[Experimental research on individual-specific rapid potassium supplementation strategy for fatal severe hypokalemia]

To explore the effectiveness and safety of the individual-specific rapid potassium supplementation strategy, and to provide experimental basis for treating fatal severe hypokalemia.

An acute fatal severe hypokalemia model was reproduced in 20 healthy adult Japanese big ear white rabbits with half lethal dose (LD50) of barium chloride (BaCl₂) solution 168 mg×5 mL^-1×kg^-1. The rabbits were divided into conventional potassium supplementation group and individual-specific rapid potassium supplementation group according to random number table method with 10 rabbits in each group. All the animals were injected with 3% KCl through the auricular marginal veins by a micro-injection pump, and the target plasma potassium concentration was 4 mmol/L. The rabbits in conventional potassium supplementation group were administered continuously potassium infusion at the standard infusion rate of 0.4 mmol×kg^-1×h^-1. And those in the individual-specific rapid potassium supplementation group were treated in two steps: first, a loading dose of potassium was rapidly injected within 5 minutes, and this step was repeated until the plasma potassium concentration increased to 3.5 mmol/L; second, a sustaining dose of potassium infusion was continued at the rate of 0.4 mmol×kg^-1×h^-1 after the increase in plasma potassium concentration. The changes in electrocardiogram, blood pressure, respiratory rate (RR), plasma potassium concentration, urine potassium concentration, urine volume, potassium content in extracellular fluid (ECF) and other parameters were monitored. The potassium supplementation, potassium excretion and potassium cross cell status were recorded. Adverse reactions and 7-day death were observed.

Since the BaCl₂ administration, the plasma potassium concentration of all experimental rabbits were significantly lower than baseline at 0.5 hour, which was decreased below 2.5 mmol/L at 2.0 hours when the ventricular arrhythmias appeared, indicating the reproduction of fatal severe hypokalemia model was successful. There was no significant difference in gender, weight, baseline heart rate (HR), RR, mean arterial pressure (MAP), blood gas analysis or K⁺, Na⁺, Cl^- levels between the two groups. Compared with baseline levels, MAP was significantly decreased and RR was significantly increased before potassium supplementation in both groups, but the parameters were improved significantly and restored to the baseline after potassium supplementation. There was no significant difference in MAP or RR during potassium supplementation between the two groups. The amount of potassium supplementation in two groups showed no significant differences. However, compared with the conventional potassium supplementation group, in the individual-specific rapid potassium supplementation group, the increase in plasma potassium concentration, urine potassium concentration, and the increase in potassium content in ECF were significantly increased [the increase in plasma potassium concentration (mmol/L): 2.40±0.33 vs. 1.51±0.75, urine potassium concentration (mmol/L): 164.94±18.07 vs. 108.35±19.67, the increase in potassium content in ECF (mmol): 1.17±0.16 vs. 0.73±0.35], the duration of potassium infusion was shortened (hours: 2.1±0.7 vs. 4.7±1.4), the total urine volume, renal excretion of potassium, and the amount of transcellular potassium shift were significantly decreased [total urine volume (mL): 6.40±1.78 vs. 13.60±4.69, renal excretion of potassium (mmol): 1.04±0.26 vs. 1.46±0.51, amount of transcellular potassium shift (mmol): 1.39±0.21 vs. 1.84±0.62], the duration of arrhythmia was shortened (minutes: 19.60±8.92 vs. 71.80±9.84), with statistically significant differences (all P < 0.05). Hyperkalemia did not occur in both groups. The rabbits of the individual-specific rapid potassium supplementation group were all alive, while 4 died in the conventional potassium supplementation group, and statistically significant difference was found between the two groups (P < 0.01).

These data demonstrate that the individual-specific rapid potassium supplementation strategy can shorten the time for correcting hypokalemia, which is a better option to reverse life-threatening arrhythmia caused by severe hypokalemia, with a high rescue success rate. The process of potassium supplement is safe and effective.