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Managing Pain (effectively!)

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Presentation on theme: "Managing Pain (effectively!)"— Presentation transcript:

1 Managing Pain (effectively!)
Alec Price-Forbes Consultant Rheumatologist March 21st 2012

2 Mrs W OA, Inflammatory arthritis April 2010 unwell anaemic, APR raised
July 2010 presumed osteomyelitis right ankle September 2010 Staph sepsis Cervical discitis ? SBE

3 Mrs W 3/12 IV antibiotics November 2010 - septic - CCU for inotropes
- drowsy On fentanyl 175mcg/hr What is PRN dose What dose of diamorphine would you convert to?

4 Aims To consider general aspects of pain relief What is pain?
To consider issues around assessing and diagnosing pain To understand the principles of choosing an analgesic To understand the use of morphine and appropriate dose calculations

5 What is pain? How would you describe and define pain?
- please share thoughts with your neighbour

6 The background 6

7 What is pain? Pain is perceived along a spectrum from peripheral pain receptors to the cerebral cortex and is modified at every step along its travel Pain is an unpleasant, complex, sensory and emotional experience Pain is a distressing experience for the patient Pain is what the patient says it is

8 Causes of failure to relieve pain
Reasons Belief that pain is inevitable Inaccurate diagnosis of the cause Lack of understanding of analgesics Unrealistic objectives Infrequent review Insufficient attention to mood and morale Consequences Unnecessary pain Inappropriate Rx Use of inappropriate, insufficient or infrequent analgesics Dissatisfaction with Rx Rejection of Rx by patient Lowered pain threshold Adapted from Twycross Update 1972

9 Total Pain Spiritual Physical Total Pain Social Psychological
Saunders 1964

10 Chronic pain is different…

11 Ms. Unhappy Why can’t you fix my back and fxxk off 11

12 Ms. Unhappy 33 year old woman, accident at work
“lifted something heavy and felt a click at the back” MRI: unremarkable Nociception 12

13 Ms. Unhappy She felt so bad that she cannot sleep, cannot eat, and became irritable Affect 13

14 Ms. Unhappy She cannot work, cannot go out, cannot do housework, cannot…. Social 14

15 Ms. Unhappy She insisted in using a walking aid, visited 4 doctors for the “right diagnosis”, alcohol to “knock me off the pain” Behavior 15

16 Acute versus chronic pain
Acute (eg fracture) Obviously in pain Complains of pain Understands why they have pain Primarily affects patient Chronic (eg neuralgia) May only seem depressed May only complain of discomfort May see pain as never-ending/meaningless Pain overflows to affect others

17 Definitions Nociception Pain threshold versus pain tolerance Allodynia
Analgesia Dysasthesia

Nociceptive – associated with tissue distortion or injury Caused by tissue damage injury – information carried to the brain via normal nerves

Neuropathic – associated with nerve compression or injury The nerves carrying the information to the brain are abnormal and are associated with abnormal sensations Nerve compression Nerve crushing/destruction Nerve being cut

20 Issues in assessing pain
Where is it? What is it like? How long has it been present? How severe is it? Does it spread anywhere else How is it affecting functioning? What are the goals for the pain?

21 Managing Pain Take a good history and examine the patient
Think about the cause or type of pain Somatic Visceral Neuropathic Establish patient’s expectations, priorities Choose appropriate medication Set realistic goals, negotiate a plan 3 Types Can be acute or chronic Can all occur together or alone and at different times Somatic -activation of pain receptors in cutaneous or deep (muskuloskeletal) tissues (e.g. bone metastasis, post surgical incision pain) Dull/aching, localized for deep, sharper or prickling if superficial Visceral -activation of pain receptors from stretching, compression, infiltration of viscera (e.g. pancreatic pain) Pressure, deep, squeezing, not well-localised Neuropathic -compression, invasion or damage to nervous system Severe, burning, tingling

22 Problems in assessing pain
Think about TWO problems that could make it difficult to assess someone’s pain?

23 Common mistakes in pain management
Forgetting there may be more than one pain Reluctance to prescribe morphine Failure to explore holistically Failure to educate patient about dose, timing, side effects and deal with their fears Reducing the interval instead of increasing the dose

24 Problems in assessing pain
The number of different pains (50% of patients have 3 or more different pains) Not all pains respond to morphine Patients underplaying their pain Patients reacting markedly to their pain (usually anxiety, anger or depression are present) Staff or partners assessing a patient’s pain The patient with poor or absent communication

25 Help with assessing pain
Ask the patient highly accurate Ask the partner subject to bias Body chart involves patient VAS some patients stuggle with the concept Pain diary qualitative research Pain questionnaire

26 Diagnosing Pain Bone metastases produce pain worsened with movement
Muscle pain produces pain on active movement Chest infection causes pain worse on inspiration Constipation causes pain at rest in the abdomen which is periodic Neuropathic pain causes an unpleasant sensory change at rest, sometimes with pain on touching

