Gill Bradley C, Fletter Paul C, Zaszczurynski Paul J, Perlin Alfred, Yachia Daniel, Damaser Margot S
Department of Biomedical Engineering, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio 44195, USA.
Neurourol Urodyn. 2008;27(6):525-31. doi: 10.1002/nau.20551.
Ambulatory urodynamics has the potential to provide measurements of bladder function during activities of daily living; however, no method of real-time continuous bladder volume measurement exists. The present study was conducted to determine the feasibility of using fluid volume conductance to continuously assess bladder volume.
Prototype devices consisted of four electrodes mounted on a polymer body. Each was tested in an in vitro organ bath system using latex vessels filled to 500 ml with saline matching the conductivity of urine. One device was selected and used to test the effects of fluid concentration (25%, 50%, 100%, 200%, and 400% physiological saline) in latex vessels as well as the effects of fluid concentration (25%, 50%, 100%, 200%, and 400% Tyrodes solution) and temperature (32, 37, and 42 degrees C) in excised pig bladders.
Conductance demonstrated a linear increase at low volumes but approached an asymptotic value at high volumes. Conductivity increased with increased temperature or concentration. With the exception of the differences between 25% and 50% concentrations, 32 degrees C and 37 degrees C, and 37 degrees C and 42 degrees C temperatures, each concentration and temperature produced statistically different conductance measurements from all others.
The conductance method is sensitive to changes in both concentration and temperature of the intravesical solution, likely due to changes in solution conductivity. Clinical application of conductance for measurement of bladder volume will require real-time conductivity compensation for the dynamically varying properties of urine. However, improved sensitivity at high volumes is necessary before this method has the potential to provide real-time bladder volume measurement for use in ambulatory urodynamics.
动态尿动力学有潜力在日常生活活动期间提供膀胱功能的测量值；然而，不存在实时连续膀胱容量测量方法。本研究旨在确定使用液体体积电导来连续评估膀胱容量的可行性。
原型设备由安装在聚合物主体上的四个电极组成。每个设备都在体外器官浴系统中进行测试，使用填充有500毫升与尿液电导率匹配的盐水的乳胶容器。选择一个设备并用于测试乳胶容器中液体浓度（25%、50%、100%、200%和400%生理盐水）的影响，以及在切除的猪膀胱中液体浓度（25%、50%、100%、200%和400%台氏液）和温度（32、37和42摄氏度）的影响。
电导在低容量时呈线性增加，但在高容量时接近渐近值。电导率随温度或浓度的增加而增加。除了25%和50%浓度、32摄氏度和37摄氏度以及37摄氏度和42摄氏度温度之间的差异外，每种浓度和温度产生的电导测量值与其他所有值在统计学上均有差异。
电导方法对膀胱内溶液的浓度和温度变化敏感，可能是由于溶液电导率的变化。电导用于测量膀胱容量的临床应用将需要对尿液动态变化的特性进行实时电导率补偿。然而，在该方法有潜力为动态尿动力学提供实时膀胱容量测量之前，提高高容量时的灵敏度是必要的。
