A study on the effects of the rapid intravenous infusion of hypertonic Na and K solutions into normal conscious sheep on some cardiac characteristics and blood analytes

Five normal, conscious, aged Merino ewes were infused with 200 ml of an aqueous solution containing 5% NaCl and 0.25% KCl (HNaK) at a mean rate of 0.024 ml/kg/s and four similar sheep with 0.9% saline at a mean rate of 0.018 ml/kg/s. Five ECG tracings were obtained over a 6-h period-two (20 s each) before, one (continuous tracing) during the infusion, and two (20 s each) afterwards. The heart was auscultated during the infusion. Seven heparinized blood samples were obtained-three before the infusion (1.5 h, 1.0 h, and immediately before), and four afterwards (immediately, 2.5 h, 4.5 h, and 24 h after). Determinations were made of changes in mean PCV, red cell counts, mean corpuscular volumes, plasma Na, K, Ca and Mg, and of erythrocyte Na and K concentrations. Analysis of variance revealed increases in heart rate when the results from both groups were combined, but no significant effects on cardiac rhythm. Auscultation revealed marked fluctuations in cardiac intensity within individual sheep and marked differences between sheep, particularly in those infused with HNaK. In the HNaK group there were significant increases in erythrocyte and plasma Na, erythrocyte K and plasma Ca during the infusion. Plasma K increased from the termination of the infusion to 2.5 h afterwards in the saline group but decreased unexpectedly during the same period in the group infused with HNaK