Pain Management

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Objectives

The following module was designed to supplement medical students’ learning in the clinic. Please take the time to read through each section by clicking the headings below. Information on prevalence, classification, syndromes, assessment of cancer pain along with principles of pain management is provided.
By the end of the tutorial, the following objectives should be addressed:
  1. Describe the prevalence of pain in cancer patient
  2. Describe a general approach to pain management
  3. Classify and be able to characterize pain
  4. Describe common pain syndromes in patients with cancer
  5. Describe an approach to assessing pain
  6. Recognize the importance of patient education in pain management
  7. Utilize the WHO pain ladder to choose analgesic medication appropriate to pain level
  8. Understand the use of non-opioid analgesics in cancer pain control
  9. Understand the use of pharmacology and metabolism of opioid analgesics
  10. Describe factors to consider when selecting an opioid for pain management
  11. Convert between opioids while maintaining analgesia
  12. Understand the differences between immediate-release opioid preparations, extended-release opioid preparations, and breakthrough opioid preparation.
  13. Understand the use of adjuvant analgesic agents
  14. Acknowledge common adverse effects of analgesic agents
  15. Understand the different routes of administration for opioids
  16. Describe precautions during chronic opioid use
  17. Understand principle methods of interventional and other non-pharmacological approaches to pain management

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[restab title=”Prevalence”]

Prevalence

Pain management is an important part of oncology care. Pain is a significant player in patient morbidity. Most patients with advanced cancer and up to 60% of patients with any stage of the disease experience significant pain. The World Health Organization estimates that 25% of all cancer patients die with unrelieved pain.

References:

Pazdur R, Coia LR, Hoskins WJ, Wagman LD. Cancer Management: A Multidisciplinary Approach 6th Edition. PRR, Melville, NY; 2002.[/restab]
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Approach:

Below is an easy to follow general approach when considering cancer pain assessment and management [1].

Approach-to-pain-managment-big

The ABCDE system, developed by the Agency for Health Care Policy and Research, is another good tool [2].

A Ask about pain regularly. Assess pain systematically
B Believe the patient and family in their reports of pain and what relieves it
C Choose pain control options appropriate for the patient, family and setting
D Deliver intervention in a timely, logical and coordinated fashion
E Empower patients and their families. Enable them to control their course to the greatest extent possible
Patient Education:

Studies suggest that patient education can be highly effective in managing pain. For a cancer patient already taking opioid analgesics, education may be more effective than the addition of co-analgesic therapies such as gabapentin and paracetamol (reduction of about one point on a 0-10 scale) [3].

  • Patient education should occur in an appropriate setting with sufficient time allotted to discuss any patient concerns. It should be conducted when patient and preferably also the care giving is present.
  • Specific areas to address include dispelling misconceptions about pain and pain management, promoting user involvement through the provision of education about pain and its management, and the use of appropriate teaching materials especially when literacy is an issue [3].
References:

[1] Advisory Committee. BC Guidelines & Protocols: Pain and symptom management. 2011. Available at www.bcguidelines.ca/pdf/palliative2_pain.pdf. Accessed June 20th 2013.

[2] Bistros, BS. Advocating for Management of Cancer Pain. Journal of the American Osteopathic Association December 1, 2007 vol. 107 no. suppl 7 ES4-ES8.

[3] Bennett, Michael I, Flemming, Kate, Closs, Jose S. Education in cancer pain management. Current Opinion in Supportive & Palliative Care 2011; Vol 5, Issue 1, 20-24.[/restab]
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Assessment

Classification:

Physical pain can be largely classified as nociceptive or neuropathic. It is helpful to find out what kind of pain the patient is experiencing as it will guide the selection of medication and or procedures.

It is also important to realize patients’ total pain may have more than one cause or presentation.

Table 1: Classification of Pain [1], [2], [3]
Nociceptive pain
Arises from direct activation of nociceptors located in the peripheral somatosensory nervous system
Somatic Received from skin, bone, and muscle
Sensation: Sharp, aching or throbbing
Visceral Received from internal structures such as the gastrointestinal tractSensation: Crampy
Neuropathic pain
Pain occurring with a abnormally functioning somatosensory nervous system
Primary nervous system lesions Result of ischemia, compression, infiltration, metabolic injury, or transaction of the nerve
Sensation: Burning, tingling, numbness, shooting, stabbing, or electric-like feelings
Dysfunction of the nervous system Abnormal signalling system magnifying the response to a given stimulus.
Sensation: Burning, tingling, numbness, shooting, stabbing, or electric-like feelings
Common Cancer Pain Syndromes:

Common pain syndromes in patients with cancer: There are three major categories of pain syndromes [4].

