Pulmonary function in obese subjects with a normal FEV1/FVC ratio

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• Obesity is associated with various health complications, including potential respiratory issues.
• Understanding the respiratory profile of obese individuals without overt obstructive airway disease is crucial for early detection of lung dysfunction.

Purpose of the Study:

• To assess pulmonary function test (PFT) parameters and respiratory muscle strength (RMS) in obese males without diagnosed obstructive airway disease.
• To identify potential subgroups within this population exhibiting distinct respiratory characteristics.

Main Methods:

• Prospective study involving 63 obese male subjects (BMI > 27.8 kg/m2) with a normal FEV1/FVC ratio (>80%).
• Standard PFTs and measurements of maximum static inspiratory (PImax) and expiratory (PEmax) mouth pressures were conducted.
• Respiratory muscle strength (RMS) was calculated as (PImax+PEmax)/2. Subjects were categorized based on maximum voluntary ventilation (MVV).

Main Results:

• Obese subjects with low MVV (<80% predicted) demonstrated significantly lower inspiratory and expiratory flow rates, lung volumes, PImax, and RMS compared to those with normal MVV.
• The residual volume/total lung capacity (RV/TLC) ratio was significantly higher in the low MVV group.
• MVV showed significant correlations with multiple PFT parameters, most strongly with maximum inspiratory flow rate (MIFR).

Conclusions:

• Standard PFTs can identify a subgroup of obese individuals without overt obstructive airway disease who exhibit more severe lung dysfunction, marked by low MVV.
• Peripheral airway abnormalities are suggested as a potential cause for the observed lung dysfunction in this subgroup.