Oscillating ventilation

sunnycalifRN · Nov 22, 2009

Thanks for setting me straight. Just one more question, are you using the SensorMedics oscillator? It's the only one I could find. I want to put together some info to give to our ICU director.

Pediatric Critical Care Columnist · Nov 22, 2009

Yes that's what we use. There are some other models of ventilator that can deliver HFOV but we never use them for that. (Hummingbird and Dragonfly servo vents can deliver HFOV but only in neonates.) Sensormedics 3100A and 3100B have the whole corner to themselves. They look kinda primitive, but the principle is so simple that there really isn't much need to reinvent the wheel.

One practice difference I've noted is that in my former unit, the circuit was always maintained perfectly perpendicular to the patient and supported so there were no dependent areas, providing a linear column of air and pressure. This meant ensuring both the bed brakes and the brakes on the ventilator were engaged. As an added safety measure we would use pink tape to secure the bed wheels to the floor. Where I work now there isn't the same emphasis on this and it seems not to make any difference to the efficacy of the treatment. But I wonder if there is a physical difference in the delivery of the oscillations.

sunnycalifRN · Nov 22, 2009

It's been a long time since I've seen HFOV. Years ago as an RT in NICU and at that time the oscillator looked like a large speaker (maybe 12-16" diameter) and the circuit was heavy plastic tubing, to transmit the pressure pulse without tubing loss. As I recall (memory is fading), the circuit tubing was so stiff, I don't think it would bend. Thanks for the info . . . maybe we'll be able to get one in for a trial cuz we definitely have intractable ARDS patients.

Pediatric Critical Care Columnist · Nov 22, 2009

Well, if you look at photos of the Sensormedics, it probably doesn't look all that different from what you're remembering! The piston and diaphragm are probably a foot across. And the circuit is heavy - very heavy... it could pull a baby off the bed if it was bumped! - especially with an ETCO2 sensor on it. But we heat and humidify the gas so much now that the plastic softens a lot. It definitely bends.

FOCKER0014 · Nov 24, 2009

We use Oscillatorsall the time on adult patients. It is a lung protecting strategy. The unfortunate thing though is that many times the intensivists or trauma MD's wait too long to place the pt on an oscillator and the end result is usually quite poor. If a patient is placed right away on one then they SEEM to have a better outcomes at least in the Surgical Trauma ICU that I work in. ARDS is the typical indication for oscillation however i have seen it used with bilateral flail chests, salt-water drownings, and recently a lot due to the SWINE (d/t ARDS). I am a fan of oscillators...They work great when used at the right time.

menemsha · Mar 30, 2011

Can you please explain about the piston & the purpose behind centering it?????????

Pediatric Critical Care Columnist · Mar 30, 2011

The piston is what delivers the ventilation. The piston action forces air into the lung and then pulls it back out. The rate of piston movement is noted in Hertz, which represents the number of oscillations per minute. 1 Hz = 100 oscillations. Having the piston centered ensures that the impetus of each oscillation is delivered in the most direct route, maintaining the pressure inside the alveoli at the desired level. The goal is to prevent collapse of the alveoli. Having said that, I've been told by one of our respiratory therapists that it's not as important as all that to center the piston and that having the circuit drooping doesn't diminish the effectiveness of the strategy.

menemsha · Mar 30, 2011

Thanks, I appreciate your reply & your way of explaination.

I work in NICU & have been using the Sensormedics in recent times.

I must admit I am having a bit of a tough time getting my head around the terms Power & Amplitude.

To me it is just so different to conventional ventilation.

Also people keep talking about "Centering the Piston" & I haven't figured out whether it really is that important.

Can you recommend any online teaching regarding HFOV.

Thanks again & well done.

Pediatric Critical Care Columnist · Mar 30, 2011

Here's an article that should be right up your alley: http://www.hkjpaed.org/pdf/2003;8;113-120.pdf

Amplitude refers to the difference between the pressure in the lungs at the peak of push and the nadir of pull. You may hear it referred to as Delta-P. And Power is the Hz. Mean airway pressure is the third number we toss around. The other two settings are tweaked to maintain the mean airway pressure at the desired level. The principle of high rate and low tidal volumes has been described as similar to a dog panting. The combination splints the alveoli open to improve gas exchange and minimize baro/volutrauma. Effective HFOV will produce a "wiggle" to at least the mid thigh on an infant. I hope your unit provides earplugs for those babes!

menemsha · Mar 30, 2011

Thank you for the article.

I have lots of reading/learning to do.

We only have the Natus Ear muffs................I think ear plugs may be a whole lot better.

Creamsoda, ASN, RN · Mar 31, 2011

Ive seen it used when patients keep blowing pneumos, really bad ARDS ect because traditional ventilation just made things worse. On the otherhand these people are usually extremely sick, and the ones I have seen on an oscillator usually ended up dying.

Maevish, ASN, RN · May 3, 2011

Yeah they use it on adults in our ICU as well, but all the RTs say it's primarily used in peds. We don't see them very often though.