Despite association with lung growth and long-term respiratory morbidity, there is a lack of normative lung function data for unsedated infants conforming to latest European Respiratory Society/American Thoracic Society standards.Lung function was measured using an ultrasonic flow meter in 342 unsedated, healthy, termborn infants at a mean¡SD age of 5.1¡0.8 weeks during natural sleep according to the latest standards. Tidal breathing flow-volume loops (TBFVL) and exhaled nitric oxide (eNO) measurements were obtained from 100 regular breaths. We aimed for three acceptable measurements for multiple-breath washout and 5-10 acceptable interruption resistance (Rint) measurements.Acceptable ) for Rint. In males, TBFVL outcomes were associated with anthropometric parameters and in females, with maternal smoking during pregnancy, maternal asthma and Caesarean section.This large normative data set in unsedated infants offers reference values for future research and particularly for studies where sedation may put infants at risk. Furthermore, it highlights the impact of maternal and environmental risk factors on neonatal lung function.

In cystic fibrosis (CF), tests for ventilation inhomogeneity are sensitive but not established for clinical routine. We assessed feasibility of a new double-tracer gas single-breath washout (SBW) in school-aged children with CF and control subjects, and compared SBW between groups and with multiple-breath nitrogen washout (MBNW).Three SBW and MBNW were performed in 118 children (66 with CF) using a side-stream ultrasonic flowmeter setup. The double-tracer gas containing 5% sulfur hexafluoride and 26.3% helium was applied during one tidal breath. Outcomes were SBW phase III slope (SIIIDTG), MBNWderived lung clearance index (LCI), and indices of acinar (Sacin) and conductive (Scond) ventilation inhomogeneity.SBW took significantly less time to perform than MBNW. SBW and MBNW were feasible in 109 (92.4%) and 98 (83.0%) children, respectively. SIIIDTG differed between children with CF and controls, mean¡SD was -456.7¡492.8 and -88.4¡129.1 mg?mol?L -1 , respectively. Abnormal SIIIDTG was present in 36 (59%) children with CF. SIIIDTG was associated with LCI (r5 -0.58) and Sacin (r5 -0.58), but not with Scond.In CF, steeply sloping SIIIDTG potentially reflects ventilation inhomogeneity near the acinus entrance. This tidal SBW is a promising test to assess ventilation inhomogeneity in an easy and fast way.

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Fractional exhaled nitric oxide monitoring revealed changes in FeNO prior to moderate exacerbations. Whether this can be used to prevent loss of asthma control should be further explored.