The encrustation and blockage of long-term indwelling bladder catheters: a way forward in prevention and control.

OBJECTIVES: To review the literature showing that understanding how Foley catheters become encrusted and blocked by crystalline bacterial biofilms has led to strategies for the control of this complication in the care of patients undergoing long-term indwelling bladder catheterization. METHODS: A comprehensive PubMed search of the literature published between 1980 and December 2009 was made for relevant articles using the Medical Subject Heading terms 'biofilms', 'urinary catheterization', 'catheter-associated urinary tract infection' and 'urolithiasis'. Papers on catheter-associated urinary tract infections and bacterial biofilms collected during 40 years of working in the field were also reviewed. RESULTS: There is strong experimental and epidemiological evidence that infection by Proteus mirabilis is the main cause of the crystalline biofilms that encrust and block Foley catheters. The ability of P. mirabilis to generate alkaline urine and to colonize all available types of indwelling catheters allows it to take up stable residence in the catheterized tract in bladder stones and cause recurrent catheter blockage. CONCLUSION: The elimination of P. mirabilis by antibiotic therapy as soon as it appears in the catheterized urinary tract could improve the quality of life for many patients and reduce the current expenditure of resources when managing the complications of catheter encrustation and blockage. For patients who are already chronic blockers and stone formers, antibiotic treatment is unlikely to be effective owing to the resistance of cells in the crystalline biofilms. Strategies such as increasing fluid intake with citrated drinks could control the problem until bladder stone removal can be organized.

Factors modulating the pH at which calcium and magnesium phosphates precipitate from human urine.

The factors controlling the rate at which crystalline bacterial biofilms develop on indwelling bladder catheters are poorly understood. It is known that normally the pH of voided urine (pHv) is lower than the pH at which calcium and magnesium phosphates come out of urine solution (pHn). In patients who develop infections with urease producing bacteria, however, the pHv rises above the pHn and precipitation of the phosphates occurs in the urine and the biofilm. The aim of this study was to examine ways of manipulating the pHn of urine so that more of its calcium and magnesium remain in solution under alkaline conditions. The experimental data show that pHn can be elevated by decreasing the calcium, magnesium and phosphate concentrations. Increasing the fluid intake of a human subject so that the urinary calcium fell from 120 mg/l to 25 mg/l, for example, resulted in the pHn increasing from 6.48 to 8.22. The addition of citrate to urine also produced a rise in the pHn. The daily consumption of 500 ml of fresh orange juice increased urinary citrate concentrations from 0.35 to around 1.21 mg/ml and the pHn rose from 7.24 to 8.2. The pHn of urine is thus a highly variable parameter. It can be manipulated by controlling the urinary concentrations of magnesium, calcium, phosphate and citrate ions. We suggest that increasing fluid intake with citrate containing drinks would reduce the extent of encrustation on catheters in patients infected with urease producing bacteria.

Does the valve regulated release of urine from the bladder decrease encrustation and blockage of indwelling catheters by crystalline proteus mirabilis biofilms?

PURPOSE: We tested whether valve regulated, intermittent flow of urine from catheterized bladders decreases catheter encrustation. MATERIALS AND METHODS: Laboratory models of the catheterized bladder were infected with Proteus mirabilis. Urine was allowed to drain continuously through the catheters or regulated by valves to drain intermittently at predetermined intervals. The time that catheters required to become blocked was recorded and encrustation was visualized by scanning electron microscopy. RESULTS: When a manual valve was used to drain urine from the bladder at 2-hour intervals 4 times during the day, catheters required significantly longer to become blocked than those on continuous drainage (mean 62.6 vs 35.9 hours, p = 0.039). A similar 1.7-fold increase occurred when urine was drained at 4-hour intervals 3 times daily. Experiments with an automatic valve in which urine was released at 2 or 4-hour intervals through the day and night also showed a significant increase in mean time to blockage compared with continuous drainage (p = 0.001). Scanning electron microscopy confirmed that crystalline biofilm was less extensive on valve regulated catheters. CONCLUSIONS: Valve regulated, intermittent flow of urine through catheters increases the time that catheters require to become blocked with crystalline biofilm. The most beneficial effect was recorded when urine was released from the bladder at 4-hour intervals throughout the day and night by an automatic valve.

Genotyping demonstrates that the strains of Proteus mirabilis from bladder stones and catheter encrustations of patients undergoing long-term bladder catheterization are identical.

