Qualcomm, San Diego, CA 92121, USA.
Physiol Meas. 2011 Jun;32(6):701-15. doi: 10.1088/0967-3334/32/6/007. Epub 2011 May 23.
This paper presents the design, construction and testing of a device to measure pressure-volume loops in the left ventricle of conscious, ambulatory rats. Pressure is measured with a standard sensor, but volume is derived from data collected from a tetrapolar electrode catheter using a novel admittance technique. There are two main advantages of the admittance technique to measure volume. First, the contribution from the adjacent muscle can be instantaneously removed. Second, the admittance technique incorporates the nonlinear relationship between the electric field generated by the catheter and the blood volume. A low power instrument weighing 27 g was designed, which takes pressure-volume loops every 2 min and runs for 24 h. Pressure-volume data are transmitted wirelessly to a base station. The device was first validated on 13 rats with an acute preparation with 2D echocardiography used to measure true volume. From an accuracy standpoint, the admittance technique is superior to both the conductance technique calibrated with hypertonic saline injections, and calibrated with cuvettes. The device was then tested on six rats with 24 h chronic preparation. Stability of animal preparation and careful calibration are important factors affecting the success of the device.
本文介绍了一种用于测量清醒、活动大鼠左心室压力-容积环的设备的设计、构建和测试。压力通过标准传感器测量，而容积则源自使用新颖的导纳技术从四极电极导管收集的数据得出。导纳技术测量容积有两个主要优点。首先，可以立即消除相邻肌肉的贡献。其次，导纳技术结合了导管产生的电场与血液量之间的非线性关系。设计了一种重量为 27 克的低功耗仪器，它可以每 2 分钟采集一次压力-容积环，并持续运行 24 小时。压力-容积数据通过无线传输到基站。该设备首先在 13 只具有二维超声心动图的急性制备大鼠上进行了验证，以测量真实容积。从准确性的角度来看，导纳技术优于用高渗盐水注射校准的电导技术和用比色皿校准的电导技术。然后，该设备在 6 只具有 24 小时慢性制备的大鼠上进行了测试。动物准备的稳定性和仔细的校准是影响设备成功的重要因素。
