SAQ 410 – Toxicology – wide-complex hypotension after syncope

Toxicology – wide-complex hypotension after syncope.

a. ECG description

• Wide complex rhythm with broad QRS greater than 200 ms.
• Prominent R wave in aVR and R/S ratio in aVR greater than 0.7.
• Borderline tachycardia around 96/min.
• Prolonged QTc around 506 ms.
• Relevant negatives: no sinus tachycardia greater than 120/min and no AV block, with P waves before all complexes in aVF.
• Overall pattern is consistent with sodium-channel blocker toxicity such as tricyclic antidepressant overdose.

b. Treating hypotension

• Give IV crystalloid with a clear endpoint.
• Give sodium bicarbonate 50-100 mmol IV, repeating every 3-5 minutes until a perfusing rhythm and aiming for QRS less than 100 ms, then continue as needed.
• Start an inotrope or vasopressor such as adrenaline or noradrenaline.
• Intubate and hyperventilate if required, aiming for alkalinisation around pH 7.5.
• Consider rescue therapies such as intralipid, high-dose insulin euglycaemic therapy, balloon pump, ECMO, or bypass in refractory shock.
• Treat hyperkalaemia if present.

c. Activated charcoal