1. Direct tumor involvement: tumor invasion of bone (e.g. metastases to the base of skull, jugular foramen syndrome, clivus metastases, sphenoid sinus metastases, metastases to vertebral bodies), tumor infiltration of nerve, plexus, meninges and spinal cord

2. Pain associated with cancer therapy:

  • post surgical pain syndromes: post mastectomy pain syndrome, post thoractomy pain syndrome, post-radical neck syndromes, phantom limb and stump pain
  • post chemotherapy pain syndromes: peripheral neuropathy, steroid pseudorheumatism, aseptic necrosis of bone, postherpetic neuralgia
  • Post radiation pain syndromes: radiation fibrosis of the brachial plexus, radiation myelopathy

3. Pain not related to cancer or cancer therapy: accurate diagnosis in this group of patients clearly alters both therapy and prognosis

The table below shows the percentages of cancer pain accounted for by each of the three etiologies.

Table 2: Breakdown of Cancer Pain Syndromes
Percentage of cancer inpatient pain accounted for Percentage of cancer outpatient pain accounted for
Direct tumor involvement 78% 65%
Associated with cancer therapy 19% 25%
Not related to cancer or cancer therapy 3% 10%
Assessment:

1. History – when managing pain, it is important to elicit a detailed and focused history. It is useful to inquire for the following [1], [5]:  (P,Q,R,S,T, AAA)

  • Precipitating factors
  • Quality: listen for typical features for nociceptive and neuropathic pain
  • Radiation
  • Severity: use pain scale out of 10
  • Timing: duration and if sporadic or continuous
  • Aggravating and alleviating factors: inquire response to past and current analgesic therapy and related adverse effects
  • Associated symptoms
  • Activities of daily living, any fear they have about analgesics
  • Other aspects that may contribute to total pain such as psychologic, social, and spiritual factors

2. Physical, psychological, laboratory and imaging assessments and tests

  • These coupled with a detailed pain history can be useful in identifying relevant pathophysiology underlying the pain. Determine whether the pain is directly or indirectly related to the cancer, associated with therapeutic interventions or unrelated. This may help elucidate the pathophysiology of the pain and direct therapy [1].

3. Pain assessment tools

  • Pain is a uniquely subjective experience. As practitioners, we need to trust our patients’ ratings of their pain
  • Verbal analogue scale is a simple and widely used tool. Ask the patient to quantify their pain on a scale of 0 to 10, 0 being no pain, 10 being the worst pain imaginable.
  • It is sometimes helpful to conceptualize the numeric rating scale (5):
    • 0 = No Pain
    • 1-3 = Mild Pain (nagging, annoying, interfering little with ADLs)
    • 4–6 = Moderate Pain (interferes significantly with ADLs)
    • 7-10 = Severe Pain (disabling; unable to perform ADLs)

pain-scale

References:

[1] National Cancer Institute: Cancer Pain Management Module 2. Available at: http://www.cancer.gov/cancertopics/cancerlibrary/epeco/selfstudy/module-2/module-2-pdf. Accessed June 13th 2013.

[2] International Association for the Study of Pain: Taxonomy. Available at: http://www.iasp-pain.org/AM/Template.cfm?Section=Pain_Definitions. Accessed June 10th, 2013.

[3] International Association for Study of Pain: Clinical Updates Vol. XVIII, Issue 7. Diagnosis and Classifi cation of Neuropathic Pain. 2010. Available at http://www.iasp-pain.org/AM/Template.cfm?Section=Pain_Definitions&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=15084. Accessed June 15th 2013.

[4] Holleb AI, Fink DJ, Murphy GP. American Cancer Society textbook of clinical oncology. 1st Edition. American Cancer Society, Atlanta, GA. 1991.

[5] University of Toronto: Pain Management. Available at: http://www.cme.utoronto.ca/endoflife/PAIN%20MANAGEMENT.pdf. Accessed June 13th 2013.

