a client who has emphysema is receiving mechanical ventilation This is a topic that many people are looking for. thevoltreport.com is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, thevoltreport.com would like to introduce to you Relevance of intrinsic PEEP in the mechanically ventilated COPD patient G Bellani 2015. Following along are instructions in the video below:
You very much thank you for staying these are my conflicts of interests and i i would like to say that part of the research. I will show you has supported by some companies dealing with mechanical ventilation so when we talk about intrinsic peep. I think its important to understand first what is intrinsic peep and which could be the effects of intrinsic peep exactly what is the relevance of intrinsic peek.
Which is quite different the effects are quite different if we consider intrinsic peep you are in control ventilation and during the assist ventilation these are two quite separate items intrinsic peep is the pressure that remains in the ovilus at the end of normal expiration. So for example. Here you can have an intrinsic peep of 10 centimeters of water and by the very nature of the way intrinsic peep is generated in the copd patient.
This intrinsic peep can be offset by an extrinsic peep applied to the ventilator or you can look at it. The other way around you can decrease the peep on the ventilator. But nothing will happen in the alveoli below a certain pressure so the image that is frequently used for that is that of the damned where you have a lake on one side and until the water on the other side of the wall does not get to the same level as in your lake.
The level of the water will not increase. So meaning that and we have a given pressure in the alveolus and the alveolus will never drop below that pressure and once we compensate that pressure with the peep. We apply on the ventilator and that point also the alveoli will start to see this pressure.
We are applying on the ventilator. This is a classical example of intrinsic peep. This is a patient ventilated between 0 35 centimeters of water normally when you increase peep peak inspiratory pressure will increase plateau pressure will increase.
But here. You see that there was a peep increase. Here beeping crease here and here and nothing happens to the peak pressure.
This is because there was an intrinsic peep in the avalos and the alveolus will never be below these five centimeters of water pressure as soon as we overcome this pressure. Then the alveolus will see the pressure in the airways and so also the peak pressure will increase and only at this stage the peak pressure that the volume of the lung will increase once again you can look at it also the other way around if you want to decrease the lung volume. You cannot do this just by decreasing peep.
Because the the alveoli will do not deflate below a certain level of peep. This is an image. Weve published on the blue journal with thomas omalley.
A couple of years ago. Its done by electrical impedance tomography. You see this is the airway pressure and its clear that below a certain level of peep of extrinsic peep peak inspiratory pressure is not decreasing anymore because we are trapping gas in the lungs.
And so this is the lung deflating down here in green. We start from a baseline. We decrease peep and there is a certain loss of volume which we see here in green decrease peep.
The volume decreases more. But then at some point. We the the lung volume stops decreasing because we are trapping gas here so this is the i would say classical intrinsic peep in the mechanically ventilated patients once the patient is on controlled ventilation the main effect of intrinsic peep is the distension of the alveoli so clearly plateau pressure will increase either i will be distended and that thats the mechanism by which copd patients end up in emphysema and of course.
We will have a pneumo dynamic effect. This is a study from about 20 years ago by the group of antonia artiguez. Where he studies tf of the mo dynamic effect of application of peep in copd patient.
So they will start from a peep of zero. An extrinsic people of zero centimeters of water and then apply six and eleven centimeters of water where this column in the middle is the peep that compensates exactly the intrinsic peep of the patients and indeed you will see that from the people of zero to these increased in peep peak change a big pressure changes not much what happens to hemodynamics you have a long list of abbreviations here so just look at cardiac output. You see that even if we apply five centimeters of water of peep nothing happens to cardiac output.
And nothing happens to for example. The pressure in the right ventricle.
Though when we overcome when we exceed the intrinsic peep and we apply four centimeters of water more at this stage. We start to see some hemodynamic impairment caused by application of peep so this is just to summarize the main effects of intrinsic people during volume during control ventilation which are related why as i said to distinction of the lungs and to the risk of hemodynamic impairment. Because intrinsic peep will act on hemodynamic exactly like in extrinsic peep.
However i think i personally found a little bit more intriguing the mechanism of intrinsic peep during assisted modes of ventilation as we all know intrinsic peep can lead to an increased work of breathing. Why is that this is the alveolus of a patient that has a 6 centimeters of water intrinsic peep and the people plied on the ventilator is zero the patient starts to breathe. It generates a negative pressure.
But he has to overcome the intrinsic beep before he is able to receive any flow from the ventilator and so as soon as the overcomes intrinsic peep at this point. The flow will come from the ventilator to the alveoli of the patient. If we now apply an extrinsic peep on the airway of our patient patient.
We will help the the respiratory muscles because as soon as the breathing effort begins. There is already a pressure gradient from the alveoli which are still stuck at six centimeters of water between sorry. The alveoli and the airways and so the flow will start earlier and this is a classical example showing you how you might detect intrinsic peep by looking at esophageal pressure here.
