Water Immersion Technique (WIT) uses a small amount of water instead of air during intubation. Unlike conventional air insufflation methods, WIT makes easier and faster intubation possible, because:

1. Small volume of water does not distend the colon like air.

2. Water works as lubricant, which makes intubation more smooth and can avoid elongation of the colon.

Furthermore, by not making complicated loops, this technique is very effective for difficult cases, with fewer prolonged examinations. Thus the average cecal intubation time is shorter than air insufflation as well.

HISTORY OF WATER IMMERSION TECHNIQUE

Professor Kunihiko Tsubura of Tokyo University assumed that the main reason why colonoscopy was so formidable for novice physicians was that they tended to insufflate too much air. He instructed his apprentice doctors not to use air at all during intubation, what is called "Non-air-insufflation Technique.' Dr. Masafumi Tabuchi, one of Professor Tsubura's students, found that instilling some water with a syringe made intubation easier. While I was also learning from the professor, I modified this method with an electric pedal pump, a unique and revolutionary 'One-pattern method' usage of lucent caps, and the development of a system for selecting scopes. I named it Water Immersion Technique upon completion.

Professor Kunihiko Tsubura; invented "Non-air-insufflation Technique" (in 1980's) Dr. Masafumi Tabuchi; initiated "Non-air-insufflation with Water Instillation Technique" (1987) Dr. Toshio Goto; completed "Water Immersion Technique" (1994) [INSET 1-1 HISTORY OF WATER IMMERSION TECHNIQUE]

　

ELECTRIC PEDAL PUMP

Water is instilled through a scope channel only when the foot-switch is stepped upon.

[INSET 1-2 ELECTRIC PEDAL PUMP] Dr. Goto developed the pedal pump for Water Immersion Technique in 1992.

I filed for a Japanese patent on the electric instillation pedal pump for colonoscopy in 1995. This invention was made as an auxiliary device for the purpose of easier insertion of a colonoscope. This invention makes it possible to instill a large amount of water rapidly with the endoscopist's hands free while lessening the endoscopist's burden and shortening the examination time, which were problems associated with the conventional Water Immersion Technique. I compared two groups of 100 patients each, one group of the conventional method of water injection with a syringe and one group of water instillation with the electric pedal pump, with the same endoscopists at Kagoshima Tokushukai Hospital in 1994. As a result, the decrease in the burden of the endoscopists was confirmed during intubation of the scope and the average intubation time was shortened from 15 minutes to 7 minutes per patient. It led to an increase in the possible maximum number of examinations per day from 7 patients to 15 patients. This data is an excerpt from the patent application.

WATER IMMERSION TECHNIQUE IS NOT SLOW

Water Immersion Technique (WIT) does not apply quick movements. The basic movement is as if to flip folds one by one slowly. Thus, even the easiest case takes more than two minutes. However, this technique has fewer difficult cases and prolonged cases, which results in shorter average examination times.

I keep a record of the cecal intubation time of all WIT cases because it can be useful information for future examinations. The first step on the foot-switch in the rectum by the endoscopist as a cue, a stopwatch starts, and when the first picture is taken at cecum the intubation is recorded. Shown is the graph of my cecal intubation time with Water Immersion Technique at Shonan Atsugi Hospital. Cases under two minutes and over ten minutes are fewer, about 5% occurrences of each. One characteristic of Water Immersion Technique and One-pattern Method is less dispersion among cases. The average time is shorter than five minutes. It implies that fewer over-10-minute cases have more impact than fewer under-2-minute cases. Also, 'difficult cases' are usually deemed over-30-minute cases, so a conclusion is that with Water Immersion Technique there are fewer difficult cases.

ADVANTAGE OF WATER IMMERSION TECHNIQUE-PAIN FREE

The biggest advantage of Water Immersion Technique is that it is a painless procedure. The graph below shows the surveillance of pain experienced by patients at Chiba-Nishi General Hospital. "Very painful" and "Extremely painful" are 5% combined, and only one out of twenty unsedated patients claims to have experienced pain during the procedure.