[Obesity in childhood: What are the respiratory risks?]

In childhood and adolescence overweight is defined as a body mass index (BMI) above the 97th percentile for age and sex, according to the curves established by the International Obesity Task Force (IOTF). In France, it is estimated that 25 % of children under 18 years old are overweight. Overweight and obesity in this population are multifactorial, with an important influence of genetic factors, modulated by pre and post-natal (maternal smoking), societal and psychological determinants. The impact of obesity on respiratory function in children is mostly characterized by a decreased FEV1/FCV. Moreover, several studies have shown an association between asthma and overweight/obesity, with a pejorative impact of BMI on asthma control. However, asthma is still poorly characterized in this population, and the determinants of bronchial obstruction seem to differ from non-obese children, with less eosinophilic inflammation. Obstructive sleep apnea syndrome (OSAS) is a frequent complication of obesity, affecting up to 80% of obese children and adolescents. It has a specific polysomnographic definition in children. Symptoms are similar to adult OSAS, but with cognitive and neurobehavioral alterations often more important in adolescents. The treatment consists in ENT surgery when indicated (with systematic post-operative polysomnography), and nocturnal continuous positive airway pressure (CPAP). The obesity-hypoventilation syndrome (OHS) has the same definition in children as in adults and affects up to 20% of obese patients. Treatment consists in nocturnal ventilation using bilevel positive airway pressure (BiPAP). Finally, in some extreme cases, bariatric surgery can be performed. The indication should be discussed in a specialised paediatric reference centre.