Digoxin in the critically ill patient.
OBJECTIVE
To review the pharmacodynamic and pharmacokinetic properties of digoxin in health and disease and the potential use and toxic effects of digoxin in the critically ill patient.


METHODS
A review of studies reported from 1966 to 1998 and identified through a MEDLINE search of the literature on digoxin and the use of digoxin in critical illness.


RESULTS
Digoxin inhibits the sarcolemmal NaK-ATPase in many tissues with the effects on myocardial contractile and conducting tissue, neural tissue and smooth muscle providing the major physiological effects in health and disease. Currently the major indications for its clinical use include systolic heart failure, where, in addition to angiotensin conversion enzyme inhibitors and diuretics, it reduces the incidence of pulmonary oedema, and in the management of patients with supraventricular tachycardia, where it reduces the ventricular rate. In the critically ill patient, digoxin is used infrequently as there are other agents that have a superior inotropic effect, a greater ability to control and reverse supraventricular tachyarrhythmias, have a larger therapeutic window and are easier to regulate. As the myocardial depression associated with septic shock is manifest by ventricular dilation and reduction in ejection fraction, it would seem that digoxin may be of some therapeutic benefit in this disorder, particularly as early experimental and clinical studies have reported an improvement in the myocardial dysfunction associated with sepsis with the use of intravenous digoxin (750 - 1000 mug/70 kg). However, large prospective randomised controlled trials are lacking.


CONCLUSIONS
Digoxin is a therapeutic agent with unique effects. It should be considered in all patients with systolic heart failure, supraventricular tachycardia, and, in association with other treatment, as a single dose of 750 -1000 mug/70 kg in patients not treated previously with digoxin who have septic shock. It should be avoided in patients with critical coronary artery disease and ischaemic or hypertrophic diastolic failure.
Worthley
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Department of Critical Care Medicine, Flinders Medical Centre, Adelaide, SA 5042, Australia lindsay.Worthley@flinders.edu.au.
Holt
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