Effect of hypertonic NaCl on cardiac arrhythmias

¹ Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York City

Rapid CO₂ washout with 100% oxygen after a period of severe hypercapnic acidosis produces in dogs a marked elevation of plasma K⁺ and ventricular fibrillation. The administration of 1.5 m NaCl to five dogs during CO₂ washout prevented fibrillation, and all the animals survived. This procedure, which markedly diluted extracellular fluid, corrected hyperkalemia and prevented a fall in Na concentration. The plasma Na/K ratio, which dropped to 20 during acidosis, was restored to normal—42. In 15 additional animals, when the acidosis was corrected by intravenous administration of hypertonic THAM [tris(hydroxymethyl)aminomethane] or mannitol-glucose, asystole or arrhythmia occurred instead of fibrillation. The plasma Na concentration fell from 143 to 98 mEq/liter and the Na/K ratio was about 10 at asystole. A single injection of hypertonic NaCl, sufficient to raise Na levels above normal and thereby to increase the Na/K ratio despite an elevated K, produced resumption of systole. Similar results can be obtained with one-tenth the amount of calcium chloride.