27 Pain behaviours/signs where communication impaired
Expressive: grimacing, clenched teeth, shut eyes, wide open eyes Adaptive: rubbing or holding area, keeping still, reduced or absent function Distractive: rocking, pacing, biting, clenched fists Postural: increased muscle tension, limping Autonomic: sympathetic, parasympathetic

28 Analgesic Mantra By the Mouth By the Clock By the Ladder
Attention to detail and regular reassessment By the Mouth By the Clock By the Ladder Individualised Treatment Attention to detail

29 Types of analgesic Primary Non-opioids eg paracetamol
Weak opioid agonists eg codeine, DF118 Strong opioid agonists eg morphine, diamorphine, fentanyl, oxycodone Opioid partial agonist/antagonists eg buprenorphine NSAIDs NMDA antagonists eg ketamine, methadone Nitrous oxide

30 Types of analgesic Secondary analgesics
Adrenergic pathway modifiers eg clonidine Antibiotics Anticonvulsants eg CMZ, gabapentin Antidepressants eg amitriptyline Antispasmodics eg hyoscine Antispastics eg Baclofen Corticosteroids Membrane stabilising drugs eg flecanide, lidocaine NSAIDs

31 WHO Pain Ladder Consider nerve block Structured yet flexible
Selection of analgesics guided by intensity of pain vs cause Approx 80% gain relief from pain by adopting these basic principles Adjuvants: Non analgesic drugs eg Amitriptylline for neuropathic pain Psychotropic drugs eg sleeping tablets and antidepressants Side effect drugs eg antiemetics and laxatives Step 2 weak opioids and NSAIDS- ?need for step 2. Codeine metabolised to morphine via cytochrome enzymes. Codeine is much weaker agonist at mu receptors than morphine. Small proportion of Caucasians and smaller prop Asians are unable to metabolise, therefore poor responders. 8mg codeine plus paracetamol confers no benefit over paracetamol alone. Tramadol is a weak opioid and SSRI. Max dose limits usefulness

32 WHO Analgesic staircase
Use non-opioids, weak opioids and strong opioids as the 3 steps However, not all pain opioid responsive (eg colic, neuropathic pain) Consider adjuvants for each patient Different pains need different analgesics

33 Opioids Agonists at opioid receptors (mu, kappa, delta) in spinal cord and brain Differences between opioids relate to differences in receptor affinity Morphine is the strong opioid of choice- cost, effectiveness, no ceiling effect

34 CASE SCENARIO In groups of 3, work through the first 4 questions

35 Opioid choice Morphine given Orally Regularly Prevents pain
Haloperidol treats nausea Injections are unnecessary No addiction is seen and Early use is best Morphine is still the gold standard opioid: It has more evidence for its use and safety No evidence that other opioids are better 30 years use Wide safety margin Well tolerated in most people

36 ANSWER Q1 F never delay using if pain requires a strong opioid
T aim is not simply to treat pain, but prevent recurrence F injection route more potent (less drug needed for same effect) but is not more effective F morphine is converted to active metabolites so reduced liver function has little effect T active metabolites are excreted via kidney

37 Starting Opioids What concerns might patients have about starting morphine?

38 Dependence and Addiction
Dependence- state in which an abstinence syndrome may occur following abrupt opioid withdrawal or administration of opioid antagonist. Addiction - characterised by psychological dependence

39 Morphine dose timing For continuous pain analgesia should be continuous Regular administration should enable good pain control and prevent it returning Do not rely on PRN PRN = ‘PAIN RELIEF NIL’

40 Indications for injections
Inability to tolerate other routes (eg nausea and vomiting) But NOT because of poor pain control: Giving injections means need less drug to have same effect But it cannot be more effective because it’s the same drug

41 Metabolism Morphine is absorbed from small bowel, metabolised in liver to active metabolite (morphine 6-glucuronide, M6G) which is renally excreted Liver impairment has little effect; kidney impairment does affect handling Other metabolites (eg M3G) also renally excreted and can accumulate

42 Strong Opioids Immediate release (peak concentration after 1h, duration of action 1-4 hours) Oramorph, Sevredol, OxyNorm Modified release (peak concentration after 2-6 hours, duration 12-24h depending on formulation) MST, MXL, Oxycontin Oramorph 10mg/5ml and 20mg/ml strengths

43 Starting morphine (5mg – 10mg) 4hrly + 30mins prn (& laxative) (2.5 mg 4hrly if previously on non-opioid) 4hrly dose plus prn dose over 24hrs=TDD (total daily dose) TDD/2= 12 hourly (bd) dose TDD/6= prn dose Median dose for morphine is 100mg/day so PRN is 15mg 4-hrly 90% patients managed with morphine dose <500mg 43

44 Question 3 NO high dose would produce adverse effects and deter patient from continuing with an effective drug NO usually any increase is done third day NO useful rule is to increase by half (50%) Yes increase by 50% of dose every third day

