Lung function measurements in children - copsac

Children less than 7 years were tested with dry air hyperventilation as previously
described and validated in this age-group (18, 36, 132).
Fractional exhaled nitric oxide
Fractional exhaled nitric oxide (F E NO) was measured by the online single breath
method according to European Respiratory Society/American Thoracic Society task
force (40) using the NIOX equipment (Nitric Oxide Monitoring System; Aerocrine,
Sweden).
Study III:
Lung function measurement in neonates
Lung function was assessed during sedation by infant spirometry at 1 month applying
the raised volume rapid thoracic compression technique (RVRTC). The method,
equipment, data collection and analysis was performed in agreement with ATS/ERS
standards (2). Equipment was calibrated and tested prior to every lung function test. An
inflatable “squeeze”-jacket was wrapped around the infant's chest and abdomen. A
subsequent inflation of the jacket provided the passive expiration and flow was
measured using a pneumotachograph with an aircushion facemask (123, 133, 134). The
infant was administered three inflations reaching a transrespiratory pressure of 2 kPa
with passive deflations between each. A compression force transmitting an additional
pressure of 2 kPa was then applied via the squeeze-jacket to the thorax and abdomen,
leading to an airway opening of pressure of 4 kPa for forced expirations. Baseline flow
was measured as the Forced Expiratory Volume at the first 0.5 second (FEV 0.5 ) (123,
133). Other parameters not reported in this thesis comprised FVC, forced expiratory
flow at 25% of FVC (FEF 25 ), forced expiratory flow at 50% of FVC (FEF 50 ) and forced
expiratory flow at 75% of FVC (FEF 75 ). All parameters were measured five times at
baseline and three times at each challenge step, using the median value for FEV 0.5 to
decide on the continued provocation. Tidal flow was also measured but not reported in
this thesis; indexes comprised tidal volume (V T ), respiratory frequency, peak tidal
expiratory flow (PTEF), expiratory time as ratio of respiratory cycle time, time to reach
PTEF (T PTEF ), and T PTEF /expiratory time ratio (T PTEF /T E ) (123, 133).
The software defined FVC as the first plateau on the volume-time curve, and only
measurements with FVC appearing after 0.5 seconds, and with FEV 0.5 being smaller
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