URODYNAMICS LABORATORY

A laboratory for urodynamic evaluation of incontinence in elderly women needs to have the highest diagnostic capabilities possible and to be a very comfortable and congenial experience for the patient. The ambience of a urodynamics laboratory for older women is one of the most important aspects of the evaluation. Because the performance of the measurements alters the very functions that are being measured, the environment needs to feel as much like home to the patient as possible to minimize the measurement effect on the study results. A comfortable environment can make it possible for an older woman to be an active participant in the studies, and it enables the study results to provide the best possible information about her bladder and urethral function relative to symptoms experienced during her daily life.

Another important aspect of the urodynamics laboratory is the relationship between the urodynamicist and the patient. Scheduling extra time in the laboratory before the studies is helpful in developing a personal relationship that is nurturing and congenial to minimize any feelings of fear and anxiety that the older patient may experience during the studies. Older women are often more difficult to engage in active participation in the studies than younger women. Because the complexity of bladder dysfunctions and functional impairment is greater in older women compared with younger women, the studies are considerably more difficult to perform and usually require more time to complete.

When performing urodynamic studies in older women, the urodynamicist sometimes may feel like a flight attendant who says, “In the event of a sudden loss in cabin pressure, place the oxygen mask over your nose and mouth and breathe normally.” It is not likely that anyone would breathe normally under those conditions. Although it is necessary to recognize the artificial conditions of the urodynamics laboratory, the goal is to create an environment and testing experience that allows the measured behavior of the bladder in elderly women to be as normal as possible. It is one of the primary objectives during testing of older women to minimize the measurement effects of the urodynamic studies on normal bladder and urethral function.

Comprehensive urodynamic studies in older women are not like an electrocardiogram of the bladder in the way the studies are performed and interpreted. Much of the information required for interpretation of urodynamic studies is recorded by the urodynamicist as the studies are being done by describing events and sensations experienced by the older patient. The training and experience of the urodynamicist is an integral part of the diagnostic capabilities of the urodynamics laboratory.

The symptoms experienced by the older woman are less predictive of urodynamic findings than those in younger women.¹ The voiding history and physical examination do not provide enough clinical information to make decisions about treatment in older women without the additional information provided by urodynamic studies. However, the urodynamicist needs to know the clinical history and the observations made on physical examination to perform the best studies possible for the patient. Because urodynamic studies are more difficult to perform in older women and the results are so important in clinical management decisions for these patients, measurements often need to be repeated during the initial testing procedure to ensure that the clinical information provided is as complete and accurate as possible.

It is a goal of the urodynamicist to duplicate the clinical symptoms described by the patient in the urodynamics laboratory. However, the symptoms experienced during the daily life of an older woman often do not occur during the urodynamic studies. In the elderly population, another approach to evaluation may be necessary. If the clinician can identify the symptoms experienced by the patient during her daily activities as completely and thoroughly as possible, the urodynamic studies can be used to better understand why she experiences those symptoms and what can be done to treat the symptoms based on the information provided by the studies.

The diagnostic capabilities of the urodynamic testing equipment are frequently a concern of the physician. Physicians do not want to be limited in their diagnostic capabilities by the limitations of the equipment in the urodynamics laboratory. Although midlevel equipment from most manufacturers can provide the basic information needed for most patients, higher-level equipment is preferred for elderly women because of the complexity of the clinical problems. However, the most expensive equipment does not ensure high-quality studies. The ambience of the laboratory and the skill of the urodynamicist are as important as the capabilities of the equipment. Because elderly women usually have more complex voiding dysfunctions than younger women, the higher-level equipment is often required to meet the performance needs of the clinician in testing these patients.

Urodynamic studies are objective measurements that require a significant knowledge of lower urinary tract function and clinical experience for interpretation. Similar knowledge and experience are required to clinically use the urodynamic studies to make reasonable recommendations for treatment in older women. Each study or test can provide only a fraction of the clinical data, and to see the complete clinical picture and make treatment decisions, especially for older patients, the physician needs comprehensive urodynamic studies.

Urodynamic studies of older women are needed when considering pharmacologic, behavioral, or surgical therapy. It is much easier to change medications or combine pharmacologic therapy with behavioral therapy than it is to revise an operation. However, any long-term treatment needs to be based on the most complete clinical information available. Without urodynamic studies, the clinician is voluntarily relinquishing the most comprehensive objective measurements of bladder and urethral function that are available. Without urodynamic studies in this population, the opportunity of providing the most appropriate initial treatment is significantly decreased, even when nonsurgical therapy is recommended. An ineffective trial of pharmacologic therapy without urodynamic studies is rarely harmful in the long term, but the cost to the elderly woman is time and money at a moment in her life when she often feels she has little of either.

