Current Methods, Quality Control, and Translational Perspectives for Bedside Sublingual Microcirculation Monitoring in Critical Illness.

Microcirculatory abnormalities may persist after blood pressure, cardiac output, and other systemic hemodynamic targets have been restored in critically ill patients. The sublingual mucosa provides an accessible site for repeated bedside assessment of the microcirculation, but routine clinical implementation remains limited by acquisition artifacts, operator dependence, image-analysis burden, variable measurement quality, and uncertain relationships with therapeutic decision-making. This narrative review aims to examine current methods for bedside sublingual microcirculation monitoring, evaluate their strengths and limitations, and identify practical priorities for translation into routine clinical practice. The review summarizes established and emerging measurement approaches for assessing vascular morphology, vessel density, blood-cell flow patterns, regional velocity-related signals, tissue oxygenation, and data quality, emphasizing that these complementary measurements are not interchangeable and require rigorous quality control. It further outlines standardized acquisition and reporting considerations, performance metrics, repeatability testing, analytical validation, and benchmark comparisons appropriate for different measurement domains. Finally, an author-proposed modular workflow is presented to illustrate a structured framework for sensing, quality control, data processing, and bedside reporting. This conceptual framework is intended to guide future technical development and clinical validation and does not represent a clinically validated device, diagnostic system, or treatment algorithm.