Investigating Hypercapnia to Treat Neurogenic Orthostatic Hypotension

What this Trial Is About

This research aims to understand and find new ways to treat Neurogenic Orthostatic Hypotension (NOH), a condition where the body's automatic nervous system fails to maintain blood pressure when standing. This failure can cause symptoms like light-headedness, nausea, and fainting due to reduced blood flow and oxygen to the brain. The study explores how breathing higher levels of carbon dioxide might help improve blood pressure and brain blood flow in people with NOH, comparing responses between male and female patients and healthy controls. Participants will breathe different levels of carbon dioxide during a series of standing tests while researchers monitor their heart rate, blood pressure, and brain blood flow using advanced imaging called functional Optical Coherence Tomography (fOCT). Five stand tests involve breathing normal air, baseline carbon dioxide, and increased levels (+5 mmHg, +10 mmHg, and +10 mmHg CO2 with 50 mmHg oxygen) using a computerized gas delivery system. Recovery periods follow each test to return breathing to normal. The study will also include a rebreathing task to trigger changes in carbon dioxide and oxygen levels. Participants will undergo detailed monitoring of blood pressure, heart rate, stroke volume, and symptoms during each test, along with breath-by-breath measurements of oxygen and carbon dioxide levels and breathing patterns. OCT images will track blood flow in eye vessels as a measure of nervous system and brain blood flow control. The main outcome measured is the change in blood pressure between sitting and standing with and without increased carbon dioxide. The study will also look at symptom changes and brain blood flow velocity. The total participation time and follow-up details are based on these tests and assessments.

Hypercapnia in Orthostatic Hypotension