Cerebral Oxygenation during Exercise in Patients with Cardiopulmonary Diseases: A Prospective Observational Study

Background: The relationship between exercise and cerebral oxygenation has gained increasing attention. However, few studies have investigated the correlation between exercise and cerebral oxygenation in patients with cardiopulmonary diseases. Objectives: To investigate the correlation between exercise and cerebral oxygenation in patients with cardiopulmonary diseases. Methods: Thirty eligible patients with cardiopulmonary diseases underwent incremental cardiopulmonary exercising test (CPET) and near-infrared spectroscopy with both right and left sensors placed at the mid forehead to detect oxygen saturation of cerebral tissue (STO2). Parameters of cerebral oxygenation and exercise intensity were collected and analyzed. Results: The average age of the patients was 51.17 +/- 10.21 years and included 23 males and 7 females. The average maximal STO2 of the left and right brain during CPET were 51.850 +/- 1.57% and 51.755 +/- 1.90%, respectively. Meanwhile, mean oxygen consumption (VO2) while reaching maximal STO2 was 4.42 +/- 1.05 metabolic equivalents (METs) over the left brain and 4.34 +/- 1.17 METs over the right brain. The exercise intensity upon reaching maximal STO2 was 84.91 +/- 11.70% over the left brain and 83.16 +/- 14.64% over the right brain. Peak V02 was significantly correlated to VO2 upon reaching maximal STO2 over the left and right brain (R = 0.805, p < 0.001 and R = 0.739, p < 0.001, respectively). Age was significantly negatively correlated to V02 upon maximal STO2 over the left and right brain (R = -0.378, p = 0.039 and R = -0.513, p = 0.004, respectively). Conclusions: Cerebral oxygenation increases with higher exercise intensity, and it reaches a maximal STO2 between respiratory compensation point and peak exercise. The higher the peak VO2, the better the VO2 upon reaching maximal STO2.