Abstract 14998: Assessment of Microcirculatory Dysfunction by Measuring Subcutaneous Tissue Oxygen Saturation Using Near-Infrared Spectroscopy in Patients With Circulatory Failure

Abstract

Background: Patients with circulatory failure have been treated with the goal of normalizing systemic hemodynamic parameters such as blood pressure, central venous pressure, urine output, and central venous oxygen saturation. However, microcirculatory dysfunction remains even after improvement of these indices, suggesting a loss of hemodynamic coherence between the macrocirculation and the microcirculation. Recently, the usefulness of near-infrared spectroscopy (NIRS) in assessing the microcirculation has been reported. Aim: We measure regional tissue oxygenation saturation (rSO 2 ) at 3 - 5 mm subcutaneously in patients with circulatory failure using a finger-mounted tissue oximeter with the NIRS technique (Toccare: Astem Co., Ltd., Kawasaki, Japan) to investigate its relationship with microcirculation. Methods: This is a single-center prospective observational cohort study of patients with circulatory failure (systolic blood pressure ≤ 90 mmHg or lactate ≥ 2 mmol/L at presentation) transported to the emergency department of Nihon University Hospital from 15 June 2020 to 31 March 2022. We measured rSO 2 in the forehead, thenar eminence, thumb and knee using Toccare and assessed the relationship between rSO 2 and blood pressure, acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score and mottling score. Result: In patients with circulatory failure (n = 38), rSO 2 at each site showed no correlation with blood pressure, a negative correlation with SOFA score and APACHE II score and a positive correlation with mottling score. These significant correlations were also best observed in the knee. Conclusion: In patients with circulatory failure, rSO 2 measured with Toccare showed no correlation with blood pressure but a significant negative correlation with the severity of organ damage. The knee is possibly the optimal measurement site for monitoring microcirculatory dysfunction and determining the effectiveness of treatment.