[Hemodynamic effects of high-frequency oscillating ventilation in preterm and term infants]

To study the effects of high frequency oscillating ventilation (HFOV) on cerebral and abdominal circulation we measured blood flow velocities in three cerebral arteries and in the A. mesenterica superior by pulsed doppler ultrasound in 13 preterm (mean gestational age 28 weeks [25-31]) and 3 term infants during conventional ventilation (intermitted positive pressure ventilation, IPPV) and HFOV. In the preterm infants systolic blood flow velocities decreased under HFOV in all cerebral arteries. Statistically significant differences were found in the A. cerebri anterior (45.8 cm/s [sd +/- 20.6] versus 34.3 [sd +/- 10.8]; p < 0.02) and in the A. basilaris (52.8 cm/s [sd +/- 26.4] versus 44.1 [sd +/- 18.7]; p < 0.05). There was also a distinct decrease of systolic blood flow velocity in the A. mesenterica (111 cm/s [ +/- 31.3] versus 61.8 cm/s [sd +/- 18.6]; p < 0.002). The enddiastolic blood flow velocity and the Resistance Index of Pourcelot did not change significantly. The systemic blood pressure did not change during conventional ventilation or HFOV. Mean airway pressure and pCO2 were lower during HFOV, but there was not strong correlation with the reduction of flow velocities in the studied arteries (r = 0.48). In the three term infants presenting with a persistent pulmonary hypertension of the newborn, there was an increase in systolic and enddiastolic flow velocities in all studied arteries under HFOV.