Sympatholytic toxidrome

AGENTS

  • beta-blocker (BB)
  • ca2+ blocker (CCB)
  • clonidine
  • digoxin
  • true sympatholytic agents (e.g. alpha-blockers like phentolamine, and vasodilatory agents such as GTN, SNP, etc)

CLINICAL FEATURES

CCBs and BBs

  • CVS: bradycardia, hypotension, AV block, heart failure
  • CNS: lethargy, confusion, seizures, coma (generally secondary to the CVS effects)

Digoxin is also characterised by increased automaticity (e.g. PVCs, PACs and other dysrhythmias)

Propanolol causes sodium channel blockade as well as B-blocker effects

True sympatholytic agents present with vasodilation, hypotension, reflex tachycardia +/- evidence of poor perfusion

INVESTIGATIONS

– ECG: bradycardia, PR, QRS, QT prolongation, heart blocks, asystole.

SPECIFIC MANAGEMENT AND TRIGGERS FOR INTERVENTION

Decontamination

  • decontamination with activated charcoal and whole bowel irrigation (if risk assessment is for severe toxicity from a sustained release agent  before toxicity is apparent)
  • charcoal haemoperfusion in verapamil OD?

Ca2+ channel blockers and beta-blockers

  • Ca2+ chloride 1-3g -> 2-6g/hr (maintain ionized Ca2+ between 2-3mmol/L)
  • glucagon 5-10mg bolus -> 2-5mg/hr (traditional treatment, but not as useful as HIET)
  • atropine
  • vasopressors and inotropes:
    – isoprenaline 2mcg/min
    – adrenaline 0.1-1mcg/kg/min
    – noradrenaline 0.1-1mcg/kg/min
    – milrinone
    – levosimendan
  • pacing to achieve ventricular capture @ 50-80/min (often ineffective)
  • high-dose insulin euglycaemic therapy (MAINSTAY of modern therapy, start early)
  • lipid emulsion: may bind calcium channel blockers in plasma and prevent myocardial penetration
  • extracorporeal support – intra-aortic balloon pump, VA ECMO or cardiopulmonary bypass

Digoxin

  • digi-bind

Clonidine

  • supportive care (especially respiratory support)
  • IV fluids
  • rarely are vasopressors required
  • trial naloxone (controlversial: may need high doses and has inconsistent effects)

Propanolol

  • NaHCO3

True sympatholytics

  • supportive care
  • IV fluids
  • vasopressors if hypoperfusion: noradrenaline
  • correct Ca
  • treat CN toxicity from SNP

CCC Toxicology Series

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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