Expiratory Airflow Limitation in Subjects With Obesity

NCT ID: NCT00865293

Last Updated: 2009-07-14

Basic Information

• Recruitment Status: UNKNOWN
• Total Enrollment: 30 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2008-07-31

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.

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.

Conditions

Obesity

Study Design

• Observational Model Type: CASE_CONTROL
• Study Time Perspective: CROSS_SECTIONAL

Study Groups

Obesity

Subjects with obesity, defined as BMI \> 30, aged 25-60

No interventions assigned to this group

Control

Subjects with a BMI 18,5-25, aged 25-60

No interventions assigned to this group

Eligibility Criteria

Inclusion Criteria

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

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

Exclusion Criteria

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

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

• Minimum Eligible Age: 25 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Medical Center Alkmaar

OTHER

Sponsor Role: lead

Responsible Party

Medical Center Alkmaar

Principal Investigators

J. G. van den Aardweg

Role: STUDY_DIRECTOR

Medical Center Alkmaar

Other Identifiers

Obesity MCA 2009

Identifier Type: -

Identifier Source: org_study_id