EXPERIMENTAL STUDIES ON CITRIC ACID INTOXICATION A PRELIMINARY REPORT

The changes of serum Ca ion during infusion of a large dose of citric acid and its effects on whole blood clotting time, together with E. C. G. findings are experimentally studied.<br>1) The theoretical equations by McLean and Hastings concerning the Ca ion concentration in a solution containing protein and citric acid, are developed further theoretically, and a method for its solution are described.<br>A nomogram is constructed in which theoretical values of Ca ion concentrations can be obtained from the measured values of protein, total Ca and citric acid concentrations.<br>2) When citric acid is administered by infusion at a rate of 2-6mg/kg/min., the concentrations of both serum total Ca and citric acid increase, 1 hour later reaching the maximum value at the end of infusion, but their values decrease again.<br>The concentration of citric acid increases as rapidly as it is reduced, and a pyramidal curve is obtained having a peak at the end of infusion.<br>3) Although the concentration of serum Ca ion shows no significant changes during the administration of citric acid at a rate of 2-6mg/kg/min., it is reduced as the concentration of total serum citric acid becomes elevated. However, it is restored as rapidly as the restoration of citric acid concentration.<br>4) Whole blood clotting time, accompanied by the reduction of Ca ion concentration, may also be delayed, but promptly reaches the normal value with the restoration of Ca ion concentration.<br>5) The concentrations of total Ca and Ca ion are quickly elevated by intravenous administration of CaCl₂. During infusion of citric acid at a rate of 6mg/kg/min., an administration of 3-5cc of 2% CaCl₂ solution prevents the tendency toward the reduction of Ca ion concentration.<br>It is conceivable, however, that, if the intravenous administration of CaCl₂ is inadequate as to the time or the dose, there may be a danger of increasing Ca ion.<br>6) Liver resection has no significant effects on the metabolism of citric acid or of Ca ion concentration.<br>7) During the infusion of citric acid, prolongation of QT and ST, and changes of T wave which suggest the appearance of hypocalcemia can be demonstrated by E. C. G.