PURPOSE: We established the incidence of bladder stones in patients who experienced recurrent encrustation and blockage of indwelling bladder catheters and examined the relationship between isolates of Proteus mirabilis from the stones and from the crystalline biofilms on the catheters. MATERIALS AND METHODS: The first 100 patients attending a clinic for patients experiencing problems with the management of long-term bladder catheters were studied. Flexible cystoscopy was used to detect bladder stones. Catheter encrustation was assessed visually and by electron microscopy. Bacteriological analysis was performed on the stones and catheter biofilms. P. mirabilis isolates were genotyped by pulsed field gel electrophoresis of restriction enzyme digests of bacterial DNA. RESULTS: Most patients (85%) had been referred because of catheter blockage and in 61 (72%) the catheters were encrusted. P. mirabilis was recovered from 37 of 47 encrusted catheters (79%) that were examined but not from any nonencrusted catheters. Of the 61 patients with encrusted catheters 38 (62%) had bladder stones. Pairs of isolates of P. mirabilis from the stones and the catheter biofilms from 6 patients were genotyped. The DNA profiles of each pair of isolates were identical. CONCLUSIONS: The majority of patients (62%) with recurrent catheter encrustation had bladder stones. The stones harbored the strains of P. mirabilis that rapidly colonize replacement catheters with crystalline biofilm. Flexible cystoscopy to detect and remove stones might help resolve the problem of recurrent catheter encrustation.

Developing alternative devices to the long-term urinary catheter for draining urine from the bladder.

The self-retaining urinary catheter is used for long-term drainage of urine from the bladder only as a last resort because of serious associated complications, yet it remains a routine method for managing older and disabled patients with loss of bladder control. Blockage of the catheter from calcified deposits within its lumen is a common occurrence, obstructing the passage of urine and causing an urgent, unpredictable problem for patients, carers and the nursing staff. The need for further research on the subject has been recognized for many years. The SuPort Project aimed to develop an alternative suprapubic urine collection system. This report outlines the approach adopted towards the design and selection of the novel device, the production problems that ensued and the small clinical trial of a modified prototype.

Urinary catheter 'deflation cuff' formation: clinical audit and quantitative in vitro analysis.

OBJECTIVE: To investigate reports from district nursing staff of difficulty in removing long-term urinary catheters (LTCs) because of the formation of a 'cuff' on deflating the self-retaining balloon. PATIENTS AND METHODS: Problems experienced by district nurses when removing urethral and suprapubic LTCs were audited, noting the type of problem, the catheter and any action taken. Quantitative in vitro studies were conducted on the deflated self-retaining balloons after incubating a similar range of catheters in saline at 37 degrees C for 6 weeks, using suprapubic profilometry to assess the resistance to withdrawal (retention force). RESULTS: Questionnaires were returned on 154 patients with LTCs; 56% had urethral and 44% suprapubic catheters. The catheters were hydrogel-coated (83%), all-silicone (13%) and PTFE-coated (3%). Twenty-two (14%) of the sample reported problems with catheter removal in the previous year, including 15 (68%) with all-silicone catheters and 15 (68%) with suprapubic catheters; cuff formation was noted in 60%. In the laboratory, 10 of the balloons formed a 'cuff' on deflation, but there was great variability in the effect this had on the retention force, with values of 0.5-3 N for different catheters. CONCLUSIONS: Most problems with catheter removal involved all-silicone and suprapubic catheters. Suprapubic profilometry confirmed increased resistance to withdrawal by formation of a 'cuff' on deflation of the balloon of all-silicone catheters. These results suggest that the first choice of catheter material for long-term urethral and suprapubic use should be hydrogel-coated latex.

Preliminary results of a randomized controlled trial of prophylactic shock wave lithotripsy for small asymptomatic renal calyceal stones.

OBJECTIVE: To report a prospective, randomized study to determine whether prophylactic extracorporeal shockwave lithotripsy (ESWL) is justified as a treatment for small, asymptomatic calyceal stones. PATIENTS AND METHODS: The study included 228 patients with small (< 15 mm total diameter) asymptomatic calyceal stones; 113 patients were randomized to undergo ESWL and 115 to the control group who were kept under observation. Outcome measurements included the stone-free rate, requirement for additional treatment, symptoms, quality of life and renal function. RESULTS: In all, 200 patients had at least one annual follow-up; all outcome measurements reported were those at the most recent follow-up (mean 2.2 years, range 1-5). In the ESWL group 28 patients (28%) were stone-free, compared with 16 (17%) in the observation group (odds ratio 1.95, 95% confidence interval, CI, 0.97-3.89, P = 0.06). Additional treatment in the form of analgesics, antibiotics, ESWL, stent insertion and ureteroscopy, was required in 21 (21%) patients in the observation group and 15 (15%) in the ESWL group (odds ratio 0.66, 95% CI 0.32-1.37, P = 0.27). Ten patients in the observation group required invasive procedures, vs none in the ESWL group. There was no evidence of differences in the symptoms, quality of life or renal function tests between the arms of the trial at the final follow-up. CONCLUSIONS: Prophylactic ESWL for small asymptomatic renal calyceal stones does not appear to offer any advantage to patients in terms of stone-free rate, quality of life, renal function, symptoms or hospital admissions. However, a policy of observation is associated with a greater risk of requiring more invasive procedures. A longer follow-up is required to assess the validity of these preliminary findings.

