CLINICAL STUDIES OF THE URODYNAMICS
Fifth Report: Muscle Pressure Recording at External Urethral Sphincter
1984 Volume 75 Issue 1 Pages 59-64
Details
1984 Volume 75 Issue 1 Pages 59-64
We measured urethral sphincter muscle pressure in several normal men and in more than 50 patients with benign prostatic hypertrophy, unstable bladder and spinal cord injury using MIKRO-TIP catheter pressure transducer (Miller Instrument, Inc.) for the study of urethral sphincter function.
Cystometrography and uroflowmetry combined with urethral sphincter electromyography, its muscle pressure, pressure change at maximum urethral pressure (UPmax) and anal sphincter tone pressure were performed. These recordings changed in parallel with urethral sphincter electromyogram in normal men. We consider that the recordings of the pressure change at UPmax and the anal sphincter tone pressure are not suitable for evaluation of the outfow resistance at the external urethral sphincter quantitatively based on the facts that the detrusor pressure is superimposed on the pressure change at UPmax during voiding, the anal sphincter tone pressure can not be expressed in absolute value and there is disparity between urethral and anal sphincter electromyograms in patients with neurogenic bladder dysfunction.
The values of intravesical opening pressure were almost equal to those of urethral sphincter muscle pressure in normal men. These values were different in patients with benign prostatic hypertrophy before operation but became equal after prostatectomy. These findings suggest that the muscle pressure shows the urethral pressure at the external urethral sphincter, although the microtransducer is placed in only the part of the urethral sphincter. The urethral sphincter muscle pressure ranged from 20 to 40cmH2O during voiding in normal men and in patients with benign prostatic hypertrophy. The abdominal pressure appears to have influence on the sphincter muscle pressure. Therefore it seems appropriate to monitor the abdominal pressure in conjunction with the sphincter muscle pressure.
We feel that the recording of the urethral sphincter muscle pressure which changes in parallel with urethral sphincter electromyogram enables one to evaluate the outflow resistance at the external urethral sphincter quantitatively and it is especially useful to examine the patients with spinal cord injury who show abnormal function at the membranous urethra.
