Pressure-Volume Measurements on the AMS 800TM Cuff

Stress Urinary Incontinence

he idea of the experiment is to calculate the volume of fluid that is required to raise cuff pressure from 20 cmH2O to 120 cmH2O in the American Medical System's AMS 800 Artificial Urinary Sphincter (AUS).

The current AMS 800 is not personalized to the patient's needs. Most men only need 20 cm H2O of urethral compression to remain dry when they are sedentary, yet need 120 cm H2O of urethral compression when they are active. The current device compromises with an in between pressure - as high as it can be without exceeding safety tolerance thresholds. As such many men still leak when they are active. In fact, this compromise is so central to the device that a new term has evolved to describe men's suboptimal level of continence after the AMS 800. We call it social continence, meaning that they are dry enough to only have to wear 1-2 pads per day for protection. The market is hungry for a device that can adapt to the patient's level of activity, reducing the pressure most of the day to protect the urethra and then briefly increasing the pressure when he is more active. The experimental procedure is explained below and care will be taken to make sure the pressure sensor is sterile. The experiment involves minimal risk and will be conducted by the PI who has 10+ years of experience in AUS implantations. The procedure for implanting the AMS 800 is mentioned in the Operating Manual attached with this protocol. The treatment procedure is linked with the experimental setup designed by the PI and the research student in the following manner: 1. Follow surgical preparation steps mentioned on pages 14-15 of the AMS 800 Operating Manual. Once the cuff sizer is used to determine the cuff length (usually 4.0cm or 4.5cm), move on to next step. For graphical representation, follow steps 1 to 9b on pages 18- 20 of the AMS 800 Operating Manual. 2. The AMS 800 cuff is filled with deionized water such that pressure is 20cmH2O. Follow steps on pages 13-14 of the AMS 800 Operating Manual for filling the cuff. 3. The AMS 800 cuff around the urethra has a kink-free tubing which goes into a female connector 4. The female connector connects to the male connector of the IV tubing 5. The IV tubing is connected to a T-Connector 6. One end of the T-Connector goes to the TruWave Pressure Transducer 7. Other end goes to a syringe 8. The system is pumped with deionized water and is therefore sterile. 9. Water is pumped into the cuff with the syringe and as the volume in the cuff increases, corresponding cuff pressure changes. This is done until we have a volume for a pressure reading of 120cmH2O on the pressure transducer. 10. Once the reading is obtained, the PI will flush out the excess water from the cuff, and fill it with an optimal volume as required by the treatment procedure which he has performed for over 10 years. 11. The treatment procedure will continue to follow the steps hereafter as has been designed for AUS placement. For all other details including device description and post-operative care, refer to the AMS 800 operating Manual. All devices including the AMS 800 (PMA-P000053) and the Edward LifeSciences Pressure Transducer (501K- K142749) are FDA approved.

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