Delirium and Physostigmine: ECG helps in Management

This patient took an unknown overdose and was delirious.  The axillae were dry.  Due to delirium and dry skin, there was suspicion of anticholinergic toxicity.Here is his ECG:There is sinus tachycardia.  There is also some QRS widening and a large R-wave in aVR, and an rSR' (RV conduction delay) in lead V1.  The QRS duration is 107 ms.  There is QT prolongation as well, with a computerized (Bazett) QTc of 480 ms (prolonged).The prolonged QRS and RV conduction delay make this very suspicious for Na channel blockade, and, most worrisome, for tricyclic antidepressant overdose (TCA).Do we treat the delirium with physostigmine?  How does the ECG impact that decision?  Delirium from anticholinergic overdose may be treated with physostigmine, but there was a double case report from 1980, in which 2 moribund TCA overdose patients who were not treated with bicarbonate died after physostigmine.  Although this study has long been criticized, physo still carries a stigma that has been hard for it to overcome (pun intended). Fortunately, Rasimas et al. recently published their extensive experience using physostigmine in a wide variety of overdose patients, including those with TCA OD, without significant adverse effects.  Thanks to Jon Cole, our Poison Center Director, for calling my attention to this paper.Here is the Rasimas paper: Revival of an Antidote: Bedside Experience with Physostigmine  &nbs...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs