General anesthesia can affect tissue oxygen saturation and microcirculatory reactivity. However, the differences in microcirculation caused by anesthetic methods have not been well studied. Near-infrared spectroscopy (NIRS) measures peripheral tissue oxygen saturation noninvasively and can be used in conjunction with vascular occlusion (VOT) experiments. The purpose of this study was to examine the changes in NIRS derived tissue oxygen saturation (StO2) and microcirculatory reactivity by VOT after inhalation anesthesia in healthy population.

This prospective, observational study will be performed on 60 healthy patients who had undergone elective surgery under volatile general anesthesia. The investigators measure StO2 and microvascular reactivity using NIRS combined with vascular occlusion test (VOT). The parameters were performed twice per patient, before and after the induction of anesthesia.

Occlusion slope and recovery slope during VOT will be compared before and after anesthesia. Moreover, the changes depend on the age will be analyzed.

This prospective observational study was performed on 60 patients without comorbidities who underwent elective surgery under general anesthesia. Before and after the induction of anesthesia, StO2 monitoring and VOT were performed to investigate the effect of anesthesia on microcirculation. To investigate the effect of age on microcirculation, the patients were divided into two different groups, young (< 65 yrs) and old (> 65 yrs) groups, and the VOT-derived parameters and hemodynamics between two groups were compared.

Inclusion Criteria:

• Adult Over 18 years of age undergoing general surgery under general anesthesia.

Exclusion Criteria:

• ASA category III or IV, Diabetes, Chronic Kidney Disease, Vascular Disease

Adult male and female patients over 18 years of age undergoing general surgery under general anesthesia. American anesthesiologists association patient (ASA) category I or II.