Background and Study Aims: It has been postulated that chronic radiation proctopathy, clinically manifested by hematochezia and by the appearance of multiple telangiectasias, is caused by ischemia. This theory is base...
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Background and Study Aims: It has been postulated that chronic radiation proctopathy, clinically manifested by hematochezia and by the appearance of multiple telangiectasias, is caused by ischemia. This theory is based on reports that appeared in the 1980s which described obliterative endarteritis in patients with chronic radiation-induced ulcers. However, bleeding from radiation proctopathy is typically successfully treated endoscopically by widespread tissue coagulation, and the complications that would be expected to occur if the tissue was ischemic, such as poor wound healing, generally do not arise. We therefore hypothesized that the ischemia theory is incorrect and that rectal capillary oxygen saturation is normal in patients with telangiectasias of chronic radiation proctopathy. Patients and Methods: We developed a visible-light spectroscopy device that measures mucosal capillary hemoglobin oxygen saturation during endoscopy (having reported its operating characteristics previously). We prospectively studied 20 patients who had typical findings of multiple rectal telangiectasias, 1-20 years after undergoing external-beam irradiation for prostate or rectal carcinoma. We measured and compared the mucosal capillary oxygen saturations in the affected areas of the distal rectum and in endoscopically normal areas in the rectosigmoid colon. Results: Mucosal oxygenation was normal in all 20 patients in affected areas (64%-80%) and in unaffected areas (63%-75%). The mean mucosal hemoglobin oxygen saturation was actually slightly higher in the affected areas of the rectum than in the uninvolved rectosigmoid colon (73%vs. 69%, P < 0.01). Conclusions: The common form of chronic radiation proctopathy, characterized by multiple telangiectasias without ulcers or strictures, is not associated with ongoing mucosal ischemia. This finding may explain why endoscopic treatment of this disorder, in which large areas of the mucosa are coagulated with argon plasma or other treatment
Aims: To compare the macular capillary blood flow of patients with clinically significant diabetic macular oedema (DMO)-with that of non-diabetic subjects and to determine the relation between blood flow and capillary...
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Aims: To compare the macular capillary blood flow of patients with clinically significant diabetic macular oedema (DMO)-with that of non-diabetic subjects and to determine the relation between blood flow and capillary leakage in patients with DMO. Methods: The sample comprised 45 non-diabetic subjects (mean age 59 years) and 18 type 2 patients with clinically significant DMO (mean age 60 years). Macular capillary blood flow measurements were acquired using the Heidelberg retina flowmeter (HRF) and a 10° × 2.5° scan field centred on the fovea. Fluorescein angiographywas undertaken on each of the diabetic patients after the completion of HRF measurements. Results: Temporal macular capillary blood flow was significantly lower for the patients with clinically significant DMO compared with age matched non-diabetic subjects (ANCOVA, P=0.0011)-while relative nasal-temporal asymmetry of macular capillary blood flow was significantly higher (P=0.0125). Nasal-temporal asymmetry ofmacular capillary blood flowwas significantly higher for the patients with DMO and capillary leakage within the scan area (two tailed t test, P=0.0071). Macular capillary blood flow was always lower in areas of DMO and capillary leakage. Conclusion: Capillary blood flow was reduced in areas of DMO and capillary leakage, suggesting the presence of a localised perturbation of capillary blood flow regulation.
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