THIOPENTONE
Introduction:
- Ultrashort-acting barbiturate.
- Due to rapid redistribution.
- Careful injection technique to prevent intra arterial injection in antecubital fossa.
- Avoided in antecubital fossa & given in veins over outer aspect of forearm only.
Actions:
- Anticonvulsant action –
- DOC in neurosurgical procedures.
- Cerebroprotection –
- Decreases ICT, cerebral perfusion, O2 consumption & cerebral metabolic rate.
- DOC for cerebral protection.
- Decreases intraocular pressure.
- Poor analgesic.
- Painful procedure not be done.
- Produces hyperalgesia.
- Poor muscle relaxant property.
Uses:
- As anticonvulsant – DOC in neurosurgical procedures.
- Inducing agent in anesthesia.
- Dose for induction = 3-5 mg/ kg.
- Medically induced coma.
- Euthanasia – IV thiopental is rapid way accomplishing euthanasia.
- Phobia – For desensitization.
- Truth serum:
- Used to uncover truth.
- By suppressing higher cortical neurons involved in lying without affecting truth revealing centers.
- To facilitate recall of painful repressed memories.
Contraindications
- Acute intermittent prophyria.
- Cardiovascular instability or shock.
- Respiratory obstruction.
- No availability of airway equipment
- Status asthmaticus.
- Pericardial Tamponade.
- In hypovolemia & shock.
- Avoided in antecubital fossa – To prevent intra-arterial injection complication.
Adverse effects:
- IV injection of thiopentone is painful.
- Hypotension due to vasodilation –-> Reflex tachycardia.
- May result in cardiovascular collapse in presence of hypovolemia, shock or sepsis.
- Cause respiratory depression, laryngospasm & bronchospasm.
- Mild muscular excitatory movement (tremor, twitching, cough, hiccup).
- Produce hypersensitivity, rash, angioedema, photosensitivity.
- Dreadful complications on intra-arterial injection.
Intra-arterial injection of thiopentone:
- Common with injection in antecubital vein.
- Avoided at antecubital fossa.
- Produces thrombosis, vasospasm ischemia, necrosis —> gangrene.
- 1st symptom = Burning pain.
- 1st sign = Blanching of hand due to vasospasm.
- Prevented by given in veins over outer aspect of forearm only.
Management:
- Leaving needle in-situ in artery.
- Brachial block (stellate ganglion block).
- Heparin injection – To prevent thrombosis.
- Dilution of thiopental by injection of saline into artery.
- Papaverine or prostacyclin injection – To relieve spasm.
- Urokinase, streptokinase, vasodilators, steroid & lignocaine used.
Exam Important
- Thiopentone is ultrashort-acting barbiturate due to rapid redistribution.
- Thiopentone needs careful injection technique to prevent intra arterial injection, particularly in antecubital fossa.
- Thiopentone injections are avoided in antecubital fossa & given in veins over outer aspect of forearm only.
- Thiopentone has anticonvulsant action, hence DOC in neurosurgical procedures.
- Thiopentone decreases ICT, cerebral perfusion, O2 consumption & cerebral metabolic rate & hence, cerebroprotective.
- Thiopentone decreases IOT, has poor muscle relaxant property & is poor analgesic hence not used for painful procedure.
- Thiopentone is used for medically induced coma & as truth serum.
- IV injection of thiopentone is painful.
- Thiopentone produces dreadful complications on intra-arterial injection, particularly on antecubital fossa.
- Thiopentone injections are avoided in antecubital fossa to prevent intraarterial complications.
- Intraarterial injection complication of thiopentone is mostly due to accidental injection into antecubital vein.
- Intraarterial injection complication of thiopentone is prevented by given in veins over outer aspect of forearm only.
- Intra-arterial injection of thiopentone produces thrombosis, vasospasm ischemia, necrosis leading to gangrene.
- 1st symptom of intra-arterial injection of thiopentone is burning pain.
- 1st sign of intra-arterial injection of thiopentone is blanching of hand due to vasospasm.
- Intraarterial injection complication of thiopentone is managed by leaving needle in-situ in artery, brachial block (stellate ganglion block), Heparin injection preventing thrombosis, Papaverine or prostacyclin injection relieving spasm.
- Thiopentone causes hypotension due to vasodilation, hence contraindicated in hypovolemia, shock or sepsis.
- Thiopentone produce hypersensitivity, rash, angioedema, photosensitivity.
- Mild muscular excitatory movement like tremor, twitching, cough, hiccup are seen with thiopentone.
- Thiopentone is contraindicated in status asthmaticus, respiratory obstruction & in acute intermittent porphyria.
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