Many premature infants require respiratory support in the newborn period. Mechanical ventilation although life-saving is linked to complications for the lungs and other organs and its duration should be kept to a minimum. The use of supplemental oxygen may also increase the risk of comorbidities such as retinopathy of prematurity. Therefore, oxygen saturation levels and the amount of inspired oxygen concentration provided should be continuously monitored.

Oxygen control can be performed manually or with the use of a computer software incorporated into the ventilator that is called 'closed loop automated oxygen control'(CLAC). The software uses an algorithm that automatically adjusts the amount of inspired oxygen to maintain oxygen saturation levels in a target range. Evidence suggests that CLAC increases the time spent in the desired oxygen target range but there are no data to determine the effect on important clinical outcomes. A previous study has also demonstrated that CLAC reduces the inspired oxygen concentration more rapidly when compared to manual control. That could help infants come off the ventilator sooner.

With this study we want to compare the time preterm infants spend on the ventilator when we use the software to automatically monitor their oxygen levels with those infants whose oxygen is adjusted manually by the clinical team. That could help us understand if the use of automated oxygen control reduces the duration of mechanical ventilation and subsequently the complications related to it.

This will be a randomised controlled trial. The investigators aim to recruit a minimum of seventy premature ventilated infants born at less than 31 weeks gestation. Participants will be randomised to either closed-loop automated oxygen control or manually controlled oxygen from recruitment to successful extubation. The investigators will also record basic epidemiologic parameters and associated comorbidities that may impact on the duration of mechanical ventilation. Infants with known congenital anomalies will be excluded from the study.

Informed written consent will be requested from the parents or legal guardians of the infants and the attending Neonatal Consultant will be requested to assent to the study.

Eligible infants whose parents consent to the study will be enrolled within 48 hours of initiation of mechanical ventilation.

Randomisation will be performed using an online randomisation generator. Patients will be ventilated using SLE6000 ventilators. Ventilation settings will be manually adjusted by the clinical team as per unit's protocol. The intervention group, in addition to standard care will be also connected to the OxyGenie closed-loop oxygen saturation monitoring software (SLE). This software uses oxygen saturations from the SpO2 probe attached to the neonate, fed into an algorithm, to automatically adjust the percentage of inspired oxygen to maintain oxygen saturations within the target range. Manual adjustments including the percentage of FiO2 will be allowed at any point during the study if deemed appropriate by the clinical team.

The nurse-to-patient ratio will be according to the unit's protocol that is determined on the patient's acuity.

Patients will be studied from enrolment until successful extubation. If an infant fails extubation and requires reintubation within 48 hours, he will be studied in his initial arm if less than 28 days old. Therefore, for those infants randomised at the intervention group CLAC will resume. Preterm infants that remain ventilated beyond day 28 of life will continue at their study arm (closed-loop automated oxygen control or manual oxygen control) till their first extubation attempt.

Inclusion Criteria:

• Preterm infants less than 31 weeks completed gestation at birth requiring mechanical ventilation and admitted to King's NICU in the first 48 hours after birth

Exclusion Criteria:

• Preterm infants above 31 weeks completed gestation or term born infants
• Infants with major congenital abnormalities