Substudy 001B is not required at this stage of the PIP

Haemodynamic insufficiency after birth is seen commonly in babies born prematurely and is associated with adverse outcomes. In current clinical practice, a combination of blood pressure and clinical signs is used to guide therapy. However, blood pressure is a poor surrogate of systemic and organ (brain) blood flow distribution during transitional circulation. This state is characterised by increased peripheral vascular resistance and increased afterload causing myocardial depression and impaired blood flow distribution in spite of 'normal' blood pressure. Echocardiography-Doppler (Echo-D) measurement of superior vena cava (SVC) flow has been proposed as a more clinically relevant marker of circulatory impairment shortly after birth than systemic hypotension. When there is low SVC flow, several small-scale clinical trials have suggested dobutamine as the optimal therapeutic option. However the associations between SVC flow and short- and long- term outcomes are not strong enough to allow SVC flow alone to be the basis for the inclusion of patients into a confirmatory trial to demonstrate the efficacy and safety of dobutamine.

NeoCirc-001 - The primary objective is to answer some important questions required for the design of a subsequent placebo-controlled trial (NeoCirc-003), which will evaluate the effectiveness of a new neonatal formulation of dobutamine to treat haemodynamic insufficiency in the first 72 hours after birth in babies born at less than 33 weeks' gestation. Observational data will be collected from this population with a view to determining the degree to which diagnostic measures influence treatment decisions. The primary outcome is death or worst cranial ultrasound (CUS) appearance at or before 36 weeks' gestation.

NeoCirc-001A - The primary objective is to estimate the elimination half-life, and consequently the time to steady-state of dobutamine in extremely premature neonates.

NeoCirc-001B - The primary objective is to construct a population pharmacokinetic pharmacodynamic model that will be validated using samples collected during the confirmatory trial (NeoCirc-003).

Inclusion criteria for NeoCirc-001, 001A and 001B -

Target population for informed consent:

• neonates 24 to 32+6 weeks´ gestation,
• postnatal age <72 hours;

Infants eligible for circulatory failure pathway:

• parental informed consent obtained;
• The infants will be assessed, as per routine clinical practice, for clinical signs indicating infants at risk of poor perfusion, and will be recruited if they develop haemodynamic insufficiency defined as: either two or more of: (i) Mean blood pressure (MBP) < gestational age (GA)-1 mmHg (invasive/non-invasive, two readings 15 min apart); (ii) SVC flow < 51 ml/kg/min; (iii) capillary refill time (CRT) > 4 sec; (iv) Lactate > 4 mmol/l (v) Base excess <-9 mmol/l or: MBP < GA -5 mmHg (invasive/non-invasive, two readings 15 min apart)

Exclusion Criteria: NeoCirc-001, 001A and 001B -

• non-viability;
• congenital hydrops or malformations likely to affect cardiovascular adaptation;
• surgery planned within 72 hours of birth;
• chromosomal anomalies;
• informed consent form (ICF) not signed.