Expiratory Airflow Limitation in Subjects With Obesity (EFL)

July 13, 2009 updated by: Medical Center Alkmaar

Obesity and Expiratory Flow Limitation (EFL)

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.

Study Overview

Status

Unknown

Conditions

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

Enrollment (Anticipated)

30

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

25 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Healty volunteers

Description

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)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Control
  • Time Perspectives: Cross-Sectional

Cohorts and Interventions

Group / Cohort
Obesity
Subjects with obesity, defined as BMI > 30, aged 25-60
Control
Subjects with a BMI 18,5-25, aged 25-60

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The difference in mean values of FEF25-75/FVC between subjects with obesity and controls in supine position
Time Frame: 6 months
6 months

Secondary Outcome Measures

Outcome Measure
Time Frame
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
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical Center Alkmaar

Investigators

  • Study Director: J. G. van den Aardweg, Medical Center Alkmaar

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

July 1, 2008

Study Registration Dates

First Submitted

March 18, 2009

First Submitted That Met QC Criteria

March 18, 2009

First Posted (Estimate)

March 19, 2009

Study Record Updates

Last Update Posted (Estimate)

July 14, 2009

Last Update Submitted That Met QC Criteria

July 13, 2009

Last Verified

July 1, 2009

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Obesity MCA 2009

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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