Pain Management

Clinical Fundamentals

Module Summary

This module covers the basic anatomy behind pain, overall pain assessment, and the management of both acute and cancer related pain. It also addresses the different classes of pharmacologic agents used to treat pain, the etiologies of head and neck pain and the differences in evaluation and treatment in pediatric, elderly and substance abuse patients.

Module Learning Objectives

Descibe the basic anatomy behind pain.
Explain the assessment of a patient in pain.
Discuss the management of acute pain.
Give examples of the management of cancer pain.
Recognize the basic classes of pharmacologic agents used to treat pain.
Summarize the major etiologies of head and neck pain.
Review the evaluation and treatment of the pediatric patient, the elderly patient, and the substance abuse patient.

Topics

Anatomy

Pathogenesis

Patient Evaluation

Treatment

Learning Objectives

Understand that for acute pain, rigid prescriptions for postoperative pain are not appropriate.
Understand pain control options.
1. Cognitive-behavioral interventions (relaxation, imagery).
2. Systemic administrations of medications on the prn or otc basis.
3. Patient-controlled anesthesia.
4. Spinal analgesia.
5. Intermittent or continuous local neural blockage—blocks associated with general anesthesia decrease postoperative pain more than general anesthesia alone.
6. Massage or heat/cold.
7. Electroanalgesia (transcutaneous electrical nerve stimulation)—(electrodes may be placed intraoperatively).
8. Surgery.
Recite the common errors physicians make in managing pain.
1. Inadequate use of analgesics.
2. Allow patients to misuse analgesics.
3. Failure to recognize patients’ psychiatric comorbidities.
4. Failure to use available therapies.
Know the following approaches to treating different types of pain:
1. dental:
  1. pain usually surround the affected tooth but may be diffuse.
  2. usually treat with nonsteroidal anti-inflammatory drugs (NSAIDS).
2. trigeminal neuralgia:
  1. trigger points bring lancinating pain within the distribution of the trigeminal nerve.
  2. can immediately relieve with blockade of the involved nerve/branches.
  3. can treat with carbamazepine or phenytoin.
  4. refractory cases can get chemical or radiofrequency rhizotomy or division of the nerve.
3. headache:
  1. can be from upper cervical, V, IX, X, dura.
  2. etiology:
    1. myofascial or skeletal via c-spine.
    2. abnormalities in blood flow to the brain.
    3. facial diseases (sinusitis, temporomandibular joint).
  3. treatment:
    1. treat migraine with dietary restrictions, caffeine, ergot alkaloids, sumatriptan.
    2. treat tension headaches with relaxation, mild analgesics. and anxiolytics.
    3. treat cluster headaches with sumatriptan.
    4. treat ice cream headache with avoidance.
    5. treat headache associated with head trauma with long-term analgesics.
4. temporomandibular Joint (TMJ) pain:
  1. NSAIDS, dental prostheses, oral surgery, biofeedback.
5. chronic sinusitis:
  1. usually well controlled with medication.
6. glossopharyngeal neuralgia:
  1. lancinating pain in the back of the throat.
  2. usually triggered from the nasopharynx on the ninth nerve.
  3. pain may be associated with cardiac arrhythmia.
  4. diagnosis: anesthetize trigger point with cocaine.
  5. treatment:
    1. if not associated with cardiac problem, then can treat with carbamazepine or phenytoin.
    2. if associated with cardiac abnormalities—microvascular decompression.
7. postherpetic neuralgia:
  1. constant burning pain.
  2. difficult to treat, mainstay is long-acting narcotics.
  3. some have tried sympathetic blocks.
8. atypical facial pain:
  1. pain does not fit any distribution.
  2. it is diffuse with a burning sensation or paresthesia.
  3. treat medically.
9. Opioids for chronic non-malignant pain
  1. trial of acetaminophen or NSAIIDS (nociceptive pain)
  2. trial of Tricyclics or anticonvulsants (neuropathic pain)
  3. consider treatment contracts with patient before initiating Opiates
    1. There is little evidence that opioids are advantageous
    2. Structured management in vital
  4. codeine as first line opiate
  5. tramadol, oxycodone as second line
  6. fentanyl patch or methadone as third line
  7. outcome assessment
    1. analgesia
    2. activities of daily living
    3. adverse effects
    4. aberrant drug use
10. cancer pain:
  1. 40% of cancer patients have moderate to severe pain; it can be effectively managed in 90% of patients.
  2. pain associated with cancer is undertreated in adults and children.
  3. causes of cancer pain:
    1. tumor progression.
    2. operations to diagnose and treat.
    3. toxicities of chemotherapy and radiation.
    4. Infection.
    5. muscle aches from chronic infirmity.
  4. importance of treating pain:
    1. unnecessary suffering.
    2. diminishes activity, appetite, and sleep.
    3. worsens helplessness, anxiety, depression.
  5. barriers to cancer pain management:
    1. Problems related to health care professionals
      - inadequate knowledge of pain management.
      - poor assessment of pain.
      - fear of patient addiction.
      - concern about side effects.
