Pain Control.

Pain Control Methods.

• Pharmacological methods.– How to decide where to start.– Individual drugs.

• Non-pharmacological methods.– Physical methods.– Psychological methods.

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What is pain?

• “An unpleasant sensory and emotional experience associated with actual or potential tissue damage. Each individual learns the application of the word through experiences related to injury in early life.”

• “Pain is what the patient says it is.”

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Pharmacological Methods of Pain Control.

• Paracetamol

• NSAIDS

• Opiates

• Local Anaesthetics

• Nitrous Oxide

• Medications aimed at treating the underlying pathology e.g. GTN for Angina

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WHO Pain Ladder.

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Paracetamol.

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Paracetamol.

• Weak inhibitor of prostaglandin synthesis.

• However no anti-inflammatory effect.

• Is there another mechanism of action?

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Paracetamol.

Side effects.

• Rashes

• Renal Impairment

• Increased risk of hepato-toxicity in liver failure.

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Aspirin.

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Meadowsweet.

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NSAIDs

Mechanism of action

• Inhibition of cyclo-oxygenase enzyme that converts Platelet Activating Factor into Prostaglandins.

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NSAIDs

Cautions and Contraindications.

• Hypersensitivity to Aspirin or NSAIDs

• Active Peptic Ulceration.

• Pregnancy – premature closure of Ductus Arteriosus.

• Renal Impairment.

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NSAIDs

Side effects.

• Hypersensitivity.

• GI Bleeding – less common with Ibuprofen

• Bronchospasm.

• Renal failure.

• Fluid retention.

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Opiates.

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Opiates.

Mechanism of action –

• Agonists/Partial Agonists at mu type Opiate Receptors.

• These are mainly in CNS, but also found in other tissues.

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Opiates.

Side effects.Type A – Related to opiate receptors inside CNS.

Hallucinations.Dysphoria.Respiratory depression.Vomiting.

Related to opiate receptors outside CNS.Constipation.Urinary retention.Hypotension.

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Opiates.

Type B - Non opiate receptor mediated histamine release.

Urticaria

Anaphylaxis

ARDS

These usually respond to anti-histamines not naloxone.

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Local Anaesthetics.

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Novocaine.

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Local Anaesthetics.

Mechanism of action.

• Defuse into axons in non ionised form.

• Ionised form blocks fast sodium channels from the inside.

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Local Anaesthetics.

Side effects - CNS.

• Circumoral numbness.

• Lightheadedness.

• Tinnitus.

• Convulsions.

• Coma.

• Respiratory arrest.

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Local Anaesthetics.

Side effects - CVS.Bradydysrhythmias.Loss of vasomotor tone.Ventricular tachydysrhythmias.

Also, Allergic reactions.Nerve injuries.Infarction of appendages with adrenaline.Pain at injection site.

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Local Anaesthetics.

• Lignocaine 3mg/kg

(double mixed with 1:200 000 adrenaline)

• Bupivucaine 2mg/kg

• Prilocaine 5mg/kg

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Entonox.

Mixture of 50% Oxygen and 50% Nitrous Oxide.

Unknown mechanism of action.

Doesn’t cause respiratory depression.

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Entonox.

• Cautions and Contraindications.

Nitrous oxide defuses out of the blood

faster than Nitrogen dissolves into it.

Entonox should not be given in any situation where expansion of a gas filled space may have an adverse effect on the patient.

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Entonox.

• Cautions and Contraindications.• Pneumothorax

• Intestinal Obstruction/Grossly distended abdomen.

• Diving injuries.

• Severe head injuries (maybe pneumocephalus)

• Middle ear surgery.

• Unconscious patients.

• Severe facial trauma.

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Other drugs.

• Amitryptaline.

• Gabapentin.

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Non Pharmacologicalmethods of pain control.

• Physical.

• Psychological.

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Stabilisation.

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“Rubbing it better”

• Gate theory of pain

• Topical preparations

• Acupressure?

Kober A, Scheck T, Greher M, Lieba F, Fleischhackl R, Fleischhackl S, Randunsky F, Hoerauf K (2002).

Prehospital analgesia with acupressure in victims of minor trauma: a prospective, randomised, double blinded trial.

Anaesth Analg 95(3) 723-727.

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Non-pharmacological methodsof Pain Control.

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Remember a time when you were alone and afraid?

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Remember a time when you werehappy?

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“children tolerate pain well”

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Distraction.

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Any questions?

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Summary.

• How to choose which drugs to use for pain control based on;– Aetiology of pain.– Amount of pain.– Individual drugs.

• Physical methods of pain control.

• Psychological methods of pain control.

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Thank You.