Background High frequency oscillatory ventilation (HFOV) theorically limits baro/volutrauma using subdeadspace volumes but lack of direct control over tidal volume resulting in fluctuating PCO2 level. Volume guarantee plus high-frequency oscillatory ventilation (HFOV+VG) is a new ventilation mode allows the clinician to set a mean tidal volume to be delivered.
Method The randomised, crossover study was conducted at the Neonatal Intensive Care Unit (NICU) at Dokuz Eylul University Hospital in Izmir, Turkey after approval of the local Ethics Committee. Inborn infants at less than 32 weeks of gestation with respiratory distress syndrome (RDS) were enrolled in the study if they required mechanical ventilation. All enrolled infants were received surfactant treatment (200 mg/kg, Curosurf®, Chiesi, Italy) in the delivery room or in the NICU, depending on where endotracheal intubation was performed and ventilated using the Assist Control (A/C) with VG mode (VN500, Draeger, Lubeck, Germany). Patients were randomised to receive either HFOV+VG or HFOV as the initial ventilator mode and were treated for 2 h with the first mode of ventilation. At the end of the initial 2 h patients were then crossed over to the other mode of ventilation for 2 h. There was 15 min “washout” period between the changes in the ventilator modes. HFOV was performed with “optimum volume strategy”. Ventilation started at a frequency of 10 Hz and the amplitude set at equal to the MAP value at the beginning, was increased, if necessary, until the infant’s chest was seen to be “bouncing”. In the HFOV+VG mode, the VThf was set at 2 ml/kg initially on the basis of our clinical experience. The Amplitude limit was set at 15–20% above the average amplitude needed to achieve the target VTHf. Moreover during each 2 h observation period, the following variables were continuously display at 5-min intervals: FiO2, MAP, VThf, Carbon dioxide diffusion co efficiency (DCO2), Amplitude (DeltaPhf), from the ventilator records and heart rate, mean blood pressure, SpO2 from the standard cardiorespiratory monitor.
Results The mean gestational age was 28,2 (24–32) week and the mean gestational weight was 1087 (704–1960) gr. There was no significant difference in the mean PCO2, FiO2, DeltaPhf, MAP, VTHf, DCO2, Minute ventilation (MVe), Dynamic compliance (CDyn), Resistance (R). Hypocarbia event (PCO2 <40 mmHg) occurred eleven (%36) sample during HFOV+VG period against seven sample (%23) during HFOV period but not statistical significant.
Conclusion This preliminary result demonstrated that VG option, when combined with HFOV, a stable and feasible ventilation mode for neonatal patients and can achieve equivalent gas exchange After a careful analysis of the results, a set VTHf of 1,5 ml/kg seems to be successful achieving equivalent gas exchange using lover airway pressure.