NONINVASIVE URINARY FLOW STUDIES

Noninvasive urinary flow studies are relatively easy to perform in younger women but can be difficult to perform in older women for many reasons. Older patients with urinary incontinence often have an impaired ability to inhibit involuntary detrusor contractions and an impaired ability to voluntarily initiate a bladder contraction.² The older woman is usually instructed to arrive at the urodynamics laboratory with her bladder as full as possible so that the noninvasive urinary flow study can be done. She might have “had to go” just before coming to the urodynamics laboratory, or she might have had an “accident” just before arrival. She may be unable to voluntarily void even though she has not voided for hours. Catheterization of the bladder in an elderly woman who is unable to void often demonstrates a relatively large amount of urine in the bladder. The volume of urine obtained in this case is not a postvoid residual urine volume because the patient was unable to void. It is common for older women with urinary incontinence to be unable to prevent or initiate a bladder contraction. In contrast, young women can usually voluntarily void at almost any time.

It is helpful to have a urinary flow unit in the office so that measurement of urinary flow rate can be done many times for older women to determine as closely as possible the urinary flow characteristics of the patient. An ultrasound postvoid residual volume measurement unit in the office allows the assessment to be done with each office visit to obtain multiple determinations. Ultrasound bladder volume measurements have been shown to have a high correlation with catheterized volume measurements in elderly patients.³ Although the measurement of the postvoid residual urine volume is a simple method to evaluate bladder emptying in elderly patients, it is not possible to predict the type of bladder dysfunction that the patient has without additional studies.⁴

Urethral Pressure Profile

The maximum urethral pressure and urethral length decrease in continent women with increasing age.⁵ Clinical evaluation of urethral function in older women is one of the most important aspects of assessment of lower urinary tract function. However, urethral function remains one of the most elusive measurements of lower urinary tract function. Urethral dysfunction of some type is usually a component of urinary incontinence in older women. The urethral pressure profile (UPP) measurements in women significantly correlate with incontinence episodes and absorbent pad use.⁶ Although the UPP measurements have a significant correlation with incontinence severity, the UPP is a measurement of resting urethral pressure and not a direct measurement of continence. This distinction is important when using the UPP measurement in clinical decisions.

Assessment of urethral sphincter dysfunction may require a composite of historic, urodynamic, anatomic, and clinical severity criteria.⁷ The composite of intrinsic sphincter deficiency has been suggested to include a maximum urethral closure pressure less than or equal to 20 cm/H₂O, a Valsalva leak point pressure of less than or equal to 50 cm/H₂O, and a stress urethral axis less than or equal to 20.⁷

The concept that intrinsic functional properties of the urethra exist that contribute to the integrity of the urethral continence mechanism resulted from many years of clinical work by McGuire and others.^8,⁹ During the 1970s, McGuire and Lytton⁸ observed that women who had failed previous incontinence procedures had poor urethral function indicated by low urethral pressure. McGuire and colleagues⁹ subsequently categorized women who have poor urethral function as having type III incontinence. Type III incontinence refers to a poorly closed proximal sphincter identified by video urodynamics and leak point pressure measurement. Intrinsic sphincter deficiency refers to a low-pressure urethra identified using UPP measurements recorded in the mid-urethral high-pressure zone. The UPP and abdominal leak point pressure (ALPP) assessments are performed differently and identify different characteristics of urethral function. Although the low-pressure urethra and the type III urethra identify different aspects of urethral function, the clinical objective of both studies is to recognize women who have severely compromised urethral function. Because clinical evaluation of urethral function in older women is important in the management of incontinence, the UPP and ALPP measurements can be used to better characterize urethral dysfunction. Although the UPP has many limitations, the measurements can contribute to the information obtained from ALPP assessment if the UPP is used appropriately. Elderly women who have intrinsic sphincter deficiency based on the UPP should be clinically identified and counseled about treatment because of the higher risk for failure of any therapeutic approach in this group.^10,¹¹

The maximum urethral closure pressure and the Valsalva leak point pressure are significantly decreased with increasing severity of the incontinence grade.¹³ Some studies have suggested a statistically significant relationship between the UPP and ALPP.¹²^–¹⁵ From a clinical management perspective, the UPP and ALPP are different measurements of urethral function that can be useful in combination, but they are not comparable measurements.

UPP measurements are usually performed using micro tip transducers. Although many techniques have been used, the microtip transducer remains the clinical standard for UPP measurements. A dual-channel microtip catheter is preferred. It has a microtip transducer located at the tip of the catheter for bladder pressure measurement and a microtip transducer located approximately 5 cm proximally for measurement of urethral pressure. The subtraction of intravesical pressure from urethral pressure produces the urethral closure pressure profile.¹⁶ The dual-channel microtip transducer allows the urodynamicist to perform stress UPP measurements. An electronic catheter puller is used to ensure a constant rate as the catheter passes through the urethra. Because of measurement variations in the UPP, many measurements are done to determine the maximum resting urethral pressure. The UPP measurement in older women is usually performed in the supine position because of measurement artifact that occurs in the standing position.

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