Muzi M, Ebert T J, Tristani F E, Jeutter D C, Barney J A, Smith J J
J Appl Physiol (1985). 1985 Jan;58(1):200-5. doi: 10.1152/jappl.1985.58.1.200.
Although impedance cardiography provides safe and reliable noninvasive estimates of stroke volume in humans, its usefulness is limited by the necessity for subjects to be apneic and motionless. In an effort to circumvent this restriction we studied the validity of ensemble-averaging of impedance data in exercising normal subjects and in intensive-care patients. The correlation coefficient (r value) between 128 ensemble-averaged and standard hand-digitized determinations of stroke volume index from the same records taken during rest and exercise in six normal male subjects was +0.97 (P less than 0.001). The r value for ensemble-averaged stroke volume indices during free breathing and breath hold in the same subjects was +0.92 (P less than 0.001), suggesting that breath hold did not significantly affect the stroke volume estimation. In 14 freely breathing hospital intensive-care patients the r value between simultaneous thermodilution cardiac output readings and ensemble-averaged impedance determinations was +0.87 (P less than 0.01). The results indicate that ensemble-averaging of transthoracic impedance data provides waveforms from which reliable estimates of cardiac output can be made during normal respiration in healthy human subjects at rest and exercise and in critically ill patients.
尽管阻抗心动描记术能为人体心输出量提供安全可靠的无创评估，但由于受试者必须处于呼吸暂停和静止状态，其应用受到了限制。为了规避这一限制，我们研究了在正常运动受试者和重症监护患者中对阻抗数据进行总体平均的有效性。在六名正常男性受试者休息和运动期间，从相同记录中获取的128次总体平均心输出量指数与标准手工数字化测定的心输出量指数之间的相关系数（r值）为+0.97（P小于0.001）。同一受试者在自由呼吸和屏气期间总体平均心输出量指数的r值为+0.92（P小于0.001），这表明屏气对心输出量估计没有显著影响。在14名自由呼吸的医院重症监护患者中，同时进行的热稀释法心输出量读数与总体平均阻抗测定之间的r值为+0.87（P小于0.01）。结果表明，对经胸阻抗数据进行总体平均可提供波形，据此可在健康人体受试者休息和运动时以及重症患者正常呼吸期间可靠地估计心输出量。
