Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
2001-08-31
2004-04-13
Marmor, Charles (Department: 3736)
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
C604S544000
Reexamination Certificate
active
06719709
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to medical devices, more particularly to a diagnostic urethral assembly and attendant methodology for assessing lower urinary tract symptoms.
BACKGROUND OF THE INVENTION
A diagram of the male urinary bladder and urinary passage (i.e., the lower urinary tract) is presented in FIG.
1
. The bladder
200
temporarily stores urine
210
and periodically expels it when the bladder neck
220
opens, as the bladder
200
contracts. Urine
210
passes through the prostatic urethra
230
, which is completely surrounded by the prostate
240
. The distal limit of prostate
240
is marked by a small projection called the verumontanum
250
. This is a important landmark because distal thereto, is the external urethral sphincter
260
, which relaxes prior to the urination process beginning. Beyond this is the urethra
270
, affording a free passage of urine
220
external to body, beyond the external urethral meatus
280
.
Presently, millions of men in the United States alone exhibit some form of lower urinary tract symptoms (LUTS), with bladder outlet obstructions (BOOs) being a major subgroup of LUTS. BOOs are primarily caused by the enlargement of the prostate gland (e.g., benign prostate hyperplasia (BHP)) which results in radial compression of the urethra surrounded thereby (i.e., the prostatic urethra), thus obstructing (i.e., constricting) urine flow, resulting in incomplete emptying of the bladder (i.e., there being what is clinically referred to as a “post void residual” (PVR) remaining in the bladder). Persons exhibiting an abnormal PVR will often need to urinate more frequently, and are likely to experience other physical discomfort, such as frequent urges to urinate, and physical exhaustion due to sleep deprivation, a condition clinically referred to as nocturia. Heretofore, such symptoms would be treated using surgical procedures such as transurethral resection of the prostate (TURP), or non-surgical procedures such as thermal treatment of the prostate.
As bladder outlet obstruction patients are a subgroup of patients with LUTS, proper treatment of the specific problem requires a knowledge of complete urodynamic status of the patient in order determine the cause of the symptoms. Causes may include bladder deficiencies such as bladder decompensation or hypertrophy, sphincter dysnergia, prostatic obstruction, urethral lesions and others.
There are diagnostic procedures available to clinical urologists, the purpose of which is to assess the physiologic properties of the lower urinary tract and symptoms related thereto. Such tests, which address the filling/emptying conditions (i.e., dynamics) of the bladder, include, but are not limited to, the use of video fluoroscopy simultaneously with the holding and release of urine, cystometry, urethral pressure profiling, ultrasonic volume assessments, and uroflowmetry. The subject invention provides additional heretofore unknown diagnostic options which allow for relatively simple and increased understanding of the urinary tract by assessing the elements (i.e., structures or architecture) thereof, more particularly the prostatic urethra and their influence on urine flows.
One of the urodynamic tests frequently performed in urodynamic investigations is cystometry, a test of bladder function in which pressure and volume of fluid in the bladder is measured during filling, storage, and voiding. A cystometry study is performed to diagnose problems with urination, including incontinence, urinary retention, and recurrent urinary tract infections. Urinary difficulties may occur because of weak or hyperactive sphincter or detrusor (i.e., the main muscle of the bladder wall), or incoordination of their two activities. Infection of the bladder or urethra may cause incontinence, as can obstruction of the urethra from scar tissue, prostate enlargement, or other benign or cancerous growths. Loss of sensation due to nerve damage can lead to chronic overfilling.
This test of detrusor muscle function generally consists of distending the bladder with a known volume of a fluid (i.e., liquid (e.g., water, saline, etc.) or gas (e.g., air, carbon dioxide, etc.)) while recording the intravesical pressure. The desired fluid may be introduced either through the urethra or suprapubically, in most cases the fluid is instilled through a double lumen catheter at a rate of approximately 10 cc/min, with the catheter employed permitting both filling of the bladder and recording of bladder pressure. As the bladder is composed mostly of small muscles, which are to a large degree under voluntary control, and muscle bundles which run in different directions and from layer to layer, adaptation of the bladder to changing fluid volume is primarily due to the viscal-elastic property of the organ. The bladder wall, in a healthy individual, is able to expand without any significant increase in tension as the bladder fills with fluid.
When the bladder is artificially filled, the pressure which is required to fill that bladder will provide for clinical characterization of the bladder and its general health. If a bladder is non-compliant, the pressure to fill the bladder will increase prematurely. If it is decompensated, meaning it has lost some of its tone, the filling pressure will be minimal while the bladder volume may be large. When the bladder is becoming full, the patient will experience a strong sensation of needing to urinate.
In a typical cystometric study, the filling phase looks at the bladder's ability to comply to increased volume. The detrusor muscle normally expands as volume increases so that the bladder initially rises very little in pressure to the time the patient voids (i.e., in a plot of pressure against volume of contents during filling (i.e., a “cystometrogram” (CMG)), the early portion of this graph is substantially flat for a healthy individual). The normal bladder should not begin contractions during filling and should initially expand without resistance. A feeling of fullness occurs with a volume of about 100-200 ml, with an adult bladder capacity on the order of about 300-500 ml. The sphincter should relax and open when the patient wills it, accompanied by detrusor contractions. During voiding, detrusor contraction should be smooth and lead to a steady urine stream.
If bladder pressure continually rises during filling, it can be due to a number of factors which would bear further investigation. For instance, inability of the bladder to relax during filling, or low bladder volume, may indicate interstitial cystitis, prostate enlargement, or bladder cancer. Contraction of the bladder during filling (i.e., any rise in bladder pressure that is not accompanied by a rise in abdominal pressure) may be due to irritation from infection or cysts, obstruction of the bladder outlet, or neurological disease such as stroke, multiple sclerosis, or spinal cord injury. Diminished sensation may occur with nerve lesions, peripheral neuropathy, or chronic overfilling.
A procedure generically referred to as “bedside cystometry” is used to determine, at a basic level, whether the bladder appears decompensated. This is accomplished by simply filling the bladder through a catheter with a known fluid volume, often ranging from about 250-400 ml. The patient is ask to inform the physician when he or she has a strong urge to urinate. Should the patient lack such urge, even when the bladder accommodates the introduced fluid volume, it is likely that some degree of bladder decompensation is present. As the bladder capacities increase, the probability of decompensation increases.
Whether monitoring filling pressures and volumes for the purpose of bladder characterization, or at a bedside procedure which only monitors initiation of flows, information with regard to bladder emptying is typically not acquired. Even if such information were acquired, meaningful diagnosis of BOOs is not possible.
Another standard urodynamic test is called the urethral pressure profile (UPP), (i.e., perfusion urethral profilometry), a procedure wh
Reid John M.
Whalen Mark J.
Willard Lloyd K.
AbbeyMoor Medical, Inc.
Marmor Charles
Nawrocki, Rooney & Sivertson P.A.
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