Urodynamics Made Easy (Chapple) Flashcards
What is Urethral Pressure Profile (UPP) and how is it done?
> Measurement of urethral intraluminal pressure along the length of the urethra
Performed by withdrawing the measuring catheter mechanically at a constant speed while measuring pressure along the way (bladder neck to meatus)
3 components: resting, stress (coughing or valsalva) and voiding
What is the perfusion method (Brown and Wickham) of urethral pressure profilometry?
Catheter is withdrawn at a constant speed, with concomittent perfusion 2-10 ml/s, while measuring the changes in intramural pressure
What does a high or low Maximum Urethral Closure Pressure mean (MUCP)?
A low MUCP (<20 cmH20) is associated with intrinsic sphincter deficiency, high MUCP with urethral hypermobility, but studies do not have strong evidence.
What are the physiologic pressures in the upper tracts under normal circumstances?
resting pressure in the renal pelvis: 5 cm H20
on pelvic distension after filling: 10 cm H20
on peristalsis: intrabolus pressures of 20-60 cm H20
How is the Whittaker test done and what information can we get form it?
Kind of upper tract urodynamics where a PNT is inserted and measurement of both upper tract and lower tract pressure is done while infusing at a rate of 10 ml/min. Then get diff of upper - lower tract pressure.
if <15 cm H20, excludes obstruction
if 15-22 cm H20, equivocal
if >22 cm H20, confirms obstruction
if both upper and lower pressure rises together: VUR
note: invasive, so only use if non invasive means are still equivocal; it is done together with contrast for anatomic evaluation
What is the gold standard for urodynamic investigation and what are its components?
Videocystometrography/Video urodynamics is the gold standard. It takes abdominal pressure, intravesical pressure (to get detrusor pressure Pdet = Pves - Pabd), then also involves placing contrast to visualize lower tract during storage and voiding phases.
What are the expected ranges of intraabdominal and intravesical pressures in different positions?
Supine 5-20 cm H20
Sitting 15-40 cm H20
Standing 30-50 cm H20
During filling cystometry, what is the best fill rate for non neurogenic and neurogenic patients?
Medium fill rate is best 10-100 ml/min. Non-neurogenic, best to fill 50 ml/min, 20 ml/min for neurogenic patients. Cough every 50 ml infused.
What is the most direct and accurate method of determining the initial residual and attempts to ensure that the investigation commences on an empty bladder?
Draining the urine at catheterization.
During storage phase, what is seen in normal detrusor function vs patients with detrusor overactivity?
Normally, there are no involuntary detrusor contractions (IDCs) in the storage phase. In DO, these IDCs occur and they may be phasic, terminal, idiopathic or neurogenic.
What are the provocation maneuvers done to provoke detrusor overactivity during storage phase, and when should they be used?
They are used if there is a strong suspicion of DO but is not evident during the storage phase. Ask the patient what are the usual provoking events leading to incontinence and try to imitate it in the test, near his/her maximum cystometric capacity.
Maneuvers include: bending, changing posture, coughing, jogging, running, hand washing or increasing filling rate or using cooled filling fluid (do a new fill cycle)
What is bladder compliance, how is it computed and what are the normal values?
Bladder compliance is the ability of the bladder to expand in volume (fill) with no significant change in pressure. Compliance (mL/cmH20) = (change in volume mL)/(change in detrusor pressure cmH20).
normal compliance = 30 - 40 mL/cmH20
poor compliance < 30 mL/cm H20
*if poor compliance, check if still poor even if with a slower fill rate
Differentiate urodynamic stress incontinence vs urethral relaxation incontinence.
Urodynamic stress incontinence: leakage during increased abdominal pressure in the absence of detrusor contraction
Urethral relaxation incontinence: leakage due to urethral relaxation in the absence of inc abdominal pressure
What is the significance of abdominal leak point pressure (ALPP)?
Interchanged with VLPP (Valsalva) or CLPP (cough), depending on what you make the patient due to elicit it. It is the Pves when there is a leak due to an increase in Pabd
What is the significance of detrusor leak point pressure (DLPP)
It is the lowest Pdet where urine leak occurs even without detrusor contraction or increased abdominal
