Morning Report: 7/29/2014

by Jay Khadpe MD • July 29, 2014 • Comments Off

Thanks to Dr. Freedman for today’s Morning Report!

Digoxin Toxicity

Background:

Naturally occurring chemical compounds
Na+/ATPase Channel blockers
Prone to poisoning
- Large volume of distribution
- Long half-life, ~36 hours
- Narrow therapeutic window, 0.6 – 1.3 ng/mL

Digoxin:

An Old Drug: CHF, A fib
- ~2% of all international patients.
- One of the 50 most commonly prescribed in U.S.
- 1,601 acute ingestions in U.S. in 2011
- In U.S., 1% of outpatients and ~18% of NH patients will develop toxicity
- 0.4% of all U.S hospital admissions

Plant Cardiac Glycosides:

Many different flowering plants
- Foxglove, oleander, lily of the valley et al.

2.6% of all toxic plant exposures
1,336 in U.S. in 2011

Acute Ingestions

Epidemiology: the young (one pill kill)

Adults: LD50 10mg
Pediatrics: LD 50 0.3mgkg

Presentation: Cardiac symptoms

Bradycardia +/- hypotension
Dysrhythmias
- Sinus
- Junctional
- AV block
- Slow a fib/flutter
- Bidirectional V tach

Chronic Toxicity

Epidemiology: Elderly, chronically ill

Normal or sub-therapeutic levels
Triggered by:
- Electrolyte disturbance
- Hypovolemia
- Drug-drug interactions

Presentation: Often non-specific

Altered mental status, weakness, fatigue
Nausea/vomiting, abdominal pain
Visual complaints

ECG findings:

“Scooped” ST segment, Digitalis Effect
Any of the acute dysrhythmias

ED Management

ABCs
- Supportive care
- Correction of electrolyte disturbance

H+P
- Acute?
  - When, how much?

Chronic?
- Index of suspicion
- Trigger?

Lab Studies
- Digoxin Level
  - 6 hour level
  - Earlier levels don’t reflect steady state
- Potassium
  - Marker of acute toxicity
  - Prognostic value

Interventions
- Bowel decontamination
  - Consider if <1-2 hours
- Atropine
  - Not contra-indicated….
- Pacing
  - Not recommended
- Dialysis
  - Not plausible
- Digi-Fab
  - Ingestion of 10 mg in adults, or 0.3 mg/kg in children
  - Acute ingestion with steady-state level > 10ng/mL
  - Chronic ingestion with steady-state level > 6ng/mL
  - Any dysrhythmia, irrespective of level
  - Serum potassium > 5.5 in acute ingestion
  - Any plant toxicity

Emergency Medicine Mythology:

Intravenous calcium is contraindicated in digoxin toxicity. “Stone Heart” Syndrome. Based on case studies. No data to support theory. Weak data exist to suggest calcium is safe in dig-toxic. Bottom-line: Give IV calcium if you suspect hyperkalemia.

Bidirectional V tach

mr07292014p1

The views expressed on this blog are the author's own and do not reflect the views of their employer. Please read our full disclaimer here. Any references to clinical cases refer to patients treated at a virtual hospital, Janus General Hospital.

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Jay Khadpe MD

Editor in Chief of "The Original Kings of County" Assistant Professor of Emergency Medicine Assistant Residency Director SUNY Downstate / Kings County Hospital