Editing Functional: Urodynamics (section)

== Analysis and interpretation ==

* '''<span style="color:#ff0000">Each phase is described separately</span>'''
** '''<span style="color:#ff0000">Filling/storage phase:</span>''' consists primarily of CMG and provocative testing (e.g. measurement of abdominal leak point pressure, and urethral pressure measurement during storage)
** '''<span style="color:#ff0000">Voiding phase:</span>''' evaluates bladder contractility, bladder outlet resistance, and sphincter coordination by pressure-flow analysis and EMG
* '''<span style="color:#ff0000">The 9 Cs of Pressure-Flow UDS</span>'''§
** '''Filling and storage'''
**# '''Contractions (involuntary detrusor)'''
**# '''Compliance'''
**# '''Coarse sensation'''
**# '''Continence'''
**# '''Cystometric capacity'''
** '''Emptying'''
**# '''Contractility'''
**# '''Complete emptying'''
**# '''Coordination'''
**# '''Clinical obstruction'''

=== Filling/storage phase ===

* '''Normal Pdet should remain near zero during the entire filling cycle until voluntary voiding is initiated'''
** '''Baseline pressure stays constant (and low) and there are no involuntary contractions.'''
*** '''See Figure of normal UDS'''
** '''Contractions/detrusor overactivity (DO)'''
*** '''A urodynamic observation characterized by involuntary detrusor contractions during the filling phase.'''
**** '''See Figure of DO on UDS'''
*** '''May be characterized as:'''
**** '''Neurogenic, when DO is associated with a relevant neurologic condition (e.g. spinal cord injury, multiple sclerosis), vs. idiopathic (non-neurogenic), when there is no defined cause'''
**** '''Spontaneous vs. provoked (e.g. DO triggered by a rise in Pabd)'''
**** '''Single event vs. multiple involuntary detrusor contractions'''
**** '''Phasic, sporadic, or terminal'''
***** '''Phasic DO: characterized by contractions of increasing amplitude as the bladder volume increases.'''
****** '''Any phasic detrusor contraction during filling constitutes DO, regardless of amplitude'''
******* '''Non-phasic changes in detrusor pressure before micturition should be regarded as changes in bladder compliance rather than as DO.'''
***** '''Terminal DO is a single involuntary detrusor contraction occurring at cystometric capacity, which causes incontinence'''
*** '''Presence must be interpreted in the context of patient symptoms and condition'''.
**** Ideally, patient symptoms should be reproduced during UDS, so DO would be expected to be accompanied by urgency and urgency incontinence. '''However, DO can also be test induced or clinically insignificant'''.
**** It is important that the person performing the UDS study be absolutely sure that the contraction is indeed involuntary. Sometimes, patients may become confused during the study and actually void as soon as they feel the desire.
*** '''Failure to demonstrate DO does not rule out its existence.'''
**** Detection can be influenced by the patient’s position.
* '''<span style="color:#ff0000">Compliance</span>'''
** '''<span style="color:#ff0000">Definition: compliance is change in bladder volume divided by change in Pdet (∆volume/∆pressure)</span>'''
** Measured in mL/cm H2O
** Difficult to define normal compliance, but '''normal considered 46-124 mL/cm H2O'''
** '''See Figure of low compliance on UDS'''
** '''<span style="color:#ff0000">Causes of impaired compliance:</span>'''
**# '''<span style="color:#ff0000">Neurologic conditions</span>''' (spinal cord injury, spina bifida)
**#* Usually results from increased outlet resistance (e.g. detrusor external sphincter dyssynergia or decentralization in the case of lower motor neuron lesions
**# '''<span style="color:#ff0000">Long-term bladder outlet obstruction</span>'''
**# '''<span style="color:#ff0000">Radiation cystitis</span>'''
**# '''<span style="color:#ff0000">Tuberculosis</span>'''
** '''Causes of false-positive:'''
*** '''Rapid filling'''
**** '''If filling is stopped, and the pressure returns to baseline, the compliance is not impaired.'''
** '''Causes of false-negative:'''
*** '''“Pop-off mechanisms”, such as vesicoureteral reflux and bladder diverticulae, can make compliance seem higher than it actually is'''
** '''Absolute pressure is more useful than a compliance value; storage pressure > 40 cm H2O is associated with harmful effects on the upper tract'''
* '''<span style="color:#ff0000">Continence</span>'''
