Pain Management. Overview Barriers to pain management Goals of pain Management WHO ladder Dosing and titration Routes of admin. “Breakthrough pain” Opiophobia.

Pain Management

Overview Barriers to pain

management Goals of pain

Management WHO ladder Dosing and

titration Routes of admin.

“Breakthrough pain”

Opiophobia Equianalgesic

ratios Opioid substitution Side effects Organ failure

Clinician-Related Barriers to Pain Assessment

Lack of formal training in pain management

Insufficient knowledge Lack of pain-assessment skills Rigidity or timidity in prescribing practices Fear of regulatory oversight

Portenoy RK Contemporary Diagnosis and Management of Pain in Oncologic and AIDS Patients 2001 Handbooks in Heathcare

Patient-Related Barriers to Pain Assessment

Reluctance to report pain (eg fear of distracting doctors from cure)

Reluctance to take opioid drugs Poor adherence

Portenoy RK 2001

System-Related Barriers to Pain Assessment

Low priority given to symptom control

(Availability of opioid analgesics) Inaccessibility/low profile of

specialised care Cost of outpatient pain medication

Portenoy RK 2001

Pain Assessment: Goals Assess the pain context Characterize the pain Identify pain syndrome Diagnose the cause Evaluate physical and

psychosocial co-morbidity Assess degree and nature of disability Develop a therapeutic strategy

Portenoy RK 2001

TOTALTOTALPAINPAIN

SOMATIC SOURCE

ANGERDEPRESSION

ANXIETY

Symptoms of debility

Side effects of therapy

Non-cancer pathology

Cancer

Bureaucratic bungling

Friends not visiting

Delays in diagnosis

Unavailable doctors

Irritability

Therapeutic failure

Fear of hospitalor nursing home

Worry about family

Fear of death

Spiritual (existential) unrest

Fear of pain

Family finances

Loss of choices

Uncertainty about future

Loss of social position

Loss of job prestigeand income

Loss of role in family

Chronic fatigueand insomnia

Sense of helplessness

Disfigurement

The Context

Pain Assessment: Goals

Diagnose the cause

Pathophysiology

Nociceptive pain

Neuropathic pain

Commensurate with

identifiable tissue damage

May be abnormal, unfamiliar pain, probably caused by dysfunction in PNS or CNS

Nociceptive Pain Related to ongoing activation of primary

afferent neurons in response to noxious stimuli

Pain is consistent with the degree of tissue injury

Subtypes Somatic: well localized, described as sharp,

aching, throbbing Visceral: more diffuse, described as

gnawing or cramping Portenoy RK 2001

Neuropathic Pain Pain believed to be sustained by aberrant

somatosensory processing in the peripheral or central nervous system

Pain history

Pain is what the patient says hurts

Pain historyphenomenology

Temporal • Acute / recurrent / persistent• onset and duration• daily course

Intensity: ask the patient to rate• Average/worst / least / current

Topography: determine if pain is• Focal / multifocal / referred / deep

Quality: ask if it is• Numb/aching/stabbing/shooting/burning

Exacerbating relieving factors,

Pain history continued Medication

Side effects Organ function

Fears

Psychosocial context

World view/meaning

Narrative

Measurement

Visual Analogue Scale

0 1 2 3 4 5 6 7 8 9 10

No pain Moderate pain

Worst pain

imaginable

Examination (Diagnose the cause)

Appearance

Location

Tenderness

Weakness

Paraesthesia

Investigationif it will aid management.

Only if potential benefit to patient May help identify management

option,XRAY (bone or joint pathology/ bowel obstruction) ,Bone Scan, CT, MRI

Investigation

Always in context benefit v burden

No mater how ‘simple’ the test, it may be abandoned as futile, if burden (as perceived by patient) outweighs potential benefit to patient.

Equally investigation may significantly guide appropriate treatment eg fractured neck of femur, best pain management is surgical management.

Approach to Pain Management

Raise the patients pain threshold Peripherally acting drugs eg paracetamol, Identify and engage a patient’s

psycho/social/spiritual resources Decrease the noxious stimulus

If appropriate disease modifying treatments eg surgery, chemotherapy, radiotherapy.

Treat other cause eg infection Use appropriately titrated strong opioid (centrally

acting). Diagnose, appropriately manage neuropathic pain,

consider specialist referral.

