The Comparative Validity of the Sublabial Fossa to the Sublingual Triangle in Sidestream Dark Field Videomicroscopy for Measuring Microcirculatory Parameters.

OBJECTIVE

This study compared microcirculatory measures using sidestream dark field (SDF) videomicroscopy at sublingual and sublabial regions, examining whether novice examiners can achieve comparable reliability to experienced operators and the effect of operator experience on sublabial image quality.

METHODS

Microcirculatory imaging was performed using SDF videomicroscopy at the sublingual and sublabial regions. Sublingually, the probe was placed under the tongue on the mucosa of the floor of the mouth, in a stable, flat position to minimize tissue distortion. Sub-labially, the probe was positioned on the mucosa medial to the superior labial frenulum and stabilized between the central and lateral incisors. Participants were positioned at a 40-degree incline. Both novice and experienced operators captured images, and manually analyzed clips in AVA 3.2 software. All images were evaluated using the microcirculatory image quality score. Total vessel density, perfused vessel density, portion of perfused vessels, microvascular flow index, and heterogeneity index were calculated.

RESULTS

No statistically significant differences in image quality scores were found between observers at the sublabial site. Vessel density measures demonstrated reliable inter-observer agreement, while some flow indices showed proportional bias (MFI, p = 0.01). No significant differences were detected between sublingual and sublabial regions for most measures, except for the microvascular flow index.

CONCLUSIONS

The sublabial site is a valid alternative to the sublingual region for measuring certain microcirculatory parameters, though it requires further evaluation in flow metrics.