prof. mridul m. panditrao's pain pathophysiology, management & role of anaesthesiologist

Pain!!!!!

Dr. Mridul M. Panditrao

CONSULTANT DEPARTMENT OF ANESTHESIOLOGY AND INTENSIVE CARE

RAND MEMORIAL HOSPITAL

FREEPORT, GRAND BAHAMA

THE COMMONWEALTH OF BAHAMAS

Till 18th century there was nothing!

Remedies like Opium, Alcohol, Mandragora,

soporific sponges and Magical potions were

tried, but the dark ages of “Pain and suffering”

continued unabated

A universal problem!

For eternity, it has plagued mankind

Pain

AGE OF DARKNESS

NO ANALGESIANO ANAESTHESIA

NO DEFINED SURGERY

“AGONY GALORE!!!”

BARBARIC PRACTICES

WOODEN BOWL & WOODEN HAMMER”

PARTIAL STRANGULATION

“WHISKY BOTTLE: ½ YOU & ½ ME”

MAGIC & WITCH-CRAFT

MANDRAGORA / HASHISH / HERBS

‘ DECREE OF CHURCH’

METHODS OF PAIN RELIEF

“ DAWN OF ANALGESIA ”

FREDERICH SERTURNER:1806 MORPHINE

“LAUGHING GAS ” PARTIES & HORACE WELLS : Dec. 10, 1844, N2O IN

DENTISTRY

DEBACLE OF N2O DEMONSTRATION & SETBACK

GQC COLTON : RE-INTRODUCES N2O AS A CARRIER GAS

SWEET OIL OF VITRIOL (“WHIFF OF ETHER”)

16TH OCTOBER 1846

William Thomas Greene MORTONUSHERING IN OF “ ERA OF

ANAESTHESIA”

“INVENTOR AND REVEALER OF ANESTHETIC INHALATIONBEFORE WHOM IN ALL TIME, SURGERY WAS AGONY

BY WHOM PAIN IN SURGERY WAS AVERTED AND ANNULLEDSINCE WHOM SCIENCE HAS CONTROL OF PAIN”

WORLD ANAESTHESIA DAY

“GOOD OUT OF BAD”

LEAF CHEWING NATIVES OF ANDIES (PERU & BOLIVIA): “NUMBNESS OF

MOUTH”

COCAINE

ADVENT OF LOCAL ANALGESICS

REGIONAL: SPINAL, EPIDURAL, FIELD

“POST-OPERATIVE ANALGESIA”

“MORPHINE & COMPANY”

• NEWER OPIOIDS: FENTANYL….• “NEURO-LEPT ANAESTHESIA”• ENDOGENOUS OPIOIDS:

ENDORPHINES, ENCEPHALINS• OPIOID RECEPTORS: μ, κ, σ, δ, ε• “CUSTOM OPIOIDS” : REMIFENTANIL

INTRODUCTION

For All The Happiness Mankind can gain.Is not in pleasure

But in rest from “pain”

JOHN DRYDEN

INTRODUCTION (Contd.)

MAGNITUDE Of PROBLEM Millions of Post-op pts : 48-53% unrelieved Moderate pain in hospitalized pts: ~ 40% Child- bearing age group females : 35-43% Ch. Non-oncogenic pain; Ch. Arthritis : 25-30% Cancer Patients suffering from pain: 80%+

Panditrao MM, Pain and it’s Physiological considerations, eds, Deshpande S et al. Principles of Anaesthesia, Paras, Hyderabad, 1st edition. 2007 : 180

INTRODUCTION (Contd.)

Nociception: Transduction Transmission Modulation Perception

“Gate Control Theory of Melzac & Wall” : 1965

INTRODUCTION (Contd.)

“Reynolds Theory of ‘Supra-Spinal Descending Control in Modulation in Dorsal Horn’ ”: 1969

“Woolf C.J - Supra spinal inhibition of nociception” : 1989

INTRODUCTION (Contd.)

Definition

The International Association for the Study of Pain

“Unpleasant sensory & emotional experience associated with actual or potential tissue damage or described in term of such damage.”

CLASSIFICATION OF PAIN

• Origin

• Pathology

• Onset & Duration

Classification of Pain by Origin

Somato-sensory Pain

Deep Visceral Pain

Referred Pain

Psychogenic Pain

Classification of Pain by Pathology

Nociceptive pain

Neuropathic Pain

Classification of Pain by Onset & Duration

1. Acute- a) Surgical- (i) Pre-operative(ii) Intra-operative(iii) Post-operative

b) Non-surgical- (i) Traumatic(ii) Organic- Physiological

Pathological(iii) Psychosomatic

Classification of Pain by Onset & Duration

2. Chronic- a) Oncogenic

b) Non-oncogenic (i) Organic

(ii) Neuropathic

• Hyperesthesia• Hyperpathia• Hypesthesia• Neuralgia• Paresthesia• Radiculopathy

Terms Used In Pain Management

Terms Used In Pain Management

• Allodynia• Analgesia• Anesthesia• Anesthesia dolorosa• Dysesthesia• Hypalgesia• Hyperalgesia

Psychological and behavioural response to acute pain

fear

general sense of unpleasantness or unease

Anxiety

Negative emotions: depression

Sleep deprivation

Existential suffering: may lead to

patients seeking actively end of life.

