Rapid clinical assessment of the sublingual microcirculation - Visual scoring using microVAS in comparison to standard semi-automated analysis

RATIONALE: Alterations in human microcirculation occur in many disease states leading to morbidity and mortality, however assessing the microcirculation is not standard clinical practice. Standard microcirculation analysis using semi-automated analysis is expensive, time consuming, and expertise dependent making it unfeasible. We proposed a novel visual scoring system (microVAS) for the analysis of microcirculation videos that can be performed at the patient bedside in real time. OBJECTIVE: Validate our microVAS score by training health professionals unfamiliar with the microcirculation field to use our microVAS score and compare their scores to the standard method of semi-automated analysis using AVA3 software. METHODS: Using a prospective double-blind study design, we recruited and trained 20 participants to use our microVAS score. Participants scored 40 videos (from 22 healthy and 18 septic patients) for MFI and PPV. The same 40 videos were analysed by an expert using the gold standard semi-automated method of analysis. The results of the participants and the expert were analysed by Pearson's linear regression. Krippendorff's alpha was used to assess inter-rater reliability of the participants. RESULTS: Overall correlation of MFI was r=0.33 (95% CI 0.27-0.39), p<0.05; overall correlation of PPV was r=-0.11 (95% CI -0.18 to -0.04), p<0.05. The Krippendorff's alpha for MFI was 0.56 (healthy videos: α=0.34, sepsis videos: α=0.31). For PPV Krippendorff's alpha was 0.43 (healthy videos: α=0.56, sepsis videos: α=0.17). CONCLUSIONS: Overall for both MFI and PPV, there was a small correlation between our microVAS score and AVA 3 scores. Regarding inter-rater reliability both MFI and PPV showed fair agreement between raters. Going forward multiple improvements to the microVAS scoring system as well as the training program are suggested to improve reliability and consistency.