Impedance-cardiogramの波形解析—左房負荷と気道内加圧時のdz／dt波，ΔZ波の変化について

Analytical Study of Impedance Cardiogram:Effects of overloading on the left atrium and endotracheal positive pressure on the dz/dt and delta Z waves

　Impedance-cardiographyは，循環動態の無侵襲計測法として，心拍出量の測定に利用されているが，その波形の成因については，充分解明されていない。

　胸部インピーダンスには，大動脈からの拍出だけでなく，肺循環系の変化も含まれている。そこで肺循環系に影響を与える方法として，左心耳よりバルーンカテーテルを挿入し，左房圧上昇に伴う肺うっ血，および気道内加圧により肺循環動態の変化した状態を作り上げ，インピーダンスΔZ,dz／dt波に及ぼす影響について検討を加えた。

The effect of pulmonary circulation on the wave form of impedance-cardiogram taken from the thoracic cage was studied in dogs. Aortic blood pressure and flow rate, pulmonary arterial pressure and flow rate, left atrial pressure and endotracheal pressure were all recorded on a polygraph, and analyzed according to the various components of the impedance-cardiogram.

As the endotracheal pressure increased, the delta Z wave from the systolic to diastolic phases showed a damped curvature. When the left atrial pressure was increased by inflating the balloon inserted into the atrium, arterial pressure decreased without any change in its flow pattern, and the height of the delta Z wave increased during the diastolic phase more than in the systolic phase. The form of the delta Z wave became biphasic at the beginning and later ex-hibited 3 peaks.