Experimental nociceptive stimulation of the fetus and neonate induces pulmonary artery vasoconstriction. The investigators assessed whether echocardiography for Ductus arteriosus screening may generate this hemodynamic response and whether postural support would be able to modulate it.

Study design

Prospective, single center, randomized study in less than 29 weeks of gestation neonates, with a post natal age < 48 hours, and requiring invasive mechanical ventilation.

Crossover design with order of echocardiographies determined by computer randomization: in one group ultrasounds are performed with postural support, than standard conditions, in the other, ultrasounds are performed in standard conditions than with postural support.

The objective of the study is to assess the ratio of the acceleration time/ejection time of pulmonary arterial flow.

The others objectives are to assess echocardiographic-Doppler features (ductus arteriosus shunt pattern, pulmonary flow pattern, estimated systolic pulmonary arterial pressure, right and left ventricular functions using tissue Doppler imaging and speckle-tracking echocardiography), pain assessment with a clinical scale and heart rate variability analysis.

Inclusion Criteria:

• Newborn than 30 weeks of gestation neonates,
• Newborn with a post natal age < 48 hours,
• Newborn requiring invasive mechanical ventilation.
• Signed consent form of parent

Exclusion Criteria:

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