イオン性および非イオン性造影剤による循環血液量の変化—血液膠質浸透圧測定による検討

Contrast medium-induced expansion of circulating blood volume:Comparison between nonionic and ionic contrast media

　【目的】イオン性および非イオン性造影剤による循環血液量の変化を比較検討した。【方法】対象はイヌ10頭，イオン性造影剤としてmeglumine iothalamate（MI）（1.28 gl／kg）を5頭にまた非イオン性造影剤として，iohexol（IH）（1.28 gl／kg）を他の5頭に使用した。造影剤をbolus静注し，静注前，静注後1，3，5，10分に他側静脈より採血し，膠質浸透圧を測定し，循環血液変化量を算出した。また造影剤を交換し同様の実験を施行した。【結果】造影剤静注後，循環血液量は直ちに増加し，約1分の時点で最大値を示しその後徐々に回復した。IHによる循環血液量の増加はMIに比し，1，3，5，10分何れの時点においても有意に低い値を示した。【総括】イオン性造影剤に比較し，非イオン性造影剤の循環血液量に対する影響は有意に少なく，非イオン性造影剤の副作用が少ない要因の一つと考えられた。

We assessed whether the osmotic expansion of circulating blood volume (CBV) induced by nonionic contrast medium (NCM) is less than that induced byionic contrast medium (ICM). Iohexol (Io) (NCM: 795mOsm,kg H₂O), 1.28g iodine/kg, was injected in-travenously into 5 mongrel dogs and blood samples were drawn at certain times. One week later, me-glumine iothalamate (Ml) (ICM:1470mOsm/kgH₂O), 1.28g iodine/kg, was injected into the same dogs. Another 5 dogs received MI first and Io one week later. Colloid oncotic pressure (COP) of the blood samples was measured by a needle osmometer, and changes in CBV were calculated from the COP val-ues. The injection of to or MI resulted in an im-mediate decrease in COP, and an increase in CBV at 1 min. MI induced significantly more severe and longlasting changes in COP and CBV than Io. Nei-ther MI nor Io modified COP when they were added to the control blood samples. Thus, although NCM considerably expanded CBV, the magnitude of ex-pansion induced by NCM was less than that induced by ICM. This may explain one of the reasons why NCM causes fewer adverse reactions than ICM.