Haemodynamic features during high-frequency oscillatory ventilation in preterms

Aim: To compare the haemodynamic status during high-frequency oscillatory ventilation and conventional mechanical ventilation in very preterm infants with respiratory distress syndrome. Methods: Thirty-two neonates of less than 30 wk gestation randomly assigned to high-frequency oscillatory ventilation ( n = 15) or conventional mechanical ventilation ( n = 17) had three echocardiographies and one cerebral Doppler-echography under the same ventilation during the first 48 h of life. Results: Mean airway pressure was 2 cm H2O higher in infants ventilated with high-frequency oscillatory ventilation at the different echocardiographies. Comparable right ventricular indexes were observed in the two groups. Reduction of the ductus arteriosus diameter and ductal closure were significant only in neonates ventilated conventionally. Left ventricular performance and left ventricular contractility did not differ between the groups. The high-frequency group had lower end diastolic velocity and a higher resistance index in the anterior cerebral artery. Conclusion: Compared with conventional mechanical ventilation, high-frequency oscillatory ventilation was achieved without altering cardiac function. However, the inability of the left ventricle to improve its performance in the presence of a significant ductal shunt suggests a narrow range of optimal pressures under this ventilatory mode.