Become a Creator today!Start creating today - Share your story with the world!
Start for free
00:00:00
00:00:01
Initial Management Of ARDS
11 Plays6 years ago
Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure that affects approximately 200,000 patients each year in the United States, resulting in nearly 75,000 deaths annually. In this episode of Critical Matters, our guest Dr. R. Phillip Dellinger discusses the current management of patients with ARDS. Dr. Dellinger is a recognized thought leader in the field, a prolific author, an accomplished researcher, and the recipient of multiple awards for his contributions to critical care.
ADDITIONAL RESOURCES:
The PROSEVA clinical trial showed that in patients with severe ARDS prone position ventilation improved mortality: https://bit.ly/2Dp3LdS
The ACURASYS clinical study showed that in patients with severe ARDS 48 hours of neuromuscular blockade was associated with improved mortality: https://bit.ly/2FqI7Zn
The EOLIA study was stooped early for futility. However, many think that it still has important findings regarding the use of ECMO in severe ARDS: https://bit.ly/2QI1Cxu
BOOKS MENTIONED IN THIS EPISODE:
Evidence-Based Critical Care: A Case Study Approach: https://amzn.to/2PYeD8V
Recommended
Transcript
Introduction to Critical Matters Podcast
00:00:09
Speaker
Welcome to Critical Matters, a sound critical care podcast covering a broad range of topics related to the practice of intensive care medicine.
00:00:17
Speaker
And now, your host, Dr. Sergio Zanotti.
Understanding ARDS: Impact and Research
00:00:23
Speaker
Acute respiratory distress syndrome, ARDS, is a severe form of respiratory failure that affects approximately 200,000 patients each year in the United States, resulting in nearly 75,000 deaths annually.
00:00:36
Speaker
Over the last decades, tremendous efforts and research have advanced our understanding and improved our treatment of patients with ARDS.
00:00:44
Speaker
However, the mortality and morbidity of ARDS remains high.
Expert Insights with Dr. R. Philip Dellinger
00:00:48
Speaker
In today's episode of Critical Matters, our guest, Dr. R. Philip Dellinger, will share with us his thoughts on the current management of patients with ARDS.
00:00:58
Speaker
Dr. Philip Dellinger is Professor of Medicine and Distinguished Scholar at Cooper Medical School of Rowan University.
00:01:04
Speaker
He is Senior Critical Care Attending and Director of the Cooper Research Institute at Cooper University Health.
00:01:10
Speaker
Dr. Dellinger is a prolific author and researcher.
00:01:13
Speaker
He co-edited the second, third, and fourth edition of Critical Care Medicine, a major textbook published by Mosby, and co-edits the fifth edition to be published in early 2019.
00:01:22
Speaker
He is associate editor of Critical Care Medicine, the journal, and he has received multiple accolades for his contributions to Critical Care Medicine, including being inducted as a Master Fellow in the College of Critical Care Medicine in 2012,
00:01:39
Speaker
being a past president of the Society of Critical Care Medicine, and being the recipient of the Society of Critical Care Medicine Lifetime Achievement Award in 2015.
00:01:48
Speaker
Dr. Dellinger was the lead author of the 2004, 2008, and 2012 Surviving Sepsis Campaign International Guidelines on the Managed Severe Sepsis and Septic Shock, and a senior author on the most recent guidelines.
00:02:01
Speaker
He also has a long history of publishing research and editorial comments in research in ARDS.
00:02:09
Speaker
But most importantly, Dr. Dellinger has been a phenomenal teacher, a great mentor, and is a dear friend.
00:02:16
Speaker
Those who have grown under him in the world of critical care affectionately refer to him as Dr. D. Dr. D, welcome to Critical Matters.
Defining ARDS: The Berlin Definition
00:02:25
Speaker
Thank you, Sergio.
00:02:27
Speaker
It's a pleasure to be here.
00:02:29
Speaker
So today the topic is ARDS, and I think that as many of the things that we preoccupy ourselves with in critical care, ARDS is a syndrome, and that has a
00:02:39
Speaker
presented its challenges in terms of definitions and making sure that we're recognizing the right patients.
00:02:44
Speaker
So why don't we start with definitions, a little bit maybe of historical perspective, and maybe talk about the most current definition or the Berlin definition.
00:02:55
Speaker
Certainly.
