LABORIE Nexam Pro WPU-L4 User Manual page 229

Figure 13.13 Schäfer Detrusor/flow plot
A linear-PURR (Passive Urethral Resistance Relation) is determined by
drawing a straight line from P to P .
muo qmax
P represents the relative lowest detrusor pressure at which flow starts or
muo
stops. P is the pressure at maximum flowrate.
Qmax
For easy application of the linear PURR, a diagram was developed by dr.
Schäfer, which allows a grading of the bladder outflow condition (seven
classes) as well as a crude judgement of detrusor strength (four classes). The
point representing the peak flow and the detrusor pressure at peak flow
determines the classes for the micturition.
Additional information about PURR
The real pressure-flow relations often shows complex patterns, but is easy to
abstract the most pertinent information. The linear PURR is a simple way of
analyzing pressure/flow recordings and in combination with the detrusor/flow
plot it represents a specific grading of detrusor strength and urethral
obstruction.
The passive urethra resistance ratio is a line with a simple quadratic shape
derived from fluid dynamic considerations which is starts at Pmuo and then
peak flow. The PURR by position and slope provides information about the
urethral opening pressure (Pmuo) and the effective lumen size of the flow rate
controlling zone.
Analysis Program Nexam Pro User Manual 229