Hypertonic saline treatment of severe hyperkalemia in nonnephrectomized dogs

Objectives: To determine whether a hypertonic saline bolus improves cardiac conduction or plasma potassium levels more than normal saline infusion wit hin 15 minutes of treatment for severe hyperkalemia. Previously with this m odel, 8.4% sodium chloride (NaCl) and 8.4% sodium bicarbonate (NaHCO3) lowe red plasma potassium equally effectively. Methods: This was a crossover stu dy using ten conditioned dogs (14-20 kg) that received, in random order, ea ch of three intravenous (IV) treatments in separate experiments at least on e week apart: 1) 2 mmol/kg of 8.4% NaCl over 5 minutes (bolus); 2) 2 mmol/k g of 0.9% NaCl over one hour (infusion); or 3) no treatment (control). Usin g isoflurane anesthesia and ventilation (pCO(2) = 35-40 torr), 2 mmol/kg/hr of IV potassium chloride (KCI) was infused until conduction delays (both a bsent p-waves and greater than or equal to 20% decrease in ventricular rate in less than or equal to 5 minutes) were sustained for 15 minutes. The KCl was then decreased to 1 mmol/kg/hr (maintenance) for 2 hours and 45 minute s. Treatment (0 minutes) began after 45 minutes of maintenance KCl. Results : From 0 to 15 minutes, mean heart rate increased 29.6 (95% CI = 12.2 to 46 ; p < 0.005) beats/min more with bolus than infusion and 23.4 (95% CI = 2.6 to 43.5; p < 0.03) beats/min more with bolus than control. No clinically o r statistically significant difference was seen in heart rate changes from 0 to 30 minutes. Decreases in potassium from 0 to 15 minutes were similar w ith bolus, infusion, and control. Conclusions: In this model, 8.4% NaCl bol us reversed cardiac conduction abnormalities within the first 15 minutes af ter treatment, more rapidly than did the 0.9% NaCl infusion or control. Thi s reversal occurred despite similar reductions in potassium levels.