Work of breathing in children with diffuse parenchymal lung disease.

Respiratory mechanics have been poorly studied in children with chronic diffuse parenchymal lung disease (DPLD). The aim of the study was to assess the usefulness of respiratory mechanics to monitor lung function alteration in children with DPLD. Respiratory mechanics, total (WOBt), elastic (WOBe) and resistive (WOBr) work of breathing, gas exchange, lung function and respiratory muscle strength were measured in 10 children, aged 1.8-18.4 years old, who were followed in our national reference centre. Mean tidal volume (Vt) was normal (11±4mL/kg) but respiratory rate (fr, 32±19breaths/min), fr/Vt (118±75breaths/min/L) and total lung resistance (10.2±4.8cmH2OL(-1)s) were increased. Mean WOBt was increased mainly due to WOBe. Dynamic lung compliance (Cldyn) was severely reduced (26±24mL/cmH2O). Cldyn and the oesophageal pressure-time product strongly correlated with vital capacity and functional residual capacity. Respiratory muscle strength was within the normal range. In conclusion, lung mechanics may be considered as useful complementary or alternative markers of functional abnormalities in children with DPLD.