Air-charged Catheters Research Articles

Comparison of Air-charged Catheter and Water-filled Catheter in Female Urethral Pressure Profile

ObjectivesTo compared the maximum urethral pressure (Pura@max) and functional urethral length (FUL) obtained with water‐filled catheters and air‐charged catheters during female urethral pressure profile (UPP) in a retrospective study. Subjects and methodsOne hundred and five female patients were enrolled in our investigation. At Beijing Chao-Yang Hospital, patients who had lower urinary tract dysfunction underwent UPP using a modified UPP equipment. In one UPP, both a water-filled catheter (WFC) and an air-charged catheter (ACC) were employed simultaneously. The paired t-test was used to compare the differences between the two systems. Bias and correlations between the two systems were analyzed according to the American Clinical and Laboratory Standardization Institute (CLSI) EP9-A3 recommendations. ResultThere were 105 female participants in this study. The patients were 55.5±14.2 years old on average. By using the ACC and WFC systems, the mean functional urethral length (FUL) was determined to be 39.7±16.2mm and 33.9±13.9mm, respectively. The FUL findings of two systems differed significantly from one another (P<0.01), and a linear fit with R2=0.94 indicates a strong linear correlation. The findings of the maximum urethral pressure (Pura@max) measurements made by the ACC and WFC systems, respectively, were 134.3±39.1cmH2O and 99.2±27.6cmH2O, are substantially different (P<0.01), and the linear fit R2=0.67. The Pura@max of two systems did not linearly correlate with one another. Conclusion：For UPP, air-charged catheters often provide higher readings than water-filled catheters, and there is a significant difference in the readings between the two systems. The pressure values derived from the two systems do not correlate, although the FUL does have a significant linear correlation. Results from the ACC and WFC cannot be used interchangeably.

Reproducibility evaluation of air-charged catheter for rest urethral pressure profilometry

We retrospectively included 53 (9 males, 44 females) patients who underwent rest urethral pressure profilometry (RUPP) due to lower urinary tract symptoms (LUTS) in Beijing Chaoyang Hospital from May 2021 to March 2022. The age of patients was (55±16) (25-76) years old. The clinical diagnoses of the included patients with lower urinary tract symptoms were classified as: benign prostatic hyperplasia in 9 cases, interstitial cystitis in 1 case, stress urinary incontinence in 11 cases and non-obstructive dysuria in 32 cases. The full set of urodynamic examination was composed of bladder pressure measurement during the filling period, pressure flow study (PFS) and RUPP. All the urodynamic examination was performed by air-charged catheter (ACC) and corresponding equipment. All patients underwent RUPP measurements twice. The vesical pressure (Pves) values were (35.30±6.15), (35.81±5.91) cmH2O (1 cmH2O=0.098 kPa); the Pura@max were (141.91±36.53), (145.02±38.85) cmH2O; functional urethral length were (41.70±16.34), (42.55±16.40) mm; the maximum urethral closure pressure for the two RUPP measurements were (106.57±36.44), (109.41±39.27) cmH2O. There was no statistical difference between the two RUPP measurements (P>0.05). The reproducibility of the RUPP measurements obtained by ACC is good and deserves further study.

Diagnostic value of urethral pressure profile for female bladder neck obstruction using air-charged catheters

Objective: To evaluate the measurements of urethral pressure profile (UPP) using air-charged catheters (ACC) in women with bladder neck obstruction and to preliminarily analyze the diagnostic value of UPP based on ACC for female bladder neck obstruction. Methods: Retrospective inclusion of 63 female patients with bladder neck obstruction diagnosed in the Department of Urology of Beijing Chao-yang Hospital from September 2020 to December 2021 were included as the observation group, and 45 female patients who came to the hospital due to lower urinary tract symptoms with non-bladder neck obstruction during the same period were selected as the control group. All patients received urodynamic examination and UPP examination based on ACC, and urethral pressure measurements [M (Q1, Q3)] were compared between the two groups and analyzed the predictive value of the relevant measurements for female bladder neck obstruction. Results: The age of the observation group was 61 (47, 67) years and body mass index (BMI) was 24.1 (21.6, 27.9) kg/m2, the age of the control group was 65 (58, 71) years and BMI was 25.0 (22.8, 27.6) kg/m2. The urethral pressure at the bladder neck and urinary sphincter position in the observation group were higher than control group[104.00 (83.00, 124.00) cmH2O (1 cmH2O=0.098 kPa) vs 42.00 (31.00, 65.50) cmH2O, 125.0 (107.0, 154.0) cmH2O vs 99.0 (77.0, 124.0) cmH2O, P<0.001]. The results of the receiver operating characteristic (ROC) curve showed that the area under the curve (AUC) of urethral pressure at the bladder neck position had the highest predictive value for female bladder neck obstruction (AUC: 0.946, 95%CI: 0.886-0.981, sensitivity: 87.3%, specificity: 91.1%), and the results of interaction point plot showed that the cut-off value was 72 cmH2O. The cut-off value of urethral pressure at the bladder neck position was used as positive cut-off value to predict female patients with bladder neck obstruction. Sixty-three patients with bladder neck obstruction were detected by UPP measurement using ACC in 59 cases (59/63, 93.7%) and the Kappa value was 0.774 (95%CI: 0.654-0.894), indicating that UPP had high consistency with pressure-flow study. Conclusions: UPP examination based on ACC can show the pressure values of the bladder neck and urethral sphincter position. When the urethral pressure of the bladder neck position is greater than 72 cmH2O, it is helpful for the diagnosis of female bladder neck obstruction and has guiding significance for the diagnosis and treatment of this disease.

