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6. High Frequency Oscillator Mode
The VT PLUS, with firmware version 1.08.04 and higher, has a function for testing highfrequency flow and airway pressure.
To access the high-frequency oscillator function, follow these steps:
1.
Press the MORE/4 key.
2.
Use the ∧ and ∨ soft keys to highlight HIGH FREQUENCY OSCILLATOR.
3.
Press the soft key below ENTER.
The high-frequency oscillator mode samples flow and airway pressure at a much faster rate
(5x) than the VT PLUS does in normal operation. It is useful for monitoring the function of
extremely high-frequency breath rates, (up to 800 bpm). In HFO mode, the VT PLUS collects
two seconds worth of data at a time. After the data is collected, it is processed to calculate
parameters and the first half-second of data is plotted on the display.
The mean, min, and max values are calculated for both the pressure and flow signals. Please
note that these values apply to the whole two seconds of data, not just the half-second that is
plotted. The breath rate is calculated and displayed in both breaths per minute and Hz. The
inspiratory time and tidal volume are also calculated.
To run the HFO test once press the START soft key. The AUTO soft key will start the HFO
test in automatic mode. In automatic mode the HFO test is run every 15 seconds. When in
automatic mode, press the STOP soft key to end the high-frequency oscillator test.
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Special Functions