Baseline Anorectal Manometry
The Subjects underwent a digital rectal examination and baseline anorectal manometry in the lateral decubitus position using a device from Dynacompact (Menfis Biomedica Corp., Bologna, Italy) using an 8 channel polyvinyl (PVC) catheter with the measuring orifices oriented radially. Resting and maximal pressure in the anal canal were measured by pulling the catheter out of the anorectum at a speed of 0.5 mm/sec (the 'rapid pull through' technique)
Recordings of Anal Resting Pressure on Electronic Bidet and Sitz Bath
The subjects underwent clinical experiments for recordings of anal resting pressure changes using the electronic bidet and taking the sitz bath. For the measurement of effects of electronic bidet on anal resting pressure, a different manometry catheter (8 spirally arranged channels, 0.5 cm apart) was inserted into the anal canal placing the upper channels (channels No. 1-2) with a temperature probe in the rectum and the lower channels (channel No. 3-8) in the anal canal. The catheter was fixed in the buttock area using waterproof tape and subjects sat on a toilet equipped with an electronic bidet (Coway Corp, Seoul, Korea). After anal resting pressure had stabilized at the sitting position, anal resting pressure at high pressure zone (HPZ) was checked as control value to measure the change of anal resting pressure. The anal high pressure zone (HPZ) was defined as the channel representing the highest pressure within the anal canal for each subject. The pressures while sitting were adjusted for gravity. A water flow of the electronic bidet was applied to the anus for 3 minute. We designed the new water flow system of the electronic bidet, which was fountain type with very low force (10mN), as water falls down immediately after contacting the perineal area (Fig 1A). Before applying the water flow, mist type of water particles was sprayed for a few seconds for gentle contact with water first. The water used in the electronic bidet was a tap water of warm temperature about 38 degree celsius. Anal resting pressure at the channel of HPZ was checked at 1, 2 and 3 minutes after using the electronic bidet and percentage of anal resting pressure was calculated with compared to control value checked before using the electronic bidet. Maximum and minimum pressures in the HPZ during application of the electronic bidet were noted.
Sitz bath was also undergone at another day. After insertion of catheter, the subjects were seated on a chair with small tub filled with warm water of about 38 degree celsius and sink their buttock (Fig 1B). The measurements of anal resting pressure were similar to the electronic bidet. Anal resting pressures of HPZ were checked before and after using the electronic bidet for 3 minutes. Maximum and minimum pressures were also checked.