Psychological response to chronic pain

Intermittent pain produces a physiologic response similar to acute pain.

Persistent pain allows for adaptation (functions of the body are normal but the pain is not relieved)

Chronic pain produces significant behavioural and psychological changes

The main changes are:- depression - an attempt to keep pain - related behaviour to a minimum

- sleeping disorders- preoccupation with the pain

- tendency to deny pain

Psychological response to chronic pain

• often is associated with a sense of

hopelessness and helplessness• abnormal temperature regulation,

tactile dysfunctionAlteration in sensory function dysfunctions of the general or special senses chronic pain

Immunological effects of Pain

• Decrease natural killer cell counts• Effects on other lymphocytes not yet defined.

Nociception

Transduction Transmission Modulation Perception

Panditrao MM, Pain and it’s Physiological considerations, eds, Deshpande S et al. Principles of Anaesthesia, Paras, Hyderabad, 1st edition. 2007 : 180

Nociception

• “Gate Control Theory of Melzac & Wall” : 1965

Nociception

“Reynolds Theory of ‘Supra-Spinal Descending Control in Modulation in Dorsal Horn’ ”: 1969

“Woolf C.J - Supra spinal inhibition of nociception” : 1989

Peripheral and Central Pathways for Pain

Ascending Tracts Descending Tracts

Cortex

Midbrain

Medulla

Spinal Cord

Thalamus

Pons

(Brookoff, 2000)

Pain-Sensing System in the Malfunction in Chronic Pain

(Illustration: Seward Hung, 2000)

Acute pain:Pain-sensing signals are initiated in response to a stimulus• They elicit a pain-

relieving response

Chronic pain:Pain signals are

generated for no reason and may be intensified

• Pain-relieving mechanisms may be defective or deactivated

Pain Sensing

In chronic pain, pain signals are generated without physiologic significance

Pain Pathway:s & Multimodal Analgesia

From: Gottschalk et al. Am Fam Physician. 2001;63:1979-1984.

Descending modulation

Dorsal horn

Ascendinginput

Spinothalamic tract

Dorsal root ganglion

Peripheral nerve

Peripheral nociceptors

Pain

Trauma

Local anesthetics & blocksOpioids ,2-agonistsNMDA antagonistsInterventional modalities

Opioids 2 -agonists Centrally acting analgesicsCOX-2 selective inhibitorsTraditional NSAIDs

Local anesthetics

Local anesthetics COX-2 selective inhibitors Traditional NSAIDs

Panditrao MM, Pain and it’s Management, eds, Deshpande S et al. Principles of Anaesthesia, Paras, Hyderabad, 1st edition. 2007 : 845

THE ANAESTHESIOLOGISTNOT JUST IN THE OPERATING ROOM

• Operating roomhospitalphysician office

• Labor & delivery suite• Other procedural areas• Intensive care unit• PACU• Pain management

acutechronic / cancer

• “CPCR” team• Respiratory therapy• Administration

operating roomhospitalMedical College

• Educationhealth professionalspublic

• Research

The management of pain is a multidisciplinary team effort involving physicians, psychologists,

nurses, and physical therapists.

Anesthesiologists are ‘physicians and experts’ in the diagnosis and treatment of acute and

chronic pain disorders.

American Society of Anesthesiologists. 2003

ANAESTHESIA

FOR “PAIN MANAGEMENT”:ACUTE : OPERATIVE

PHARMACOTHERAPY & SPECIAL PROCEDURES

REGIONAL & LOCAL BLOCKS

NEURAXIAL PROCEDURES

Pharmacological

Depending upon site of Action

CNS: GAAs, N2O, OpioidsPeripherally :-------- NSAIDS LAAsNeuraxially : -------- ADJUVANTS

Panditrao MM, Pain and it’s Physiological considerations, eds, Deshpande S et al. Principles of Anaesthesia, Paras, Hyderabad, 1st edition. 2007 : 180

Panditrao MM, Pain and it’s Management, eds, Deshpande S et al. Principles of Anaesthesia, Paras, Hyderabad, 1st edition. 2007 : 845

Adjuvants to Neuraxial Blockade: Why needed? Problems of LAAS

• If duration of action to be prolonged? • Motor blockade causing interference with the

mobility of the patient• Sympathetic blockade leading to bradycardia

and hypotension.

