Urology & Urogynecology > Education and Reference

CLINICAL APPLICATION NOTES

UPP PROCEDURE GENERAL INFORMATION

Urethral pressure measurement and the Urethral Pressure Profile are techniques used to provide information about the ability of the urethra to prevent leakage. The Urethral Pressure Profile is a specific study, in which a special design catheter is pulled through the urethra at a slow, continuous rate. The resulting “bell shaped” curve illustrates the function of the urethra from the beginning of the bladder neck out through the meatus.

The International Continence Society has described the purpose of the UPP procedure. They have also laid out the requirements for techniques to be used and proper documentation of the UPP. “The Standardization of Terminology of Lower Urinary Tract Function” (Abrams P, Blaivas JG, et al.) is available for download on the ICS website. See pages 406 – 409 of the standardization document for UPP information.

SYSTEM CONSIDERATIONS

All Life-Tech Urodynamic systems, when equipped with the appropriate options, may be used to perform UPPs. Option considerations include:

Having the necessary number of pressures and channels. In System V you can assign pura labeling and function to any of the pressure inputs (P1, P2 or P3) purchased for your system.
The software to calculate transmission ratios for the UPP or UP analysis reports, or generate the Transmission Ratio Plot is an optional purchase. If your system doesn’t have this capability and you want more information, contact your Life-Tech representative.

CATHETER SELECTION

The Urethral Pressure Profile (UPP) is performed using either special design fluid-filled catheters or Mikro-Tip® catheters. Both types of catheters are available for purchase from Life-Tech.

The fluid-filled catheters designed for UPPs are sterile, single use hollow, PVC catheters with multiple, radial (or opposing) lumen openings from the pura lumen. It is essential that UPPs be performed using catheters designed specifically for the procedure because of the anatomy and dynamics in the urethra.

The closed urethra is not cylindrical. The “mucosa is organized in longitudinal folds, giving the urethral lumen a stellate appearance when closed,”(1) as illustrated to the left. This structure makes it imperative that the fluid-filled catheters used for acquiring UPPs have more than one lumen opening in the urethra. Multiple “eye” catheters improve the quality of urethral pressure traces because they increase the availability of the lumen to an open space, improving the quality of the pressures traces being recorded.

In addition, the pressures in the urethra differ rotationally, being greater in the anterior urethra and less in the posterior urethra. Multiple eyes transmit an “averaged” intra-luminal pressure.(2)

The urethral lumen of fluid-filled catheters must be perfused with solution (water or saline) at a very slow rate (4-12 cc/min) during the UPP. This is also due to the anatomy of the urethra.

Fluid-filled catheters for UPPs are available from Life-Tech in single, double and triple lumen designs. Selection of the model would depend upon user procedure preference. The acceptable size range for fluid-filled catheters is quite wide. Abrams reports “no appreciable difference in pressure measurement, provided the catheter is between sizes 4 and 10 Fr.” (2)

FLUID-FILLED CATHETER DESCRIPTIONS AND SETUP

The Single-lumen UPP Catheter (i.e., UPP-6P, UPP-8D, UPP-10D) is used only to perform urethral pressure profilometry. The design of this catheter precludes using it for any other type of procedure. Therefore, the patient must be recatheterized with an appropriate design for filling (at a higher rate) and measuring pressure in the bladder. The advantage of the single-lumen catheter design is that the larger diameter lumen construction permits the placement of three circumferential eyes (lumen openings) on the catheter. Multiple eyes increase access to the urethra, improving the quality and reproducibility of fluid pressure measurements.

Supply List:

UPP-6P, 8D or 10D catheter
4-SCA (4-way stopcock)
IPTS-DC-LT1 (2011/1711) / IPTS-DC-LT2 (3011) if pump perfusion

The Dual-lumen CMG/UPP Catheter (i.e., DLUPP-6P, DLUPP-7D) may be used to perform a CMG or CMG-PF and a UPP. The lumens function as illustrated below.

Note: In the dual-lumen catheter, the lumen designed to measure urethral pressure must be used for bladder filling during cystometry. If you prefer to continuously monitor urethral pressure during the CMG or CMG-P/F, you should use a triple-lumen catheter instead of a dual-lumen.

Supply List:

DLUPP-6P or DLUPP-7D catheter catheter
4-SCA (4-way stopcock)
IPTS-DC-LT1 (2011/1711) / IPTS-DC-LT2 (3011) if pump perfusion
AS-72A if pressurized cuff for perfusion

The Triple-lumen UPP Catheter may be used to perform a CMG or CMG-PF and a UPP. The triple-lumen design permits simultaneous bladder filling, with measurement of both vesical and urethral pressures. Model numbers containing the letters XRO have radiopaque markers at the tip and at the location of the pura lumen openings. The lumens function as illustrated below.

Supply List:

TLC-7M/F, CTLC-7M, TLCXRO-7M/F, CTLCXRO-7M, TLC-9M/F, CTLC-9M, TLCRO-9M/F, CTLCXRO-9M catheter
4-SCA (4-way stopcock)
IPTS-DC-LT1 (2011/1711) / IPTS-DC-LT2 (3011) if pump perfusion
AS-72A if pressurized cuff for perfusion

MIKRO-TIP® CATHETERS

Life-Tech is the exclusive distributor of Millar® Mikro-Tip® catheters in the US.

Mikro-Tip catheters are reusable electronic catheters, requiring an initial investment. However, when reused with consistent, practical care and handling, they prove to be quite cost effective during their expected lifespan.
Mikro-Tip catheters simplify UPPs. This is because the transducer is placed directly into the urethra, eliminating the extra fluid lines, extra pump or pressurized solution bag necessary to perfuse the urethral lumen of a fluid-filled catheter.
When Mikro-Tips are used, it is typically recommended that the pura sensor be in a lateral position in the urethra. (1, 3)
The Millar Mikro-Tip catheters are marked (as illustrated below) with the centimeter marking dots in a straight line with the urethral transducer.

