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Keywords:

  • high-frequency oscillatory ventilation;
  • infant;
  • mechanical ventilation;
  • neonate

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.