usmleasr
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what is the rationale of using NaHco3 (sodium bicarbonate) in a case of a tricyclic antidepressant overdose?
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| cache
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The main treatment for TCA overdose is alkalinization of the blood with sodium bicarbonate. This alters the TCA effect on myocardial cells. Therapy with bicarbonate is indicated if the QRS complex is >100 milliseconds.
rational for using NaHCO3 : reducing TCA-induced QRS duration, ameliorating hypotension, and treating ventricular dysrhythmias
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| usmleasr
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hi cache,
i was also thinking like what u said...but i read a different explanation in q bank(usmleworld)...saying that ...NaHco3 helps by providing lot of Na+ ions that help to overcome Na channel blockade effect of TCA overdose(which causes QRS prolongation) :roll:
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| prep4usmle
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Besides the anticholonergic effect and norepinephrine uptake blockade the other mechanism by which TCA cause cardiac toxicity is the blockade of fast Na chanels (membrane stabilizing effect; quinidine-like; class Ia antiarrhythmic like).
Both hypersaline infusion (Na+ ions; rarely used) and plasma alkalinisation (hyperventilation to a target pCO2 = 30 mmHg, ph=7.5 ) have shown to affect the proarrhythmic cardiotoxicity of TCA.
NaHCO3 infusion combines Na loading and systemic alkalinisation.
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| usmleasr
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that is a good link ...and explanation...thanks a lot prep4usmle.. 
have u joined residency?..wish to have a senior like u who will teach things in simple way 8)
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| prep4usmle
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I'm looking for a position in 2005. #-o
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| usmleasr
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hi prep4,
u will do it...All The Best :icon_thumb:
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| asmi
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Hi all ,
Thanks for the good points
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