Typical value ranges and signal patterns in patients with neurogenic bladder: Quality control in urodynamics using an air-charged catheter system.

To establish typical value ranges (TVRs) of the air-charged catheter (ACC) system, and analyze the typical signal patterns (TSPs) of cough under different bladder volumes for quality control of a urodynamic study using the ACC system. The urodynamic traces of 1977 patients with neurogenic bladder (NB) were analyzed for intravesical pressure (pves ), abdominal pressure (pabd ), and detrusor pressure (pdet ) in the cough test at our center from July 2017 to December 2021. The pdet cough signals were described and classified. The pdet cough signal patterns in different bladder volumes and postures were analyzed. The 50% range of the initial resting pves , pabd , and pdet in the supine and sitting positions were 7-15, 7-14, and 0-0 cmH2 O, and 24-33, 24-33, and 0-0 cmH2 O, respectively. The cough amplitudes for pves and pabd were similar in the 50% range, as follows: 10-27 and 8-25 cmH2 O in the supine position, respectively; and 18-43 and 17-40 cmH2 O in the sitting position, respectively. The cough amplitude of pves and pabd was not related to bladder volume (p > 0.05). The cough spikes of pdet were divided into three types: type I, in which pdet has a minimal change (<5 cmH2 O); type II, a monophasic cough spike, in which could be a positive (IIa, ≥5 cmH2 O) or negative spike (IIb, ≥5 cmH2 O); and type III, a biphasic spike, in which could be a positive-to-negative biphasic (IIIa) or negative-to-positive spike (IIIb). Under different bladder volumes, the cough signals of pdet were all expressed as type I, II, or III, and the cough signals were unrelated to bladder volume (p > 0.05). TVRs of the initial resting state in patients with NB were established to provide guidance for quantitative quality control of the ACC system. The TSPs of the pdet cough signal under different bladder volume and posture were described, which could be used for qualitative quality control of the ACC system.

Usability and safety of the new 5 French air-charged catheter for performing urodynamic studies on pediatric patients.

To assess the performance and safety of the T-DOC® 5 French air-charged urodynamic catheters in pediatric patients and obtain feedback from providers related to usability performance. Patients ages 12 years and younger undergoing urodynamics were prospectively recruited from two institutions. The T-DOC® 5 French air-charged catheters were used. Issues with catheter placement, adverse events (AEs), and pain scores were assessed. A follow-up telephone call was made to assess for post-urodynamic AEs. Providers completed a clinical user questionnaire. Likert scale was used (1 = most negative and 5 = most positive response) and reported in mean (range). A total of 28 patients completed the study. The mean age was 55 months (5-130) (10 females, 18 males). One problem was noted with the insertion of an abdominal catheter, secondary to stool impaction. Catheters stayed in place on all subjects, except for one related to patient hyperactivity. There were no AEs during the studies. In total four reported post-urodynamics AEs (one hematochezia, three dysuria). Among nine patients, pain level on the bladder and abdominal insertion was 3.6/10 (0-10) and 3.1/10 (0-10). Five providers completed the questionnaire. The overall ease of use was rated 4.3/5 (3-5). The ease of insertion was 4.1/5 (2-5) and set-up/clean-up time was 4.4/5 (3-5). Tracing stability, subtraction accuracy, and artifact sensitivity were all perceived favorably (respectively 4.8/5 [4-5], 4.6/5 [4-5], and 4.4/5 [4-5]). The T-DOC® 5 French air-charged catheter was considered safe and effective in pediatric patients. No AEs occurred during the studies. Providers, using the catheters, reported favorably on catheter usage.

