Intravenous dobutamine will be administered at a dose of 5 mcg/kg/min. Weaning and stopping of the dobutamine infusion will be determined by the attending physician, following local policies.

Intravenous dobutamine will be administered at a dose of 7.5 mcg/kg/min. Weaning and stopping of the dobutamine infusion will be determined by the attending physician, following local policies.

Intravenous dobutamine will be administered at a dose of 10 mcg/kg/min. Weaning and stopping of the dobutamine infusion will be determined by the attending physician, following local policies.

Intravenous dobutamine will be administered at a dose of 12.5 mcg/kg/min. Weaning and stopping of the dobutamine infusion will be determined by the attending physician, following local policies.

Intravenous dobutamine will be administered at a dose of 5 mcg/kg/min.

Short-term pharmacodynamics (PD) endpoint: Minimum dobutamine dose to reach and maintain a superior vena cava (SVC) flow above 55 ml/kg/min on an echocardiogram performed at 1 and 3 hours after effective infusion of the allocated dose.

The effective start of the infusion (t0) will be calculated as the time at which the infusion pump is switched on plus the empirical value for the interval arising from the dead space. We summarize t0 as "the time at which dobutamine is expected to reach the circulation"

Proportion of neonates achieving and maintaining a clinically acceptable haemodynamic status with the dobutamine infusion alone in the first 72 hours from birth.

Acceptable hemodynamic status is defined as the achievement and maintenance of dose success during the first 72 h from birth. The loss of such acceptable haemodynamic status occurs whenever there is a change in therapeutic strategy that involves cardiovascular treatment other than dobutamine alone due to exceeded safety parameters, treatment failure of the investigational infusion or the need for rescue treatment or death; any additional fluid bolus is considered as cardiovascular treatment.