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Servo I in NIV mode?
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Seatac has made great point regarding the clinical use of the Servo I and it's a very responsive and highly functional ventilator. The orginal issue was regarding getting rid of Visions and depending on the Servo I for all funcitons of NIV. I believe ventilator products are not at the one ventilator for all aspects yet. The two issues on the top of my thoughts are education and cost. Seatac gave a nice overview of the adjustments for NIV and I completely agree. Unfortunately, ventilator development is behind in thought and function as it relates to bedside reality. We are asking the every day RT to change out an inexpensive BIPAP (and over-priced)to a tradition closed circuit dual limb ventilator or modified single limb circuit. Why doesn't the ventilator switch function to mimic the simple BIPAP? I believe for this to be practical all ventilators should be albe to mimic the BIPAP better and not require changing PSV expiratory cycle flows to the proper leak rate or other stop gap measures. What are we sacrificing towards work of breathing by not having a properly timed breath? More importantly, are we getting the information into every RT professional and Physician that manages ventilators? So, we have two important obsticles; poor development and incomplete education.

The cost issue would be related to the number of operational ventilators and BIPAPs versus ventilation population, intubated versus non invasive, the cost of dispoables, cost of maintenance, and cost of service. I know that a study of NIV cost versus invasive gives NIV a favorable result of using NIV. I am not aware of any information that would comclude using a single ventilator is more cost effective than have BIPAPs.

I believe the Servo I is a very functional ventilator but it joins the rest of the ventilator products being lacking in design to be a favorable everyday NIV option. The exception for NIV might be the Espree. I haven't used the Espree myself but it's downfall based on what I've seen in demonstration is the lack of capibility in other aspects but I can't comment much on it. My hope is that NIV evolves quickly because of the important clinical benefits of not sticking invasive airways into patients. I would love the Servo I as well as other ventilators being used to have an NIV option equal to or better the BiPAP.
 
Posts: 32 | Location: Powder Springs, GA | Registered: January 18, 2003Reply With QuoteReport This Post
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I think there are two issues being discussed. One is cost, the other is function.

Regarding cost. It probably is not practical to get rid of all free standing bipap units. Again, as I said in my first post, I would not advocate putting a vent with NIV capability on the floor. However, for ER or ICU a combined option might be a good choice. Call and get a price quote on a Vision. I think you will be suprised at the cost. They are not inexpensive. Ugrading a Servo with NIV would be less costly if you already own the vent. What about the cost of PM's. There can be a high cost associated with maintainence on equipment. I have to assume that's where this biomed's motivation is. Now let's speak of efficiency. A compromised patient hits the ER. The doc wants to try NIV prior to intubation. The RT has to run around, find a machine and get the patient set up. The patient ultimately fails and requires intubation. Now they have the task of pulling the bipap out and setting up a vent. One could repeat this same scenario in the ICU. Seems a bit inefficient in my opinion.

Now let's talk function. I have to disagree with your assessment that the bipap is the be all end all of non-invasive. I have yet to come across an RCT that shows difference in outcome or tolerance comparing bipap to a ventilator with NIV capability. I agree bipap is superior if you try and get away with using a vent in the invasive mode, which is what is often done. For your second comment that we should not have to worry about cycle off is curious. Are you trying to imply that the Vision will sync perfectly with the patient. I'm sorry, but if the breath is not timed and you are delivering positive pressure there has to be some cycle off criteria. Degredation of flow is most common. The Vision emloys an automatic algorithm for this which may work great. That may be a feature that would be desirable to incorportate into ventilator NIV capability.
I think someone mentioned it earlier. NAVA on
the Servoi may make all of this obsolete. It will revolutionize not only invasive, but hopefully non-invasive ventilation as well. What could be a more perfect computer to cycle the breath on/off and determine support levels, than the brain.
 
Posts: 21 | Registered: December 10, 2007Reply With QuoteReport This Post
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Thank you all for your responses. I agree with the fact that the vision is superior in function to a vent setup as a dual purpose unit. I am not educated enough in the ways of business and materials mangment to discuss the cost benefit ratios. But tas one person said "the right tool for the job". Hopefully the "boss" can be convinced of the same. Again thank you all.

-Bill W
 
Posts: 2 | Location: NH | Registered: December 08, 2007Reply With QuoteReport This Post
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In reference to Renton, what is the PAV option on the Vision? I am unfamiliar with that option and use S/T with great success. However, I'm all ears to new technology if it help the patients.
 
Posts: 13 | Location: Roanoke, Va | Registered: April 08, 2007Reply With QuoteReport This Post
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The PAV option on the Vision is not available in the US. Renton is from Canada where it is an option. The difficulty lies in companies ability to get 510K from the FDA. There is probably not a predicate device to gain their 510K to distribute in the US. It comes down to the $$ required to get approval.
 
Posts: 21 | Registered: December 10, 2007Reply With QuoteReport This Post
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For yomonk1:

I will try an answer in a few words.. PAV is somewhat difficult to explain in a nutshell... espacialy for me (as seatac pointed out, I am canadian, but from Québec, I'm french speaking...)

