The effect of a 6 Fr catheter in women: Are they obstructive?

Richard, Patrick O.; Ordonez, Nydia Icaza; Tu, Le Mai

doi:10.5489/cuaj.1320

Cited by 8 publications

(7 citation statements)

References 24 publications

(25 reference statements)

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“…In addition, the catheter blocks free flow of fluid out of the bladder and may cause non-physiologically high bladder pressures and low flow. [2][3][4][5] This underlines the importance of a catheter-free methodology for measuring voiding bladder pressures. We hypothesize that, using pressure dependent acoustic properties of ultrasound (US) contrast microbubbles (MBs), we can measure voiding bladder pressure without a catheter.…”

mentioning

confidence: 91%

“…However, due to catheter related anxiety and discomfort and/or complete occlusion of urethra, not all patients can void. In addition, the catheter blocks free flow of fluid out of the bladder and may cause non-physiologically high bladder pressures and low flow 2–5 . This underlines the importance of a catheter-free methodology for measuring voiding bladder pressures.…”

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confidence: 99%

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Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography—A Path to a Catheter-Free Voiding Cystometrogram

Kalayeh¹,

Fowlkes²,

Chen³

et al. 2022

Invest Radiol

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ObjectivesThe long-term goal of this study is to investigate the efficacy of a novel, ultrasound-based technique called subharmonic-aided pressure estimation (SHAPE) to measure bladder pressure as a part of a cystometrogram (CMG) in a urodynamic test (ie, pressure-flow study). SHAPE is based on the principle that subharmonic emissions from ultrasound contrast microbubbles (MBs) decrease linearly with an increase in ambient pressure. We hypothesize that, using the SHAPE technique, we can measure voiding bladder pressure catheter-free. This is of importance because the CMG catheter, due to its space-occupying property and non-physiological effects, can undermine the reliability of the test during voiding and cause misdiagnosis. In this study, we tested this hypothesis and optimized the protocol in a controlled benchtop environment.Materials and MethodsA bladder phantom was designed and built, capable of simulating clinically relevant bladder pressures. Laboratory-made lipid-shelled MBs (similar in composition to the commercial agent, DEFINITY) was diluted in 0.9% normal saline and infused into the bladder phantom using the CMG infusion system. A typical simulated CMG consists of 1 filling and 4 post-filling events. During CMG events, the bladder phantom is pressurized multiple times at different clinically relevant levels (small, medium, and large) to simulate bladder pressures. Simultaneous with pressurization, MB subharmonic signal was acquired. For each event, the change in MB subharmonic amplitude was correlated linearly with the change in bladder phantom pressure, and the SHAPE conversion factor (slope of the linear fit) was determined. In doing so, a specific signal processing technique (based on a small temporal window) was used to account for time-decay of MB subharmonic signal during a simulated CMG.ResultsA strong inverse linear relationship was found to exist between SHAPE and bladder phantom pressures for each of the CMG filling and post-filling events (r2 > 0.9, root mean square error <0.3 dB, standard error <0.01 dB, and P < 0.001). SHAPE showed a transient behavior in measuring bladder phantom pressure. The SHAPE conversion factor (in dB/cm H2O) varied between filling and post-filling events, as well as by post-filling time. The magnitude of the SHAPE conversion factor tended to increase immediately after filling and then decreases with time.ConclusionsMicrobubble subharmonic emission is an excellent indicator of bladder phantom pressure variation. The strong correlation between SHAPE signal and bladder phantom pressure is indicative of the applicability of this method in measuring bladder pressure during a CMG. Our results suggest that different SHAPE conversion factors may be needed for different events during a CMG (ie, at different time points of a CMG). These findings will help us better protocolize this method for introduction into human subjects and allow us to take the next step toward developing a catheter-free voiding CMG using SHAPE.

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confidence: 91%

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confidence: 99%

Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography—A Path to a Catheter-Free Voiding Cystometrogram

Kalayeh¹,

Fowlkes²,

Chen³

et al. 2022

Invest Radiol

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“…Besides the stress of being examined, the presence of urethral catheters has been broadly reported to influence the values of maximum flow rate during pressure‐flow study (PFS) 4 . This observation has been confirmed in female population 5,6 and in a myriad of clinical conditions 7 . The size of the catheter seems to be one of the factors explaining this phenomenon but not the only one 8,9 .…”

Section: Introductionmentioning

confidence: 97%

Defining bladder outlet obstruction and detrusor underactivity in females with overactive bladder: Are we forgetting about the free uroflowmetry?

