Introduction

Urethral catheterization (UC) is a common practice in the healthcare setting, with over 30 million catheters being inserted annually in the United States [1]. A majority of these are performed with standard balloon Foley catheters, which have remained highly popular since coming onto the market in 1933 [2]. However, despite its frequency of use, UC has been shown to be associated with a number of complications, including UTI, representing the fourth most common healthcare-associated infection As such, UC has been the subject of much investigation into reducing these problems and avoiding unnecessary catheterization in the inpatient population. Some of these complications are seemingly unavoidable in catheterization, given its inherently invasive nature, while others appear to relate more to the Foley catheter’s balloon-based design. A 2013 review by Dellimore et al. concluded that the top five most frequent complications as a result of UC were due to mechanical interaction of the catheter and the urethra, highlighting the need for more ideal catheter design. These complications included symptomatic bacterial infection, severe mechanical trauma, hypersensitivity to latex, urethral stenosis/stricture, and calculi/encrustations/blockage [8]. In fact, one retrospective study found that UC-related trauma was actually a more frequent occurrence than UC-associated UTI, at 0.5% versus 0.3% of Foley catheter days [5].

Further studies have sought to elucidate the incidence of UC-related urethral injury, specifically. A prospective investigation of two tertiary academic centers by Davis et al. showed a 6.7 per 1000 rate of iatrogenic UC complications, estimated to cost more than $371,000 during the 6-month study period. They also noted that the majority of these issues were a function of the presence of a catheter balloon, specifically its inflation intraurethrally [7]. A similar prospective study noted an incidence of 3.2 injuries per 1000 patients at their single institution, which dropped to 0.7 per 1000 after implementation of a hospital-wide nursing education program emphasizing proper inflation of the Foley balloon, again, avoiding doing so inside of the urethra [6]. While this study focused on improving nursing care, problematic catheter design was a requisite to development of these injuries. Issues specific to the Foley balloon have been investigated, as well. Wu et al. determined that catheter balloon filling pressures were 1.9-times higher in a cadaver urethra versus bladder. They determined that significant force was required to forcibly remove an inflated Foley catheter from the bladder. Interestingly, in latex but not silicon catheters the neck of the balloon port acted as a pressure valve that expanded over a pressure threshold, while some silicon catheters burst at similar removal forces.

These authors urged the importance of better catheter design to avoid these urethral injuries [4]. Furthermore, transvaginal ultrasound has been used to demonstrate the poor emptying capacity of Foley catheters versus straight catheters, with mean PVRs of 77 mL and 0 mL, respectively [9].Over the years, different designs have been investigated in attempts to minimize UC morbidity rates, including impregnation of catheter surface with lubricating and antimicrobial tips, as well as the dual balloon catheter [2]. Unfortunately enough, these variations still share the disadvantages inherent to a balloon-based model. The Lotus catheter seeks to minimize these pitfalls with its deployable Malecot-like soft-winged retention mechanism, effectively replacing the inflatable balloon of a standard Foley catheter (Figure 1a-d).

Ideally, this places the lumen of the catheter at the level of the bladder neck, improving urinary drainage, due to its larger openings. It also offers improved safety due to its compressibility in the urethra in the event of premature activation of the wings or accidental forceful dislodgement. We sought to observe and document the Lotus catheter in a clinical setting, representing the first assessment of its performance in the literature to date.

Materials & Methods

Patients were identified who were anticipated to require less than five days of drainage via urinary catheter between July 1^st, 2015and June 31^st, 2016. They were educated on the risks and benefits of catheter placement, written consent was obtained and the Lotus catheters were placed. Insertion was performed by experienced healthcare providers, who recorded ease of placement and removal on a subjective scale of one to seven, seven representing absolute ease of insertion/removal and one representing extreme difficulty. Patient discomfort was recorded on a scale from zero (absolute comfort) to ten (extreme discomfort). After removal, patients underwent bedside bladder ultrasound to determine post-void residual urine volume. Duration of time needed for catheter insertion (in seconds), as well as presence or absence of gross hematuria were also recorded. Follow-up was performed to monitor for development of complications. Six patients in the study reported previous severe discomfort from a balloon catheter previously dislodged from the bladder. All patient data was collected in our Institutional Review Board (IRB) approved prospective database.

Results

Our prospective cohort consisted on 50 patients at a single tertiary referral institution (Table 1).

Summarizes the results of Lotus catheter insertions. Mean time needed for insertion was 4 seconds, with a range of 1 to 20 seconds. Mean discomfort rating was 0 out of 10. Mean ease of insertion was 7 out of 7, extremely easy. No gross hematuria was demonstrated post insertion in the cohort, with no other complications noted at follow-up (Table 2).

reports similar results for Lotus catheter removal. Average removal time was 3 seconds (1 - 10 seconds). Mean discomfort was 2 out of 10, ease of removal 7 out of 7, with a mean PVR of 4.8 mL (ranging from 0 to 76 mL). A single patient had ascites, compromising accurate PVR recording, and was excluded from this measurement. In the entire cohort, 3 patients experienced complications, including one accidental removal, which caused no subsequent injury, and a case of bladder spasming, requiring use of anticholinergic medication.

