Expiratory Airflow Limitation in Subjects With Obesity (EFL)

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: NCT00865293
Recruitment Status : Unknown
Verified July 2009 by Medical Center Alkmaar.
Recruitment status was:  Active, not recruiting
First Posted : March 19, 2009
Last Update Posted : July 14, 2009
Information provided by:
Medical Center Alkmaar

Brief Summary:
The purpose of this study is to investigate posture dependent small airway obstruction in subjects with obesity, and to study the capacity of FOT as a measurement tool for small airways obstruction.

Condition or disease

Detailed Description:

Obesity is a cause of dyspnea due to mechanical impairment of pulmonary ventilation. One of the causes of this impairment is expiratory flow limitation, which is related to decreased lung volume. As a result, obesity can cause an asthma-like symptoms. Therefore, some patients with obesity are misdiagnosed as asthma-patients, and treated with asthma medication. The effects of bronchodilators on the mechanical airway obstruction in obese subjects have not been well established.

Posture also has effect on lung volumes: they are decreased in supine position. Therefore, the interaction of obesity and supine posture might result in a larger decrease in lung volumes, and thereby a more increased airflow limitation. It has been suggested that both obesity and supine posture result in an obstruction of peripheral airways. Such an obstruction can be measured by spirometry, using the ratio of forced expiratory flow between 25 and 75% and vital capacity. This measure is highly variable, however.

The forced oscillation technique (FOT) is a non-invasive method to measure the resistance and reactant of the respiratory system. Particularly the reactance has been shown useful in the measurement of airflow limitations.

The investigators hypothesize that obesity causes a posture dependent end- expiratory airflow limitation due to a mechanical compression of lung tissue, resulting in increased resistance and reactance in the airways. Therefore, the investigators expect no protective effect of bronchodilation by salbutamol. The investigators expect that reactance measured by FOT detects differences in airflow limitation and correlates with airflow limitation as measured by spirometry.

Study Type : Observational
Estimated Enrollment : 30 participants
Observational Model: Case Control
Time Perspective: Cross-Sectional
Official Title: Obesity and Expiratory Flow Limitation (EFL)
Study Start Date : July 2008

Subjects with obesity, defined as BMI > 30, aged 25-60
Subjects with a BMI 18,5-25, aged 25-60

Primary Outcome Measures :
  1. The difference in mean values of FEF25-75/FVC between subjects with obesity and controls in supine position [ Time Frame: 6 months ]

Secondary Outcome Measures :
  1. The capacity of FOT as a measurement tool for small airways obstruction. The effects of posture and obesity on lung volumes, diffusion capacity, air flow limitation. The effect of bronchodilation by salbutamol on posture dependent flow limitation. [ Time Frame: 6 months ]

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Ages Eligible for Study:   25 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
Healty volunteers

Inclusion Criteria obese population:

  • Male/female, age 25-60
  • BMI (body mass index) 30-40 kg/m2
  • Non or ex smokers with < 10 packyears

Inclusion Criteria control population:

  • Male/female, age 25-60
  • BMI (body mass index) 18.5-25 kg/m2
  • Non or ex smokers with <10 packyears

Exclusion Criteria obese population:

  • Asthma
  • COPD (FEV1/FVC<0.70)
  • Reversibility >9% in FEV1 (400 microgram salbutamol)
  • Other significant neuromuscular, cardiac or lung disease

Exclusion Criteria control population:

  • Asthma
  • COPD (FEV1/FVC<0.70)
  • Other significant neuromuscular, cardiac or lung disease
  • Reversibility >9% in FEV1 (400 microgram salbutamol)

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): NCT00865293

Sponsors and Collaborators
Medical Center Alkmaar
Study Director: J. G. van den Aardweg Medical Center Alkmaar

Responsible Party: Dr. J.G. van den Aardweg, Medical Center Alkmaar Identifier: NCT00865293     History of Changes
Other Study ID Numbers: Obesity MCA 2009
First Posted: March 19, 2009    Key Record Dates
Last Update Posted: July 14, 2009
Last Verified: July 2009

Keywords provided by Medical Center Alkmaar:
expiratory flow limitation
small airways obstruction

Additional relevant MeSH terms:
Nutrition Disorders
Body Weight
Signs and Symptoms