Introduction The Babylog VN500 ventilator (Draeger, Lubeck, Germany) in High frequency oscillation mode (HFOV) has the ability to control tidal volume (VThf) using a Volume Guarantee function. However, appropriate VThf values during this mode of ventilation has not been established.

Aim The aim of this study was to establish normative data for VThf/kg during HFOV and explore its correlation with FiO₂, day of life (DOL), gestational age (GA) and frequency (Freq).

Methods Newborns admitted to the level III NICU from January 2012 till September 2013 treated with VN-500 in HFOV mode according to strict clinical protocol were included. Indications for HFOV were: PCO₂ > 65 on two consecutive blood gases and RR > 60. Blood gases with corresponding vent settings, time, patient’s weight and clinical diagnosis, were prospectively recorded. Measured VThf values were included only when PCO₂ was in the ‘normocapneic range’ of 40–55 torr. Univariate analysis for FiO₂, DOL, GA and Freq as well as Spearman’s rank correlation coefficient was done.

Results 37 patients were treated with rescue HFOV; BW = 875.9 g ± 163.7 and GA = 26.4 ± 1.4 (mean ± SD). 201 of 425 sets of blood gases met normocapnic criteria. The PCO₂ was 46.5 ± 3.7 mmHg and VThf/kg 2.00 ± 0.59 mL/kg (mean ± SD). Correlation with GA, DOL, FiO₂ and Freq are shown in the Table (*p < 0.05 in univariate correlation).

Conclusions The mean VThf during normocapnia on HFOV is 2 mL/kg but its value is affected by GA, DOL, FiO₂ and Freq.