Acetazolamide-Induced Cerebral Vasoreactivity Assessed by Near Infrared Spectroscopy in COPD Patients-Prospective, Interventional, Non-Randomized Study

Background: Chronic obstructive pulmonary disease (COPD) is associated with affection of the cerebral vasculature, resulting in a higher incidence of stroke and cognitive decline. The exact pathophysiological background is not known, but among others, an altered function of the cerebral microvasculature is proposed as an underlying mechanism. The present work aimed to assess cerebrovascular reactivity to the patent vasodilatory stimulus acetazolamide (ACZ) in COPD patients. Methods: COPD patients and healthy controls underwent near-infrared spectroscopy monitoring of cerebral oxygen saturation using intravenous administration of 15 mg/kg BW ACZ. Cerebrovascular reactivity (CVR) was defined as the percent increase in cerebral oxygen saturation (SpcO2) at 5, 10, 15, and 20 min after administration of ACZ, measured using near-infrared spectroscopy. Maximal percent increase in SpcO2 after ACZ was defined as cerebrovascular reserve capacity (CRC). Results: 35 COPD patients with different spirometric grades of airflow obstruction (GOLD grade 2: n = 8; GOLD grade 3: n = 18; GOLD grade 4: n = 9) and 10 healthy patients underwent ACZ tests. Administration of ACZ resulted in a significant decrease in pH and an increase in PaO2 and PaCO2. CVR and CRC values did not show any difference between COPD patients and healthy controls. CRC values were independent of spirometric grade of airflow obstruction (GOLD4: 11.3 ± 6.8; GOLD3: 11.9 ± 6.6; GOLD2: 10.9 ± 4.5%, respectively, p = 0.53). A significant negative correlation was found between SpcO2 at rest and CRC values r = −0.56). A significant negative correlation was found between CRC and FVC% and a positive correlation with FEV1/FVC, but not with other lung function parameters. Conclusions: After administration of acetazolamide, no difference was found in the percent increase of cerebral oxygen saturation between healthy and COPD subjects, indicating a comparable increase in oxygen delivery to the brain tissue. Trial registration: The study was registered at the Clinical Trials registry (EUDRACT number: 2022-004076-41; registration date: 28 November 2022).