[6] National Institute of Health: Pain Intensity Instruments. 2003. Available at: http://painconsortium.nih.gov/pain_scales/NumericRatingScale.pdf. Accessed June 13th 2013.[/restab]
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Analgesic Medication

Analgesic drugs remain key in managing cancer pain. A general principle is to match the severity of pain to the strength of the analgesic i.e. strong analgesics for severe pain [1].

The WHO has a 3-step model to guide analgesic choice based on this principle. It is not necessary to traverse each step sequentially, a patient with severe pain may need to have step 3 opioids right away.

Figure 1: WHO Pain Ladder

WHO-pain-ladder-corrected1

Non-opioid Analgesics
Opioid Analgesics
Adjuvant Therapy
References:

[1] National Cancer Institute: Cancer Pain Management Module 2. Available at: http://www.cancer.gov/cancertopics/cancerlibrary/epeco/selfstudy/module-2/module-2-pdf. Accessed June 13th 2013.[/restab]
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Non-Pharmacological Therapy

Besides pharmacologically, cancer pain can also be managed with various other approaches which will be briefly discussed below. Although the discussion here is brief, these may be very beneficial to some patients when used appropriately.

Table 1: Other Management Options
Anesthetic and neurosurgical approaches Local anesthetic blocks, intraspinal analgesia, and neuroablative procedures (neurolysis, destroying the nervous structures implicated in the transmission of pain).
Physical therapy Massage, ultrasound, hydrotherapy, transcutaneous electrical nerve stimulation, electo-acupuncture, trigger point manipulation are indicated for musculoskeletal pain. Electrical stimulation may also be applied to the peripheral nerves, spinal cord, and even to deep brain structures.
Psychological, sociocultural, and spiritual management Multifactorial approach to pain management that recognizes the complexity of the human being, especially in the terminally ill patient.
Radiation therapy Localized external-beam radiation, wide-field external-beam radiation, or systemic treatment with radioactive isotopes.Cancer pain that is amenable to radiation include bone metastasis, CNS involvement, pain due to localized neural involvement (eg, brachial plexus or sciatic nerve), visceral pain (eg, liver or adrenal), and pain due to obstruction (eg, esophageal). Of note, bone metastasis is the most common cause of cancer and radiation is an extremely effective means of palliating painful bone metastases.
Surgery The objectives of surgery are to palliate pain, reduce patient anxiety, improve patient mobility and function, facilitate nursing care, and control local tumor when nonsurgical therapies fail.
References:

Pazdur R, Coia LR, Hoskins WJ, Wagman LD. Cancer Management: A Multidisciplinary Approach 6th Edition. PRR, Melville, NY; 2002.[/restab]
[restab title=”Summary”]

Summary

1.  Describe the prevalence of pain in cancer patients

Pain is a significant player in patient morbidity. Most patients with advanced cancer and up to 60% of patients with any stage of the disease experience significant pain. The World Health Organization estimates that 25% of all cancer patients die with unrelieved pain.

2.  Describe a general approach to pain management
  • Identify cancer pain and provide support
  • Treat underlying disease if possible
  • Qualify cancer pain
  • Start pharmacological therapy using WHO pain ladder as guide
  • Choose adjuvant appropriate to quality of pain as needed
  • Switch opioid if adverse reaction or if previous opioid is minimally effective
3.  Recognize the importance of patient education in pain management

Studies suggest that patient education can be highly effective in managing pain. For a cancer patient already taking opioid analgesics, education may be more effective than the addition of coanalgesic therapies such as gabapentin and paracetamol.