PAV: Proportionnal Assist Ventilation: Developped in the 90' by Dr Magdy Younes (Canada). It is an option (or mode, I don't care for semantics) in which the patient always initiate a cycle (hense spontaneous), but the limit (pressure) is variable. It cycles (from inspiration to expiration) differently to.

The pressure support is an amplification (by an algorithym) of the work of breathing, or more specificaly, the pressure needed to create a volume in the alveoli. The motion equation is very helpful here:

Paw = Pe + Pr or Pa + Pta

if we continue:

Paw = E * Vt + V * R

E: Elastance, Vt: tidal volume, V: Flow, R Resistance.

Usually: Paw = Pmus (pressure from the muscles)

And knowing that we use a vent to creat that volume: Paw = Papp (pressure applied by the vent), and that we want to give the patient a break (for the emergency setting: Pmus =0)

So the vent needs to determine the pressure (Paw) to support the composants of WOB: Pe and Pr. Since the vent knows the flow and volume of the patient at any time of the inspiration (a calculation is made every 5 ms on the PB840, I don't remember the value for Vision), the vent needs only to know the Elastance and resistance of the patient. That is the tricky part: how do you calculate theses things in an emergency and ICU settings...

Well, you guest! The two main setting on PAV are Flow Assist (FA) and Volume assist (VA).. Theses names are "fraudulous" and wre probably invented by biomed guys (no offense intented. Since we are in a spontaneous mode, VT and V are set by the patient. Theses setting sould be named Elastance compasation and Resistance compasation. When you look at the actual device, you clearly see cmH2O/l under VA and cmH2O/l/s under FA.

So you start low (FA: 2 and VA 5) and you go up until the patient's WOB is 0, point when E and R are totally compensated (the patient doesn't choke anymore...).

When that happens, the vent knows, at every point of inspiration Vt, V, R and E, and can calculate PS, which varies not only from respiration to respiration, but also inside one inspiration (sorry for the way the last sentence was translated...)

For a better explaination, I suggest the PAV chapter in:

TOBIN, M. Principals and practice of mechanical Ventilation.New-York, McGraw-Hill. 2006.

It is my personnal "Bible" on ,mechanical ventilation.

Hope this helps...
 
Posts: 49 | Location: Ste-Agathe-Des-Monts, Québec, Canada | Registered: October 14, 2005Reply With QuoteReport This Post
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Are you aware that the Esprit is getting the Auto trac that the vision already has? This will allow the NIV mode on the Esprit to respond just like the Vision It will compensate for the leaks and sensitivity that Vision is known for
Hope this helps
 
Posts: 1 | Registered: January 21, 2008Reply With QuoteReport This Post
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Dear all,

The unit I am working in (NICU and PICU) started to use Servo I late last year, during handling with NIV mode, we came across 2 main problems
1. the leakage from the system is too extensive
2. the mechine cannot sense patient trigger, so it starts the apnea alarm all the time
We did not able to deal with the problems and need to switch back to use the traditional ventilator (infant star, which will soon be fade out)
I would like to see if any of you have similar experiences and any suggestions to deal with them?? I would also like to know the mechanism of NIV in Servo I.
Thanks for the help in advance
 
Posts: 1 | Registered: January 24, 2008Reply With QuoteReport This Post
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To yylb,

I just want to "double check" someting with you:

1-Do you put an "expiratory" or whispering valve before your NIV mask? If so, remove it. All expiratory gases must go in the expiratory tubing.

2-Most of the time, we had leakage because of the type of NIV mask that we used. The best , in my opinion, is the tubing and mask combo from Fisher-Paykel (expensive however...). The leakage from the mask could also explain the "non-trigerring" aspect of your problem.

Hope this helps.
 
Posts: 49 | Location: Ste-Agathe-Des-Monts, Québec, Canada | Registered: October 14, 2005Reply With QuoteReport This Post
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Renton is correct. Leaks come from the interface not the ventilator. Some seem to work better than others (F&P, Hudson, Argyle). INCA seems to be problematic. Pediatric interfaces are just plain hard to come by. No one makes a good one for this patient population. The Servoi will compensate for leakage in the infant category up to 15lpm. That's a lot of flow! If you have a larger ped patient, switch to the adult category. Then you get up to 40lpm compensation. In regards to trigger, NIV in Infant is approved for patients greater than 3kg. It was never intended for small babies despite people trying to use it that way. However, there has been some success using NIV in pressure control for small babies that cannot generate enough pressure drop to trigger. It won't be synchronized, but what is there currently on the market that is? Pressure support will not work in these kids because it will always go into apnea ventilation. Hopefully NAVA will change all the issues with trigger and leak, primarily during NIV. I would contact your rep to get some training on the equipment if you are having trouble.

Seatac
 
Posts: 21 | Registered: December 10, 2007Reply With QuoteReport This Post
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