Dräger VN500's oscillatory performance has a frequency-dependent threshold

Aim: The aim of this study is to compare the high-frequency pressure amplitude (oscillatory change in pressure (ΔP)) and tidal volume (high-frequency tidal volume at the airway opening (VTHF )) delivered by the Dräger VN500 (Drägerwerk Ag & Co., Lübeck, Germany) and the Sensormedics 3100 (SM3100; CareFusion, San Diego, CA, USA) through a range of oscillatory frequencies.

Methods: In this benchtop study, high-frequency oscillations were applied to an infant test lung at unrestricted set amplitudes. Pressure and flow were measured as a function of frequency, incremented by 1 Hz from 5 to 15 Hz. Measurements were repeated for a range of ventilator settings, and lung resistive and compliance states.

Results: The VN500, but not the SM3100, demonstrated an exponential decrease in airway opening ΔP as frequency increased. The difference between the SM3100- and VN500-delivered VTHF became greater with each frequency increment. At 15 Hz, VN500 VTHF was 49% of SM3100 VTHF .

Conclusions: The VN500 demonstrates a frequency-related reduction in ΔP not observed in the SM3100. Clinicians need to be aware of these differences in performance characteristics.