Role of Hyperkalemia in Production of Ventricular Fibrillation Following Hypercapnia. ∗

Abstract

Summary and Conclusions

1. Dogs regularly show an increase in plasma potassium concentration during breathing of 30% and 40% CO₂ mixtures. Immediately following return to air breathing, there is a further sharp rise in this concentration. This secondary rise reaches a peak after 5 minutes of air breathing. 2. Concentration of plasma potassium following 4 hrs of high C_O2 breathing is not as high as that which is necessary to produce fibrillation or arrest when KCl solution is administered as an intravenous drip to normal or acidotic dogs. 3. Rapid return to air breathing following 30 minutes of high CO₂ breathing does not produce cardiac arrhythmias, ventricular fibrillation, or cardiac arrest in dogs. However, when this rapid elevation in blood pH and/or fall in pCO₂ takes place in the presence of sub-lethal but elevated plasma potassium concentrations, cardiac arrest or ventricular fibrillation may occur. Although this does not provide an explanation of the mechanism involved, it appears that the combination of elevated but sub-lethal plasma potassium concentration and a rapid fall in CO₂ tension and/or hydrogen ion concentration, work together to produce the damage to the heart.