Near-Infrared Spectroscopy Measurements in Chronic Obstructive Pulmonary Disease

This study was a prospective observational analysis involving patients with diagnosed Chronic Obstructive Pulmonary Disease (COPD) and Chronic Kidney Disease (CKD). Participants were recruited from the pulmonary and nephrology clinics at Gaziosmanpasa University Health Application and Research Centre during their stay in the ward. The study was approved by the Tokat Gaziosmanpasa Research Ethics Committee (Grant number: 20-KAEK-212) and all patients provided informed consent prior to participation. Data collection involved baseline assessments of demographic characteristics, COPD severity, renal function, and comorbidities. Participants were divided into three groups: control, COPD, and CRD. Patients were visited during their stay in the ward and the measurement was initiated after five minutes of rest. Venous blood gas analysis was performed using the same sample of blood obtained for routine complete blood count analysis. A vascular occlusion test was conducted with NIRS measurements taken throughout. Three minutes of baseline measurement placing the probe on thenar eminence of the right hand was completed while the patient was lying with 45 degrees back up position. After baseline measurements a non-invasive blood pressure cuff was placed on the right arm and it was inflated to 250 mmHg. The cuff was held inflated for two minutes; after two minutes, the cuff was deflated and the measurement had been continued for another three minutes and stopped. Near-infrared spectroscopy measurements were obtained during and after vascular occlusion, including the area under curve (AUC) during occlusion (representing tissue hyperemia) and the angles of descent and ascent, which reflect muscle oxygen consumption and microcirculatory function, respectively.