• So alternatives to LAAs were tried

ALTERNATIVES TO LAAs:Problems:

• Side effects of Opioids • Difficulty in procuring• Minimal muscle relaxation • Other agents viz. Clonidine, Neostigmine,

Ketamine, Midazolam and their side effects

LAAs & ADJUVANTS

COMBINATION!!!!

Advantages of Adjuvants

• Improvement of quality of block• Onset of analgesic effect of LAAs is enhanced • Duration of action of LAAs is prolonged• Dose requirement of each drug is reduced • Lower incidence of side effects

Routes of Administration

• In sub-arachnoid space when only SA is given

• In epidural space through epidural catheter when Combined Spinal Epidural (CSE) Analgesia is given

Various drugs used as Adjuvants

• Opioids agonists: Morphine, Fentanyl etc. Agonist /antagonist: Butorphanol,

Buprenorphine• Clonidine• Neostigmine• Ketamine• Midazolam• Tramadol

SUB-ARACHNOID BLOCK

Combined Spinal Epidural (CSE)in the Same Intervertebral

Space

Using Combipack

Combined Spinal & Epidural (CSE) in two

different Intervertebral Spaces

CONTINUOUSSUPRA-CLAVICULARBRACHIAL-PLEXUS

BLOCK

CHRONIC PAIN

Prevalence of chronic pain• - 35% in the society• - 40% in females, 31% in males• - 25% ≤ 18 years, 55% ≥ 65 years• 20% of the chronic pain population = postsurgical chronic pain

23rd International Winter Symposium in Leuven, Dr. Jan Maeyaert, 11-12 january 2008

CHRONIC PAIN

Prevalence of chronic pain• - 35% in the society• - 40% in females, 31% in males• - 25% ≤ 18 years, 55% ≥ 65 years• 20% of the chronic pain population = postsurgical chronic pain

23rd International Winter Symposium in Leuven, Dr. Jan Maeyaert, 11-12 january 2008

Prevalence and Impact of Chronic Pain on Society

• Chronic pain is one of the most common conditions for which people seek medical treatment

• 35% of Americans suffer from chronic pain

• >50 million Americans are partially or totally disabled by chronic pain

• 50 million workdays are lost per year

• $100 billion is the estimated annual cost in lost productivity, medical costs, and lost income

(American Pain Society, 2001; Gitlin, 1999; Glajchen 2001; Loesser et al, 2001)

Undertreatment of Chronic Pain>40% to 50% of patients in routine practice

settings fail to achieve adequate pain relief

In a recent study of 805 chronic pain sufferers, >50% had to change physicians to achieve relief because the physician:

was unwilling to treat pain aggressively

did not take the patient’s pain seriously

had inadequate knowledge about pain treatment

(American Pain Society, 2001; Glajchen, 2001; Lister, 1996; Portenoy, 1996)

The story of chronic pain

WHY?- Such a high incidence

- Increasing incidence by aging

- Higher in females

The story of chronic pain

The answer: a CUMULATIVE STATE of

CENTRAL SENSITIZATION over time

Ideal cocktail for

SENSITIZATION

ACUTE SOMATIC

nociceptive

ACUTE VISCERAL

nociception

Psychogenic factors(stress, anxiety)

NEUROGENIC

DAMAGE

CENTRALSENSITIZATION

Somatic Nociceptive

pain(Trauma & Surgery)

VISCERALNOCICEPTIVE

PAIN(renal/biliary

colic,dysmenorhea)

PSYCHOGENIC PAIN

(anxiety, depresseion,

prolonged stress)

NEUROPATHIC PAIN

(nerve dysfunction,nerve injury)

CENTRAL

SENSITIZATIONWIND

UP

If prolonge

d

Damage to the CNS

•Death of inhibitory neurons•Loss of

descending inhibition•Genetic

transformation of

nociceptive neurons from

high to low threshold

INTRACTABLE CHRONIC PAIN UNRESPONSIVE TO ANALGESICS

• Whatever is the initial pain mechanism• All types of unrelieved pain end as

CENTRAL NEUROPATHIC PAIN

CHRONIC PAIN is a provoked irreversibleprogressive or stabledysfunctional or neurodegenerative disease of the CNS

Role of the Anesthesiologist

Define the patients at risk

Development of preventive strategies

Early and prompt diagnosis and treatment

Information of the public and medical community

23rd International Winter Symposium in Leuven, Dr. Jan Maeyaert, 11-12 Januari 2008

