Effect of Body Position on Spirometry in Abdominal Obesity.

Completed

Conditions studied: Obesity, Abdominal

In brief

Objective: Study the effect of body position on spirometry in obese patients as defined by waist to hip ratio (WHR) of greater than 0.85 in women, and 0.9 in men Background: Spirometry is routinely ordered to work up dyspnea in obesity. The most common abnormality is a restrictive disease pattern. The underlying mechanisms of this pattern are not completely understood. One plausible explanation is diaphragmatic weakness or skeletal muscle weakness. The change in forced vital capacity (FVC) from sitting to supine is a very sensitive and specific test for detecting diaphragmatic weakness. The effect of body position on spirometry in obesity has not been extensively studied, and there are no studies that look at this when obesity is measured by waist to hip ratio. Effect of body position has been studied in normal patients, and it is expected the FVC can decrease as much as 10% when changing from sitting to supine. The investigators do not know what would be considered 'the normal' amount for FVC to decrease by in the obese population, and thus would like to test patients with increased WHR both in sitting and supine position. The investigators also want to do muscle strength test by measuring the maximal inspiratory and expiratory pressures (MIPs and MEPs). Anticipated results: the investigators anticipate that our study population will replicate the restrictive disease pattern usually seen in obesity. The investigators also anticipate for the FVC to decrease when in the supine position compared to sitting. The amount by which it decreases will likely fall between 10 -25%. The investigators anticipate to not find any abnormalities in MIPs and MEPs in obesity.

Key facts

Study ID

NCT03347604

Run by

Rush University Medical Center

People needed

30

Starts

2017-10-06

Expected to finish

2018-12-30

Last updated by the study team

2019-07-08

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Individuals of both genders, age of 18 years or older
• Individuals with abdominal obesity with WHR > 0.85 in women, > 0.9 in men
• Ability of patients to transfer themselves into a cardiac chair
• Able to understand and comply with testing instructions

You may not qualify if…

• Patients who are less than 18 years old
• Patients who are unable to perform an acceptable and repeatable forced vital capacity
• Airflow limitation as evidenced by sitting FEV1/VC < lower limit of normal
• Patients who have a WHR < 0.85 in women, or < 0.9 in men
• Patients who become lightheaded during sitting spirometry
• Patients who cannot transfer themselves independently to a cardiac chair
• History of lung disease (known obstructive or restrictive lung disease)
• Chest wall abnormalities or kyphoscoliosis
• Neuromuscular disease
• Active hemoptysis or recent angina

Where it is running

• Rush University Medical Center — Chicago, Illinois, United States

Full record on ClinicalTrials.gov

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