Figure 4
From: Elucidating the high compliance mechanism by which the urinary bladder fills under low pressures
Analysis of bladder compliance for illustrative Case 1. (A) Raw data for pressure vs. volume curve with three filling regimes (Toe, Transition, High Pressure). The linear fits used to identify the beginning and end of the transition regime are shown in (B) and (C) respectively. Here the infused volume and filling pressure are shown, adjusted to remove the initial pressure spike seen in (A). For (B), a linear fit (\(\hbox {R}^2=0.9931\)) is applied from 0.15 to 0.68 ml to obtain transition values of \(V_{t1}=0.68\) ml and \(P_{t1}=3.72\) mmHg. For (C), a linear fit to the high pressure regime is shown (\(\hbox {R}^2=0.9946\)) across the volume 0.78 to 1.00 ml with resulting values of \(V_{t2}=0.78\) ml and \(P_{t2}=4.73\) mmHg. The corresponding compliance (slope) in the toe and high-pressure regions are 0.35 ml/mmHg and 0.050 ml/mmHg respectively. A representative image of the infused bladder is shown (D) at zero infused volume, the origin of curve in (A). An ellipse was fit to the bladder region (outer dashed curve) as well as the dye filled region (inner dashed curve) and used to estimate volume in these two domains.
