Respiratory distress syndrome of prematurity (RDSP) is an acute respiratory condition that occurs in preterm infants due to pulmonary surfactant deficiency.

Exogenous surfactant administration is a crucial therapeutic measure in the management of RDSP, being the 'less invasive surfactant administration technique' (LISA) the gold standard, according to the latest reviews.

Oximetry based on near-infrared spectroscopy is a non-invasive monitoring modality that provides continuous information on the degree of regional hemoglobin saturation present in the underlying tissue, mainly in the venous compartment. It is thus, a reflection of the balance between oxygen supply and demand of oxygen to the tissues.

We intend to perform a prospective analysis of newborns under 32 weeks of gestational age who require surfactant administration, as we wish to study cerebral and renal perfusion by oximetry in the group of patients who receive surfactant by LISA and in the group of patients who receive surfactant via endotracheal tube (patients intubated at birth for stabilization), since there are few data published in the literature.

Our main hypothesis is that the administration of surfactant by LISA technique does not negatively influence cerebral and renal oximetry.

Our secondary hypothesis is that patients requiring intubation at birth will present greater hemodynamic and respiratory instability in the first 72 hours of life, with a greater decrease in cerebral and renal oximetry with the administration of surfactant, compared to the group that does not require intubation at birth.

Inclusion Criteria:

• preterm infants less than 32 weeks gestational age requiring surfactant administration

Exclusion Criteria:

• major congenital malformations
• chromosomopathies

Patients less than 32 weeks gestational age born in our center (Hospital General Universitario Gregorio Marañon) who require surfactant administration will be included