Pain and Pain Relief- a Brief Introduction

Dr. Reino Pöyhiä, MD, PhDConsultant in AnaesthesiologySpecial Competence in Pain Medicine, Cardiac Anaesthesia and Palliative Medicine, FinlandAssociate Professor of Anaesthesiology and Palliative Medicine, Helsinki and Turku University, FinlandHead of the Dept of Anaesthesia, Helsinki Univ Central Hosp

What is pain?

• PAIN is an unpleasant sensory AND emotional experience associated with actual or potential tissue damage OR described in terms of such damage

• IASP = International Association for the Study of Pain 1979

→ physiological sensation→ emotional experience

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Physiology

Descartes 1677, Tractus de homini

INHIBITORY DESCENDING TRACT

Different types of pain – different treatmentsTypes of pain Examples Treatments

Somatic (nociceptive) pain Rheumatoid arthritisVisceral painAcute postoperative pain

NSAID, paracetamol, steroids, opioids

Nerve (neuropatic) pain Postherpetic neuralgia Antidepressants (AMITR), antiepileptics (CARBAMAZ)

Psychogenic pain (?) Psychological problems Psychological support

Non-cancer chr pain Ischaemic heart pain Nitrates, NSAID, neuropathic pain drugs, (opioids)

Cancer pain Bone metasthases NSAID, opioids, adjuvants

Pain in advanced and progressive disease

AIDS NSAID, opioids, adjuvants- Think mechanisms!

Acute Pain Labour pain, postop pain Mechanism based!

Chronic Pain (> 6 months) Cancer pain, arthrosis Mechanism based!

Visceral pain

Assess and record pain• What´s causing the pain?• Intensity of pain

– when resting/moving– before and after treatment

• What pain prevents• Observation of “pain-related behaviour”• Surrogates of acute pain

– HR ↑– BP ↑– RR ↑

Set a goal

• Intensity of pain ALWAYS < 3/10- if not, something must be done …

• In cancer pain / palliative care– pain-free night– improvement in functionality

• Assess and follow

Transduction- nociceptive stimulus in peripheral nerve endings

-action potential in Aδ/C fibers

Transmission- Nociceptive signal ”goes” in sensory nerves to the dorsal column in spinal cord → projection neuron → spinothalamic tract → brain

Modulation- spinal cord

- brain stem, brain

- Inhibitory descending tracts

Perception- brain: ACC, SSC

Effect site of analgesics

opioids

α2-agonists

paracetamol

Psychotherapy (CBP)

Antidepressants, antiepileptics

- serotonin ja noradrenalin ↑ in the inhibitory descending tracts

TNS, DCS

α2-agonists

opioids

local anaesthetics

local anaesthetics

NSAID

physical therapy

ointments, gel

Acute postoperative pain

What can acute pain cause?

– respiratory depression– cardiovascular stress– endocrine stress– abdominal irritation (ulcus)– muscle spasms– immobilisation, thrombosis– psychologic distress– genetic changes in the body ?

Poor postoperative pain relief

• Ethically wrong!• Prolongs recovery from surgery• May lead to chronic pain!• An international problem

– which could be (easily?) solved (!)

Chronic postoperative painKehlet et al. Lancet 2006; 367: 1618-25

How well are we doing?Wu & Raja, Lancet 2011

• the number of the patients with moderate to severe postoperative pain ↓ about 2%/y 1973–1999

• but still 15-40 % patients have moderate to severe pain after surgery

Postoperative pain relief

• good surgery• preoperative planning• multimodal approach• possibilities:

– opioids– NSAIDs, paracetamol– antiepileptics, antidepressants– blocks

• choiche depends on– procedure – patient– resources

www.ebandolier.com, Feb 2003

How to improve postop pain relief?1. Assessment of pain2. Protocols

- must be composed locally – by an expert group- each patient should get NSAID/paracetamol at fixed intervals- tramadol PRN after minor surgery- pethidin or oral morphine PRN

3. Individual tailoring- if preoperative pain, consider carbamazepine preoperatively- if protocols fail, ketamine im or orally in small doses- intercostal block with bupivacaine for cholecystectomy- wound injection of bupivacaine

Chronic pain

What can chronic pain cause?