      - concern about patients becoming tolerant to analgesics.
    2. problems related to patients:
      - reluctance to report pain.
      - reluctance to take pain medications.
    3. problems related to the healthcare system:
      - low priority given to cancer pain treatment.
      - inadequate reimbursement.
      - restrictive regulations of controlled substances.
      - problems of availability of treatment and access.
  6. nonpharmacologic management of cancer pain:
    1. cutaneous stimulation.
    2. avoid prolonged immobilization.
    3. acupuncture.
    4. psychosocial interventions as adjuvant to pharmacotherapy.
    5. peer support groups/pastoral care.
  7. pharmacologic management of cancer pain crucial to individualize treatment to patient:
    1. use simplest dosage schedules with least-invasive modalities first.
    2. NSAIDS: mild to moderate pain is best treated with NSAIDS.
    3. opioids if pain persists or increases.
    4. consider around-the-clock (ATC) dosing for persistent pain to keep a constant drug level in the patient.
    5. opioid tolerance and physical dependence are expected with long-term treatment.
    6. route of opioid administration: oral is preferred, intramuscular is least preferred.
    7. side effects:
      - treat constipation prophylactically.
      - noloxone should be used for respiratory depression; it should be titrated for respiratory function, but not to reverse analgesia.
11. World Health Organization analgesic ladder:
  1. adjuvant drugs for cancer pain.
  2. corticosteroids: may cause mood elevation, anti-inflammatory effects, antiemetic, appetite stimulation.
  3. anticonvulsants: good for neuropathic pain.
  4. tricyclic antidepressants: good for neuropathic pain, mood elevation, and may potentiate the analgesic effects of opioids.
  5. neuroleptics: adjunctive analgesics.
  6. hydroxyzine: mild anxiolytic with antiemetic, sedating. and analgesic properties.
  7. bisphosphonates and calcitonin: for pain from bony metastases.
  8. antineoplastic chemotherapy and radiation: may produce analgesia through tumor shrinkage.
12. head and neck surgical patients:
  1. oral procedures such as mandibular fractures and mandibular resections may preclude oral medications.
  2. pain that does not respond to these measures should raise a flag about infection, osteitis, nerve injury, development of chronic pain.
13. radical head and neck surgery:
  1. frequently have gastrostomy and trach.
  2. flaps usually increase the number of operative sites.
  3. need intraoperative protection with padding and cushion supports.
  4. may need liquid pain medicine, topical lidocaine.
  5. NSAIDS relatively contraindicated because of risk of bleeding and airway obstruction.
Pediatric patients are frequently not given opioid analgesics after surgery and are often given less potent or inadequate doses.
1. Pediatric pain assessment:
  1. must be tailored to developmental level and the child’s personality and includes pain history, evaluation of location, evaluation of severity, observation of the child with special attention to responses to the environment.
  2. parents and family members are essential.
2. Pharmacology in pediatrics:
  1. local anesthestics: includes topical.
  2. opioids: intravenous (IV) has rapid effect, ease of titration.
  3. benzodiazepines (oral or IV), provide sedation, not anesthesia; good in combination with opioids for painful procedures (increased risk of respiratory depression).
  4. barbiturates: no analgesia, only sedation; last for many hours; respiratory depression can be a problem (especially in combination with opioids).
Elderly patients: two-fold higher incidence of pain in those over age 60 years compared with those under 60.
1. Increased risk for drug-drug interactions, complications, and side effects.
  1. Risk for under- and overtreatment—changes in pharmacokinetics with age.
  2. NSAIDS have increased risk for gastric and renal toxicity, as well as unusual drug reactions.
  3. Opioids are very effective in the elderly.
    - Elderly have a higher peak and longer duration of pain relief with opioids (higher fat to lean body mass, decreased glomerular flow rate (GFR).
    - More sensitive to sedation and respiratory depression.
2. Pain assessment in the elderly.
  1. Generally, more stoic about pain.
  2. Have some difference in acute pain perception (silent myocardial infarction, “painless” acute abdomen).
  3. Delerium and dementia can complicate pain assessment.
Patients who are substance abusers:
1. assessment:
  1. increased sympathetic responses may be from pain, or from opioid withdrawal.
  2. physician needs to distinguish between the temporal characteristics of the abuse behavior.
    - Active users may require higher starting doses of opioids.
    - Avoid mixed agonist-antagonists in abusers as this may initiate withdrawal.
    - May benefit from using nonopioids concomitantly with opioids.
    - Specific drug abuse behavior (tampering with patient-controlled analgesia (PCA), storing opioids, self-injection) need to be dealt with resolutely.
    - On the outpatient basis: only one physician should be the prescriber of opioids.
    - Consider substance abuse consult.

