Continence (Mar 2022)
Development and initial testing of valves opened by Valsalva (abdominal straining): Proof of principle for urinary catheters or male urethra
Abstract
We hypothesised that raising the abdominal pressure could provide a non-manual approach to opening a urinary valve, with potential application for indwelling catheters or an intraurethral device. The ‘Vysera’ valve remains closed during short high amplitude spikes but opens when a pre-defined low-amplitude pressure is maintained for a pre-specified duration, allowing sustained abdominal straining to achieve voluntary opening. The valve was subjected to in vitro performance and microbiological tests. Parameters for valve specification were selected by review of a large urodynamic database with nominal opening pressure of 75 cmH2O ＋/−15 cmH2O (range 60–90 cmH2O) and valve pressure was refined using early clinical results. Valve housings were designed for the end of a Foley catheter, and for male post-prostatectomy intraurethral placement. Preliminary clinical evaluation was undertaken for both designs, incorporating qualitative feedback. In vitro testing of the catheter valve demonstrated only minimal encrustation. On clinical evaluation of the catheter-sited valve, six of seven patients (86%) were able to open the valve intentionally by straining. When inactive, none of the patients experienced leakage (7/7 = 100%), while five (71%) leaked when they coughed. The intraurethral device was successfully placed with image intensifier guidance under general anaesthetic in five of nine patients. Three patients used the device; initial leakage resolved as patients mobilised. However, in contrast to the catheter-sited valve, the intraurethral device was difficult to tolerate for even a few hours. Removal was performed under local anaesthesia with a flexible cystoscope and stent grasper. We conclude that storage and bladder emptying using a strain-activated valve are feasible for a catheter valve and an intra-urethral device. The valve parameters need to be matched to individual patients. For the intraurethral device, additional development is needed to improve the stent housing and valve performance.