Novel implantable pressure and acceleration sensor for bladder monitoring.

To test the hypothesis that an implantable sensing system containing accelerometers can detect small-scale autonomous movements, also termed micromotions, which might be relevant to bladder physiology. We developed a 6-mm submucosal implant containing a pressure sensor (MS5637) and a triaxial accelerometer (BMA280). Sensor prototypes were tested by implantation in the bladders of Gottingen minipigs. Repeated awake voiding cystometry was carried out with air-charged catheters in a standard urodynamic set-up as comparators. We identified four phases of voiding similar to cystometry in other animal models based on submucosal pressure. Acceleration signals were separated by frequency characteristics to isolate linear acceleration from the baseline acceleration. The total linear acceleration was calculated by the root mean square of the three measurement axes. Acceleration activity during voiding was investigated to adjacent 1-s windows and was compared with the registered pressure. We observed a total of 19 consecutive voids in five measurement sessions. A good correlation (r>0.75) was observed between submucosal and catheter pressure in 14 of 19 premicturition traces. The peak-to-peak interval between maximum total linear acceleration was correlated with the interval between submucosal voiding pressure peaks (r=0.760, P<0.001). The total linear acceleration was higher during voiding compared with pre- and postmicturition periods (start of voiding/phase1). To the best of our knowledge, this is the first report of bladder wall acceleration, a novel metric that reflects bladder wall movement. Submucosal sensors containing accelerometers can measure bladder pressure and acceleration.

Urethral pressure profilometry in artificial urinary sphincter implantation: A case report

BACKGROUNDArtificial urethral sphincter (AUS) implantation is currently the gold standard for treating moderate and severe urinary incontinence. Currently, cuffs are chosen based on the surgeon’s experience, and adjusting cuff tightness is crucial. The T-DOC air-charged catheter has not been proven to be inferior to traditional catheters. We report how intraoperative urethral pressure profilometry is performed using a T-DOC air-charged catheter with ambulatory urodynamic equipment, to guide cuff selection and adjustment.CASE SUMMARYA 67-year-old man presented to our hospital with complete urinary incontinence following transurethral prostatectomy, using five pads/d to maintain local dryness. Preoperatively, the maximum urethral pressure (MUP) and maximum urethral closure pressure (MUCP) were 52 cmH2O and 17 cmH2O, respectively. An AUS was implanted. Intraoperatively, in the inactivated state, the MUP and MUCP were 53 cmH2O and 50 cmH2O, respectively; in the activated state, they were 112 cmH2O and 109 cmH2O, respectively. The pump was activated 6 wk postoperatively. Re-measurement of the urethral pressure on the same day showed that in the inactivated state, MUP and MUCP were 89 cmH2O and 51 cmH2O, respectively, and in the activated state, 120 cmH2O and 92 cmH2O, respectively. One month after device activation, telephonic follow-up revealed that pad use had decreased from five pads/d to one pad/d, which met the standard for social continence (0-1 pad per day). There were no complications.CONCLUSIONThe relationship between intraoperative urethral pressure and urinary continence post-surgery can provide data for standardizing AUS implantation and evaluating efficacy.

Differences between water-filled and air-charged urodynamic catheters for determining the urethral pressure profile in neurogenic lower urinary tract dysfunction patients.

The maximum urethral closure pressure (MUCPs) and functional urethral length (FUL) obtained with water-filled and air-charged catheters during urethral pressure profile (UPP) determination was compared in a single, blind, randomized, and prospective trial. Thirty-three males with spinal cord injuries and neurogenic lower urinary tract dysfunction underwent UPP determinations using water-filled and air-charged catheters in random order; the patients were unaware of the catheter sequence. The variability of the same type of catheter and the agreement between the different types of catheters were compared. The Pearson correlation coefficient was used to check the correlation between the catheters and the Bland-Altman method was used to verify the agreement. The intraclass correlation coefficients for MUCPs and FULs determined using water-filled and air-charged catheters were 0.89, 0.75, 0.94, and 0.78, respectively. The interclass correlation coefficients for MUCPs and FULs between the two catheters were 0.43 and 0.28, respectively. Bland-Altman plots suggested that the values measured by air-charged catheters were significantly higher than water-filled catheters (mean difference, 26.0 and 2.4 cmH2 O, respectively). There were wide 95% limits of agreement (-54.0 to 106.0 and -0.3 to 5.1 cmH 2 O, respectively) that exceeded the clinical range for differences in MUCP and FUL. Air-charged catheters usually give higher readings than water-filled catheters for UPP. Agreement between water-filled and air-charged catheters was not good. Nevertheless, the catheter type which is more relevant to the disease requires further study.

