Clinical evaluation of the intestinal microcirculation using sidestream dark field imaging-Recommendations of a round table meeting

INTRODUCTION: In clinical setting, Sidestream Dark Field (SDF) imaging has provided unprecedented insights into the gut microcirculation mainly by studying the intestinal mucosa of patients with ileostomies. Visualizing microvascular structure and function of ileal mucosa at the bedside brings unique opportunity for clinical research, particularly in critically ill patients. Several papers that were focused on intestinal microcirculation, used different methods of assessment because an accepted scoring systems does not exist so far and it is no surprise that it is rather difficult to compare the results from these studies. The present paper presents recommendations concerning specific aspects of image acquisition and proposes some parameters for the description of the intestinal microcirculation in human studies, as suggested by the participants of a round table meeting. METHODS: The round table meeting participants reviewed all relevant literature, discussed various aspects of image acquisition by SDF technology in patients with ileostomy and parameters for the description of intestinal mucosa microcirculation. Selected key conditions for high quality and reproducible image recordings were identified. To evaluate quality of intestinal microcirculation, selected parameters and scoring system were suggested and described. RESULTS: For image acquisition in ileostomies, five key points were proposed: optimal timing, optimal SDF device probe positioning, optimal stabilization, optimal number and length of acquired video recordings, and optimal avoidance of pressure artefacts. With regard to image analysis, simplified set of quantitative and qualitative parameters for the description of the intestinal mucosa microcirculation for the clinical studies has been proposed: vessels per villus, microvascular flow index, proportion of perfused villi, and borders of villi. The proposed parameters can be included in a semi-quantitative scoring system; however, this scoring system needs further validation. This simplified analysis does not require sophisticated software and can be performed manually on the video screen. CONCLUSION: We propose a simple methodology for image acquisition and suggest specific microvascular parameters to analyze SDF imaging studies of the intestinal mucosa microcirculation in patients with ileostomy. Proposed scoring system needs to be validated in further clinical studies.