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 Overview
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
The Context Symptoms of debility Non-cancer pathology Side effects of therapy Cancer Loss of social position Bureaucratic bungling Loss of job prestige and income SOMATIC SOURCE Friends not visiting Loss of role in family TOTAL PAIN Delays in diagnosis Chronic fatigue and insomnia DEPRESSION ANGER Unavailable doctors Sense of helplessness Irritability ANXIETY Disfigurement Therapeutic failure Fear of pain Fear of hospital or nursing home Family finances Worry about family Loss of choices Fear of death Uncertainty about future Spiritual (existential) unrest
Pain Assessment: Goals Diagnose the cause
Nociceptive pain Neuropathic pain Commensurate with identifiable tissue damage May be abnormal, unfamiliar pain, probably caused by dysfunction in PNS or CNS Pathophysiology
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 Worst pain imaginable No pain Moderate pain
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 classes • Nonopioid (paracetamol and NSAIDs), • Opioid (weak and strong) and • Adjuvant (e.g.corticosteroids, antidepressants, anticonvulsants, muscle relaxants).
'By the mouth’ i.e. oral 'By the clock’ i.e. regular 'By the ladder' (next slide) Individualise treatment Pay attention to detail WHO Method for Relief of Cancer Pain:
WHO ladder Strong opioid + non opioid +/- adjuvant Weak opioid + non opioid +/- adjuvant Step 3 Non opioids +/- adjuvant Step 2 Step 1 World Health Organization (1986) Cancer Pain Relief. World HealthOrganization, 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 paina transient exacerbation of pain • Superimposes otherwise stable baseline pain. • Describes worsening pain intensity as well as the transient nature of BTP symptoms.
Breakthrough paina 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 • 75% of cancer pain can be controlled with simple measures eg appropriately titrated morphine and regular paracetamol • Don’t forget constipation prophylaxis • Dose adjust in renal failure • Have a high index of suspicion for co-morbid delirium (eg infection, hypercalcaemia) if confusion develops • Avoid the traps of opiophobia
Summary 2 • Reduce the noxious stimulus • Diagnose the cause • Treat where possible and appropriate • Use regular non-opioid eg paracetamol • Raise the patient’s pain threshold • Address bio/psycho/social/spiritual patient needs and resources • 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 • Know how to diagnose and manage neuropathic pain • Patient descriptors numb/shooting/burning/toothache like • Consult specialist as required • Don’t neglect the patients psychosocial issues Vardy J et al 2004 J Clin Oncol 22:3389-3394
References • 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 • Lickiss JN. Approaching cancer pain relief. Eur J Pain 2001; 5 (Suppl A): 514 • Glare, P et al Ongoing controversies in the pharmacological management of cancer pain. INTERNAL MEDICINE JOURNAL 34 (1-2), 45-49. • 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. • Indelicato RA, Portenoy RK, : Opioid rotation in the management of refractory cancer pain. JOURNAL OF CLINICAL ONCOLOGY 20 (1): 348-352 JAN 1 2002