Approaching cancer pain relief European Journal of Pain, Volume 5, Supplement 1, December 2001, Pages 5-14 J. Norelle Lickis

Approach to Pain Management

Address psychosocial issues Anxiety Depression Spiritual distress Family conflict Financial issues

Principles of analgesic use

Three classes1. Nonopioid (paracetamol and

NSAIDs), 2. Opioid (weak and strong) and 3. Adjuvant (e.g.corticosteroids,

antidepressants, anticonvulsants, muscle relaxants).

WHO Method for Relief of Cancer Pain: 'By the mouth’

i.e. oral 'By the clock’ i.e. regular 'By the ladder'

(next slide)

Individualise treatment

Pay attention to detail

WHO ladder

Non opioids +/- adjuvant

Step 1

Step 2

Step 3

Weak opioid

+ non opioid

+/- adjuvant

Strong opioid

+ non opioid

+/- adjuvant

World Health Organization (1986) Cancer Pain Relief. World Health Organization, Geneva.

'Broad-spectrum analgesia'

The concept behind the analgesic ladder is

drugs from each of the three classes of analgesic are used appropriately either singly or in combination, to maximise their impact.

Step 1. Non-opioid

Use regular non-opioid as basis for analgesic regimen (WHO step 1).

Continue regular non-opioid and add in other agents (WHO steps 2 and 3) regular and prn.

Paracetamol improves pain and well being in people already receiving a strong opioid regimen. Vardy J et al 2004 J Clin Oncol 22:3389-3394

Hepatic toxicity is rare in doses less than 8g/d even in patients with chronic liver disease. Benson GD: Evaluation of the safety of acetaminophen in chronic liver disease. Clin Pharmacol Ther 33:95-101, 1983

WHO Step 2. Opioid analgesia

Opioid therapy is first line approach for moderate or severe cancer pain

Opioid therapy can relieve > 75% of cancer related pain

WHO Cancer Pain Relief 2nd ed a Guide to Opioid Availability. Geneva WHO 1996.

Opioid pharmacology

Opioids mimic actions of endogenous opioid compounds (endorphins)

Mu, kappa, delta Multiple subtypes Spinal cord, brain stem and peripheral

tissue

Portenoy RK 2001.

Dosing

Take into account• Is patient ‘naïve’ to opioids• pain aetiology• current 24hr dose• Absorption (decreased in constipated pt)• organ function• age• Co-morbidity• side effect v benefit

Titration

Titrate with immediate release medication Ensure regular dose plus appropriate

breakthrough available Note equianalgesic ratios Once stable convert to:

• Slow release• Trans-dermal if indicated

Routes of administration Oral where possible Slow release once requirement stable Subcutaneous if parenteral indicated (poor

swallowing, vomiting or constipation which may decrease absorption)

No indication for intramuscular Intravenous occasionally e.g PCA (patient

controlled analgesia) Consider trans-mucosal (expensive) Transdermal (only once stable)

Breakthrough pain

A transient, symptomatic exacerbation of pain

Exacerbations Pain that can occur as a

symptomatic overlay to baseline persistent pain.

Also described as "episodic," "incidental," and "transient" pain.

Breakthrough pain a transient exacerbation of pain

Superimposes otherwise stable baseline pain.

Describes worsening pain intensity as well as the transient nature of BTP symptoms.

Breakthrough pain a transient exacerbation of pain

For this definition to apply, baseline persistent pain should be stable.

Unstable baseline pain suggests the possibility that the baseline pain may not be accurately assessed or managed.

Widely changing baseline levels of pain may indicate:

• unrecognized breakthrough phenomena or • Inadequately treatment of persistent pain

• analgesics lacking enough potency or • duration of effect (dose).

Breakthrough pain Subtypes of Breakthrough Pain (BTP)

Bennet D, Burton AW, Fishman S, et al. Consensus panel recommendations for the assessment and management of breakthrough pain: part 1. Treatment. Pharmacol Ther. 2005;30:296-301.

http://www.medscape.com/viewprogram/4270

Anticipatory doses Given prophylactively prior to

expected painful activity eg mobilising, dressing changes or other procedure.

Timed to coincide with the peak plasma concentration of particular analgesic eg 20mins Endone or oral morphine.

Dose adjustment

If the patient's pain improves, e.g. as a result of radiotherapy or a nerve block, dose reduction may be required to prevent side effects e.g. sedation.

• Hanks GW, Twycross RG, Lloyd JW. Unexpected complication of successful nerve block. Morphine induced respiration precipitated by removal of severe pain. Anaesthesia 1981; 36;37-39

Opiophobia - myths to be dispelled

Nearly all patients and many clinicians fear that morphine Is addictive even if used correctly for pain Should be reserved for patients who are

dying because • It may hasten death• Tolerance will limit duration of effective analgesia

Side effects are worse than pain

There is evidence to support the consensus that none of these are true

Tolerance to strong opioids

Patients fear tolerance (“I don’t want morphine until I really need it!”)

