At a glance
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Redistribution of Pulmonary Perfusion During Bronchoconstriction in Asthma
In Brief
A clinical study evaluating Standardized Cat Allergen Extract and Standardized Dust Mite Allergen, Computed Tomography imaging, functional Positron Emission Tomography imaging, and 1 other intervention for Asthma and Atopy. Completed, enrolled 7 participants across 1 site.
Detailed Summary
Asthma is a disease of rapidly increasing incidence that already affects more than 17 million people in the United States alone. It has long been known that areas of severely reduced airflow occur in asthma and contribute significantly to the impairment of gas exchange in this disease. However, the extent to which local blood flow changes during an asthmatic attack is unclear. The purpose of this study is using Positron Emission Tomography - Computed Tomography imaging to evaluate how the blood flow changes in the lungs during an asthma attack induced by allergens.
Study Details
Timeline
Interventions
The route of administration will be topical application of the titrated allergen via nebulized droplets to the lungs. The starting dose of allergen will be 3 dose dilutions below the estimated provocative concentration of allergen that causes a 20% fall in Forced Expired Volume in 1 second delivered for 5 minutes at tidal breathing, followed by Forced Expired Volume in 1 second at 10-minute intervals until the lowest Forced Expired Volume in 1 second is established. If the percent of Forced Expired Volume in 1 second fall is \< 20%, the next concentration is given, until the Forced Expired Volume in 1 second falls ≥ 20 percent. When this happens the Forced Expired Volume in 1 second will be followed at 10, 20, 30, 45, and 60 minutes, then hourly for 7 hours. The early asthmatic response is the maximum percent of Forced Expired Volume in 1 second fall between 0 and 3 hours and the late asthmatic response between 3 and 7 hours post allergen challenge.
Physiology study using Computed Tomography and Positron Emission Tomography imaging with Nitrogen-13 saline as radiotracer; images obtained during the early and late phases after allergen challenge
Standard methacholine challenge performed once to determine the subject's dose that causes a 20% fall in Forced Expired Volume in 1 second from baseline.