** '''<span style="color:#ff0000">Leak point pressures</span>'''
*** '''<span style="color:#ff0000">2 distinct types of leak point pressures can be measured in the incontinent patient:</span>'''
***# '''<span style="color:#ff0000">Abdominal leak point pressure</span>'''
***# '''<span style="color:#ff0000">Detrusor leak point pressure</span>'''
*** '''<span style="color:#ff0000">The ALPP measures the sphincter response to increased Pabd.</span>'''
**** '''<span style="color:#ff0000">The lower the ALPP, the weaker the sphincter.</span>'''
*** '''<span style="color:#ff0000">The DLPP measures the injured bladder response to increased outlet resistance.</span>'''
**** '''<span style="color:#ff0000">The higher the resistance (e.g. DESD), the higher the DLPP, which is potentially dangerous to upper tracts.</span>'''
*** '''<span style="color:#ff0000">Abdominal leak point pressure (ALPP)</span>'''
**** '''<span style="color:#ff0000">Definition:</span>'''
****# '''<span style="color:#ff0000">Intravesical pressure (Pves) at which urine leakage occurs</span>'''
****# '''<span style="color:#ff0000">As a result of increased Pabd</span>'''
****# '''<span style="color:#ff0000">In the absence of a detrusor contraction</span>'''
****#* '''i.e. how much abdominal pressure transmitted to the bladder results in SUI?'''
**** '''Measure of the sphincteric strength or the ability of the sphincter to resist changes in Pabd'''
***** '''Applicable to patients with SUI and can only be demonstrated in patients with SUI'''
****** '''There is no normal ALPP because patients without SUI will not leak at any physiologic Pabd.'''
****** '''<span style="color:#ff0000">The lower the ALPP, the weaker the sphincter.</span>'''
******* '''<span style="color:#ff0000">ALPP < 60cm H2O: suggestive of intrinsic sphincter deficiency (ISD)</span>'''
******* ALPP between 60-90 is equivocal.
******* '''<span style="color:#ff0000">ALPP > 90 indicates little or no ISD</span>'''
**** '''Should be measured as the total Pabd required to cause leakage, not the change in pressure.''' '''The reading is taken from the Pves channel''' as long as there is no involuntary contraction.
**** '''Current technology does not permit a method to distinguish between ISD and urethral hypermobility in women.'''
***** '''If there is no urethral hypermobility, SUI must be caused by ISD, regardless of the ALPP. Thus,''' '''an isolated measure of ALPP without considering other factors such as CMG and urethral mobility is of limited utility in predicting success for commonly performed female SUI procedures.'''
**** '''The term ALPP has been used interchangeably with Valsalva leak point pressure; however, this is not entirely correct.''' An ALPP can be measured during UDS testing by a voluntary Valsalva maneuver or by a cough. In the same person, Valsalva leak point pressure tends to be significantly lower than cough leak point pressure.
*** '''<span style="color:#ff0000">Detrusor leak point pressure (DLPP):</span>'''
**** '''<span style="color:#ff0000">Definition:</span>'''
****# '''<span style="color:#ff0000">The lowest detrusor pressure (Pdet) at which urine leakage occurs</span>'''
****# '''<span style="color:#ff0000">In the absence of either increased Pabd or a detrusor contraction</span>'''
***** The higher the urethral resistance, the higher the DLPP will be
**** '''The significance of elevated DLPP is that bladder pressures are getting too high before the pop-off mechanism of urethral leakage occurs.'''
**** '''Measure''' '''of''' Pdet in a patient with decreased '''bladder compliance'''
**** Most useful in:
****# Patients with upper motor neuron lesions with high storage pressures (usually secondary to DO and DESD)
****# Patients with lower motor neuron disease causing “decentralization”
****# Non-neurogenic patients with low bladder compliance (after multiple bladder surgeries, radiation, tuberculous cystitis).
**** '''Higher DLPP is associated with increased risk of upper tract injury as intravesical pressure is transferred to the kidneys.'''
***** '''<span style="color:#ff0000">When treating impaired compliance, concept is to aim for as low a pressure as is reasonably achievable, which would be considerably < 40cm H2O.</span>'''