What research is needed to validate new urodynamic methods? ICI-RS2017.

In recent years urodynamic innovations, although well researched, have failed to follow a standardized development pathway specifically in terms of clinical trials undertaken to demonstrate efficacy. This was discussed at the International Consultation on Incontinence Research Society (ICI-RS) in Bristol, United Kingdom, 2017 with the aim of defining minimum standards for future urodynamic research. The recent recommendations from the IDEAL (innovation, development, exploration, assessment, and long-term study) collaboration regarding surgical research were reviewed. Two examples of recent novel urodynamic technologies, the penile cuff test and air charged urodynamic catheters were used as case studies and the research programmes behind their development were critiqued. The rigorous and standardized model of surgical research proposed by the IDEAL collaboration was endorsed as an appropriate model for future urodynamic research. A methodical approach to research can fulfil a host of objectives including illustration of the clinical need, help with design and refinement of technique and proving efficacy for any new test or device. The penile cuff test is a novel urodynamic measurement technique that has been well researched and is now used in clinical practice. Further research is needed before air charged catheters can be recommended for widespread clinical use and the IDEAL framework provides a template for ongoing development. In the future, these recommendations should lead to a more standardized and uniform programme of urodynamic research and enable a thorough evaluation of new technologies prior to wider clinical uptake.

Administration of a Sol-Gel Formulation of Phenylephrine Using Low-Temperature Hollow Microneedle for Treatment of Intermittent Fecal Incontinence.

A low temperature hollow microneedle system was devised to deliver sol-gel transition formulation near the surface of the skin for extended release and local delivery of drug by a non-invasive method. This new system can improve treatment of intermittent fecal incontinence. The low-temperature system was integrated with a hollow microneedle to maintain the low temperature of the sol formulation. Various sol-gel formulations using Pluronic F-127 (PF-127) and Hydroxy-propyl-methyl-cellulose (HPMC) were prepared, and their gelation temperature, flow property, and diffusion retardation were observed. Resting anal sphincter pressure in response to a phenylephrine (PE) sol-gel formulation was measured using an air-charged catheter. The biocompatibility of the sol-gel PE formulation was evaluated by observing the immunological response. When the PF-127 25%, HPMC 1% and PE formulation (PF25-HPMC1-PE) was injected through the peri-anal skin of the rat in vivo, the highest pressure on the anal sphincter muscle occurred at 6-8h and anal pressure increased and lasted twice as long as with the phosphate-buffered saline (PBS)-PE formulation. There was no significant difference in the number of mast cells after administration into the rat in vivo between the PF25-HPMC1-PE formulation and the PBS-PE formulation. The combination of a low-pain hollow microneedle system and an injectable sol-gel formulation improved the efficacy of treatment of intermittent fecal incontinence. A low-temperature hollow microneedle system using a sol-gel formulation has many applications in medical treatments that require depot effect, local targeting, and pain control.

Performance analysis of the T-DOC® air-charged catheters: An alternate technology for urodynamics.

Urodynamics (UDS) is widely used for the diagnosis of lower urinary tract dysfunction. Air-Charged catheters (ACC), one of the newer technologies for UDS pressure recording, has been adopted in growing numbers around the world for the past 15 years. Currently, there is a lack of published studies characterizing specific performance of the ACC. Since linearity, hysteresis, pressure drift, and frequency response are important components in characterizing accuracy for catheter-manometer systems; this study aimed to assess these four aspects in ACC. A total of 180 T-DOC® ACC were used in three different laboratory settings to assess pressure linearity and hysteresis (15 dual-sensor vesical and urethral and 30 single-sensor abdominal), pressure drift over 2 h (115 single-sensor), and frequency response (20 single-sensor). Data are presented as mean ± standard deviation. ACC showed linearity of 0.99 ± 0.01, 0.99 ± 0.01, and 1.01 ± 0.01; and hysteresis of 0.57 ± 0.3%, 0.76 ± 0.48%, and 1 ± 0.89% for the abdominal, vesical, and urethral sensors, respectively. A pressure drift of 2.2 ± 1.4% at 1 h and 4.4 ± 2.5% at 2 h were observed when compared to baseline pressures. The catheters did not show any amplification factor during the sweep from 1 to 30 Hz, and recorded signals up to 5 Hz attenuating higher frequency signals. In this study the T-DOC® ACC showed a linear performance with minimal hysteresis associated with acceptable pressure drift, and adequate frequency response to capture clinically relevant pressures. The accurate results observed in this study suggest that these catheters are technically suitable to be used as a measuring instrument for UDS.