Discussion

Foley catheters have remained the standard for urinary catheterization in numerous care centers since they originally gained popularity. However, investigation into their use has elucidated several problems associated with their design. They allow for higher residual volume of urine in the bladder, following their insertion, given the position of the balloon in the bladder and the relatively small opening for drainage. This can lead to additional morbidity, especially in the form of infection, one of the most common sources of healthcare-associated infections in the country, which can further lead to encrustations and kidney stones. Foley catheters also cause mechanical complications when accidentally inflated within the urethra or forcefully removed, which can lead to long-term issues such as stricture or stenosis, which contribute a great burden of disease to affected patient. Six patients reported significant events with previous balloon catheters. Studies have repeatedly highlighted the limitations of the Foley catheter structure, hailing the need for smarter design. While attempts have been made to improve catheters, such as using novel coatings or even a double balloon model, we have yet to see a design that removes the balloon aspect entirely while still satisfactorily fulfilling the basic requirements of a urinary catheter. We believe that the Lotus catheter may have succeeded in this goal.

Based on our results, the Lotus catheter appears to avoid the pitfalls of a standard Foley catheter. It drains the bladder effectively, as evidenced by a mean post-void residual of <5mL. This would theoretically lower the risk of UTI in this population, although formal studies would need to be performed to specifically address this. There were also no recorded complications during or after insertion. The two instances of accidental removal resulted in no apparent trauma to the urethra and no gross hematuria, followed by simple reinsertion. The only other complication was that of bladder spasms, a relatively benign occurrence that was resolved with a short course of anticholinergic medication and could have been related to the surgical procedure itself. Patient discomfort was low, and insertion/removal were noted to be technically easy to perform, requiring very little time. The only negative possible event for the Lotus catheter would be the easier dislodgement of the catheter as compared to a balloon catheter. However, that can be prevented with more effective catheter fixation to the thigh and if catheter is accidentally removed, it can be easily reinserted.

To our knowledge, this is the first investigation into the performance of the Lotus catheter in a clinical setting. However, despite our promising results, our study is not without limitations. One such example is our small sample size and the single institution setting. Another restriction is the possible referral bias of working at a tertiary care center. These can all lead to poor sampling, something that could be rectified by future, larger studies involving multiple centers and patient acuity levels. Another limitation is the subjective nature of our scoring system for ease of removal and insertion, allowing for inter-user variability. On the same token, patient pain scores are also highly subjective, yielding a similar problem. Future directions after this study would likely be direct comparison of the Lotus catheter against the Foley, ideally in the form of a blinded randomized-controlled trial. An expanded patient population, both in number and sampling distribution would be optimal, perhaps in concert with additional healthcare centers.

Conclusions

Foley catheterization, despite its popularity, is a source of morbidity and even mortality for some patients in whom it is used, constituted mainly by either urinary tract infection secondary to poor emptying, or trauma from inflation of the balloon in the urethra or forceful removal. These can all be attributed to the Foley’s balloon-based design. We suggest that the Lotus catheter, by replacing the balloon mechanism for a Malecot-like model, avoids these common shortcomings, empties the bladder completely, with a low rate of complication, is easy to insert and remove, and is safe in the event of urethral inflation or accidental removal.

Figure-1a

Figure-1b

Figure-1c

Figure-1d

Figure 1a-d: Picture of Lotus Catheter Design.

Table 1: Lotus Catheter Insertion Results. 

Table 2: Lotus Catheter Removal Results. 

1. Trautner BW and Darouiche RO (2004) Catheter-associated infections: pathogenesis affects prevention. Arch Intern Med 164: 842-850.
2. Feneley RC, Hopley IB, Wells PN (2015) Urinary catheters: history, current status, adverse events and research agenda. J Med Eng Technol 39: 459-470.
3. Magill SS, Edwards JR, Bamberg W, Beldavs ZG, Dumyati G, et al. (2014) Multistate point-prevalence survey of health care-associated infections. N Engl J Med 370: 1198-1208.
4. Wu AK, Blaschko SD, Garcia M, McAninch JW, Aaronson DS (2012) Safer urethral catheters: how study of catheter balloon pressure and force can guide design. BJU Int 109: 1110-1114.
5. Leuck AM, Wright D, Ellingson L, Kraemer L, Kuskowski MA, et al. (2012) Complications of Foley catheters--is infection the greatest risk?. J Urol 187: 1662-1666.
6. Kashefi C, Messer K, Barden R, Sexton C, Parsons JK (2008) Incidence and prevention of iatrogenic urethral injuries. J Urol 179: 2254-2257.
7. Davis NF, Quinlan MR, Bhatt NR, MacCraith E, Manecksha R, et al. (2016) Incidence, cost, complications and clinical outcomes of iatrogenic urethral catheterisation injuries: A prospective multi-institutional study. J Urol 196: 1473-1477.
8. Dellimore KH, Helyer AR, Franklin SE (2013) A scoping review of important urinary catheter induced complications. J Mater Sci Mater Med 24: 1825-1835.

      9. Haylen BT, Frazer MI, MacDonald JH (1989) Assessing the effectiveness of different urinary catheters in emptying the bladder: an application of transvaginal ultrasound. Br J Urol 64: 353-356.