Objective. To assess volume guarantee (VG) ventilation combined with high-frequency oscillatory ventilation (HFOV) strategy\r\non PaCO2 regulation in an experimental model of neonatal distress syndrome. Methods. Six 2-day-old piglets weighing 2.57 �±\r\n0.26 kg were used for this interventional experimental study. Animals were ventilated during physiologic lung conditions and after\r\ndepletion of lung surfactant by bronchoalveolar lavage (BAL). The effect of HFOV combined with VG on PaCO2 was evaluated at\r\ndifferent high-frequency expired tidal volume (VThf) at constant frequency (fr) and mean airway pressure (mPaw). Fluctuations\r\nof the pressure (?Phf) around themPaw and PaCO2 were analyzed before and after lung surfactant depletion. Results. PaCO2 levels\r\nwere inversely proportional toVThf. In the physiological lung condition, an increase inVThf caused a significant decrease in PaCO2\r\nand an increase in ?Phf. After BAL, PaCO2 did not change as compared with pre-BAL situation as the VThf remained constant by\r\nthe ventilator. Conclusions. In this animal model, using HFOV combined with VG, changes in the VThf settings induced significant\r\nmodifications in PaCO2. After changing the lung condition by depletion of surfactant, PaCO2 remained unchanged, as the VThf\r\nsetting was maintained constant by modifications in the ?Phf done by the ventilator.
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