Determination of lung volume and hemodynamic changes during high-frequency ventilation recruitment in preterm neonates with respiratory distress syndrome

Objectives: To evaluate the changes in end-expiratory lung volume during an oxygenation-guided stepwise recruitment procedure in elective high-frequency ventilation. We hypothesized that high continuous distending pressure impedes pulmonary blood flow as evidenced by reduced lung volume measurements using respiratory inductive plethysmography. Changes in oxygenation, ventilation, and peripheral perfusion were evaluated as secondary outcomes. Design: A prospective, single center, observational, nonrandomized study. Setting: The study was conducted in a neonatal ICU in Italy. Patients: High-frequency ventilated preterm infants with respiratory distress syndrome. Interventions: During the recruitment procedure, end-expiratory lung volume measured by respiratory inductive plethysmography, oxygen saturation, perfusion index, regional cerebral and perirenal tissue oxygenation, heart rate, transcutaneous Pco2, and tidal volume were simultaneously recorded at each airway pressure step. Measurements and Main Results: In 12 preterm newborns (gestational age, 27.4 \ub1 0.2 wk; birth weight, 979 \ub1 198 g), highfrequency ventilation was initiated at a continuous distending pressure of 10 cm H2O and incrementally increased by 1-2 cm H2O every 2-5 minutes until Fio2 was less than or equal to 0.25. End-expiratory lung volume progressively increased during the initial recruitment, but decreased at the maximum airway pressure in nine patients, indicative of a reduction in pulmonary perfusion. At the end of recruitment, tidal volume was significantly higher (p = 0.002) and oxygenation was significantly improved (p = 0.002); however, mean perfusion index, postductal saturation, and mean renal tissue oxygenation values were significantly reduced (p < 0.05) compared with baseline. Mean cerebral tissue oxygenation and mean transcutaneous Pco2 values were reduced but failed to reach significance. Conclusions: High distending lung pressures increased oxygenation but decreased peripheral perfusion with no adverse cerebral side effects. Coupled with the reduction in respiratory inductive plethysmography-derived lung volume, high continuous distending pressure had adverse cardiopulmonary effects. Incorporation of lung volume and hemodynamic and oxygenation variables may guide optimum lung volume determination during high-frequency ventilation recruitment procedure while preventing adverse effects on the pulmonary circulation