4.  Classify and be able to characterize pain
Nociceptive pain
Arises from direct activation of nociceptors located in the peripheral somatosensory nervous system
Somatic Received from skin, bone, and muscleSensation: Sharp, aching or throbbing
Visceral Received from internal structures such as the gastrointestinal tractSensation: Crampy
Neuropathic pain
Pain occurring with a abnormally functioning somatosensory nervous system
Primary nervous system lesions Result of ischemia, compression, infiltration, metabolic injury, or transaction of the nerveSensation: Burning, tingling, numbness, shooting, stabbing, or electric-like feelings
Dysfunction of the nervous system Abnormal signalling system magnifying the response to a given stimulus.Sensation: Burning, tingling, numbness, shooting, stabbing, or electric-like feelings
5.  Describe common pain syndromes in patients with cancer
Percentage of cancer inpatient pain accounted for Percentage of cancer outpatient pain accounted for
Direct tumor involvement 78% 65%
Associated with cancer therapy 19% 25%
Not related to cancer or cancer therapy 3% 10%
6.  Describe an approach to assessing pain
  • History: PQRST AAA
  • Physical, psychological, lab, imaging assessments and tests: elucidate pathophysiology of pain
  • Pain assessment tools: Verbal and visual analogue pain scales 0-10
7.  Utilize the WHO pain ladder to choose analgesic medication appropriate to pain level

WHO-pain-ladder-corrected1

8.  Understand the use of non-opioid analgesics in cancer pain control

Acetaminophen and NSAIDS are effective WHO pain ladder step 1 analgesics and coanalgesics. They are usually used in full doses but have a ceiling effect to their analgesia and tolerable adverse effects.

NSAIDS adverse effects include gastropathy, renal failure, and inhibition of platelet aggregation.

Acetaminophen chronic doses > 4.0 g/24 h or acute doses > 6.0 g/24 h are not recommended as they may cause hepatotoxicity.

9.  Understand the use of pharmacology and metabolism of opioid analgesics
Pharmacology
  • First-order kinetics (time dependent, amount independent)
  • Reach peak effect and plasma concentration (Cmax) ~60-90 minutes post oral or rectal administration, 30 minutes post subQ or IM injection, and 6 minutes after IV (3)
Metabolism
  • Metabolized in the liver
  • Liver conjugates morphine to an active metabolite, morphine-6-glucoronide, and an inactive metabolite, morphine-3­glucuronide, that must be cleared renally (2, within: 22)
  • 90-95% excreted by the kidney
  • Evidence that other opioids such as codeine, hydrocodone, hydromorphone, and fentanyl also have active metabolites. (2, within: 23)
  • Only methadone is excreted unchanged.
10.  Describe factors to consider when selecting an opioid for pain management

There is no strong evidence that support the superiority of one opioid over another as comparative trials are very difficult to perform. However, considerations that guide the choice of opioids include combination formulation opioid, adverse effect, and available route of administration which will be discussed later in this module.

11. Convert between opioids while maintaining analgesia

Table of opioids

These dosage equivalents of immediate-release opioids to morphine 10mg s.c. have been based mainly on single dose studies. They are guidelines only in patients requiring chronic administration.

Drug

Dose s.c.* (mg) Dose p.o. (mg) Dose frequency
Useful weak opioids Codeine 120 200mg q4h
Oxycodone combination n/a 2 tabs q4h
Useful strong opioids Fentanyl (transdermal) n/a 25 ug/hr Every 2-3 days
Oxycodone n/a 5-10mg q4h
Hydromorphone 2 4-6 q4h
Morphine 10 20-30 q4h

*Values for reference only, for up to date recommendations refer to CPS text

12. Understand the differences between immediate-release opioid preparations, extended-release opioid preparations, and breakthrough opioid preparation.
Routine Oral Dosing Immediate-release opioid preparations If the pain is continuous, give immediate-release medication, usually q4h.Steady state plasma concentrations are usually attained within 1 day.
Extended-release and long half-life opioid preparations Extended- or sustained-release opioid tablets are specifically formulated to release medication in a controlled fashion over 8, 12, or 24 hours.
Breakthrough Dosing To be effective and to minimize the risk of adverse effects, consider an immediate-release preparation of the same opioid that is in use for routine dosing.If the patient needs to use breakthrough medication more than twice a day, consider increasing routine dose.
13. Understand the different routes of administration for opioids

In general, the oral route is the least invasive and more convenient route of administration. However, selected patients may benefit from other routes of administration if oral intake is not possible (vomiting, dysphagia, obstruction) or causes uncontrollable adverse effects (nausea, drowsiness, confusion). For example, transdermal fentanyl or buprenorphine can be useful in patients with swallowing difficulties.

Alternative routes of administration include enteral, transmucosal, rectal, transdermal, parenteral, intravenous, and intraspinal(2).