References

Schug SA, Chandrasena C. Pain management of the cancer patient. Expert Opin Pharmacother. 2015 Jan;16(1):5-15. doi: 10.1517/14656566.2015.980723. Epub 2014 Dec 5.
Wardhan R, Chelly J. Recent advances in acute pain management: understanding the mechanisms of acute pain, the prescription of opioids, and the role of multimodal pain therapy. F1000Res. 2017 Nov 29;6:2065. doi: 10.12688/f1000research.12286.1. eCollection 2017.
Kahan M, Srivastava A, Wilson L, et al. Opioids for managing chronic non-malignant pain: safe and effective prescribing. Can Fam Physician. 2006 Sep;52(9):1091-6.
Kissin I. Long-term opioid treatment of chronic nonmalignant pain: unproven efficacy and neglected safety? J Pain Res. 2013 Jul 4;6:513-29.
McCann, Kevin Shear et al. Structured Management of Chronic Nonmalignant Pain with Opioids in a Rural Primary Care Office. J Am Board Fam Med. 2018 Jan-Feb;31(1):57-63.
The American Pain Society in Conjunction with The American Academy of Pain Medicine. Guidelines for the Use of Chronic Opiod Therapy in Chronic Noncancer Pain. Online Resource.

Medical Therapies

Pharmacology

Learning Objectives

Understand that mild and moderate pain is best approached with NSAIDS unless contraindicated.
Know that NSAIDS decrease levels of inflammatory mediators generated at the site of injury.
Know that NSAIDS also allow the administration of less opioids, thus decreasing the potential side effects.
Be aware that all NSAIDS besides acetaminophen, salsalate, and choline magnesium may impair platelets.
1. Acetaminophen < 4 g/day short term:
  1. can cause liver and renal toxicities.
2. Ibuprofen ≤ 1,200 mg/day.
List the risk factors for possible complications from NSAID use:
1. age > 75 years.
2. congestive heart failure.
3. dehydration.
4. history of peptic ulcer disease.
5. history of renal dysfunction.
6. hypertension.
7. diuretic use.
Know that opioids are indicated for initial treatment of moderately severe to severe pain.
Know the mechanism of action for opioids:
1. opioids bind to central and peripheral opioid receptors.
2. they are either agonists, partial agonists, or mixed agonist-antagonists of the mu receptor.
  1. agonists - maximal response.
  2. partial agonists - have lesser responses.
  3. mixed - will activate one type of opioid receptor while blocking another.
  4. agonists: hydromorphone, codeine, oxycodone, hydrocodone, methadone, levorphanol, fentanyl, and meperidine:
  5. side effects: constipation, urinary retention, sedation, respiratory depression.
  6. mixed agonist/antagonist (block mu and activate kappa): pentazocine, butorphanol tartrate, nalbuphine hydrochloride.
Know that the choice of proper opioid depends on the following factors:
1. initial dose.
2. frequency of administration.
3. optimal doses of nonopioid analgesics.
4. Side-effect profile.
5. inpatient versus outpatient setting.
6. route of administration:
  1. side effects greater with IV dosing than oral.
  2. IV is best route for postop pain.
  3. sublingual or rectal, IM, or subcutaneous are alternatives.
  4. all routes other than IV have a lag time for effect.
Understand that the proper way to dose opioids is to titrate the dose based on patient response and side effects.
1. Dose may change dramatically if patients were on preoperative narcotics.
2. Consider regularly scheduled dosing initially.
3. Dose frequency can then be adjusted accordingly after the duration of analgesic action is determined for that particular patient.
Know that PCA is a safe method of administering narcotics.
1. Can be IV, subcutaneous, or IM.
2. Patient has a “loading dose” initially until pain decreases.
3. Low-dose basal infusions may allow better sleeping at night.
  1. morphine 1 mg/ml.
  2. fentanyl 10 micrograms/ml.
  3. hydromorphone 0.2 mg/ml.
  4. meperidine 10 mg/ml.
4. Use on-demand dosing for breakthrough.
5. When patients are then able to take oral meds, the basal rate can be discontinued.

References

Acute Pain Management Guideline Panel. Acute pain management: operative or medical procedures and trauma. Clinical Practice Guideline. AHCPR Publication No. 92-0032. Rockville, MD. Agency for Health Care Policy and Research, U.S. Department of Health and Human Services, Public Health Service. February 1992.
Hargreaves KM, Dionne RA. Evaluating endogenous mediators of pain and analgesia in clinical studies. In: Max M, Portenoy R, and Laska E, eds. Advances in pain research and therapy. The design of analgesic clinical trials. Vol. 19. New York: Raven Press; 1991:579-98.
Jacox A, Carr DB, Payne R, et al. Management of cancer pain. Clinical Practice Guideline No. 9. AHCPR Publication No. 94-0592. Rockville, MD: Agency for Health Care Policy and Research, U.S. Department of Health and Human Services, Public Health Service. March 1994.
Jones SL. Anatomy of pain. In: Sinatra R, Hord A, Ginsberg B, et al., eds. Acute pain: mechanisms and management. Philadelphia: Mosby; 1992:8-25.
Long D. Contemporary diagnosis and management of pain. Newtown, PA: Handbooks in health care; 1997.
Portnoy RK. Clinical application of opioid analgesics. In: Sinatra R, Hord A, Ginsberg B, et al., eds. Acute pain: mechanisms and management. Philadelphia: Mosby; 1992:93-101.

Surgical Therapies

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Pain Management

Pain Management

Anatomy

Pathogenesis

Patient Evaluation

Treatment

Medical Therapies

Pharmacology

Surgical Therapies

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