For reducing ischemic injury, it is effective to lower ionized calcium (Ca⁺⁺) level to protect myocardial cells from calcium influx during early phase of reperfusion. From this point of view, changes of Ca⁺⁺ were studied in 20 cases of infants and children and 26 adult cases during cardiopulmonary bypass (CPB). To keep low Ca⁺⁺ level during CPB, Ca⁺⁺ concentration of the pump prime was minimized to 0.03mM and no calcium salt was added when ACD blood was used. Blood sample was obtained immediately before CPB, at 5min, 30min, 60min, 90min on CPB, at aortic declamping, and at the end of CPB.
In cases of infants and children, prebypass Ca⁺⁺ concentration was 1.15±0.04mM, and at 5min on CPB, it was reduced markedly to 0.43±0.01mM by hemodilution and by the effect of ACD blood. This low Ca⁺⁺ level was persisted until aortic declamping when Ca⁺⁺ concentration was 0.74±0.05mM. After 14ml of calcium gluconate administration, Ca⁺⁺ recovered to normal range. While, in adult cases, Ca⁺⁺ decreased from control level of 1.15±0.02mM, to 0.74±0.01mM at 5min on CPB. Although it increased little by little to 0.95±0.02mM at 90min on CPB and 0.88±0.02mM at aortic declamping, these values were still lower than control level significantly.
We concluded that it is useful method for decreasing Ca⁺⁺ level during CPB to minimize Ca⁺⁺ level in the pump prime and not to add Ca salt when ACD blood was used. And this decrease of Ca⁺⁺ level during CPB, especially at early phase of reperfusion, may play an important role in reducing reperfusion injury.