Vent question please help!

High frequency ventilators work on the principal that it's easier for gas exchange to occur by delivering smaller breaths more often. They provide better gas exhange using less pressure than conventional vents. The low tidal volumes put less stress on lungs that are too fragile to be able to withstand the stretch required for a normal tidal volume.

The purpose of a conventional vent with the jet is for oxygenation purposes. High frequency breaths are too small to reach the alveoli in the lungs so you're relying on diffusion to get oxygen to the alveoli. Conventional vents can deliver oxygenated gas directly to the alveolar level by using long Itimes and large tidal volumes and can control peep. The conventional vent is run at very minimal rates (1-5 BPM). It provides what are called sigh breaths that help keep the lungs inflated. It also provides gas exchange whenever the baby wants to breathe on his own. The conventional vent is used to gradually recruit collapsed alveoli and allows the jet to provide the bulk of ventilation and to achieve the best possible blood gases with the lowest possible airway pressures.

On the jet exhalation is passive, meaning the baby has to exhale. Passive exhalation is the safest way to get gas out of the lungs.

The oscillator is a high volume strategy that is used to recruit alveoli and maintain a high lung volume, with a higher MAP but lower peak alveolar pressures to help oxygenate in diseases with low lung volumes (RDS). On the oscillator the entire breathing cycle is performed actively, requiring no passive inhalation or exhalation by the baby. Active exhalation (meaning the oscillator does the work) can lead to gas trapping which can lead to the collapse of more alveoli before exhalation is complete which is why a higher MAP is needed. It helps splint the airway open while gas is being actively withdrawn from the alveoli.

So in summary one of the biggest differences in the jet and oscillator is that with the jet exhalation is passive (baby has to exhale) and with the oscillator exhalation is active (oscillator exhales for the baby).

Other numbers you may see

Delta p (amplititude) is the change in pressure (PIP-PEEP). Delta p affects ventilation. (co2 removal) It is like setting pressure delivered on a conventional vent. To decrease the co2, increase delta p and vice versa. Delta p is set on the oscillator and is measured on the Jet.

Hertz: is the frequency of breaths per minute--the rate. Each Hz is 60 cycles/min. So in your patient the hz was 7. Hertz directly affects ventilation. Decrease the hz will decrease CO2. The smaller the Hz, the larger the tidal volume. The hertz is set on the oscillator.

On the jet: rate, PIP, and Itime are set and the conventional vent provides a backup rate (sigh breaths) and PEEP.

Oscillator: MAP, Fi02, delta p and Itime are set. ventilation is dependent on amplitude and hz while oxygenation is dependent on fi02 and Map.

Hope that helps some.

That was probably the best explanation I have ever heard!!! Thanks!!

So they were used together? Wouldn't one interfere with the other?

So they were used together? Wouldn't one interfere with the other?

Using the conventional vent is going to help you oxygenate the baby.

The jet helps you ventilate the baby.

They work in tandom.

The jet does not provide PEEP. It measures it, so you'll see a number on the jet for PEEP, but the jet is not providing it. Remember, PEEP is going to maintain the inflation of the alveoli. You need an adequate PEEP to recruit more alveoli and keep them open.

Great explaination! I haven't used a jet in many, many years. Do you still use the special OET? I remember the nightmare we had extubating and then having to reintubate with that other tube!

We don't use oscillators anymore. Only jets and conv. vents. I liked oscillators, and it was certainly easier to read the settings when you only had one vent to look at. But I think the jet works better over all. That was a FANTASTIC explaination, by the way!