Assessing the reproducibility of high definition urethral pressure profilometry and its correlation with an air-charged system.

Recently, a new urodynamic method for the assessment of stress urinary incontinence called high definition urethral pressure profilometry (HD-UPP) has been introduced. This method combines a novel microtip catheter with advanced signal processing to enable spatial data location and the reconstruction of a pressure image inside the urethra. In order to assess the reproducibility of HD-UPP data, we statistically evaluate HD-UPP datasets and compare them to data from a double balloon air-charged system. Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, urodynamic features are extracted, and compared to the air-charged system. Reproducibility of HD-UPP data is assessed by statistically evaluating consecutive, intra-individual datasets. HD-UPP delivers results in agreement with previous comparisons of microtip and air-charged systems. The average deviation of two consecutive, intra-individual pressure images is very low at 7 cm H2 O. HD-UPP provides physicians with detailed information on the pressure distribution inside the urethra. Through comparison with an air-charged catheter, it is shown that HD-UPP delivers results in agreement with previous studies on the comparison of microtip and air-charged catheters. It provides excellent reproducibility, as the difference between sequentially measured profiles from the same minipig is significantly lower than the one between profiles from different minipigs.

Maximum Urethral Closure Pressure Increases After Successful Adjustable Continence Therapy (ProACT) for Stress Urinary Incontinence After Radical Prostatectomy

To evaluate changes of the urethral pressure profile (UPP) after implantation of adjustable continence therapy (ProACT), a minimally invasive procedure in which 2 volume-adjustable balloons are placed periurethrally for treatment of male stress urinary incontinence. The working mechanism of the ProACT to achieve continence has not been fully understood. We hypothesized that successful treatment with ProACT improves urinary continence by inducing a significant increase in static urethral pressure. We included patients who underwent UPP before and after ProACT implantation. UPPs were initially performed with the Brown-Wickham water perfusion method and later with the T-DOC Air-Charged catheter method. Pre- and postoperative UPPs and International Prostate Symptom Scores were evaluated. UPP measurements of successfully (no or 1 precautionary pad per day) and unsuccessfully treated patients were compared. Twenty-seven patients were included in the study; 23 patients were successfully and 4 patients were unsuccessfully treated. Maximum urethral closure pressure (MUCP) increased significantly from median 58.0 to 79.0 cmH2O in the successfully treated group (P = .001). Within the subgroup of unsuccessfully treated patients, MUCP did not change significantly (P = .715). The change in MUCP was statistically significantly different between the successful and unsuccessful group (P = .034). Total score of the International Prostate Symptom Scores did not change significantly after ProACT implantation (P = .097). Successful treatment with ProACT is associated with a significant increase of MUCP. This implies that increased static urethral pressure contributes to the working mechanism of the ProACT device to achieve continence.

High definition urethral pressure profilometry: Evaluating a novel microtip catheter.

Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI). SUI is a significant medical, social, and economic problem, affecting about 12.5% of the population. A novel microtip catheter was developed for UPP featuring an inclination sensor and higher angular resolution compared to systems in clinical use today. Therewith, the location of each measured pressure sample can be determined and the spatial pressure distribution inside the urethra reconstructed. In order to assess the performance and plausibility of data from the microtip catheter, we compare it to data from a double balloon air charged system. Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, plotted and compared against data from the air-charged catheter. The microtip catheter delivers results in agreement with previous comparisons of microtip and air-charged systems. It additionally provides a new level of detail in the reconstructed UPPs which may lead to new insights into the sphincter mechanism of minipigs. The ability of air-charged catheters to measure pressure circumferentially is widely considered a main advantage over microtip catheters. However, directional pressure readings can provide additional information on angular fluctuations in the urethral pressure distribution. It is shown that the novel microtip catheter in combination with a signal reconstruction algorithm delivers plausible data. It offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct location within the anatomical location of the pelvic floor. Neurourol. Urodynam. 35:888-894, 2016. © 2015 Wiley Periodicals, Inc.

