 | The University of Kansas Respiratory Care Education |
| The University of Kansas Respiratory Care Education |
| The SensorMedics 3100A is a high-frequency oscillator which means it delivers a column of air vibrating at a rate of 3 - 20 Hz. The center of the gas column moves toward the alveoli while friction along the outer edge causes those gas molecules to essentially move out of the airway. For this reason exhalation is said to be active in high-frequency oscillation. |  |
| The vibrations are created by an electromagnetic valve that controls a piston. The resulting vibrations are similar to those produced by a stereo speaker. The height of the vibrational wave is the amplitude. Higher amplitudes create greater pressure fluctuations which move more gas with each vibration. The number of vibrations per minute is the frequency. One Hertz equals 60 cycles per minute. The higher amplitudes at lower frequencies will cause the greatest fluctuation in pressure and move the most gas. |  |
| Altering the % Inspiratory Time changes the proportion of the time in which the vibration or sound wave is above the baseline versus below it. Increasing the % Inspiratory Time will also increase the volume of gas moved or tidal volume. Decreasing the frequency, increasing the amplitude, and increasing the % inspiratory time will all increase tidal volume and eliminate CO2. Increasing the tidal volume will also tend to increase the mean airway pressure. |  |
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Front panel of the 3100A. |
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| A flexible circuit for the 3100A. |  |