1-2 weeks)
    • Patient education on multimodal self-management
    • Naloxone prescription if on chronic opioids or identified risk for overdose
  • Admission considerations:
    • Acute pathology requiring inpatient workup or intervention
    • Pain crisis refractory to ED management (e.g., severe sickle cell crisis)
    • Concern for inability to manage pain safely at home (e.g., suicidality, severe functional decline)
    • Need for IV analgesic regimen not feasible outpatient

See Also

External Links

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Dowell D, Ragan KR, Jones CM, Baldwin GT, Chou R. CDC Clinical Practice Guideline for Prescribing Opioids for Pain — United States, 2022. MMWR Recomm Rep. 2022;71(No. RR-3):1-95.
  2. ↑ Motov S, Strayer R, Hayes BD, et al. Pain management in the emergency department: a clinical review. Clin Exp Emerg Med. 2022;9(2):118-132.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Hatten BW, Cantrill SV, Dubin JS, et al. Clinical Policy: Critical Issues Related to Opioids in Adult Patients Presenting to the Emergency Department. Ann Emerg Med. 2020;76(3):e13-e39.
  4. ↑ 4.0 4.1 Motov S, Drapkin J, Likourezos A, et al. Sub-dissociative dose ketamine administration for managing pain in the emergency department. World J Emerg Med. 2018;9(4):249-255.
  5. ↑ Nguyen T, Mai M, Choudhary A, et al. Comparison of Nebulized Ketamine to Intravenous Subdissociative Dose Ketamine. Ann Emerg Med. 2024;84(4):354-362.
  6. ↑ 6.0 6.1 6.2 Alford DP, Compton P, Samet JH. Acute pain management for patients receiving maintenance methadone or buprenorphine therapy. Ann Intern Med. 2006;144(2):127-134.
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