Hyperventilation during rest and exercise in orthostatic intolerance and Spiky-Leaky Syndrome

Compared to the control group, patients with OIDS-and especially those with SLS-exhibited reduced metabolic parameters, particularly a decrease in peak oxygen pulse and ETCO₂ levels during both rest and exercise. These findings suggest a reduction in ventricular preload and chronic daytime hyperventilation. These exercise parameters may serve as markers for POTS physiology and sympathetic hyperactivity, both of which could play a role in the pathophysiology of SLS.