Sublingual Microcirculation in Prehospital Critical Care Medicine: A Proof-of-concept Study

Objective Diagnostic and risk stratification are limited in emergencies. The measurement of microcirculation might identify patients with poor perfusion but compensated macrocirculation such as in beginning shock. This proof-of-concept study examines whether sublingual prehospital sidestream dark-field microscopy is feasible. Methods This prospective observational study included patients receiving medical aid by an emergency ambulance who had a spontaneous circulation and offered access to the sublingual mucosa. Sublingual measurement of microcirculation was performed using a sidestream dark field camera. Video quality was evaluated with microcirculation image quality score (microcirculation image quality score). AVA 4.3C software calculated microcirculatory parameters. Results Thirty patients (47% male) were included. The average age was 63 years (+/- 20 years SD), the severity of the disease (quantified by National Advisory Committee on Aeronautics) was 3.4 (+/- 0.7 SD). Macrocirculation presented within the normal range. The most frequent cause preventing the measurement was a time-critical disease (64%). In 17 patients (57%), the videos could be analyzed immediately. The average quality of the video was 2.2 +/- 0.45 points ('acceptable'). There were minor restrictions of microcirculation. Microcirculation correlated with National Advisory Committee on Aeronautics, but not with the macrocirculation. No complications occurred. Conclusion The prehospital sublingual measurement is safe and valid. Despite normal macrocirculation, microcirculation was impaired and correlated with National Advisory Committee on Aeronautics.