THE ECG IN TOXICOLOGY

Chris Nickson FACEM FCICM Intensivist, The Alfred ICU

Financial Conflicts of Interest NO !

http://litfl.org/CONCEPTOS

ECG

IN T

OXI

CO

LOG

Y

Screening!Identify ECG toxidromes!Risk stratify !Direct therapy!Monitor response

1. Name the poison:!!

A. Quetiapine!B. Digoxin!C. Dothiepin!

Answer: (C)!Dothiepin

QRS = 200 ms!

R’ = 3mm!

S = 4mm -> R’/S = 0.75!

Right axis deviation of terminal QRS !

Terminal R wave >3 mm R/S ratio >0.7!

QRS widening !predicts TCA complications!

!>100 ms seizures !

>160 ms dysrhythmias

Worse…!

Better!!

2. Name the poison:!!

A. Quetiapine!B. Digoxin!C. Diltiazem!

Answer: (B)!Digoxin

Cardiac glycoside toxicity !!

increased automaticity!AV node blockade!

supraventricular tachycardia !

Regularised atrial fibrillation!

Atrial Flutter with high grade AV block!

Bidirectional ventricular tachycardia!

Digoxin effect!

3. Name the poison:!!

A. Citalopram!B. Sotalol!C. Diltiazem!

Answer: (B)!Sotalol

QT interval = 600 ms!

HR = 40/min!

Chan (2007) PMID:17881416 !

DANGER

SAFE

The patient is at risk of…!

We need a structured approach!

Structured approach to the electrocardio(toxo)gram!

1  Rate and rhythm2  PR interval – heart block? !3  QRS duration in lead II !4 Right axis deviation of QRS !5 QT intervals6  Ectopy and increased automaticity 7  Complications

http://litfl.org/CONCEPTOS