Early observations of the effect of extracorporeal shockwave lithotripsy on blood pressure: a prospective randomized control clinical trial.

OBJECTIVE: To determine, in a randomized controlled clinical trial, the effect of extracorporeal shock wave lithotripsy (ESWL) on blood pressure. PATIENTS AND METHODS: The trial included 228 patients with small (< 15 mm) asymptomatic calyceal stones who were randomised to undergo ESWL (113 patients) or to an untreated (observed) control group (115 patients). Blood pressure was recorded at randomization using a standardized protocol. Patients undergoing ESWL received a mean (SD) of 5281 (3462) shocks over a mean of 1.75 sessions on one of two lithotripters. Patients were then followed annually, assessing blood pressure and changes in medication. Data were analysed on an intention-to-treat basis. RESULTS: At randomization, 43% of patients in the control group and 53% in the ESWL group were hypertensive. Of the 228 randomized, 200 patients completed at least one annual follow-up, of whom 192 (93 in the control and 99 in the ESWL group) had their blood pressure recorded. The mean follow-up was 2.2 years; 35 (37%) patients in the control and 46 (46%) in the ESWL group were hypertensive (P = 0.19). Seven (7%) patients in the control group and 11 (11%) in the ESWL group were newly diagnosed to be hypertensive (P = 0.35). CONCLUSIONS: In this randomized controlled clinical trial there was no evidence that ESWL causes changes in blood pressure.

A study of current nursing management of long-term suprapubic catheters.

Problems associated with long-term catheters can place increased demands on nurses' time and resources. This article reports a study which investigated the nursing management of 113 patients with long-term suprapubic catheters. The study identified that 52% of catheters were changed routinely, 30% of catheters were changed only when they became blocked and 30% of nurses experienced problems when changing catheters. A total of 42% of patients received either a bladder 'washout' or instillation and 60% required a dressing around their suprapubic site. This study also examined the reasons for applying dressings, the type of dressing used and the frequency of dressing changes, which has long been a neglected area of research. Recommendations for future practice are discussed.

The costs of long-term catheterization in the community.

The prevalence of long-term catheterization in the adult population is of the order of 0.03-0.07%, rising to 0.5% in those over 75 years and 2% in those over 85 years old. Studies have shown that the prevalence of urinary incontinence increases with age and is higher in females. Little is known about the costs of long-term catheterization, which have consequences for care decisions. A pilot study was conducted to test (a) the applicability in the UK of a methodology developed in the USA for measuring the cost of long-term catheterization in community-based patients, and (b) the feasibility of using it in larger-scale community-based studies. The study made use of the method developed in the USA by Wagner and Hu (1998) to assess the true costs in the population. Patients were selected in order to represent as broad as possible a range of underlying disease processes and social circumstances. Eight patients were selected, drawn from 3 distinct groups of patients. The pilot study demonstrated wide variation in direct costs for 7 patients living in the community over a 3-month period, ranging from pound 118.80 to pound 2585.26. Since staffing is - for the most part - the most significant cost element, this indicates significant variation in levels of need. Resources deployed for one nursing procedure clearly impact on opportunities to undertake other procedures. An understanding of the costs of any procedure is necessary in order to make best use of the limited resources available.

Funding clinical research: the need for information and longer term strategies.

The Chief Medical Officer's Working Group on Specialist Medical Training recommended that training in research methodology should be a recognised component of all postgraduate training programmes and that further consideration be given by those responsible for postgraduate education, training and research to establishing how this might be achieved. Funding of the trainee in research is a crucial aspect of this directive, yet both trainers and trainees have described this as haphazard, invariably reliant on 'soft' money. The subject has raised wide discussion and debate. A questionnaire was sent to 205 consultant urologists in the UK, 154 (75%) replied and 130 (84%) had experience of research during their training. The first report examined their opinion about the contribution of research to their training; this report covers the questions directed towards funding, the source of their funding, whether sufficient funds, advice and information were available and where they might expect to obtain such details. The replies indicated a variety of sources of funding; knowledge about the financial support available for research was sparse and the majority considered there was insufficient advice and information available for trainees on the subject. Substantial funds are available for high quality scientific research programmes providing unprecedented opportunities for multidisciplinary collaboration that is essential for advancing clinical practice alongside technological developments. The process of obtaining support can be a time-consuming exercise, raising the need for an administrative infrastructure to select, prioritise and co-ordinate an appropriate research strategy for the future.

