Application of peripheral near infrared spectroscopy to assess risk factors in patient with coronary artery disease: Part 1

Obesity, a risk factor of coronary artery disease, is known to cause peripheral microcirculatory disturbances. This study evaluated the relationship between the degree of obesity and peripheral microcirculatory disturbances, using peripheral near infrared spectroscopy (NIRS) with a vascular occlusion test (VOT). We compared correlations between the NIRS parameter changes induced by VOT and body mass index (BMI) in patients with and without statin therapy. A NIRS probe was set on the right thenar eminence, brachial artery blood flow was blocked for 3 min, and then released. Although total hemoglobin (ΔcHb), deoxyhemoglobin (ΔHHb) and tissue oxygenation index (ΔTOI) were not correlated with BMI, a significant negative correlation was found between oxyhemoglobin (ΔO₂Hb) and BMI in the overall study population (r = −0.255, p-value 0.02). In addition, a significant negative correlation was found between ΔO₂Hb and BMI in patients without statin therapy (r = −0.353, p-value 0.02) but not in patients with statin therapy (r = −0.181, p-value 0.27). These findings suggest that ΔO₂Hb may be a useful indicator to assess peripheral microcirculation.