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correct placement of inline nebulizer
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I recently began working at a hospital and they place the inline nebulizer in a different place than I have seen can you give me feed back on where you place the inline nebulizer?
Posts: 2 | Registered: September 23, 2006Reply With QuoteReport This Post
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I should add also that this is drager ventilator. thanks
Posts: 2 | Registered: September 23, 2006Reply With QuoteReport This Post
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Posts: 1 | Registered: September 24, 2006Reply With QuoteReport This Post
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Picture of GaryMefford
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Thanks for joining us Carrie 75. This is an excellent question. Thanks also O2MAN, for joining. You seem to have a strong opinion on the subject. That is great. We have several new members recently and I hope all of you are regular posters. We appreciate your questions and comments.
The neb positioning that I have seen used most is between the wye and the patient connection often with a flex tube between the neb and the patient connection usually via an inline suction catheter. The HME may or may not be left inline during treatment. This is my observation from over a few years. Now am I saying that is best? Far from it. I don't know if you are using a gas driven neb, or an electrical mist generator (these may offer the best answer, but are a hard sell with bean counters when pneumatic nebs are relatively much lower cost per device, thus they are still not being used to the level they might), but I will figure you are talking about position in the circuit of a pneumatically driven device.

There is also a whole other question that I will discuss a little as to whether an in line MDI might be the better answer to spraying meds into our vent patient's airway. It seems there is a large contingency that hold that opinion, and for many sound reasons. I also wonder, if it is available in a canister and secretions are well controlled then MDI for most meds makes sense. With that said, my preference for most of my vent patients in recent years, (I am talking about LTAC & tough to wean ST acute vent patients) has been an in line neb. The MDI requires consideration regarding several factors where the neb when administered consistently with good technique excels. Please understand what follows is based in some ancient personal research so I won't try to cite references, hopefully some other poster will give us a few citations that will shed some light as well. This is also what I have found has given me results, or at least that is my view from more personal observation rather than scientifically collected data. MDIs used to deliver meds to the airways of vent patients may fall short for us for several reasons. Most of those things can be overcome, but frequently aren't so well. MDIs require near perfect timing with ventilator cycling, and when done optimally probably setting adjustment for delivery of deeper breath and hold. Easily overcome if all staff learns and executes consistent delivery methods. If the method trained/used is not sound (it happens, you know it does. I hope it is rare) no meds get to the desired destination. With the wrong MDI adaptor even perfect technique can result in failure to deliver. If I feel that the patient will benefit from a med via the inhaled route, and it has to be given via the ventilator, and the med is available in a solution I can give via neb, then it is my opinion that more consistent delivery of medications to the target in the lung will have the greatest chance of occurring day in and day out across all staff assigned when we give the med via the nebulizer. With that said, we have a perhaps even a larger potential of wasting our time, and usually at least a little more time is put into a neb than an MDI, however when done with consideration of maximum delivery of meds both procedures can take about the same amount of time. We are wasting our time with a nebulizer on our vent patients if we are making any of several technical errors. Again this is my opinion. If your supervisor says do it a certain way, and his or her opinion differs from mine, you can respectfully differ, you can research this and provide resources. If you want you can print my opinion and offer it or send them here to look, but if they are firm in their opinion, it may be best adhere to the departmental policy. I've seen many places that don't care where you place your neb or how you power it, as long as the treatment gets done. I know I have altered the pattern of the same old way at most of the facilities where I have practiced. The most frequent frustrating situation I have encountered has been with the old workhorse of many of my years and that is the 7200 (there are others that work basically the same way). With this vent set up with a neb inline anywhere on intermittent nebulization, I never felt my patient was getting the drug. A 3 cc load of meds seems to sometimes take 25 minutes or more to deliver depending on the settings. With larger doses the neb setting would have to be cycled several times to complete the dose. In many cases the therapist just dumps it after one cycle and goes on, having gone through the motions with no significant amount of meds delivered. There are many variations of the same theme, and some are getting better at this I understand. With the 7200 it always seemed that the neb would actuate when about half the breath had already been delivered and reach peak neb production at about the end of the breath, loading the dead space up with a good mist that would then be exhaled. It's still happening every day; there are still tons of 72s out there, although less and less, and few think about it. I am hoping there are machines out there that have overcome this with improved timing of the neb cycle, and I might reconsider it I could observe better results, and maybe someone has done a recent study, but by my limited observation, in my patient population pneumatically powered intermittent nebulization is not as good as continuous nebulization.

If one of the drawbacks of the MDI via vent is poor delivery with any level below optimal delivery method, then this also applies to the in line neb. Here are a couple of poor variations on the theme that I think have slim to no chance of getting the med in the gas stream and delivered beyond the artificial airway to the targets in the lung.
"¢ In line between the wye and the airway connection with
o either anything but perfectly timed intermittent (if it exists, let me know which machines you think have it) or
o continuous nebulization.

I look back at what I just said and I think it looks confusing so let me boil my opinion down, or restate so feel I more certain I have conveyed: If you are placing the neb at the wye, either on the insp side, or between wye and airway adaptor in the mechanical deadspace you are wasting the meds into the expiratory filter at the other end of the circuit in my humble opinion regardless of whether powered continuously or intermittently.

