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.