3100 High-Frequency Oscillatory Ventilators FAQs

Get answers to frequently asked questions about our 3100 HFOVs

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What is the upper weight limit on the 3100A High Frequency Oscillatory Ventilator (HFOV)?

There really is not any. However, at maximum settings, the driver will get hot and possibly overheat. The Driver Displacement Indicator light may start to drift, but do not try to "center the piston." Chasing the indictor light may only make the piston even more off-centered and increase the risk of overheating. As long as the settings are stable, do not adjust the piston centering knob. Keep the back side of the driver clear from any drapes or other items. A fan can be directed to the back of the driver to also help cool the driver. The newer 3100A HFOVs are manufactured with a 3 ohm driver, which runs "cooler" and quieter, allowing higher settings to be used for longer periods of time. If a patient is greater than 35 kg, the 3100B HFOV is available for use.

Why are mean airway pressures (MAPs) higher on high frequency oscillatory ventilation (HFOV)?

They seem to be because unlike conventional and jet ventilation, no conventional (tidal) breaths exist to recruit the lung. Optimal gas exchange occurs when the lung is at functional residual capacity (FRC). Depending on the severity of lung disease, the pressures required to recruit the lung to FRC may seem high."Based on the relationships between MAP, compliance, FRC and indexes of ventilation/perfusion matching, we conclude that increasing MAP to achieve normal FRC...is a simple method of optimizing lung volume in surfactant depleted subjects (during HFOV)."Source: Wood, B., Karna, P., Adams, A. Specific compliance and gas exchange during high frequency oscillatory ventilation. Crit Care Med, 2002, 30:1523–1527.

Can we use closed suction or swivel adapters?

Yes. It is best to confirm that you can adequately ventilate with these adapters in place before inserting them in the circuit. Also, these adapters add extra resistance to the circuit and may not allow the alarms to detect a disconnect. It is recommended that you have other monitors in place to detect a disconnect (e.g., a pulse oximeter).

I heard that the amplitude must never be greater than three times the mean airway pressure (MAP). Is that true?

There is no scientific evidence to support this claim. As far as we can determine, this was used in early training sessions as a signal to the clinician.However, if a relatively high amplitude (> MAP x 3) is required to maintain normocarbia, perhaps lung volume should be reassessed. In our experience, the above clinical scenario often represents underinflation, and a chest x-ray may be warranted. Underinflated lung units require higher amplitudes to achieve adequate ventilation. If the lung volume was normalized (functional residual capacity), one would often find that lower power setting (less amplitude) would be required to achieve the same degree of ventilation.The converse can also present the same clinical scenario. If the lung were overinflated, higher amplitudes may be required to achieve adequate ventilation. Once again, a chest x-ray would be your best assessment tool for lung volume determination.

The ventilator will not start, but it pressurizes. Usually, mean airway pressure (MAP) is low; less than 12. Why?

Usually, the upper alarm is set too high for the unit to start. Just as with the above situation, the ventilator requires MAP of 20% of what the upper alarm is set at to start the unit. If MAP is low and the upper alarm is set high, not enough MAP is generated to start the ventilator. Adjust the upper alarm down to at least 3 above what you have MAP set at.

Can I use a cell phone around an oscillator?

We recommend using cell phones at least 20' from an oscillator. The signal may interfere with the oscillator and cause artificial high mean airway pressure (MAP), usually greater than 50; and cause the dump valve to activate and the unit to shut off.

Is it okay that I leave the bias flow at 20 LPM?

After the patient circuit calibration and performance check are complete, we recommend adjusting the flow rate based on the type of patient on ventilation. For premature infants, we recommend a flow rate of 10 to 15 LPM; for near-term infants, 10 to 20 LPM; for small children, 15 to 25 LPM; and for large children, 20 to 30 LPM. For adults, flow rates of 20 to 40 LPM should be used. All recommendations are in both the 3100A and 3100B High Frequency Oscillatory Ventilator (HFOV) user guides.

On the 3100B High Frequency Oscillatory Ventilator (HFOV), a change in ventilation settings that is not the mean airway pressure (MAP) triggers the auto-limit?

With any change on the 3100B HFOV, the stroke volume changes, which in turn, changes the MAP. With any change in ventilation settings, we recommend that you watch the MAP and adjust it if necessary.

Amplitude is low on the performance check. What should I do?

Bypass the humidifier, check the power knob (0.0 to 10.0), adjust the Dynamic Displacement Indicator (in the user guide), replace the bellows/watertrap and take the ventilator to a factory-trained biomed.

The Battery Low light comes on every time the reset button is depressed. Why?

This is normal.

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