00:02:58
Speaker
The first consensus definitions for ARDS chose to differentiate
00:03:08
Speaker
lung infiltrates and hypoxemia due to left-sided heart barrier from infiltrates and hypoxemia due to acute lung injury and therefore required not having left-sided heart barrier infiltrates on both sides of the lung severe hypoxemia and acute
00:03:36
Speaker
The more recent Berlin definitions have attempted to offer some clarifications for benefit of the clinician, in particular, recognizing the fact that ARDS, or acute respiratory distress syndrome, can occur
00:04:02
Speaker
on top of some degree of left-sided heart barrier and therefore not having left-sided heart barrier as an exclusion factor.
00:04:12
Speaker
Furthermore, instead of dividing this non-cardiac lung injury into acute lung injury as it previously was defined as being between
00:04:33
Speaker
200 and 300 and ARDS as being less than 200.
00:04:42
Speaker
It uses ARDS only and divides it into severe, moderate and mild.
00:04:51
Speaker
And in terms of the Berlin definition, can you comment also on the
00:04:57
Speaker
the
Recognizing and Intervening in ARDS
00:04:58
Speaker
timing issue.
00:04:58
Speaker
I think that that's very important, right, because there used to be some variations in what we consider acute.
00:05:04
Speaker
Any comments on that, Dr. Dellinger?
00:05:07
Speaker
Yeah, so the previous definition said acute, but didn't offer any parameters around the acute.
00:05:15
Speaker
The Berlin definitions defined acute as within seven days and with an identifiable trigger.
00:05:24
Speaker
There has to be some
00:05:26
Speaker
some evidence of some type of an acute event that could be a trigger.
00:05:32
Speaker
And I think that another aspect that is often not discussed with progress in terms of the Berlin definition is that they also evaluated other potential physiologic parameters, but ultimately used a cohort of patients to try to test these definitions out and see if there was any ability to discriminate at a higher level at the bedside.
00:05:53
Speaker
So that's also something that we've seen with new definitions for sepsis that seems to be a work in progress, although these definitions still obviously work.
00:06:01
Speaker
are not perfect.
00:06:05
Speaker
That is correct.
00:06:06
Speaker
So can we talk a little bit more, Dr. Dellinger, about the mild, moderate, and severe?
00:06:12
Speaker
Because I think that there's also implications in terms of treatment, prognosis, and just to make sure that our audience is very clear on that, you have classified mild as being a PaO2 over FiO2 between 200 millimeters of mercury and 300 millimeters of mercury, and that is with a PEEP or CPAP of fiber grader, correct?
00:06:38
Speaker
Correct.
00:06:39
Speaker
Moderate would be 100 millimeters of mercury to 200 millimeters of mercury with the same characteristics of the PaO2 over FiO2 ratio, and severe would be a PaO2 over FiO2 ratio that is equal or less to 100 with a PEEP of 5 or more.
Severity Correlations and Outcomes in ARDS
00:06:57
Speaker
So is there a correlation between these three in terms of outcomes?
00:07:02
Speaker
Any comments on that, Dr. D.?
00:07:04
Speaker
You know, clearly, I don't have the table in front of me, but the PaO2-FiO2 ratio was clearly correlated with the increasing severity as the PaO2-FiO2 ratio got lower in these three classifications.
00:07:31
Speaker
So we have the benefits of technology.
00:07:33
Speaker
I'll bring up the table for you real quickly, but go ahead.
00:07:37
Speaker
Yeah, so, and when they added other things, it really didn't improve the performance of the predictor very much.
00:07:49
Speaker
So what they found when they published this was that the mortality for the large cohort with the mild definition was 27%.
00:07:58
Speaker
with a duration of mechanical ventilation on average of five days, for the moderate, 32%, with a duration of mechanical ventilation of seven days, and for the severe, for a mortality of 45%, with an average duration of mechanical ventilation of nine days.
00:08:15
Speaker
So like you stated, there was no added benefit in discriminating those different mortality groups if you added more complex aspects to the definition, right?
00:08:27
Speaker
That's correct.
00:08:28
Speaker
And I think that this is important for our audience because there is value in terms of making sure that you understand where your patient falls.
00:08:37
Speaker
And I think that we'll talk a little bit more further on.
00:08:41
Speaker
There might be implications of what are the type of therapies that you might be thinking of based on this mild, moderate, and severe classification.
00:08:49
Speaker
So these will be added to the show notes.
00:08:51
Speaker
Now, let me ask you, Dr. D., how do you...
Diagnosing ARDS Effectively with Dr. Dellinger
00:08:55
Speaker
implement these definitions when you're seeing patients at the bedside.
