3453 Mucosal hemodynamics in the watershed area of the normal colon and in hemodialysis and oxygendependent patients

• Published in: Gastrointestinal endoscopy Vol. 51; no. 4; p. AB96
• Main Authors: Padda, Sukhdeep, Medlin, Susan M., Tarbell, Helen E., Leung, Felix W., Ramirez, Francisco C., Hayden, Carl T.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2000
• ISSN: 0016-5107; 1097-6779
• DOI: 10.1016/S0016-5107(00)14153-7

Patients on chronic hemodialysis (HD) are prone to develop ischemic colitis. The effect of the state of tissue oxygenation upon the regulation of tissue blood flow has not been well described in human studies. Aim:We used the endoscopic reflectance spectrophotometry technique which provides an index of hemoglobin concentration (IHb) and index of oxygen saturation (ISO2) to evaluate the above issues. Methods: Controls (n=11), oxygendependent (n=7) and HD (n=9) patients underwent sigmoidoscopy and IHb and ISO2 readings were obtained at the watershed area (20 cm from the anal verge) of the sigmoid colon. In the O2-dependent patients, measurements were made off and on O2 supplementation while peripheral O2 saturation was monitored by pulse oxymetry. Results: The results are summarized in the Table below. In O2-dependent patients pulse oxymetry readings were significantly lower off O2 than on O2 (85.2 ± 0.3% vs. 94.1 ± 0.2%; p<0.05) and ISO2 readings correlated with pulse oxymetry (p<0.05). ISO2 values were significantly lower in O2-dependent patients while off O2 than controls and increased significantly to control values with O2 supplementation. A significant decrease in ISO2 along with a significant increase in IHb was seen in O2-dependent patients while off O2 (p<0.05). Conclusions:1) IHb in O2-dependent and HD patients were significantly lower (suggesting lower blood flow) than in controls in the watershed area of the colon. 2) In HD patients the reduced blood flow may contribute to their propensity to develop ischemic colitis. 3) In O2-dependent patients, ISO2 correlated with the state of O2 saturation (pulse oxymetry). 4) The reduction of IHB (decrease in flow) as ISO2 increases may reflect the detection of blood flow autoregulation by reflectance spectrophotometry.