Pain HO Training Module

Pain & Its Management

Anaesthetic House Officer Training Module

Kementerian Kesihatan Malaysia

“Those who do not feel pain seldom think that it is felt.”

Dr. Samuel Johnson

(1709-1784)

Definition of Pain

“An unpleasant sensory and emotional

experience associated with actual and potential tissue damage or described in terms of such damage”

IASP Subcommitee on Taxonomy. Pain 1980; 8:249-252

Definition of Pain

Pain is what the patient says, hurts

Nociceptors

1. A-delta fibers myelinated

2-30 m/sec (1st pain)2. C-fibers unmyelinated <2 m/sec (2nd pain)

The Pain Pathway

First Order Neurons Second Order Neurons ↓ ↓

Ascending Pain Pathway (Acute Pain) Cerebral cortex Sensory Cortex ↑ 3rd Order ↑Thalamus Spinothalamic ↑ ↑Midbrain Spinomesencephalic ↑ Pons ↑ Medulla Spinoreticular ↑ 2nd Order Dorsal Root ↑ 1st OrderNociceptors

Pain Pathway

Free nerve endings

Afferent nerve – ( A / c)

Spinal cord

Sensory cortex

Thalamus

Descending inhibitory fibres

Dorsal horn

PAG / RAS

Ascending ST tracts

5th Vital Sign: Doctors’ training module: Pain Physiology

PAIN

Effects of Pain

I. Physiological - Cardiovascular System- Respiratory system- Gastrointestinal system- Genitourinary system- Central Nervous System- Endocrine system

II. PsychologicalIII. Economic

Increased Heart RateIncreased Blood Pressure

→ increased myocardial work load→ myocardial oxygen consumption→ increased risk of myocardial ischaemia

Cardiovascular System

5th Vital Sign: Doctors’ training module: Pain Physiology

Respiratory system

Inhibition of normal respiration (unable to take deep breaths) AtelectasisHypoxia

Inability to cough Retention of secretions Increased risk of lung infection / pneumonia

5th Vital Sign: Doctors’ training module: Pain Physiology

Gastrointestinal System

Increased sympathetic and reduced parasympathetic activity

→ Reduced smooth muscle + sphincter tone→ Reduced gut motility→ Ileus, nausea + vomiting→ Impedes early feeding

5th Vital Sign: Doctors’ training module: Pain Physiology

Genitourinary System

Increased sympathetic and reduced parasympathetic tone

→ reduced smooth muscle + sphincter tone → urinary retention

5th Vital Sign: Doctors’ training module: Pain Physiology

Musculoskeletal system

Prevent mobilisation & increases muscle tone

→Increased risk of deep vein thrombosis

5th Vital Sign: Doctors’ training module: Pain Physiology

Central Nervous System

• sympathetic activity • parasympathetic activity HyperalgesiaHyperalgesia

“scarring” of pain pathways ↓

Increased risk of developing chronic pain

5th Vital Sign: Doctors’ training module: Pain Physiology

Endocrine System Stimulation of stress response ↓ Increased sympathoadrenal activation

Metabolic response to stress Hyperglycemia Catabolic state ↓

Immunosuppression ↓ ↑ risk of infection

m

5th Vital Sign: Doctors’ training module: Pain Physiology

Anxiety Agitation

→ poor sleep → uncooperative patient

Psychological

5th Vital Sign: Doctors’ training module: Pain Physiology

Economic

Delayed ambulation and feeding Increased postoperative complicationsDelayed recoveryProlonged hospital stayIncreased cost

5th Vital Sign: Doctors’ training module: Pain Physiology

Spectrum of Pain

ACUTE PAIN

CHRONICPAIN

ACUTE PAIN

Healing

NO PAIN

CHRONICPAIN

Insidious onset

post-surgical syndromes / cancer

5th Vital Sign: Doctors’ training module: Pain Physiology

5th Vital Sign: Doctors’ training module: Pain Physiology

Acute vs Chronic PainAcute Pain Chronic Pain

Onset and timing

Sudden onset, short duration.

Resolves/disappears when tissues heal.

Onset may be insiduous. Pain persists despite tissue healing.

Signal A warning sign of actual or potential tissue damage

Not a warning signal of damage : a false alarm

Severity Severity is correlates with amount of damage.

Severity not correlated with damage.“Good days” and “Bad days”.

CNS involvement

CNS intact – acute pain is a symptom

CNS may be dysfunctional – chronic pain is a disease

Psychological effects

Less, but unrelieved pain anxiety & sleeplessness (which improves when pain is relieved)

Often associated with depression, anger, fear, social withdrawal, etc

Common causes / examples

Surgery, fracture, burns, myocardial infarct, labour and childbirth, inflammatory conditions e.g. abscess

Chronic headache, back pain, chronic pelvic / abd pain, cancer pain, neuropathic pain – PHN, DPN, post stroke pain, etc

Assessment of Pain

• Pain is both a physical and a psychological phenomenon

• The pain experience is subjective

• Meaningful evaluation and successful treatment of a patient with pain requires quantification of the patient’s pain

Pain as the 5th Vital SignGuidelines for Doctors

(Management of Adult Patients)

Pain as the 5th Vital SignGuidelines for Doctors

(Management of Paediatric Patients)

How to assess pain:

• P : Place or site of pain• “Where does it hurt?” (a body chart might help describe their

pain)

• A : Aggravating factors• “What makes the pain worse?”

