Department of Medicine, Mackay Medical College, New Taipei, Taiwan.
Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Neurourol Urodyn. 2020 Jun;39(5):1304-1312. doi: 10.1002/nau.24363. Epub 2020 Apr 15.
Though the pressure-volume analysis (PVA), a method based on thermodynamics, is broadly used for assaying cardiac functions, its potential application on the physiology/pathophysiology of the urinary bladder, which processes resemble thermodynamic cycles to the heart, has not been established.
Cystometry recording intravesical pressure (IVP) and intravesical volume (IVV) of rhythmic voiding contractions caused by a constant saline infusion (0.04 mL/min) were carried out in forty urethane-anesthetized female Sprague-Dawley rats, and the PVA was established by plotting IVP against IVV.
Pressure-volume points shaped coincident enclosed loops, and loop-associated urodynamic parameters kept stable under a constant infusion rate (0.04 mL/min). Enhancing preload (by elevating infusion rates to 0.08 and 0.12 mL/min) increased the area enclosed by the loop (Apv) and shifted loops to the right and slightly upward. Augmenting afterload (by enhancing resistances using 1/4 and 1/2 urethra clamping) increased Apv and shifted loops markedly to the right and upward. Without affecting Apv, muscarine (0.01 and 0.1 mM)-induced inotropic states shifted loop to the left and upward that was as opposed to the atropine (0.01 and 0.1 mM)-induced anti-inotropic state.
Not only consistently assayed baseline bladder functions, PVA but also validly measured modified bladder functions due to altered extrinsic environment and intrinsic contractility of the bladder itself. In accompanied by cystometry, PVA could provide a clear concept about the relationship between time, pressure, and volume in the voiding activity.
尽管基于热力学的压力-容积分析（PVA）被广泛用于评估心脏功能，但它在类似于热力学循环的生理学/病理生理学方面对处理尿液的膀胱的潜在应用尚未得到证实。
通过对 40 只乌拉坦麻醉的雌性 Sprague-Dawley 大鼠进行恒速生理盐水输注（0.04mL/min）引起的有节奏排空收缩的膀胱内压（IVP）和膀胱内容积（IVV）的测压记录，建立了 PVA 并绘制 IVP 与 IVV 的关系。
压力-容积点形成一致的封闭环，在恒速输注率（0.04mL/min）下，环相关的尿动力学参数保持稳定。增加前负荷（通过将输注率提高到 0.08 和 0.12mL/min）会增加环的面积（Apv）并使环向右和略微向上移动。增加后负荷（通过使用 1/4 和 1/2 尿道夹增强阻力）会增加 Apv 并使环明显向右和向上移动。而不影响 Apv 的情况下，毒蕈碱（0.01 和 0.1mM）引起的变力状态会使环向左和向上移动，这与阿托品（0.01 和 0.1mM）引起的抗变力状态相反。
PVA 不仅可以一致地评估膀胱的基本功能，还可以有效地测量由于外在环境和膀胱自身内在收缩性改变而导致的膀胱功能的改变。在伴随测压的情况下，PVA 可以提供关于排空活动中时间、压力和体积之间关系的清晰概念。
