Effect of CPAP on respiratory mechanics in obese children.

<bold>Background:</bold> Continuous positive airway pressure (CPAP) support can be used in obese patients with respiratory failure to compensate for the increased mechanical load on the respiratory system and the decreased lung volumes. <bold>Aim:</bold> To assess how CPAP affects respiratory mechanics in obese children. <bold>Methods:</bold> Children were recruited (BMI z-score ≥1) from our outpatient clinic in obesity. Intrabreath oscillometry (IB-Osc) was performed at CPAP levels of 0, 5 and 10 cmH2O in sitting and supine positions using a custom-made setup. From the 10-Hz IB-Osc data resistance (R) and reactance (X) at end-expiration (ReE and XeE) and end-inspiration (ReI and XeI), and the corresponding tidal differences (deltaR and deltaX) were estimated. The effects of body position and CPAP level on the IB-Osc measures were assessed (fig.1). <bold>Results:</bold> Of the 43 children enrolled, 34 (17 boys; age:11.6±3.2 yrs; BMI Z-score: 2.3±0.3) had successful measurements in both positions. In general, lung mechanics were worse in supine position and improved with each CPAP level significantly. ReE and XeE were the most sensitive to changes in pressure, although with great inter-individual differences. <bold>Conclusions:</bold> Oscillometry during CPAP support is feasible in children. The IB-Osc measures are good indicators of position and the improvement in lung mechanics with pressure support. The clinical significance of the data regarding the indication of long-term ventilation needs further research. <fig><object-id>erj;64/suppl_68/OA4660/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>