00:09:00
Speaker
So I think that one of the problems is that we probably under-recognize ARDS or not calling it as such.
00:09:05
Speaker
We just talk about respiratory failure, but we might be missing patients that may be a little bit sicker if we actually thought about it in a more rigorous way.
00:09:12
Speaker
So how do you make this operational as a clinician?
00:09:18
Speaker
So I do it a little bit differently than I
00:09:21
Speaker
perhaps the textbook response would be, I tend to apply the ARDSnet therapeutic approach with the low tidal volume and PEEP setting and then see where my patient falls and make decision based on PAO2, FiO2 ratio
00:09:49
Speaker
for additional therapeutic intervention.
00:09:55
Speaker
I think it's very difficult to try to assess the PAO2-FIO2 ratio out front because a patient, you may be called to see a patient that's being totally inappropriately treated is on
00:10:18
Speaker
minimal or no therapeutic PEEP, has terrible oxygenation, is on various amounts of FiO2.
00:10:30
Speaker
So to me, it's more helpful to try to standardize my patients.
00:10:36
Speaker
So I think that if I'm hearing you correctly, a way to approach this at the bedside would be to think about
00:10:44
Speaker
When you're trying to make a diagnosis of ARDS, maybe think about the timing first.
00:10:48
Speaker
Has this occurred in the last seven days?
00:10:51
Speaker
Look at your chest imaging.
00:10:53
Speaker
Do you have bilateral infiltrates that are not fully explained by effusions, lung collapse, or nodules?
00:11:00
Speaker
Think of the origin of the edema, and that was an important point you made earlier, that it doesn't mean that you can't have some degree of heart-induced cardiogenic edema, but what you really are looking for is respiratory failure that's not fully explained by cardiac failure or fluid overload.
00:11:18
Speaker
Or I would even say that you think it's predominantly not related to cardiac, because if you think it's predominantly related to cardiac, then...
00:11:29
Speaker
the therapy should target the left-sided filling pressures.
00:11:34
Speaker
And I think that exactly, and I think that if those three are met, you then kind of optimize mechanical ventilation or step one, and then you make an evaluation of how severe the oxygenation problems are, and that gives you a mild, moderate, severe, which I think is a great way to think about it because at the end of the day, as we'll talk probably a little bit later, we can only help people by applying some of the basic evidence-based mechanical ventilation concepts to all these patients.
Mechanical Ventilation Strategies for ARDS
00:12:02
Speaker
Yeah, and can I give an example very quickly?
00:12:05
Speaker
If I come to the bedside of a patient that had a PaO2, FiO2 ratio of 80, but they haven't had any PEEP therapy applied, and when I exact the ARGNET initial ventilator setup strategy,
00:12:28
Speaker
and the PAO2, FiO2 ratio on 14 of PEEP goes to 210 versus 14 of PEEP, it's still in the toilet.
00:12:45
Speaker
You know, that's two very different patients that require two very different approaches.
00:12:52
Speaker
And I think that's a very, very important point.
00:12:54
Speaker
But I think that these definitions clearly can help our clinicians at the bedside think about these patients.
00:13:00
Speaker
But I think that the point of really making the final assessment of degree of severity and mild, moderate, severe should be after you have done some basic interventions that provide a baseline of what would be evidence-based.
00:13:13
Speaker
So I think that would be a great
00:13:15
Speaker
segue into talking about mechanical ventilation and ARDS.
00:13:19
Speaker
And I think that, how would you define in broad terms, Dr. D, the goals here?
00:13:28
Speaker
Well, I think the goal is to minimize overinflation and minimize collapse of lung at end expiration of
00:13:43
Speaker
due to inadequate PEEP settings.
00:13:49
Speaker
And that is what we traditionally have referred to as ventilator-induced lung injury, volutrauma, atelectotrauma, and I guess that's where this whole concept of protective lung strategy comes from.
00:14:00
Speaker
Correct.
00:14:03
Speaker
How would you do that?
00:14:04
Speaker
So how would you implement a protective lung strategy?
00:14:06
Speaker
What does the evidence tell us that we should be doing all these patients?
00:14:11
Speaker
So I think step one is to go as quickly as possible to six mLs per kilogram predicted body weight.
00:14:24
Speaker
If someone is on 12, for example, when you begin ventilator strategy, you would not go from 12 to six because you want to make sure it's tolerated.
00:14:39
Speaker
So you would decrease 12, 10, 8 with the goal of getting to six.
