Diagnosis of voiding dysfunction by pressure-flow study in women

Figure 1 Hill curves relating active force to velocity of shortening at a given muscle length. Curves are shown for two different muscle lengths, corresponding to the same bladder when full (upper curve) and when nearly empty (lower curve: Volume approximately 12.5% of capacity). (From Griffiths[8]. Assessment of detrusor contraction strength or contractility. Neurourol Urodyn 1991; 10: 1; with permission).

Figure 2 Bladder output relations relating active detrusor pressure to rate of urine flow at a given bladder volume. Curves show Bladder output relations for the same two situations as in Figure 1, corresponding to a full bladder (curve with higher maximum possible flow rate) and a nearly empty bladder (lower maximum possible flow rate; volume approximately 12.5% of capacity). (From Griffiths[8]. Assessment of detrusor contraction strength or contractility. Neurourol Urodyn 1991; 10: 1; with permission).

Figure 3 Bladder outlet obstruction nomogram for women. (From Blaivas et al[24]. Bladder outlet obstruction nomogram for women with lower urinary tract symptomatology. Neurourol Urodyn 2000; 19: 553; with permission).

Figure 4 To determine projected isovolumetric pressure 1 the point representing the pressure and flow rate measured during uninterrupted voiding is projected back to the axis with a line of slope -1 cm H₂O/mL per second. (Note that the value of original PIP would be much larger). For this void, the value of PIP1 is about 60 cm H₂O, and the void falls in the band of typical values (unshaded). Values in the regions shaded gray would represent either ST or W contractions than those typical of the subjects in this group. (From Tan et al[30]. Stop test or pressure-flow study? Measuring detrusor contractility in older females. Neurourol Urodyn 2004: 23: 184 with permission). PIP: Projected isovolumetric pressure; ST: Stronger; W: Weaker.