Arévalo-Vega

Ponce

Valdevenito

et al. 2023

Neurourology and Urodynamics

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Introduction: Both detrusor underactivity (DU) and bladder outlet obstruction (BOO) can coexist in patients with overactive bladder. Definitions of both DU and BOO are based on pressure-flow study (PFS) data. However, invasive urodynamics study can differ from a natural micturition, in fact, discrepancies between free uroflowmetry (UFM) and PFS have been largely described. Our goal is to assess the correlation of free-flowmetry and PFS among patients with OAB and to evaluate how different definitions of DU/BOO are able to discriminate patients with different free UFMs. Methods: A retrospective review of urodynamics performed at a single institution was conducted. Females with OAB who voided more than 150 mL in both UFM and PFS were included. Parameters from both voiding episodes were compared with nonparametric test. Two definitions of DU were applied; PIP1: Pdet@Qmax+Qmax < 30 and Gammie: Pdet@Qmax < 20 cmH 2 O, Qmax < 15 mL/s, and BVE < 90% (Bladder voiding efficiency). Also, two definitions of obstruction were chosen; Defretias: Pdet@Qmax ≥25 cmH 2 O and Qmax ≤ 12 mL/s and Solomon-Greenwell female BOO index ≥ 18.Patients who matched with each definition were compared to those who did not, to assess if any definitions were able to discriminate different noninvasive uroflowmetries.Results: A total of 195 patients were included. Overall, mean age was 55 ± 12 years, 90.8% had mixed urinary incontinence, and 39% complained of at least one voiding symptom. Globally, Qmax and BVE correlated poorly between UFM and PFS, showing that most of the variation corresponded to a systematic error. Twenty-two individuals were found to have DU, they had a difference of 13 mL/s on both maximum flows. Fifty-four patients showed BOO, with a difference between their Qmax of 19 mL/s. Among the four definitions analyzed, only PIP1 and Defreitas were able to discriminate patients with actually a lower Qmax on the free UFM.

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“…They found that urodynamics for identifying BOO was inferior and actually falsely elevated the number of women with BOO. 1 This situation is not isolated to the over-diagnosis of BOO by obstructing catheters. Many other lower urinary tract problems are also difficult to demonstrate reliably and consistently on urodynamics.…”

mentioning

confidence: 99%

“…Richard and colleagues suggest that there may be issues with using a pressure flow study (PFS) to diagnose bladder outlet obstruction (BOO) in women. 1 They clearly demonstrate that a 6 French catheter used during a PFS can be obstructive and over-diagnose BOO in over 11% of women. They found that urodynamics for identifying BOO was inferior and actually falsely elevated the number of women with BOO.…”

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confidence: 99%

Are urodynamics still useful?

Steele

2013

CUAJ

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A sk a room full of urologists about the usefulness of urodynamics (UDS) and you are likely to get a plethora of opinions. But is this a question we need to ask? I would suggest that it is, and we need to explore the accumulating data to answer that question. Richard and colleagues suggest that there may be issues with using a pressure flow study (PFS) to diagnose bladder outlet obstruction (BOO) in women.1 They clearly demonstrate that a 6 French catheter used during a PFS can be obstructive and over-diagnose BOO in over 11% of women. They found that urodynamics for identifying BOO was inferior and actually falsely elevated the number of women with BOO. 1This situation is not isolated to the over-diagnosis of BOO by obstructing catheters. Many other lower urinary tract problems are also difficult to demonstrate reliably and consistently on urodynamics. Detrusor overactivity (DO) is particularly troublesome, and cystometry often fails to diagnose DO despite severe symptoms of overactive bladder.2 In fact, the reproducibility of finding DO can vary on the same patient whether the studies are performed consecutively or on different days. 3,4 In addition, many urologists perform UDS on women with stress urinary incontinence (SUI), yet the data suggest that over 50% of women with SUI will not leak during urodynamics with the urethral catheter in place. 5,6 So why do we perform urodynamics? Does it change how we treat our patients? Does it change our results? The answers might surprise you. A recent study published in Neurourology and Urodynamics suggests that for women undergoing UDS for predominantly SUI, the UDS increased physicians' confidence in their clinical diagnosis, but it did not correlate with treatment success. 7 In fact, even in cases where UDS significantly changed clinical diagnosis it infrequently changed the treatment plan or the surgeons' decision to cancel, change or modify surgical plans. 8Some of the issues may revolve around the test itself. There is widespread variability in the technique and interpretation of urodynamics.2 This is not surprising, since we are attempting to recreate a real-life situation in a laboratory setting where the resulting imagery more closely resembles something out of an old Frankenstein movie. Think I am over exaggerating? Go into a UDS suite and watch the poor patient standing naked in the middle of the room with a catheter in their rectum and bladder coughing, while a nurse tries to quantify the amount of urinary leakage. Is it any wonder that there is such variability in UDS tracings?However, even with the widespread variability in tracings and interpretations, UDS can still be a useful entity if incorporated properly into the patient assessment. UDS need to be interpreted in the context of the global assessment of the patient, including examination, diaries and residual urine as well as other pertinent information.2 Using all the resources at our disposal to diagnose and treat our patients has always been the best treatment algorithm. The danger lies in allowing...

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The effect of a 6 Fr catheter in women: Are they obstructive?

Cited by 8 publications

References 24 publications

Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography—A Path to a Catheter-Free Voiding Cystometrogram

Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography—A Path to a Catheter-Free Voiding Cystometrogram

Defining bladder outlet obstruction and detrusor underactivity in females with overactive bladder: Are we forgetting about the free uroflowmetry?

Are urodynamics still useful?

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