00:14:45
Speaker
But as you go down, you'll need to make decisions about tolerance by the patient.
00:14:54
Speaker
But I think you take your patient to six mLs per kg and then you PEEP set.
00:15:00
Speaker
And you look for the PEEP setting that gives you, with that fixed tidal volume, the PEEP setting
00:15:08
Speaker
that gives you the optimum balance of overinflation and not having excessive atelactasis at end expiration.
00:15:26
Speaker
So as you go up on PEEP,
00:15:29
Speaker
you're going to induce some overinflation in some areas of the lung that have relatively normal compliance, but you're also going to open up lung that was previously closed and also create better compliance in lung units as you increase the volume in the alveolus.
00:15:54
Speaker
So you're looking for that sweet spot with your PEEP
00:15:59
Speaker
that gives you the best balance of minimizing adalecta trauma or lung collapse at end expiration and avoiding overinflation.
00:16:15
Speaker
So we spoke about using the low tidal volume and you said how you would get there.
00:16:19
Speaker
For example, somebody was at a higher tidal volume when you first saw them.
00:16:22
Speaker
What if you happen to intubate the patient?
00:16:25
Speaker
Do you usually start around eight and then go down?
00:16:28
Speaker
Do you start at six and see if they tolerate it?
00:16:30
Speaker
If this is a newly intubated patient that you suspect has ARDS?
Analyzing PEEP Settings in ARDS
00:16:35
Speaker
Yeah.
00:16:35
Speaker
So it depends on, you know, how severe the hypoxemia is.
00:16:40
Speaker
If
00:16:41
Speaker
If the patient looks like they're trying to die on me from hypoxemia, I'll have a mental image of the chest X-ray and how bad it looks.
00:16:53
Speaker
I'll know what the oxygenation was on high-frequency nasal cannula oxygen.
00:17:02
Speaker
And then I'll say, I don't have time to be ginger with my PEEP application, so I'm just going to start
00:17:11
Speaker
at 12, and ideally, in the best possible worlds, you would like to start low and use incremental recruitment by going up slowly on peak
00:17:36
Speaker
in order to make that decision on where's my sweet spot for PEEP.
00:17:42
Speaker
If you have a patient that's now getting six mls per kg predicted body weight title volume, and you go from a PEEP of eight to a PEEP of 10 to a PEEP of 12 to a PEEP of 14 to a PEEP of 16 to a PEEP of 18, and as you go, there's, there's,
00:18:07
Speaker
a variable called driving pressure, which is the difference between the PEEP and the plateau pressure measured with an inspiratory hold, where at the end of inspiration, instead of opening the expiratory valve and closing the inspiratory valve, you
00:18:32
Speaker
you close the inspiratory valve and you don't open the expiratory valve and that gives you an end inspiratory pause pressure, which is an estimate of the alveolar pressure at end inspiration.
00:18:46
Speaker
And the difference between the total PEEP, which is typically the set PEEP, in the plateau pressure is driving pressure and that represents compliance.
00:19:03
Speaker
with a fixed tidal volume, and in the absence, with a fixed tidal volume, the driving pressure represents compliance, and the lower the driving pressure, the better the compliance.
00:19:20
Speaker
So if you look for the PEEP that gives you the lowest driving pressure, that would tell you that you're in that sweet spot
00:19:33
Speaker
for opening up lung on one hand and overinflation on the other.
00:19:41
Speaker
And as a point of reference, I mean, the value that people talk about for driving pressure is usually to have it below 15, like 13 to 15.
00:19:49
Speaker
It would be a good target, correct?
00:19:53
Speaker
Correct.
00:19:54
Speaker
I think that, you know, there's database data looking at
00:19:59
Speaker
you know, what driving pressures give better outcomes, and that is a range of driving pressures that you would like to reach.
00:20:09
Speaker
In actuality, as long as you can improve by decreasing driving pressure, by definition, you know, you are improving compliance.
00:20:22
Speaker
Now, someone might say you're improving compliance, but some
00:20:29
Speaker
at some expense of more overinflation by definition,
00:20:35
Speaker
So maybe you just leave good enough alone if you get it to 13 to 15.
00:20:40
Speaker
And I think that the other measurement that we didn't touch on, which I think is part of this conversation, is just looking at your plateau pressures.
00:20:49
Speaker
And can you talk a little bit about the airway plateau pressure, what it means?
00:20:54
Speaker
And you talked about how you measure it already, but what numbers should we be targeting in patients with ARDS?
