Emergency step-by-step specific immunotherapy in severe digoxin poisoning: an observational cohort study

To evaluate the efficacy and safety of a step-by-step fixed dose of specific immunotherapy protocol in case of severe digoxin poisoning in an open uncontrolled prospective study.

Twenty consecutive patients were admitted because of severe digoxin poisoning. The inclusion criteria were: digoxin overdose and either life-threatening arrhythmia; high-degree atrioventricular block, ventricular arrhythmia, or bradycardia less than 50 bpm and hyperkalaemia (>5.5 mmol/l). A two-step protocol of antidigoxin antibodies treatment was carried out. At admission, every patient received two vials of specific Fab-fragments. If after 1 h following infusion ECG signs regressed, no more treatment was given. If ECG signs did not regress, patients were given two more vials. At inclusion and 6 h after immunotherapy, clinical (cardiac rhythm, ECG records) and biological (serum digoxin concentration, potassium) findings were recorded.

Patients had a median (interquartile range) age of 83 (75-90) years. Four patients had acute poisoning and 16 chronic overdoses. Eleven patients showed ventricular arrhythmia, and five had high-degree atrioventricular block. Seventy percent of the patients needed only the first step. Significant decreases were observed in the number of cardiac dysrhythmia (16 vs. three patients), in the median (interquartile range) of serum digoxin concentration [5 microg/l (3.8-6.2) vs. 0.4 microg/l (0.3-2.2)] and in serum potassium [4.6 mmol/l (4.1-5.5) vs. 3.85 mmol/l (3.7-4.55)] before and after immunotherapy. The digoxin-related mortality was 5%.

This protocol of step-by-step digoxin-specific immunotherapy seems to be as effective as the equimolar treatment, and there was significant cost reduction in case of acute poisoning.