7071 Endoscopy without air insufflation.

Abstract

Background: Most gastrointestinal endoscopy is performed with inflation with air to distend the viscus. For some applications and the development of new endoscopic methods airless endoscopy is likely to become important. Little is known about the efficacy and limitations of airless gastrointestinal endoscopy. Methods: A variety of experimental airless endoscopes were constructed. These included: 1. short focal length lens of a) curved shape, b) conical shape were mounted on the tip. 2.Wire cage fronted endoscope. 3. Transparent balloon fronted airless endoscope: balloon filled with a) clear gas, b) clear water. 4.Water immersed endoscope. Lighting was transmitted either through the lens, cage, balloon, water or by mounting the light source coaxially adjacent to the lens or optics. These experimental endoscopies were tested in post mortem and live oesophagus, stomach, small bowel and colon. Results: Reasonably good quality video images were obtained using all these experimental endoscopes in airless endoscopy of the GI tract. Short focal length lenses required careful focussing to optimise image quality. Reflections from the cage were diminished by using a non-reflecting paint. Mucus adherence was occasionally a problem but mucus was often wiped off as the endoscope moved. Movement of the endoscope allowed assessment of whether the mucus was adherent to the lens or tissue. Gas and water filled transparent balloons gave moderately good views but were unreliable and not robust. Tissue laying on the lenses sometimes impaired the view although this was less of a problem in live supported bowel. Practically, it was difficult to maintain water in the GI tract for immersion endoscopy. Curved shape short focal length lenses gave the best images overall. Conclusion: Despite some limitations airless endoscopy was able to give high quality images of the small bowel and oesophagus. Better than expected views could also be obtained in the stomach and large bowel but were limited by the diameter of the viscus. Problems with illumination with internal reflection were encountered and resolved. Background: Most gastrointestinal endoscopy is performed with inflation with air to distend the viscus. For some applications and the development of new endoscopic methods airless endoscopy is likely to become important. Little is known about the efficacy and limitations of airless gastrointestinal endoscopy. Methods: A variety of experimental airless endoscopes were constructed. These included: 1. short focal length lens of a) curved shape, b) conical shape were mounted on the tip. 2.Wire cage fronted endoscope. 3. Transparent balloon fronted airless endoscope: balloon filled with a) clear gas, b) clear water. 4.Water immersed endoscope. Lighting was transmitted either through the lens, cage, balloon, water or by mounting the light source coaxially adjacent to the lens or optics. These experimental endoscopies were tested in post mortem and live oesophagus, stomach, small bowel and colon. Results: Reasonably good quality video images were obtained using all these experimental endoscopes in airless endoscopy of the GI tract. Short focal length lenses required careful focussing to optimise image quality. Reflections from the cage were diminished by using a non-reflecting paint. Mucus adherence was occasionally a problem but mucus was often wiped off as the endoscope moved. Movement of the endoscope allowed assessment of whether the mucus was adherent to the lens or tissue. Gas and water filled transparent balloons gave moderately good views but were unreliable and not robust. Tissue laying on the lenses sometimes impaired the view although this was less of a problem in live supported bowel. Practically, it was difficult to maintain water in the GI tract for immersion endoscopy. Curved shape short focal length lenses gave the best images overall. Conclusion: Despite some limitations airless endoscopy was able to give high quality images of the small bowel and oesophagus. Better than expected views could also be obtained in the stomach and large bowel but were limited by the diameter of the viscus. Problems with illumination with internal reflection were encountered and resolved.