digoxin and Alkalosis

Reviews of large series of patients with digitalis-induced arrhythmias create a seeming paradox: Hypokalemia is infrequently associated with digitalis-induced arrhythmias but the clinical benefit of supplementation of potassium for most digitalis-induced arrhythmias is obvious. Examination of the electrophysiologic abnormalities induced by digitalis coupled with the electrophysiologic effects dependent on the ratio of intracellular to extracellular concentrations of potassium clarifies the issue. We present evidence that supports additive effects of the toxicity of digitalis and abnormal ratios of concentrations of potassium inside and outside the cardiac cell using metabolic alkalosis as a marker of intracellular potassium depletion. Patients with metabolic alkalosis and normokalemia with "therapeutic" concentrations of digoxin had significantly greater prevalence of arrhythmias than did patients without alkalosis. We presume this effect of alkalosis to be mediated by effects on extra- to intracellular ratios of potassium.

Topics: Adult; Aged; Alkalosis; Arrhythmias, Cardiac; Digitalis Glycosides; Digoxin; Female; Humans; Intracellular Fluid; Male; Middle Aged; Potassium

Reviews of large series of patients with digitalis-induced arrhythmias create a seeming paradox: Hypokalemia is infrequently associated with digitalis-induced arrhythmias but the clinical benefit of supplementation of potassium for most digitalis-induced arrhythmias is obvious. Examination of the electrophysiologic abnormalities induced by digitalis coupled with the electrophysiologic effects dependent on the ratio intracellular to extracellular concentrations of potassium clarifies the issue. We present evidence that supports additive effects of the toxicity of digitalis and abnormal ratios of concentrations of potassium inside and outside the cardiac cell. We provide guidelines for assessing this crucial ratio of intracellular to extracellular concentrations of potassium to aid the clinician in the diagnosis and effective treatment of digitalis-induced arrhythmias.

Topics: Adult; Aged; Alkalosis; Arrhythmias, Cardiac; Digoxin; Female; Humans; Male; Middle Aged; Potassium; Potassium Deficiency; Prospective Studies

A diagram based on in-vivo relationships between arterial hydrogen ion activity (H+) and carbon dioxide tension (PCO2) in primary abnormalities of acid base homeostasis is presented. It is designed to facilitate the interpretation of pH data by including the 95% confidence limits described in patients with simple metabolic and respiratory acid base disorders. These bands have been formulated from observation of simple acid base abnormalities and indicate the appropriate respiratory or renal compensatory response to the primary pH defect. A plot which falls outside these limits therefore indicates the presence of a mixed acid base disorder. The diagram presents a physiological approach to clinical disorders of pH regulation demonstrating maintenance of intra-cellular fluid homeostasis during primary extracellular fluid disturbances. Diagnostic and therapeutic advantages are further illustrated and discussed in six case reports.

Topics: Acid-Base Imbalance; Acidosis; Adolescent; Adult; Aged; Alkalosis; Alkalosis, Respiratory; Dehydration; Diabetic Ketoacidosis; Digoxin; Female; Humans; Hydrogen-Ion Concentration; Insulin; Male; Middle Aged; Sodium Chloride

Topics: Alkalosis; Biological Transport, Active; Cell Membrane Permeability; Depression, Chemical; Digitalis Glycosides; Digoxin; Erythrocytes; Fludrocortisone; Humans; Hypokalemia; Leg; Potassium; Radioimmunoassay; Sodium; Stimulation, Chemical; Time Factors

Topics: Acidosis; Alkalosis; Anti-Bacterial Agents; Blood Transfusion; Body Temperature; Digoxin; Diuretics; Drainage; Glucose; Heart Arrest; Heart Defects, Congenital; Humans; Hypoglycemia; Hypoproteinemia; Infant, Newborn; Intubation, Intratracheal; Isoproterenol; Parenteral Nutrition; Positive-Pressure Respiration; Postoperative Care; Serum Albumin; Thrombocytopenia; Water-Electrolyte Balance

Topics: Acetanilides; Acidosis, Respiratory; Alkalosis; Amino Alcohols; Animals; Bicarbonates; Blood Pressure; Cardiac Complexes, Premature; Cats; Digitoxin; Digoxin; Electrocardiography; Female; Guinea Pigs; Heart; Heart Atria; Heart Ventricles; Hydrogen-Ion Concentration; Male; Microelectrodes; Propylamines; Reserpine; Sodium; Strophanthins; Tromethamine