Imaging Study of the Lungs During an Allergic Asthma Attack

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.

Conditions

• Asthma
• Atopy

Interventions

BIOLOGICAL

Standardized Cat Allergen Extract and Standardized Dust Mite Allergen

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.

RADIATION

Computed Tomography imaging, functional Positron Emission Tomography imaging

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

DRUG

Nebulized methacholine inhalation

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.

Sponsors & Collaborators

• National Heart, Lung, and Blood Institute (NHLBI)

  collaborator NIH

• Massachusetts General Hospital

  lead OTHER

Principal Investigators

• R. Scott Harris, MD · Massachusetts General Hospital

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2012-05-31

Primary Completion

2013-10-31

Completion

2013-10-31

Countries

• United States

Study Locations