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Digital thermal monitor (DTM) during arm-cuff induced reactive hyperemia is a surrogate of vascular function assessment in research. The purpose of this work is to evaluate the relationship between blood oxygen signal in digital thermal monitor and cardiovascular diseases (CVDs).
A self-developed device was used for recording temperature and oxygen signals of DTM simultaneously. DTM signals were obtained during 2-minute cuff inflation and 5-minute cuff deflation. Eighty healthy control subjects (age 37.20±14.10 years, BMI 23.31±2.79 kg/m2, 47.5% male) and thirty nine patients (age 52.05±7.59 years, BMI 26.34±3.86 kg/m2, 56.4% male) underwent DTM. Based on the characters of occlusion time and digital temperature curve, three critical moments were recorded: t0, the moment of occlusion beginning (corresponding to initial temperature); t1, the moment of occlusion ending; t2, the moment of temperature falling back to initial temperature. Two digital blood oxygen indices, R1 and R2, indicated the post and pre cuff-occlusion values comparison, R1 was the ratio of blood oxygen average to oxygen change scope (from t0 to t1), and R2 was the ratio of blood oxygen of t2 moment to oxygen of t1 moment. R1 and R2 were used to analyze relationship between digital blood oxygen signal and CVDs.
R1 and R1 were significantly higher in patients compared to healthy control group (R1: P<0.001, R2: P=0.001). Adjusted for age, BMI,systolic blood pressure, diastolic blood pressure, human body temperature and cardiac output, the odds ratio of patients compared with healthy control group were 1.93 for R1(P=0.044) and 3.83 for R2 (P=0.037). ROC curve area of blood oxygen indices were 0.894 for R1 and 0.889 for R2.
Digital blood oxygen indices during and after cuff-occlusion have an obvious relation with CVDs, independent of age, BMI and those factors,which could potentially be used to access CVDs.