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Anyone have any experience with variable tidal volume ventilation?
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This is my first post, so hello everyone!

Has anyone had any experience with either variable tidal volume CMV or variable pressure support aka "noisy pressure support." It seems like alot of studies have been done on animal models but only one clinical study on humans (variable CMV)

Just curious what people think about practical applications of this mode. Do any ventilators offer variable pressure support yet? It sounds superior to volume ventilation, but wouldn't unsupported/unassisted breathing be better when weaning?

This message has been edited. Last edited by: rtED71,
 
Posts: 6 | Registered: July 23, 2010Reply With QuoteReport This Post
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Thanks for the post and welcome. It is on the Drager Evita Infinity. I don't know if it is on other Dragers, and I haven't yet heard about it on any other companies vents. It is certainly a different concept of vent support. It has been recognized that it is a natural occurrence for depth of respiration to vary infinitely. My initial take is that PS breaths are already infinitely variable in their depth as well as duration/rate as determined by the strength and duration/rate of the contraction of the inspiratory muscles. They claim clinical improvement when this is used. http://www.draeger.com/media/1...rt_PI_210x280_uk.pdf but I wonder if a variable level of pressure support might not have some sort of confusing effect on pneumotaxic feed back loop between lung, stretch receptors and brain. If so it would probably not have any significant negative effect. Although it is natural to have infinite variability in depth of respirations, it is not natural to have that variation in the gradient between pull of inspiration and the source of inspired gas which in nature is at consistent ambient pressures. My initial humble opinion may be wrong. I kind of hope so as I like new stuff to be good stuff, but this seems like chicken soup to me (cant't hurt, might help, probably won't).
 
Posts: 147 | Location: Buckeye Az | Registered: January 27, 2006Reply With QuoteReport This Post
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Hey Gary,

Thank you for the response. Tobin found that healthy subjects and a variable vt of +/- 40% (if I remember correctly). I'm guessing Variable CMV is an improvement over CMV (then again what isn't). I still like the idea of providing a patient with adequate PEEP and ATC than pressure assisted ventilation during weaning, unless dealing with tough to wean COPD patients (maybe SmartCare and ASV will gain ground eventually for those situations). I'll admit I have a bias towards pressure control and APRV.
 
Posts: 6 | Registered: July 23, 2010Reply With QuoteReport This Post
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If you think about it...noisy pressure support is almost the opposite of volume targeted pressure control (AutoFlow, Volume Guarantee, PRVC). In those modes the pressure is adjusted to maintain a constant tidal volume and is dependent on patient interaction and lung mechanics. In noisy pressure support the pressure is adjusted to prevent a constant tidal volume and is independent of patient interaction and lung mechanics.
 
Posts: 6 | Registered: July 23, 2010Reply With QuoteReport This Post
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