14. Acknowledge common adverse effects of opioid analgesic agents
Constipation Opioid analgesics produce a decrease in intestinal secretions and peristalsis, resulting in a dry stool and constipation.At the time opioid analgesics are started, prophylactic provisions for regular bowel regimen including cathartics and stool softeners should be instituted.
Sedation Management includes reducing the individual drug dose and prescribing the drug more frequently or switching to an analgesic with a shorter plasma half-life. Amphetamines and methylphenidate in combination with an opioid can be used to counteract the sedative effects.
Nausea and vomiting Incidence is markedly increased in ambulatory patients.Switch the patient to an alternative opioid analgesic or prescribe an antiemetic, eg, prochlorperazine or metoclopramide, in combination with the opioid.
15.  Describe precautions during chronic opioid use

Normeperidine is a toxic metabolite of meperidine that accumulates with repetitive dosing; thus, use of meperidine for chronic pain should be limited. Propoxyphene is also relatively contraindicated due to accumulation of norporpoxyphene.

Physical withdrawal symptoms can be avoided by tapering doses

A change in mental status should not be attributed to opioid therapy until medical and neurologic factors have been fully evaluated

Mixed agonist-antagonist drugs and partial agonist drugs are not recommended for cancer pain.

16.  Understand the use of adjuvant analgesic agents
Steroids Potentiates analgesia, sometimes elevates mood and appetite
Antidepressants Potentiates analgesia, elevates mood,  induces sleepEffective for neuropathic pain
Anxiolytics Potentiates opioid analgesia, reduces anxiety, antiemetic, sedative
Phenothiazines Reduces anxiety, sometimes with analgesic and antiemetic effects
Anticonvulsants Anticonvulsant, decreases abnormal CNS neuronal activities, sometimes muscle relaxant effectsUseful for neuropathic pain
Amphetamines Potentiates narcotic analgesia, elevates moodFor terminally ill patients with pain, depression, and lethargy
Topical local anesthetic Reduces neuronal firing, depletes substance P from nerve terminalsReduce neuropathic pain
17.  Understand principle methods of interventional and other non-pharmacological approaches to pain management
Anesthetic and neurosurgical approaches Local anesthetic blocks, intraspinal analgesia, and neuroablative procedures (neurolysis, destroying the nervous structures implicated in the transmission of pain).
Physical therapy Massage, ultrasound, hydrotherapy, transcutaneous electrical nerve stimulation, electo-acupuncture, trigger point manipulation are indicated for musculoskeletal pain. Electrical stimulation may also be applied to the peripheral nerves, spinal cord, and even to deep brain structures.
Psychological, sociocultural, and spiritual management Multifactorial approach to pain management that recognizes the complexity of the human being, especially in the terminally ill patient.
Radiation therapy Localized external-beam radiation, wide-field external-beam radiation, or systemic treatment with radioactive isotopes.Cancer pain that is amenable to radiation include bone metastasis, CNS involvement, pain due to localized neural involvement (eg, brachial plexus or sciatic nerve), visceral pain (eg, liver or adrenal), and pain due to obstruction (eg, esophageal). Of note, bone metastasis is the most common cause of cancer and radiation is an extremely effective means of palliating painful bone metastases.
Surgery The objectives of surgery are to palliate pain, reduce patient anxiety, improve patient mobility and function, facilitate nursing care, and control local tumor when nonsurgical therapies fail.

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Virtual Patient Case

This case study was designed to supplement your knowledge on cancer pain management and test what you have learned after going through the pain management module. Use your mouse to click through the slides and answer each question in the text box provided.

Note: This case can be completed on an Ipad. To do this download the (free) Articulate Mobile Player for the Ipad by clicking here.

Click here to start the Pain Management Virtual Patient Case[/restab]
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Evaluation

Thank you for using Learn Oncology. This website was designed to supplement teaching in oncology. While the material is targeted to medical students it is our hope that a variety of health care professionals can use this site. Feedback on your experience will help us to improve the resources. Responses are anonymous. Thank you.

Click here to fill out the Pain Management Module Survey[/restab]
[restab title=”Authors”]

Major Contributors:

Selina Li – Medical Student
Dr. Paris Ann Ingledew – MD, FRCP Radiation Oncologist[/restab][/restabs]


Last Updated: August 2014