橈骨動脈圧波形から構築した五要素電気回路モデルによる循環動態の非侵襲的評価法  [in Japanese] Noninvasive Method for Circulatory System by Five Element Electric Circuit Arterial Model Constructed from Radial Pressure Pulse  [in Japanese]

血管のコンプライアンスを中枢側と末梢側に分けて配置した動脈系電気回路モデルの回路構成を橈骨動脈圧波形の近似式をもとに考察した結果, 中枢側コンプライアンスに相当する静電容量を電気回路モデルの入力端子に並列に, 末梢側コンプライアンスに相当する静電容量を出力端子に並列に配置した五要素集中定数動脈系電気回路モデルを構築した. 本電気回路モデルの入力電圧を正弦半波で近似した左心室圧波形に, 出力電圧を橈骨動脈圧波形に, 1秒間当たりの心拍出量を平均電流に対応させて血管拡張剤(nifedipine)を投与した前後での本電気回路モデルのパラメータを算出した結果, 橈骨動脈の平均血圧, 脈圧(橈骨動脈の最高血圧と最低血圧の差), 1回拍出量の経時的変化をモデルの5つのパラメータの変化として動脈系中枢側と末梢側に分けて定性的に評価することができた.

In this paper we introduced an approximated radial pressure pulse equation which is adjustable to wide variation of the real measured pressure pulse. The equation consists of two terms. The first is dominant at the earlier stage of a wave, and the second is at the later stage. We introduced two equivalent circuits corresponding to each terms, then integrated them to unique five-factor constant electrical circuit model by the principle of superposition, in which two capacitors corresponding to central and peripheral compliance are included. For the input voltage to the circuit, we use the wave-form corresponding to the left ventricular pressure approximated by the sequences of half-sine-waves. For the inspection of propriety of this circuit model, we measured the following effects before and after the dosage of vasodilator drug. The responses on radial pressure pulse, average blood pressure, pulse pressure (difference between max. and min. blood pressure) and stroke volume, can be sufficiently explained by this circuit model qualitatively.