The patient starts is or her breathing effort and until the level of pressure. Which is inside the alveoli is not overcome. There will be no positive flow.
So this pressure drop is spent to counterbalance intrinsic peep and so you see in this case. This patient is wasting at every breath six centimeters of water of pressure just to generate flow. So we studied this problem in ten mechanically ventilated patients actually not all of them were copd.
But its something you end up seeing frequently in many ventilated patient. Even yang without a story and history of of copd. We compare the pressure support and nava and weve studied sequential levels of extrinsic peep applied to the airways.
So from 12. Sorry from 2 up to 14 centimeters of water of positive and expiratory pressure in pressure. Support and nava.
What did we find first of all we found that the application of extrinsic peep would lead would lead so would lead both in pressure support and nava to decrease in the auto peep which you can or intrinsic peep. Which you see here as these once again drop in esophageal pressure. And this is an expected result.
But its just to show you that our population behaves like what you would expect weve also shown that this level of intrinsic peep is mirrored. We had both edi catheter and esophageal catheters in these patients is mirrored on the edi. Which is exactly almost symmetrical to the esophageal pressure.
And as you see here. We have a given level of edi. Which we called intrinsic edi or otto edi to comply with the reviewers request that we that the patient has to generate before he is able or she is able to trigger the ventilator and so you see that you can actually see the same phenomenon of the decrease of intrinsic peep by looking at these intrinsic edi or otto edi which is just this level of edi that you have once the flow starts and not surprisingly.
There is a tight correlation between the level of intrinsic edi and the level intrinsic peep. So much so that one of the conclusions of our work. Is that so fragile pressure is out of discussion.
The gold standard to track the spontaneous breathing activity of the patients. But if you want you may want to use edi catheters as well leading to similar findings. Another finding of our study.
When we looked at these increase of the increase of extrinsic peep applied is this one this on this line is the peak level of edi or peak level of primos. So basically is the peak level of inspiratory effort during every single tidal volume.
And what you see here is that as soon as we increase in extrinsic peep. The inspiratory activity of the patient decreases because he has to waste less pressure to overcome intrinsic peep and so overall. The total level of pressure that the patient needs to generate is lower.
So you see for example here. You have 10 centimeters of water of peak inspiratory. Pressure.
And which as soon as we apply a string sig peep drops down to 6 centimeters of water so really applying an intrinsic peep allows to improve patient ventilator synchrony and to decrease the total work of breathing of the patient another way of looking at the presence of intrinsic peep by an edi catheter is to look at here the delay between the onset once again of the edi signal. And the inspire ettore flow and roughly speaking. Weve seen that when this delay over is above 80 milliseconds then we start to have quite.
I would say clinically. Significant relevant levels of intrinsic people and well. This is just to show you that that increased peak in pea mosque.
And edi which ive shown you before is not just due to a better mechanical property of the lungs. But is it is really due to the presence of the intrinsic peak. Another maybe its not funny.
But interesting thing weve seen is how intrinsic peep has some strange effects on ventilation such as nava. Which clearly as ive shown you improves the patient ventilator synchrony when the when the neural trigger is used as opposed to the pneumatic trigger. But sometimes if you have intrinsic and nava you could see some strange waveforms in the airway pressure like this and it took us a while to realize why was that why this was the case but the patient has a given intrinsic peep meaning that the pressure in the alveolus is higher than the peeps of for example is lets say eight centimeters of water while here.
We have four centimeters of water in the ventilator. Then what happens here at this point that the ventilator is detecting. A neural trigger coming from the patient.
So the ventilator realises that it has to deliver flow. Because it has been triggered and so it closes. The expiratory valve.
But as soon as this happens we see the intrinsic peep. The airway pressure goes up because of the intrinsic peep and so that the ventilator has to wait for a while allow the pressure to go down. And then it will give flow again so its rather strange pattern.
Very typical of of nava. But if you are starting to use this ventilatory mode especially in patients. With with copd and intrinsic peep.
You might see it the the most i mean the worst condition causing. Which is caused by intrinsic peep is the present is the presence of ineffective efforts. So when intrinsic peep is that high that the patient is not able to trigger the ventilator.
The ventilator will recognize only every other for example trigger coming from the patient. And so here. The patient is tried to trigger the ventilator.
But the only things he is able to achieve is a bump on the flow curve because the the over the auto peep is too high to be overcome and so getting to the conclusion intrinsic peep is certainly relevant in copd and no copd patient is relevant both during mechanic control ventilation and assisted ventilation. Although the effects are ultimately different in these two conditions. And i think that the possibility of monitoring physic peopie.
Is official pressure or as emg are getting closer and closer to the bedside and so hopefully. We will be able to understand more and use it more these tools in our clinical practice. Thank you very much for your attention applause .
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