Role of the Anaesthesiologist

Define the patients at risk

• Unrelieved acute pain• Anxiety• Depression• Prolonged stress• Nerve damage CNS/PNS• Recurrent surgery• Female sex/genetic predisposition

Role of the Anaesthesiologist

Develop preventive strategies

• Neuraxial or regional nerve blocks• Multimodal pain treatment protocols• Early use of antidepressants and anti-epileptics

in patients with nerve damage• Use of COX-II inhibitors• Opiate sparing strategies

Role of the Anaesthesiologist

Start early diagnosis and treatment when pain persists

• 50% reduction of chronic pain in CVA and postherpetic neuralgia pain patients by starting amitryptiline in the acute phase

• 8 fold decrease of chronic low back pain by starting multimodal therapy in the acute phase

• Patients with acute neuropathic pain after surgery do better when amitryptiline and gabapentin are started early after surgery

Role of the AnaesthesiologistInform the patients / medical community

• Negative consequences of unrelieved pain

• Possibilities to manage the pain

• Inform the surgeons - to use minimal invasive techniques - To take care of neurogenic structures - Repeat surgery for chronic pain is not an option - Surgery in a patient with a chronic pain condition is less successful - To infiltrate the site of incision with long acting local anesthetics

Chronic Pain : Oncogenic

• “Pain is what the patient says hurts!”

• “Accept the pain as what the patient says it is and not what you think it should be”

• “ Your pain is your’s and is real!”

• “Addiction/Dependance has lost it’s significance in these patients”

Chronic Pain : OncogenicTreatment Modalities:

1. Treatment of Disease (cancer) itself2. Analgesics and Adjuvants (WHO ladder)3. Custom Opioids4. Computerized drug Delivery : ‘pumps’.. PCA,

CCIP(Computerized controlled infusion pumps’5. Non-Invasive drug Delivery Devices (NIDDS):

TTS-fentanyl, EMLA, TMDS, intra-nasal, Pulm6. Implantable Neuraxial Delivery Devices (INDDS):

If pain occurs, there should be prompt oral administration of drugs in the following order: nonopioids (aspirin and paracetamol); then, as necessary, mild opioids (codeine); then strong

opioids such as morphine, until the patient is free of pain. To calm fears and anxiety, additional drugs – “adjuvants” – should be used. To maintain freedom from pain, drugs should be given “by

the clock”, that is every 3-6 hours, rather than “on demand” This three-step approach of administering the right drug in the right dose at the right time is inexpensive and 80-90%

effective. Surgical intervention on appropriate nerves may provide further pain relief if drugs are not wholly effective.

Modified WHO Analgesic Ladder

Proposed 4th Step

Pain

Step 1±Nonopioid± Adjuvant

Pain persisting or increasing

Step 2Opioid for mild to moderate pain

±Nonopioid ± Adjuvant

Pain persisting or increasing

Pain persisting or increasing

Step 3Opioid for moderate to severe pain

±Nonopioid ±Adjuvant

Invasive treatments

Opioid Delivery

Quality of Life

Deer, et al., 1999

Chronic Pain : OncogenicTreatment Modalities:

7. Neuro-stimulation-Lysis-Surgical/Anaesthesia/: tri-cyclics, anti-convulsants, TENS, Ketamine

8. Psycho Therapy & Counselling

9. Physio and Occupational Therapy

10. Miscellaneous: N/V, infections, Patho-fractures, constipation.....

CONCEPT OF PAIN CLINIC

PAIN CLINIC

Definition

The Care provided to the patients for the relief of Acute or Chronic pain of oncogenic as well as non-oncogenic origin on comprehensive, inter disciplinary and multi-dimensional basis by a team of experts with broad base of knowledge, and skills under one roof is called “multi-disciplinary approach to management of Pain” and such an establishment is called as pain Clinic.

PAIN CLINIC (CONTD.)

TEAMPhysicians : Anaesthesiologists Oncologists medical surgical radiationPsychologist/Behavioural TherapistPhysio/Occupational Therapist Nursing staffSocial Worker

CONCLUSIONPAIN

• Is all encompassing, everlasting & complex• Quest for MANAGEMENT is unending• Journey from non- existent /barbarism to

PCAs, CCIPs, TTSs, NIIDs or INDDs• From Opium, Hashish, alcohol, Mandragora &

herbs to Remifentanil, ropivacane.Must go on & on & on.........never-ending search.

..... For that avails

Valour or strength though matchless, quelled with pain

Which all subdues and makes remiss the hands

of mightiest? Sense of pleasure we may well

Spare out of life perhaps, and not repine

But live content – which is calmest life ;

But pain is the perfect misery, the worst

Of evils and excessive over turns

All patience.

John Milton - Paradise Lost

Book VI

Nociception

Transduction Transmission Modulation Perception