Patent
Local Anaesthetic Medical Device – Brighton University-2002 Registration
Fluid Delivery Device – Pub No: WO/2001/083018 – International PCT/GB2001/002039
FLUID DELIVERY DEVICE
Intraurethral procedures are painful to the patient and it is therefore highly desirable to anaesthetise the urethra before insertion of surgical instruments or medical devices. Current clinical practice is to anaesthetise locally the urethra during intraurethral procedures using a commercially available topical preparation which may contain, for instance, lignocaine hydrochloride 2%.
Despite the use of topical anaesthetic agents, patients still experience considerable pain and discomfort during intraurethral procedures. Indeed, research suggests that attempting to anaesthetise the urethra using the methods of current clinical practice may have little advantage over using a plain lubricating gel (“Prospective, randomized, double-blind study comparing lignocaine gel and plain lubricating gel in relieving pain during flexible cystoscopy”, S Choong et al British Journal of Urology [1997] vol. 80, 69-71).
The current clinical practice is to deliver the anaesthetic agent with a common syringe. Such a crude delivery method has many limitations because of the nature of the urinary tract. The most severe pain during intraurethral instrumentation is experienced when a surgical instrument is in the region of the membranous and prostatic segments of the urethra.
However, to reach these areas, the anaesthetic agent has to pass beyond the external (voluntary) urinary sphincter which normally exerts a pressure of about 80 cm of water into the urethra. The sphincter may contract further if the patient is in pain thereby further increasing the pressure. The sphincter thus impedes the path of the anaesthetic fluid which will tend to be forced back out around the sides of the syringe nozzle.
WO/2001/083018 FLUID DELIVERY DEVICE – WIPO
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