The contribution of research to urological training in the United Kingdom.

OBJECTIVES: To report the findings of a questionnaire survey among consultant urologists in the United Kingdom (UK) designed to examine their personal experience of research and their opinion of its contribution in urological training. METHODS: A questionnaire was sent to 205 consultant urologists in the UK and 154 (75%) replied. Their replies were examined to ascertain the time spent in research, the production of publications, presentations and in gaining a higher university degree. Subsequent research activity was also related to the achievement of these endpoints. RESULTS: Among the 154 consultant urologists who replied. 130 (84%) had undertaken research during their training, for a period varying from 6 months to more than 2 years. Among the 130, 99 (76%) considered this to have been well spent; 76 (58%) obtained a higher degree, 86 (66%) achieved at least three publications in peer-reviewed journals and 90 (69%) had given at least five presentations to learned societies. Inadequate supervision in particular was cited as contributing to underachievement and motivation was also considered important to success. CONCLUSIONS: The contribution of research in urological training has been assessed traditionally by the presentation of a thesis to a university for a higher degree, but alternative methods of assessment should perhaps be sought for those wishing to spend less than 18 months in research.

Detrusor myectomy for detrusor overactivity: a minimum 1-year follow-up.

OBJECTIVE: To evaluate the clinical and urodynamic outcome of partial detrusor myectomy in patients with idiopathic detrusor instability and neuropathic hyper-reflexia. PATIENTS AND METHODS: Seventeen patients with idiopathic detrusor instability and 10 with hyper-reflexia and symptoms not responding to non-surgical treatment underwent partial detrusor myectomy. The clinical and urodynamic results before and after myectomy were compared and the patient's subjective assessment of the outcome documented. RESULTS: There was an overall improvement in 17 of 27 patients (63%) but the success rate was higher in those with idiopathic instability (12 of 17) than in those with neuropathy (five of 10). There was urodynamic evidence of reduced bladder contractility and an improvement in the storage characteristics of the bladder in most of the patients treated. CONCLUSIONS: Partial detrusor myectomy is relatively simple and is associated with minimum morbidity and an acceptable success rate. The procedure alters the urodynamic behaviour of the bladder and leads to symptomatic and objective improvement, giving better results with idiopathic than with neuropathic detrusor overactivity. Detrusor myectomy may be offered to patients with detrusor overactivity unresponsive to conventional management. The option of enterocystoplasty is still open to patients with an unsuccessful outcome. However, the long-term results and surgical variations of the technique should be evaluated further.

A modified semi-automated technique for in vitro assessment of encrustation of materials.

In vitro study of encrustation is an important part of assessment of materials as potential alloplasts or devices in the urinary tract. This modified semi-automated technique comprises a circular reaction chamber with an encrustation mixture, the level of which is controlled by a float switch which operates the exit peristaltic pump. The composition of the reactants used simulates infected urine with alkaline pH. Results of a preliminary study of the deposits by scanning electron micrography (SEM) and energy dispersive X-ray (EDX) microanalysis are consistent with struvite and hydroxyapatite, similar to the main minerals deposited on urinary catheters. It is a relatively simple, effective and inexpensive set-up for study of encrustation on materials.

Long-term catheterization of the bladder: prevalence and morbidity.

OBJECTIVE: To estimate the prevalence and morbidity of long-term catheterization (LTC) of the urinary bladder. PATIENTS AND METHODS: A postal survey was conducted over two successive years from February 1989 to determine the incidence of LTC in three Bristol Health Districts with a total population of 827,595. During the first year the number of patients requiring emergency treatment for complications of LTC was also monitored over a 6-month period. In the second year, 54 patients were selected from the first survey and each was visited by one investigator every 2 weeks for 12 weeks to obtain information on catheter management, the incidence and type of complications, the attitudes of the patients or carers about the catheter and to assess the pH and microbiology of the patient's urine. RESULTS: The initial surveys identified 457 and 467 patients with long-term catheters during the 2 years, respectively; there were similar numbers of men and women in both years. The survey of catheter complications recorded 506 emergency referrals during the 6 months and the detailed study of 54 patients showed that 48% experienced catheter blockage, 37% reported urine by-passing the catheter and 30% noted haematuria. Patients found the catheter uncomfortable and depended on nursing support. Catheter blockage was associated with bladder stones, a high urinary pH and the presence of Proteus spp in the urine. CONCLUSION: The prevalence and high morbidity of LTC cause a considerable demand on the available District and Hospital nursing services; most patients with long-term catheters are elderly, disabled or debilitated and more nurses need to be trained in the technique of catheterization and the management of the catheterized patient. Further research is required to reduce the morbidity of LTC by investigating measures to reduce catheter blockage and encrustation at the urine/biomaterial interface.