– depression– insomnia– mental irritation– helplesness– loss of apetite– loss of social contacts↓– libido ↓– human value ↓– genetic changes in the body ?

Pain in HIV/AIDSOral/skin Visceral Somatic Neuropathy/Headache

Kaposi´sSarcomaOral cavity Herpes zostercandidiasis

TumorsGastritisPancreatitisInfectionBiliary tract problems

Rheumatological diseaseBack painmyopathies

HIV related headaches:- encephalitis, meningitisIatrogenic-AZT-DDI, D4T toxic neuropathyPeripheral neuropathyHerpes zosterAlcohol, malnutritionHIV unrelated:- tension headache, migraine etc

What is causing pain in cancer patients?Cancer with different mechanisms!

– Distension of visceral organs– Arterial/venous embolisms– Bone methastases → algesic substances from the bone– Nerve compression or infiltration

Side-effects of the oncological therapies– Nerve damage due to radiation therapy/ chemotherapy– Postsurgical syndromes

Non-malignant pain– Muscular pain– Angina pectoris

Cancerpain prevalencevan den Beuken-van Everdingen et al. Oncology 2007; 18: 1437-49

• Prevalence – at all stages: 53%– at the end-of-life (methastatic cancer): 64%

• Moderate to severe pain in> 1/3 of patients during active treatments

> 2/3 of patients at the end-of-life

Undertreatment of cancer pain- an international problem

• Japani: 75 % Okayama -04

• Hollanti: 65 % Enting -07

• Saksa: 61 % Felleiter -05

• Italia: 10-55 % Apolone -09

• Kanada: 40-48 % Krou-Mauro -09

Undertreatment - why?

• patient does not tell about the pain/ask for relief • doctor does not listen/alleviate

– lack of basic knowledge– lack of pain specialists

• both – society: fear of opioids– dependency– tolerans– side-effects

• shortage of analgesics• lack of other resources

NIH Cancer Institute, British Pain Society

WHO cancer pain relief with analgesics

– By the mouth

– By the clock

– By the ladder← concomitant use of different drugs with different mechanisms

1986 Geneve

+ breakthrough pain relief

75-80 % can achieve excellent pain relief with the WHO guide

WHO analgesics ladder

■ Morphine

■ ± Adjuvants

■ ± NSAIDS

3 severe

2 moderate

■ Tramadol

■ (A/Codeine)

■ ± Adjuvant

■ ± NSAIDs

1 mild

■ ASA

■ Acetaminophen

■ NSAIDs

■ ± Adjuvants (amitriptyline, carbamzepine, ketamine)

IBUPROFEN + DICLOFENAC

TRAMAL + MORPHIN

BUT YES:IBUPROFEN + (PARACETAMOL) + (AMITRIPTYLINE) + TRAMADOLIBUPROFEN + (PARACETAMOL) + AMITRIPTYLINE + MORPHINE

How to use morphine for cancer/AIDS pain?

– individual tailoring– by the clock + PRN!– dose ↑ → effect ↑– treat side-effects: start always a laxative– when pain increases increase the dosing

• by 30-50 % of the previous daily dose OR • by adding the PRN doses to the maintenance dose

Side-effects of opioidsAddiction?

– Psychological: NEVER!– Physiological: ALWAYS! → don´t stop opioids immediatedly but

slowly, if neededTolerans?

– Vaihtelevasti, valmisteen vaihto voi auttaa! Other:

– Constipation → laxatives, stool softeners, stimulants– Nausea, vomiting → antiemetics; haloperidol, metoclopramide,

5HT-inhibitors– Itching– Respiratory depression: only in acute use– Dizziness, sleepiness, hallucinations

Side-effects vs analgesia at E-o-L

• PAIN RELIEF >> SIDE-EFFECTS (unless untolerable)

Summary• pain analysis is important• record the intensity and influence of pain before and

after treatments• treatments of pain should be based on pain

mechanisms – multimodal analgesia• undertreatment of pain is common

– may severe effects on recovery• defined protocols may improve postop pain relief• WHO cancer pain relief programme is highly effective• don´t be afraid of opioids• pain relief can be increased with supportive methods