2.2 Pressure-flow study and pressure-volume analyses
Our protocols of cystometry complied with the guidelines of the
International Continence Society (ICS).20 Briefly, a
multi-channel urodynamic study, in which warm saline (37 °C) was infused
(80 ml/min) into patients’ bladder, was recorded (MMS UD-200, Medical
Measurement System, Enschede, Netherlands) and analyzed (Biopac MP36,
Biopac Systems, Santa Barbra, US) using computer systems. The vesical
pressure (Figure 1A Pves), abdominal pressure (Pabd), detrusor pressure
(Pdet), urethral flow (Flow), voided volume (Vvod), infused volume
(Vinf), and intra-vesical volume (Vive) were online recorded; and the
mean voiding pressure (Figure 1B Pv; the mean Pdet during fluid
emission), the voided volume (Vv; the volume of emitted fluid), the
voiding time (Tv; the time latency of fluid emission), and the mean
voiding resistance (Rv; calculated by Pv/(Vv/Tv)) were off-line
analyzed.
Derived from the cystemetry (Figure 2A), the pressure-volume analysis
(PVA) of the voiding cycle was established by plotting Pdet against Vive
(Figure 2B);18,21 and the trajectory-enclosed area
(Apv) was analyzed using an image processing program (Image J, LOCI,
Madison, WI, USA).
Although cough and Valsalva tests markedly interfere Pves and Pabd, a
previous publication22 and our data (Figure 1A)
demonstrated these tests displayed little effect on the Pdet in the
cystometry. Moreover, our data discovered cough and Valsalva maneuver
impacted trivially on the trajectory of PVA. In addition, cough and
Valsalva tests were carried out during the storage phase in our protocol
that would hardly affect the voiding dynamics. Therefore, cystometry
data of SUI patients who underwent stress tests (coughs and/or Valsalva)
were pooled together with those cystometry data without these tests.