eNO measurement
THORACIC
eNO measurement was performed during unsedated, behaviourally defined quiet sleep. Infants were tested in the supine position, with infant sized masks (sizes 0, 0/1 and 1; Homedica AG, Huenenberg, Switzerland), according to the European Respiratory Society (ERS)/American Thoracic Society (ATS) standards for infant eNO measurement [