Data material will be stored on a separate computer in a sheltered home Directory. All data will be anonymous. Edi signals are transported from Servo-I ventilator with neural access through a communication port to a personal computer.Respiratory parameters will be stored in Picis (High Performance Hospital Information System). For the Statistical analyzes a T-test will be carried out, and data from the pilot study will decide the power to see whether we reject or retain the 0 hypothesis: " There are no changes in the preterm infants respiratory effort in transition from CPAP to HFNC".