Hemodynamic characteristics of postural hyperventilation: POTS with hyperventilation versus panic versus voluntary hyperventilation.

Upright hyperventilation occurs in ~25% of our patients with postural tachycardia syndrome (POTS). Poikilocapnic hyperventilation alone causes tachycardia. Here, we examined changes in respiration and hemodynamics comprising cardiac output (CO), systemic vascular resistance (SVR), and blood pressure (BP) measured during head-up tilt (HUT) in three groups: patients with POTS and hyperventilation (POTS-HV), patients with panic disorder who hyperventilate (Panic), and healthy controls performing voluntary upright hyperpnea (Voluntary-HV).

Postural Hyperventilation as a Cause of Postural Tachycardia Syndrome: Increased Systemic Vascular Resistance and Decreased Cardiac Output When Upright in All Postural Tachycardia Syndrome Variants.

Background: Postural tachycardia syndrome (POTS) is a heterogeneous condition. We stratified patients previously evaluated for POTS on the basis of supine resting cardiac output (CO) or with the complaint of platypnea or "shortness of breath" during orthostasis. We hypothesize that postural hyperventilation is one cause of POTS and that hyperventilation-associated POTS occurs when initial reduction in CO is sufficiently large.