Ventilated neonates frequently require supplementary oxygen to allow for adequate oxygen delivery to the tissues and normal cell metabolism. Oxygen treatment should be monitored carefully as both excessive and inadequate dosing can have detrimental effects for the infants. Hypoxia (giving too little oxygen) increases mortality and later disability whereas hyperoxia (giving too much oxygen) increases the risk of complications such as retinopathy of prematurity and lung disease. Although very preterm and low birth weight infants represent the majority of ventilated neonates, more mature infants may also require mechanical ventilation at birth and provision of supplementary oxygen. Therefore, they may suffer from complications related to hypoxia or hyperoxia. Hence, their oxygen saturation levels and the amount of the inspired oxygen concentration provided should be continuously monitored.

Oxygen control is traditionally monitored and adjusted manually by the nurse looking after the infant. Closed-loop automated oxygen control (CLAC) is a more recent approach that involves the use of a computer software incorporated into the ventilator. 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, decreases the duration of hypoxia and hyperoxia and reduces the number of manual adjustments required by clinical staff. However previous studies have been limited to very small infants. With this study the investigators aim to evaluate the effectiveness of CLAC in ventilated infants born at 34 weeks gestation and beyond. The achievement of oxygen saturation targets and the number of manual adjustments required will be compared between periods of CLAC and manual control in a cohort of patients that has not been included in previous studies and could also benefit from the intervention. The investigators will also evaluate if CLAC reduces investigations performed to ventilated babies(blood gases, X-rays).

This will be a randomised controlled crossover study. The investigators aim to recruit a minimum of 31 ventilated infants born at 34 weeks completed gestation and above and admitted to the Neonatal Intensive Care Unit at King's College Hospital over one year. Participants will undergo two monitoring periods each lasting 12 hours (8:00am-20:00pm): one with standard manually controlled oxygen and one with closed-loop automated oxygen control. Randomisation will be used to determine whether the first period will be manual or closed-loop automated oxygen control. The two monitoring periods will take place on two consecutive days to allow for clinical conditions to remain as stable as possible.

Infants with known congenital cyanotic heart disease will be excluded from the study as well as those undergoing surgery or any planned procedures during the monitoring period.

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

Randomisation of eligible infants whose parents consent to the study will be performed using an online randomisation generator to determine whether the first monitoring period will be manual adjustment or closed-loop automated oxygen control ("intervention" period).

Patients will be ventilated using SLE6000 ventilators. Ventilation settings will be manually adjusted by the clinical team as per unit's protocol. During the intervention period, in addition to standard care, infants 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 including the period of automated oxygen control if deemed appropriate by the clinical team. Oxygen saturation levels and automatic adjustments to the inspired oxygen concentration will be captured by the ventilator software. Manual adjustments will be recorded during both monitoring periods. In addition to data collected from the ventilator, medical notes will be reviewed to determine any adverse events or clinical interventions to participants during the study. The number of blood gas samples taken and chest radiographs performed during each monitoring period will also be recorded.

Inclusion Criteria:

• Infants born at 34 weeks completed gestation and above requiring mechanical ventilation and admitted to King's NICU
• Any gender, ethnicity or other comorbidities

Exclusion Criteria:

• Preterm infants less than 34 weeks gestation
• Infants with cyanotic congenital heart disease
• Infants undergoing planned procedures or surgery during the monitoring period
• Infants on high frequency oscillatory ventilation (HFOV)

This will be a randomised controlled crossover study. We aim to recruit a minimum of 31 ventilated infants born at 34 weeks completed gestation and above and admitted to the Neonatal Intensive Care Unit at our hospital over one year.