Decrease in Cerebral Oxygen Saturation During the 6-Minute Walk Test in Pediatric Pulmonary Arterial Hypertension

This observational study aimed to investigate the relationship between regional cerebral oxygen saturation (rSO₂) during the 6-minute walk test (6-MWT) and the demographic/clinical features of patients with pulmonary arterial hypertension (PAH). Cerebral oxygenation was evaluated during the 6-MWT in 20 pediatric patients with PAH aged ≥ 7 years [13 male, 7 female; median age 12.25 (range 7-18) years]. In all patients, regional cerebral oxygen saturation    (rSO₂), arterial oxygen saturation (SpO₂), and heart rate (HR) were measured using near-infrared spectroscopy (NIRS) for 2 min before the test, during the 6-MWT test, and 2 min after the test. The relationship between the changes in rSO₂, heart rate, and SpO₂ values and clinical and laboratory features was compared statistically. The mean pulmonary arterial pressure (mPAP) was 77 (range 25-126) mmHg, and the median 6-minute walk distance (6-MWD) was 427.5 (300-570) m. The changes in rSO₂ measurements ranged between 3.41 and 21.8%, and 70% of the patients had a greater than 10% decrease in rSO₂ during the test compared with baseline. Eight patients showed a decrease in rSO₂ without SpO₂ changes. The present study demonstrated a significant decrease in cerebral oxygenation in pediatric patients with PAH during the 6-MWT. We hypothesized that using a combination of the 6-MWT and regional cerebral oxygenation monitoring in pediatric patients with PAH in order to evaluate exercise capacity, as a reflection of reduced daily activities, would provide more precise predictive values than the 6-MWT alone.