INTRODUCTION
Obesity and asthma commonly co-exist in children and obesity is related to more severe asthma as well as deteriorated spirometric indices such as FEV11, 2. Cottrell et al have reported that asthma prevalence shows a parallel increase with body mass index (BMI) indices3. Moreover, a prospective study in school age children demonstrated that asthma prevalence increases with obesity4. There are many theories that explain this co-existence; mechanical influences of obesity on the airway as depicted by the decreased FEV1 as mentioned above, chronic inflammation due to increased leptin and oxidative stress in obesity, hormonal changes such as decreased progesterone leading to blunted beta-2 receptor response in obese individuals and co-morbid conditions such as obesity5.
Impulse oscillometry (IOS) is a method that allows passive measurement of the airway mechanics of the airways by using sound waves. The technique does not require cooperation and the measurements are taken during tidal breathing. Airway resistance at different sound frequencies measure different parts of the airway. Measurements at low frequencies reflects both the central and peripheral airways while measurement at higher frequencies reflect the larger airways thus allowing prediction of the resistance and reactance of the small airways which are known to be primary area of involvement in asthma6, 7.
The aim of this study was to compare airway resistance between normal weight and overweight/obese children using IOS.