Pain Control

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 AnaphylaxisARDS

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 bloodfaster 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.