Well what is the better way? You might ask. Oh, that is sort of what you asked. You asked for feedback on how it is done elsewhere, it's tough for me to do that without some reasons. You leave out some details, how are you setting it up now, and how are you used to? OK, here is my logic. I believe that continuous nebulization works best, but that the neb must be placed well before the wye in the inspiratory limb. This is how I think of it. Most of my patients are advanced COPD. We typically use a pretty short insp time with them to facilitate more complete exhalation and better synchrony. Lets use a not too radical 1:4 I:E ratio for our considerations. In that relationship, 4 parts out of 5 of the breath cycle is exhalation. The direction of active gas flow in the circuit is from the patient toward the exp limb and out of the machine. For this to work any biased flow must be eliminated. It will dilute the med charge and decrease the amount delivered. Back to 4/5 gas flowing out of the machine. I have already covered the downside of intermittent neb cycling, now consider continuous neb at the patient wye. The only medication that even has the remotest chance of navigating down to the terminal airways is that which is generated by the neb during inspiration, and with a certainty only that generated during the earliest portion of the inspiratory cycle. So I am on a 1:4 I:E set up, and for grins and to keep the math simple at a rate of 12/min. Ti-1.0 sec Te=4.0 seconds. The nebulizer is running continuously at the wye. The meds generated during the 1 second of inspiratory time will be potentially propelled past the airway for the perilous journey (at least for a 5 micron particle) to the target airways. The second half to third of that mist carrying volume will make it only to the mechanical and anatomical dead spaces and not have any chance for pharmacoactivity. The 4 seconds during which exhalation occurs the medications produced from the neb turn the corner and follow the flow of exhaled gas flow.

The better way is to place your continuously driven neb back in the inspiratory limb of the circuit. I have read 18 inches is optimal. We have been able to purchase circuits with a valved neb adaptor at the halfway point in the insp limb of the circuit. Both of these are better than at the wye. Lets go back to the 1:4 I:E. With many of my patients I feel optimal placement is actually all the way back at the beginning of the circuit. During expiratory phase the nebulizer is generating a mist laden charge of gas that fills the inspiratory limb. I have observed even a small amount of spillover past the wye with normal flow to the neb, so I know that with these type of parameters my patient is getting a densely charged cloud of mist laden gas with each new breath delivered. Rain out they might counter, and they have. Yes there is some intertial impaction, and gravity rain out of larger particles, but observe the density of the mist in the gas delivered and you will have to admit this might have some validity.

I will readily admit that there is a couple of downside issues that have to be considered. First, when you introduce a flow into the circuit that the machine is not set up to account for, you way alter your exhaled volumes. High VT and VE alarms have to be basically dialed out during continuous in line neb. You also need to recognize that you will will make your machine far less sensitive to your patient temporarily with continuous neb. Also if you are using a biased flow through the circuit it needs to be switched off for this type of delivery. It will dilute the med charge. Oh yeah, the HME if used has to come out with the method I describe of course. It probably should with all methods anyway. If you use MDI in the insp limb it should as well. That breaks the circuit I know, a whole other subject that I wonder about. I'll leave it for now. Another consideration is what any continuous neb might do to the inner workings of the machine on the exhaled side. I suggest a standard bacteria filter placed before the regular exhalation filter to double filter the exhaled gas stream.

1:4 @ f12 = Te 4.0s

Neb driven by 8.0l/m gas flow

8.0/60=.133l delivered by neb/sec

.133 x 4sec=.533 l

Vent circuit we use is 72" isn't adult tubing 100 ml/ft? if so insp. Limb .6l

In theory the shorter the Te the closer it should go to the patient.

All of that said I did loops pre and post and overlaid with all inlines given with various methods for weeks one time. I did not observe a significant difference post with most treatments unless I had some secretion production. It seems that charging the insp limb from well back in the circuit stimulates more secretion production that at the wye or a MDI.

This message has been edited. Last edited by: GaryMefford,
Posts: 147 | Location: Buckeye Az | Registered: January 27, 2006Reply With QuoteReport This Post
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Hi Gary, I enjoyed reading your message and think you are well thought in your processes. One more opinion and the one frequently used in our facility is to place the nebulizer at the inspiratory out immediately from the ventilator thus charging the entire insp. limb as a "holding chamber" of sorts. Yes, it is before the humidifier cannister, but the cannister delivers vapor, not increasing size of inspired particles and/ or increasing rainout. We have found this to be optimal for our delivery and when used with a valved T adaptor, also reduces breaking the circuit and losing MAP. Win win situation in our book. I must say that this is best applied for standard bronchodilators, when we nebulize "sticky" drugs, we have found the need for a filter on both insp and exp sides to protect the inner vent.
I'm interested in any opinions and/ or experiences with this method. Best wishes to all.
Posts: 13 | Location: Roanoke, Va | Registered: April 08, 2007Reply With QuoteReport This Post
Picture of Bill C
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I concur with Gary
Posts: 74 | Registered: June 14, 2006Reply With QuoteReport This Post
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Picture of VentiMojo
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This is interesting, sorry to be weighing in so late, I personally put the neb just past the heater, It should go right out of the vent, as yomonk1 says, but I can't get myself to do it that way. Google Dean Hess, neb fanatic and all around nice guy, he has some actual proof for this.
Posts: 1 | Registered: April 18, 2008Reply With QuoteReport This Post
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Picture of RTPMA
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Hello i'm working with AVEA Ventilator my question is if there's any way of putting Nebulizations using the option in the Vent with less than Flow 15 LPM, the users manual only says it have to be on 15 lpm at least. greetings from Panama
Posts: 2 | Registered: June 22, 2008Reply With QuoteReport This Post
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