開心術にともなう下肢インピーダンスの変動に関する臨床的研究
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概要
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This study is based on 42 adult patients, who underwent open-heart surgery using extracorporeal circulation in this institution. Minnesota impedance cardiograph was used to measure tissue impedance in the right lower extremity as an indicator of tissue fluid content. At the same time, following measurements were obtained : blood aldosterone level, hemodynamic parameters, postoperative water balance, blood lactate level, acid-base balance, as well as hematocrit, serum protein level, colloid osmotic pressure. In order to assess influence of hemodynamic stability upon outcome of impedance measurement, this study group was further divided into two separate categories ; Group A : required catecholamine support to maintain satisfactory hemodynamic state when they were weaned from cardiopulmonary bypass. Group B : not required any catecholamine. Following conclusions were drawn from this study ; 1. Decline in hematocrit (Ht), serum total protein (TP) and colloid osmotic pressure (COP) during cardiopulmonary bypass using hemodilution technique was corrected soon after cessation of cardiopulmonary bypass. 2. Water level in the lower extremity measured by the impedance method began to rize after 60 minutes of cardiopu,lmonary bypass and reached its maximum level at around 6th hour after bypass. 3. We derived the term Zo diff.: this indicates percent difference between observed impedance and maximum impedance usually obtained during cardiopulmonary bypass. Zo diff. of lower extremity had significant correlation with CVP, COP-CVP, impedance value of lung tissue as well as serum aldosterone level, acid-base balance and serum lactate. 4. Study group A revealed higher value in Zo diff., CVP, serum aldosterone level and serum lactate than group B. COP-CVP was lower in study group A, along with tendency toward alkalosis in base excess. 5. Impedance measurement of lower extremity is very simple and valuable tool to assess water accumulation level in the tissue. Impedance study will invaluably shed a better light in understanding of physiolosical aspect of extracorporeal circulation and will be of immense value in improving technique of cardiopulmonary bypass.
- 神戸大学の論文