Advanced Platform Technology Center, Louis Stokes Veterans Affairs Medical Center, Cleveland, Ohio, USA.
Neurourol Urodyn. 2011 Mar;30(3):329-34. doi: 10.1002/nau.20991. Epub 2011 Feb 8.
Catheter systems are utilized to measure pressure for diagnosis of voiding dysfunction. In a clinical setting, patient movement and urodynamic pumps introduce hydrostatic and motion artifacts into measurements. Therefore, complete characterization of a catheter system includes its response to artifacts as well its frequency response. The objective of this study was to compare the response of two disposable clinical catheter systems: water-filled and air-charged, to controlled pressure signals to assess their similarities and differences in pressure transduction.
We characterized frequency response using a transient step test, which exposed the catheters to a sudden change in pressure; and a sinusoidal frequency sweep test, which exposed the catheters to a sinusoidal pressure wave from 1 to 30 Hz. The response of the catheters to motion artifacts was tested using a vortex and the response to hydrostatic pressure changes was tested by moving the catheter tips to calibrated heights.
Water-filled catheters acted as an underdamped system, resonating at 10.13 ± 1.03 Hz and attenuating signals at frequencies higher than 19 Hz. They demonstrated significant motion and hydrostatic artifacts. Air-charged catheters acted as an overdamped system and attenuated signals at frequencies higher than 3.02 ± 0.13 Hz. They demonstrated significantly less motion and hydrostatic artifacts than water-filled catheters. The transient step and frequency sweep tests gave comparable results.
Air-charged and water-filled catheters respond to pressure changes in dramatically different ways. Knowledge of the characteristics of the pressure-measuring system is essential to finding the best match for a specific application.
导管系统用于测量压力以诊断排尿功能障碍。在临床环境中，患者运动和尿动力学泵会将静水压力和运动伪影引入测量中。因此，导管系统的完整特性包括其对伪影的响应及其频率响应。本研究的目的是比较两种一次性临床导管系统（充水和充气）对受控压力信号的响应，以评估它们在压力传输方面的相似性和差异。
我们使用瞬态阶跃测试来表征频率响应，该测试使导管突然受到压力变化的影响；使用正弦频率扫描测试来使导管受到 1 至 30 Hz 的正弦压力波的影响。通过涡旋测试来测试导管对运动伪影的响应，通过将导管尖端移动到校准高度来测试导管对静水压力变化的响应。
充水导管表现为欠阻尼系统，在 10.13 ± 1.03 Hz 处共振，并在高于 19 Hz 的频率下衰减信号。它们表现出明显的运动和静水压力伪影。充气导管表现为过阻尼系统，在高于 3.02 ± 0.13 Hz 的频率下衰减信号。它们表现出的运动和静水压力伪影明显少于充水导管。瞬态阶跃和频率扫描测试给出了类似的结果。
充气和充水导管对压力变化的响应方式截然不同。了解压力测量系统的特性对于为特定应用找到最佳匹配至关重要。