Use of hollow microneedles for targeted delivery of phenylephrine to treat fecal incontinence

A hollow microneedle (HM) was prepared to deliver a phenylephrine (PE) solution into the anal sphincter muscle as a method for treating fecal incontinence. The goal of this study was the local targeted delivery of PE into the sphincter muscle through the perianal skin with minimal pain using hollow microneedles, resulting in the increase of resting anal sphincter pressure. PE was administered on the left and the right sides of the anus of a rat through the perianal skin using 1.5mm long HM. An in vivo imaging system study was conducted after injection of Rhodamine B, and a histological study was performed after injection of gentian violet. The resting anal sphincter pressure in response to various drug doses was measured by using an air-charged catheter. Anal pressure change produced by HM administration was compared with change produced by intravenous injection (IV), subcutaneous (SC) injection and intramuscular (IM) injection. The change in mean blood pressure produced by HM administration as a function of PE dose was compared with change produced by PBS injection. A pharmacokinetic study of the new HM administration method was performed. A model drug solution was localized in the muscle layer under the perianal skin at the injection site and then diffused out over time. HM administration of PE induced significant contraction of internal anal sphincter pressure over 12h after injection, and the maximum anal pressure was obtained between 5 and 6h. Compared to IV, SC and IM treatments, HM treatment produced greater anal pressure. There was no increase in blood pressure after HM administration of PE within the range of predetermined concentration. Administration of 800μg/kg of PE using HM produced 0.81±0.38h of tmax. Our study suggests that HM administration enables local delivery of a therapeutic dose of PE to the anal sphincter muscle layer with less pain. This new treatment has great potential as a clinical application because of the ease of the procedure, minimal pain, and dose-dependent response.

Are the measurements of water-filled and air-charged catheters the same in urodynamics? Response to comments

Dear Editor, We appreciate Dr. Valentini’s interest [1] in our article [2]. Her criticisms of our study are essentially that: (1) The use of two catheters to measure simultaneously intravesical pressure leads to nonphysiological conditions. This, in addition to a possible interaction between the two catheters, may affect the pressures measured. (2) Detrusor pressure should not be compared in the study. (3) Vesical pressure measured by the water-filled catheter is higher than the vesical pressure measured by the air-charged catheter. We address each of these three points below.

Comment: Are the measurements of water-filled and air-charged catheters the same in urodynamics?

Comment: Are the measurements of water-filled and air-charged catheters the same in urodynamics?

Are the measurements of water-filled and air-charged catheters the same in urodynamics?

The aim of our study was to compare air-charged and water-filled catheters simultaneously in the measurement of the intravesical, abdominal and detrusor pressure during urodynamic investigations. Consecutive women with lower urinary tract symptoms, referred for urodynamics were prospectively studied. Readings of intravesical pressure (p(ves)), abdominal pressure (p(abd)) and detrusor pressure (p(det)), recorded by both the air-charged and water-filled catheters, were displayed simultaneously and compared at the end of filling, on standing, on sitting prior to voiding and at the maximum involuntary detrusor contraction. The signals (pressures) recorded by both types of catheter were compared using the Bland-Altman plot and paired samples t test. Twenty women with a mean age of 49 (range 36-72) were recruited. One patient with normal urodynamics was excluded in view of the poor quality trace. At each of the four comparison points, the air-charged catheters consistently produced higher mean pressures than the water-filled catheters. There were wide variations in the difference between the readings produced by the two types of catheter. Pressures measured using air-charged catheters are not comparable with water-filled catheters and are therefore not interchangeable. Caution must be used when comparing urodynamic parameters using air-charged and water-filled catheters.

Author's response re: Schaefer, W Re: Re: Cooper MA, fletter PC, Zaszczurynski, Damaser MS. Comparison of air-charged and water-filled urodynamic pressure measurement catheters. Neurourol Urodyn 2011;30:1710

Author's response re: Schaefer, W Re: Re: Cooper MA, fletter PC, Zaszczurynski, Damaser MS. Comparison of air-charged and water-filled urodynamic pressure measurement catheters. Neurourol Urodyn 2011;30:1710

Re: cooper MA, fletter PC, Zaszczurynski, Damaser MS. comparison of air-charged and water-filled urodynamic pressure measurement catheters. Neurourol urodyn 2011;30:329-334

Re: cooper MA, fletter PC, Zaszczurynski, Damaser MS. comparison of air-charged and water-filled urodynamic pressure measurement catheters. Neurourol urodyn 2011;30:329-334