Disease progression is the major factor in opioid dose increases in cancer pain management.

Increase in pain will usually respond to up titration of opioid dose.

Patients who have pain and receive opioid analgesia. live longer than those who don’t receive opioids

• Collins E, Poulain P Gauvin-Piquard A et al Pain 1981; Suppl 1:S39.• A Thorns; N Sykes The Lancet; Jul 29, 2000; 356, 9227; pg. 398

Tolerance to strong opioids. In practice rarely a problem. Patients fear of developing psychological

dependence (addiction) is unfounded Should not limit the use of strong opioids for

cancer pain. Caution in this respect should be reserved for

patients with a present or past history of substance abuse.

Patients with significant cancer pain and a history of drug use often require a steep titration phase for opioid therapy. Seek specialist help.

Twycross R, Wilcox A et al Palliative Care Formulary 2002

Opioid Substitution

In patients who have intolerable adverse effects with morphine, it may be necessary to substitute an alternative strong opioid.

If increase in dose is met by unacceptable side effects with no improvement in pain.De Stouts, Bruera E, Suarez-Almazor AAM: Opioid rotation for toxicity reduction in

terminal cancer ptients. J Pain and Symptom Manage 1995; 10:378-384

Respiratory Depression

Pain is a physiological antagonist to the central depressant effects of morphine

Chronic dosing with appropriately titrated strong opioids do not cause clinically important respiratory depression in cancer patients in pain when used correctly.

Caution in sleep apnoea (CAL generally safe if correct titration)

Twycross R, Wilcox A et al Palliative Care Formulary 2002

Respiratory Depression

Less likely when patients: are not opioid naive take medication by mouth (slower

absorption, lower peak concentration) titration of the dose upwards occurs

step by step (less likelihood of an excessive dose being given).

Opioid side effects Constipation

Education and prophylaxis for almost all patients e.g. Movicol, Coloxyl with Senna

Avoid bulking agents Nausea

Consider prophylaxis if pt nervous or history of nausea

Neurotoxicity • Mild: subjective experience of altered mental state, • moderate: drowsiness, • severe: delirium, myoclonus, seizures (inappropriate

titration or organ failure)

Organ Failure Renal failure significant in terms of

increased elimination half life and accumulation of toxic metabolites Dose adjustment Dosing interval adjustment

Choice of analgesic - seek specialist advice

Organ Failure Liver failure in practice largely not

significant

Hepatic encephalopathy, as with any cause of delirium may increase neurotoxic side effects.

Summary 1

1. 75% of cancer pain can be controlled with simple measures eg appropriately titrated morphine and regular paracetamol

2. Don’t forget constipation prophylaxis3. Dose adjust in renal failure4. Have a high index of suspicion for co-

morbid delirium (eg infection, hypercalcaemia) if confusion develops

5. Avoid the traps of opiophobia

Summary 2

1. Reduce the noxious stimulus• Diagnose the cause• Treat where possible and appropriate• Use regular non-opioid eg paracetamol

2. Raise the patient’s pain threshold• Address bio/psycho/social/spiritual patient needs and resources

3. Opioids: first line treatment for moderate to severe Ca pain.

• Use appropriate regular + prn / route / choice of drug / care in renal failure.• Address myths and opio-phobia

4. Know how to diagnose and manage neuropathic pain

• Patient descriptors numb/shooting/burning/toothache like

5. Consult specialist as required6. Don’t neglect the patients psychosocial issuesVardy J et al 2004 J Clin Oncol 22:3389-3394

References

1. Hanks GW, et al. Morphine and alternative opioids in cancer pain: the EAPC recommendations BRITISH JOURNAL OF CANCER 84 (5): 587-593 MAR 2 2001

2. Lickiss JN. Approaching cancer pain relief. Eur J Pain 2001; 5 (Suppl A): 514

3. Glare, P et al Ongoing controversies in the pharmacological management of cancer pain. INTERNAL MEDICINE JOURNAL 34 (1-2), 45-49.

4. Thorns A, Sykes N. Opioid use in the last week of life and implications for end-of-life decision-making. LANCET. 2000 Jul 29;356(9227):398-9.

5. Indelicato RA, Portenoy RK, : Opioid rotation in the management of refractory cancer pain. JOURNAL OF CLINICAL ONCOLOGY 20 (1): 348-352 JAN 1 2002