45 Calculate breakthrough dose for
MST 30mg bd MST 60mg bd MST 120 mg bd MST 1500 mg bd MST 3000 mg bd 45

46 Dose titration 12 hourly dose & total prn use= new TDD
New TDD/2= new 12 hourly dose New TDD/6= new prn dose 46

47 Calculate new MST dose and breakthrough dose for
MST 10mg bd and 4 doses of oramorph 2.5 mg MST 120 mg bd and 2 doses of oramorph 40mg MST 600 mg and 6 doses of oramorph 200mg 47

48 Case scenario Please do questions 5-7

49 Q5 Morphine worries Feeling drugged is unlikely since tolerance to may side effects is rapid (effects wear off quickly) Tolerance to analgesia is not seen (pain relief does not wear off with time) Withdrawal symptoms are likely if morphine stopped abruptly but not if reduced slowly eg. over 5 days Addiction to morphine is unlikely. Circumstances in which they take morphine does jot encourage addictive behaviour Constipation is very likely Hallucinations, confusion and nightmares very unlikely

50 Q6 True intolerance to opioids very unusual and allergy rare
REAL INTOLERANCE Fear of opioids is commonest cause of intolerance but can be managed by explanation Reduced drug clearance Morphine and oxycodone accumulate in renal impairment; fentanyl, methadone little effect Opposite for liver impairment APPARENT INTOLERANCE Dose too high Titration too rapid Conversion ratio incorrect Other cause of confusion (biochemical, infections, other drugs) Constipation

51 Changing the route of administration
po morphine > sc morphine po morphine > sc diamorphine po morphine > sc oxycodone po oxycodone > sc oxycodone 1/2 1/3 1/4 51

52 STRONG OPIOIDS Morphine – global strong oral opioid of choice
Morphine – s/c if unable to take oral morphine (When changing to Morphine (s/c) from morphine (oral) give 1/2 of the PO morphine dose) Fentanyl – transdermal patch or sublingual

53 Alternative Strong Opioids
Equivalent potency to oral morphine Key points Oxycodone = 1/2 x oral morphine dose (10mg oral oxycodone = 20mg oral morphine) Patients experiencing toxicity with another opioid Diamorphine =1/3 oral morphine dose (10mg diamorphine sc = 30mg oral morphine More soluble than morphine, used in CSCI Buprenorphine BuTrans 7 day patch 20 micrograms/h = mg oral morphine Transtec 3-4 day patch 35 micrograms/h = mg oral morphine In practice main route used is transdermal Useful in renal disease or when oral route not possible For CONTROLLED pain Methadone specialist use Hydromorphone used less often as oral alternative in renal impairment or toxicity with alternative opioids Alfentanil used in renal failure

54 Alternative Opioids Fentanyl Patches
Adhesive patch delivering a constant amount of fentanyl per unit time: e.g. 25 micrograms/hour Less constipation, sedation and nausea Preferable in serious renal impairment Change every 72 hours Takes up to 24 hours to start or stop acting For controlled pain Need to supply breakthrough morphine or oxycodone

55 Equivalent doses of fentanyl
Fentanyl patch dose Approximate equivalent dose of oral morphine in 24 h Breakthrough dose of morphine 12mcg/h 45mg 5-10mg 25 mcg/h 90mg 10-20mg 50mcg/h 180mg 20-35mg 75mcg/h 270mg 35-45mg

56 STRONG OPIOIDS continued
Hydromorphone – analogue of morphine with similar pharmacokinetics Oxycodone – similar properties to morphine. Less SE’s in some patients Methadone – needs to be started as inpatient

57 Starting Opioids Dorothy, 63y diagnosed with advanced ovarian cancer
Constant low abdominal pain Bowels regular Taking co-codamol 30/500, 2 tablets qds What dose of morphine would you start? How would you advise her to take it? MR or IR titration, breakthrough analgesia, laxatives and anti-emetics

58 Name and address of the patient The name of the drug
The form and strength of the preparation The total quantity of the preparation, or the number of dose units, in both words and figures Dosing instructions Dosing instructions (“prn”  “one prn” ) Prescription valid for 28 days Quantity 30 days only (DH Guidance, 2006)

59 Nerve Damage Membrane stabilizing drugs Tricyclics
Anti-epileptic drugs eg. Carbamazepine Gabapentin

60 Routes of administration
Oral : Tablets / Liquids Rectal Sublingual / Transdermal Parenteral / Subcutaneous

61 Other forms of treatment
Physiotherapy Hot / Warm TENS stimulation Acupuncture Hypnosis Complementary therapies Relaxation therapies Treating of underlying psychological, social, spiritual distress

62 Mrs W Fentanyl 175 What is equivalent morphine/diamorphine dose?

63 Summary Pain is a subjective “total” experience and assessment and management must take this into account The WHO Ladder provides a framework for managing pain There are a number of opioid medications, with morphine being the opioid of choice in most situations Adjuvant drugs are an important part of pain management

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