ACCESSORY EQUIPMENT AND SUPPLIES:

The accessory equipment used during urethral profilometry procedures may include:

A Uropump or a pressure cuff to provide a constant perfusion of the urethral lumen when using fluid-filled urodynamic catheters.
A profilometer for catheter withdrawal, so that the UPP analysis routine can accurately compute and report the various urethral lengths and areas.

In order to obtain optimum tracings during a UPP, the pump and tubing assembly being used must:

Have adjustable speed to less than 12cc/min.
Resist or restrict the retrograde loss of pressure data into the “damped” pump tubing system (utilizing a restrictor device/tubing).
Function pulsation-free (utilizing a damping device/chamber).

The urethral pressure tracing from UPP procedures performed with a pump that does not incorporate a damping chamber will have the typical appearance shown to the right. In addition, improperly used damping chambers (i.e., full of water instead of air), will also demonstrate roller artifact.

All Life-Tech model pumps and tubings have the above capabilities.

Ouch!

Make sure that the pump infusion rate is set between 4-12 ml/min before you start infusion. Excessively high infusion rates in the urethra can cause both extreme discomfort and significant pressure artifact on the pura channel.

There is a possibility, even at slow fill rates, that the pump will add pressure artifact to the pura channel. It is important to observe the pura channel as you start infusion and then take measures to eliminate the artifact after the pressure has stabilized.

To eliminate pump pressure artifact on the pura channel:

With the catheter pura lumen openings in the bladder (pura channel is actually displaying pressure from inside the bladder at this time), start infusion.
Observe the pressure increase on the pura channel until it stabilizes.
Click pequalize (P=). Pequalize electronically adjusts pura (and pabd) to equal the current pves value, thus eliminating the pump artifact.

Note: In order to use this technique, you must use either a dual- or triple-lumen model catheter and have both a pura and a pves channel on the procedure waveform.

Perfusing with a Pressure Bag

To perfuse the pura lumen without a pump, the solution bag must be pressurized with an infusion cuff (like those used to set up arterial lines or infuse blood).

The infusion cuff should be inflated to 300 mmHg and kept near this level throughout the procedure in order to maintain the required constant urethral perfusion.
Perfusion rate is regulated by the roller clamp on the administration set.

The only means to obtain accurate functional and total urethral length is to use a profilometer for the catheter withdrawal.

The digital urodynamic system utilizes the set profilometer withdrawal rate (.25 to 5.0 mm/sec) to compute the various lengths and areas standard in urethral pressure profile reports.

Note: The catheter is to be inserted so that both the pves and pura lumen openings are in the bladder, before initiating withdrawal for the UPP.

WHY IS THAT IMPORTANT?

pura

PATIENT POSITION

Pressure is transmitted differently through the abdominal cavity into the bladder and urethra in the supine and upright positions. Sensation events are perceived at different volumes between the two positions and leakage is likely to only be reproducible in the position of function, therefore, it is typically recommended that all urodynamic procedures be performed in the position of function. Accessory equipment should be repositioned to permit Urethral Pressure Profiles to be performed with the patient sitting up or standing.

COMPUTING TRANSMISSION RATIOS

Transmission Ratios are a mathematical comparison of the change in urethral pressures to the change in vesical pressure, along the length of the urethra, during increases in abdominal pressure (cough, valsalva, heel bounce, crede). The UPP and UP analysis program calculates and reports Transmission Ratios if the Transmission Ratio option was purchased for your Life-Tech system software.

During stress maneuvers, abdominal pressure increases. The rise in abdominal pressure is reflected into the bladder and upper portion of the urethra, if the anatomic structures of the pelvic floor are in proper position. Therefore, the same rise in pressure seen in the pves channel should be seen in the proximal and mid-urethra. The demonstration of the transmission of abdominal pressure into the urethra during stress is the purpose of performing the stress UPP.

Note: Pressure is transmitted differently through the adbominal cavity into the bladder and urethrea in the supine and upright positions. Urethral pressure studies, particularly those that include stress maneuver analysis, should be done with the patient as upright as the equipment and procedure will allow (i.e. position of function).

Both pura and pves channels are required for Transmission Ratio calculation. Each pair of base and peak markers is actually placed looking at the cough spikes on the pves channel (not pura). Then, the values on pves and pura for the sets of paired markers are used to compute each transmission ratio.

The pressure increase (from base to peak) on pves is the divisor in the equation.
The pressure increase on the pura channel from the same set of base and peak markers becomes the dividend in the equation.

RECOMMENDED READING:

For additional information on UPP procedures and interpretation, we recommend the following books:

Sand PK, Ostergard DR. Urodynamics and the Evaluation of Female Incontinence: A Practical Guide, Springer, 1995, p.147-149.
Abrams, Paul, Urodynamics, 3rd ed., Springer, 2006, Softcover, ISBN: 978-1-85233-924-1,

REFERENCES:

(1) Sand PK, Ostergard DR, Urodynamics and the Evaluation of Female Incontinence: A Practical Guide, Springer, 1995, p 147-149
(2) Abrams, P, Urodynamics, 2nd ed, Springer, 1997, p. 9, 100-101.
(3) Reyes H, Weil A: Reproducibility of Simultaneous Urethrocystometry Measured with Electronic Microtransducers. Gynecol. Obstet. Invest. 15: 129-140 (1983).