• I : Intensity• “How bad is the pain?”

• N : Nature and neutralizing factors• “What does it feel like” “What makes the

pain better?”

5th Vital Sign: Doctors’ training module: Pain Assessment

P Place Where is your pain?

A Aggravating factors

What makes the pain worse?

I Intensity If 0 is no pain and 10 is the worst pain imaginable: What is your pain score now?What is the worst level of pain (score) you experience in a day?What is the least pain (score) you experience in a day?

N NatureNeutralizing factors

Describe your pain – e.g. aching, throbbing, burning, shooting, stabbing, sharp, dull, deep, pressure, etcWhat makes the pain better?

Guideline 1Pain Assessment Guide: Taking a Brief Pain History

“TELL ME ABOUT YOUR PAIN……”

Pain Measurement Tools : Adults

Combined NRS/ VAS Scale Combined NRS/ VAS Scale (KKM)

NRS/

NRS : Numerical Rating ScaleVAS : Visual Analog Scale

Pain Measurement Tools : Paediatrics

FLACC Scale Wong-Baker Faces Scale

WHICH TOOL TO USE to measure pain?

Use the standard tool for pain assessment as recommended by Ministry of Health, Malaysia

– adult patients : combined NRS / VAS scale– paediatric patients 1 month to 3 years old : FLACC – paediatric patients > 3-7 years : Wong-Baker FACES scale– paediatric patients >7 years : combined NRS/VAS scale

(same as for adults)

*Always use the same tool for the same patient*Always use the same tool for the same patient

5th Vital Sign: Doctors’ training module: Pain Assessment

Flow Chart : Pain as the 5th Vital Sign (Nurses)

Flow Chart for Pain Management in Adult Patient: (Doctors)

Analgesics↙ ↘

↙ Non Opioids

– Paracetamol– NSAIDS– COX 2 inhibitors

↘ Opioids

– Weak– Strong

315th Vital Sign: Doctors’ training module: Pharmacology

Formulations And Dosage Of Commonly Used Analgesics

0-3

4-6

RegularHigher dose of weak opioidOr IV/SC Morphine 5-10mg 4 hrly OR Aqueous morphine 10-20 mg ± PCM 1gm QID oral / rectal± NSAID / COX2 inhibitor

MILD

MODERATE

SEVERE

RegularNo medication or PCM 1gm 6hrly

RegularWeak Opioid

± PCM 1gm QID oral± NSAID / COX2 inhibitor

PRNPCM &/or

NSAID / COX2

inhibitor

7-10

PRNIV/SC Morphine 5-10mg OR Aqueous morphine

*Oral or SC Morphine may be safely given at hourly intervals

PRNAdditional weak opioid

UNCONTROLLED

To refer to APS for:PCA or Epidural or other form of analgesia

Analgesic Ladder for Acute Pain Management

Guideline 4Drugs in Acute Pain Management: The Analgesic Ladder

Post Operative Pain Management1.Conventional Methodsi. Oral Analgesics Opioids∙ ∙ NSAIDSii. IV Injections Opioids∙ ∙ NSAIDS

2. Common Methods i. Patient Controlled Analgesia (PCA)ii. Epidural Analgesiaiii. Patient Controlled Epidural Analgesia (PCEA)iv. Subcutaneous Morphine

3. Other Methodsi. Nerve & Nerve Plexus Blocksii. Transcutaneous Electrical Nerve Stimulation (TENS)iii. Rectal NSAIDS 4. Multi-modal Concepts

PATIENT CONTROLLED ANALGESIA (PCA)

• Method of analgesic delivery : computerised syringe pump is set to deliver bolus doses whenever patient presses button (patient demand)

• Allows small amounts of analgesic to be given at frequent intervals

• Patient titrates according to individual needs

DILUTION OF PCA DRUGS

Morphine: • Adults: 5 amp (50 mg) = 5 mls Dilute with N/S 45 mls Concentration : 1mg/ml (50mls)• Paeds: 0.5mg/kg of morphine and make upto 50mls with N/S. Concentration: 1ml = 10mcg/kg

Recommended settings (example )

• Drug concentration: morphine 1mg/ml

• Mode: PCA

• Loading dose: usually zero for post operative patients

• Bolus dose: <60 years morphine 1mg >60 years morphine 0.5mg

• Lockout interval :5 minutes

• 4 hour limit : usually not set

EPIDURAL ANALGESIA

Introduction of analgesic drugs into epidural space via an indwelling catheter

EPIDURAL ANALGESIA :DRUGS USED

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