Lung ultrasound procedure
LUNG
LU will be performed by the attending neonatologist. Centers participating in the study routinely use LU and all the neonatologists are trained for this technique.LUS will be calculated by performing bilateral longitudinal scans of the chest on the midclavicular, anterior axillary, and posterior axillary line as proposed by Raimondi et al. [Lung ultrasound score chest partitioningLung ultrasound area score. Lung ultrasound score for each area is attributed according to the following criteria: 0, A-pattern (defined by the presence of only A-lines; panel LU can be performed with the patient in supine position without the need of turning as the posterior axillary line is accessible from the side of the newborn [Surfactant replacement therapy should be given if LUS > 8 in subjects recruited in the LUSG.