Endoscopic visible light spectroscopy: A new, minimally invasive technique to diagnose chronic GI ischemia
Background: The diagnosis of chronic GI ischemia (CGI) remains a clinical challenge. Currently, there is no single simple test with high sensitivity available. Visible light spectroscopy (VLS) is a new technique that noninvasively measures mucosal oxygen saturation during endoscopy. Objective: To determine the diagnostic accuracy of VLS for the detection of ischemia in a large cohort of patients. Design: Prospective study, with adherence to the Standards for Reporting of Diagnostic Accuracy. Setting: Tertiary referral center. Patients: Consecutive patients referred for evaluation of possible CGI. Interventions: Patients underwent VLS along with the standard workup consisting of evaluation of symptoms, GI tonometry, and abdominal CT or magnetic resonance angiography. Main Outcome Measurements: VLS measurements and the diagnosis of CGI as established with the standard workup. Results: In 16 months, 121 patients were included: 80 in a training data set and 41 patients in a validation data set. CGI was diagnosed in 89 patients (74%). VLS cutoff values were determined based on the diagnosis of CGI and applied in the validation data set, and the results were compared with the criterion standard, resulting in a sensitivity and specificity of VLS of 90% and 60%, respectively. Repeated VLS measurements showed improvement in 80% of CGI patients after successful treatment. Limitations: Single-center study; only 43% of patients had repeated VLS measurements after treatment. Conclusions: VLS during upper endoscopy is a promising easy-to-perform and minimally invasive technique to detect mucosal hypoxemia in patients clinically suspected of having CGI, showing excellent correlation with the established ischemia workup.