[The impact of obesity on respiratory function]

Area of Science:

• Respiratory Medicine
• Obesity Research
• Pulmonary Physiology

Background:

• Obesity presents significant respiratory challenges, manifesting as both symptomatic breathlessness and functional pulmonary changes.
• Breathlessness is highly prevalent in obese adults, affecting approximately 50% at rest and 75% during exertion.

Purpose of the Study:

• To elucidate the multifaceted respiratory impacts of obesity, encompassing symptomatic and functional alterations.
• To investigate the specific changes in pulmonary function and bronchial responsiveness associated with obesity in adults and children.

Main Methods:

• Analysis of pulmonary function tests, including lung volumes (FRC, ERV, TLC, RV) and airflows.
• Assessment of bronchial hyperresponsiveness (BHR) and its potential link to obesity-induced mechanical changes.
• Evaluation of resting and exercise oxygen consumption (V'O2) and the oxygen cost of ventilation.

Main Results:

• Obese adults exhibit reduced functional residual capacity (FRC) and expiratory reserve volume (ERV), with a minority showing restrictive lung defects.
• Bronchial hyperresponsiveness (BHR) is prevalent in obesity, potentially due to impaired deep inspiration mechanics.
• Children display reduced TLC, FRC, and RV, leading to decreased FEV1/FVC ratios (dysanaptic growth) without true airflow obstruction.

Conclusions:

• Obesity induces distinct respiratory functional and symptomatic changes in adults and children, with varying effects on lung volumes and mechanics.
• While airflow is generally preserved, increased respiratory load and BHR contribute to dyspnea in obese individuals.
• The correlation between exercise dyspnea and objective respiratory function abnormalities in obesity remains limited, suggesting complex pathophysiological interactions.