Positive End-Expiratory Pressure (PEEP) Levels During Resuscitation of Preterm Infants at Birth (The POLAR Trial).

All infants born <29 weeks' postmenstrual age (PMA) require positive end-expiratory pressure (PEEP) at birth. PEEP is a simple, feasible and cost-effective therapy to support extremely preterm infants that is used globally. The effective and safe level of PEEP to use after preterm birth remains the most important unanswered question in neonatal respiratory medicine.

The Investigators will undertake an international multi-centre randomised controlled trial to address in extremely preterm infants, whether the use of a high, dynamic PEEP level strategy to support the lung during stabilisation ('resuscitation') at birth, compared to the current practice of a static PEEP level, will reduce the rate of death or bronchopulmonary dysplasia (BPD).

This trial will address the following four key knowledge gaps:

1. Assessing whether individualising (dynamic) PEEP is superior to static PEEP

2. The uncertainty regarding applied pressure strategies to support the lung during stabilisation at birth arising from the lack of a properly powered, well-designed randomised trial specifically addressing important outcomes for respiratory support in the Delivery Room

3. The optimal PEEP strategy to use

4. Determining the differential effects of PEEP at different gestational ages.

For this study, the term PEEP refers to the delivery of positive pressure (via a bias flow of gas) to the lungs during expiration by any method of assisted respiratory support, this includes:

1. Continuous Positive Applied Pressure (CPAP; a method of non-invasive respiratory support). During CPAP no other type of positive pressure is delivered as the infant supports tidal ventilation using her/his own spontaneous breathing effort. PEEP during CPAP has also been called 'continuous distending pressure.

2. Positive Pressure Ventilation (PPV). During PPV PEEP is delivered between periods of an applied inflating pressure (PIP) delivered at a clinician-determined rate. PPV can be delivered via a mask or other non-invasive interface (also termed non-invasive positive pressure ventilation; NIPPV), or via an endotracheal tube (often termed continuous mechanical ventilation; CMV).

3. High-frequency oscillatory ventilation (HFOV) or high-frequency jet ventilation. These are modes of invasive PPV in which PIP is delivered at very fast rates (>120 inflations per minute) and at very small tidal volumes. During HFOV a mean airway pressure is determined by the clinician which is equivalent to the PEEP during other modes. During high-frequency jet ventilation the clinician sets a PEEP similar to CMV.

As all of these modes of ventilation have a similar goal of applying a pressure to the lung during expiration (usually to prevent lung collapse) the term PEEP has the same physiological result despite different methods of application.

The specific aim of the trial is to establish whether the use of a high, dynamic 8-12 cmH2O PEEP level ('dynamic') strategy to support the lung during stabilisation at birth, compared with a static 5-6 cmH2O PEEP level ('static') strategy, increases the rate of survival without bronchopulmonary dysplasia (BPD) in extremely preterm infants born <29 weeks' PMA, and reduces rates of common neonatal morbidities.

The Investigators hypothesise that in preterm infants born <29 weeks PMA who receive respiratory support during stabilisation at birth, a high, dynamic PEEP strategy (i.e. PEEP 8-12 cmH2O individualised to clinical need) as compared to a standard, static PEEP of 5-6 cmH2O, will:

1. Increase survival without BPD (primary outcome); and

2. Reduce rates of common neonatal morbidities such as failure of non-invasive respiratory support in the first 72 hours of life (secondary outcome).

This trial is a phase III/IV, two parallel group, non-blinded, 1:1 randomised controlled, multi-national, multi-centre study comparing dynamic PEEP (dynamic group) with standard PEEP strategy (static group).

The intervention will take place in the Delivery Room. The intervention period will be from the time of birth until 20 minutes of life or transfer from Delivery Room to NICU (whatever comes first). The follow-up period will extend to 36 weeks PMA (primary endpoint), and 24 months corrected GA to determine important long-term neurodevelopmental and respiratory outcomes.

The clinical team within the Delivery Room managing enrolled and randomised infants will not be masked/blinded to the intervention. Clinicians need to be able to see the PEEP delivery device to assess efficacy of pressure delivery. The Research Coordinator/Study team at site will also not be masked/blinded to the intervention, as they will be entering trial data into the data management system.

Research staff based at the central Trial Coordinating Centre (TCC), the Data Coordinating Centre (DCCe) and the trial statistician will be blinded to assigned treatment.

There will be a total of 906 infants recruited (453 in the Dynamic group, 453 in the Static group), over 25 recruitment centres across Australia, Europe, the United Kingdom, the Middle East, Canada and North America.

The study will have Regional Coordinating Centres (RCCs) established in the following jurisdictions:

1. Australia - The Murdoch Children's Research Institute/Royal Women's Hospital, Melbourne, AUS

2. The Netherlands - Amsterdam University Medical Centre, Netherlands, EU

3. The United Kingdom - The University of Oxford / National Perinatal Epidemiology Unit (NPEU), Oxford, UK, and

4. North America - the Hospital of the University of Pennsylvania, Pennsylvania, USA.