The Impact of Dosimeter on Measurement of Airway Responsiveness to Methacholine

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00145990
Recruitment Status : Completed
First Posted : September 5, 2005
Last Update Posted : March 5, 2012
Information provided by (Responsible Party):
University of Florida

Brief Summary:
To determine whether there is a difference in two different breathing tests used to detect asthma. Hypothesis: The Digidoser delivers less methacholine to the airways and will result in a higher PC20 than the value determined by the Rosenthal Dosimeter.

Condition or disease Intervention/treatment Phase
Asthma Drug: methacholine Device: KoKo Digidoser Device: Rosethal Dosimeter Not Applicable

Detailed Description:

Bronchoprovocation with methacholine is used to confirm the diagnosis of asthma. The procedure involves inhaling methacholine through a nebulizer attached to a dosimeter that delivers a precise volume of methacholine. The endpoint of the test is the provocational concentration that produces a 20% decrease in FEV1 (PC20). To standardize the procedure, the American Thoracic Society (ATS) recommends that the nebulizer output be calibrated to deliver an output of 0.9 ± 0.09 mL/min.

The Rosenthal Dosimeter and the KoKo Digidoser are two commonly used dosimeters. In an attempt to follow the ATS guideline we discovered that the nebulizer output was lower with the KoKo Digidoser and could not be calibrated. However, it is unclear whether the apparent lower output is a result of the Digidoser delivering less solution or that the ATS method of determining output is not applicable to this dosimeter. To answer this question, we propose to determine the methacholine PC20 in subjects with asthma using the two dosimeters. It is our hypothesis that the Digidoser delivers less methacholine and thus will produce a higher PC20 than the Rosenthal Dosimeter.

Twelve nonsmoking subjects with mild asthma will be selected on the basis of > 18 years of age, a baseline FEV1 of > 60% predicted and a screening PC20 of < 8mg/ml. Subjects will be randomized to perform a methacholine challenge with the Digidoser and the Rosenthal Dosimeter on two different days in an unblinded, crossover manner. The geometric mean PC20 with each dosimeter will be compared with a paired t test. The results of this study will indicate whether the Digidoser has the potential of causing false negative test results or whether the ATS method of determining output should not be used with this dosimeter.

Study Type : Interventional  (Clinical Trial)
Enrollment : 12 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Study Start Date : September 2005
Actual Primary Completion Date : December 2005
Actual Study Completion Date : December 2005

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Asthma
U.S. FDA Resources

Primary Outcome Measures :
  1. Geometric mean PC20 methacholine for each dosimeter method.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Non-smoking male or female >18 years of age, with a previous diagnosis of asthma.
  • Women of child bearing age must not be pregnant or nursing and be using an acceptable method of contraception.
  • Screening FEV1 > 70% of predicted for height, age, sex, and race when bronchodilators are withheld for appropriate intervals.
  • At least a 20% decrease in FEV1 after inhaling ≤ 8 mg/ml of methacholine (i.e., a PC20 FEV1 ≤8 mg/ml) using the KoKo Digidoser system.
  • Ability to perform ATS-acceptable and reproducible spirometry.

Exclusion Criteria:

  • Cigarette smoking in past year or > 10 pack year smoking history.
  • Respiratory tract infection within the last four weeks.
  • History of severe asthma attack requiring hospitalization in the previous 12 months.
  • Short course of oral corticosteroids in the past 3 weeks.
  • Inability to withhold caffeinated beverages for 12 hours or medications for appropriate intervals prior to each methacholine challenge.
  • If female, a positive urine β-HCG test.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00145990

United States, Florida
University of Florida Asthma Research Lab
Gainesville, Florida, United States, 32610
Sponsors and Collaborators
University of Florida
Principal Investigator: Yasmeen Khan, MD University of Florida

Responsible Party: University of Florida Identifier: NCT00145990     History of Changes
Other Study ID Numbers: 257-2005
First Posted: September 5, 2005    Key Record Dates
Last Update Posted: March 5, 2012
Last Verified: March 2012

Keywords provided by University of Florida:
methacholine PC20

Additional relevant MeSH terms:
Methacholine Chloride
Autonomic Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Bronchoconstrictor Agents
Respiratory System Agents
Muscarinic Agonists
Cholinergic Agonists
Cholinergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action