00:21:01
Speaker
Yeah, so you'd like to have a plateau pressure
00:21:04
Speaker
no higher than 30 the general feeling is that the lower the plateau pressure the better but the plateau pressure is going to be determined by your peep or total peep and your tidal volume if if your plateau pressure certainly if it's higher than 30
00:21:31
Speaker
you would want to further decrease your tidal volume.
00:21:39
Speaker
You can see that there's interaction between decreasing the tidal volume to decreasing plateau pressure and driving pressure.
00:21:50
Speaker
So you can decrease driving pressure by decreasing tidal volume.
00:21:58
Speaker
But the beauty of the driving pressure is you want to have a fixed tidal volume and see what the best driving pressure is at that fixed tidal volume.
00:22:12
Speaker
And I think that you mentioned compliance as well, Dr. Dellinger, and just to review for our audience, static compliance is usually the tidal volume divided by the difference between your plateau pressure and your total PEEP.
Protective Lung Ventilation Parameters
00:22:29
Speaker
So what you're saying is that really from a practical standpoint, if your tidal volume is fixed,
00:22:35
Speaker
all you should be looking at or what you can be using at the bedside is the plateau pressure minus the total PEEP, which is your driving pressure.
00:22:42
Speaker
Is that correct?
00:22:44
Speaker
Correct.
00:22:45
Speaker
You don't have to actually calculate static compliance because you've already decided what tidal volume that you want to use.
00:22:57
Speaker
And therefore, without calculating the
00:23:04
Speaker
mLs per centimeter of water, you know that when driving pressure is going down, that compliance is improving, and when driving pressure is going up, compliance is worsening because you have a fixed tidal volume.
00:23:22
Speaker
Excellent.
00:23:23
Speaker
So I think to cap this part, clearly every patient with ARDS should receive a protective lung ventilation.
00:23:30
Speaker
And so far, what we talked about is three very important parameters that we should follow at the bedside.
00:23:35
Speaker
One is your tidal volume in mls per kg of predicted body weight, which, as our audience might recall, is not the same as ideal body weight, and it's calculated from your height.
00:23:47
Speaker
Number two is a plateau pressure of 30 or below, understanding that if it's above 30, we should probably do something to decrease it.
00:23:56
Speaker
And number three is to keep an eye on this driving pressure, which is the plateau pressure minus the total PEEP, to try to figure out what is the sweet spot for the ideal amount of PEEP in terms of
00:24:10
Speaker
preventing derecruitment of collapsed lung units, but also preventing overdistension of those lung units that are already open.
00:24:18
Speaker
Now, Dr. D, how would you incorporate or add to this your ABG?
00:24:23
Speaker
What are the targets that you're looking at in your ABG in terms of for your ventilation and oxygenation?
00:24:31
Speaker
Yeah.
00:24:32
Speaker
Sergio, could I, I think it's, we need to make one other real important point that
00:24:38
Speaker
when you just did that very nice recap, I realized the plateau pressure of 30 or less with even lower being making you feel better is that that is based on normal body habitus and that if you have a very morbidly obese or obese patient or a very anisarka-laden
Permissive Hypercapnia in ARDS Treatment
00:25:05
Speaker
patient,
00:25:06
Speaker
then that plateau pressure is not only pushing out lung, but it's pushing out the chest wall and the abdomen.
00:25:15
Speaker
And you can allow higher plateau pressures in those circumstances.
00:25:22
Speaker
You have to sort of eyeball it unless you are measuring esophageal pressure, which would give you a little better handle.
00:25:31
Speaker
That's not routinely done.
00:25:33
Speaker
I can tell you, I don't routinely monitor esophageal pressure.
00:25:36
Speaker
But I just say, you know, in this morbidly obese patient, that plateau pressure of 34 is just fine, and I'm going to leave it alone.
00:25:47
Speaker
Okay.
00:25:47
Speaker
I think that's a great point.
00:25:49
Speaker
And I think that with obesity, just recognizing that the size of your lungs might not change.
00:25:56
Speaker
That's a function of height.
00:25:58
Speaker
But the compliance and the effect of the chest wall and everything we're measuring can be dramatic.
00:26:04
Speaker
taking that into account like a dunges you mentioned is very important.
00:26:10
Speaker
So what would you say for the ABG?
00:26:12
Speaker
What are your goals or your parameters that you're looking at?
00:26:15
Speaker
What should be the targets to complement that with the measurements that we're doing at the vent side?
00:26:23
Speaker
So you anticipate in the more severe ARDS patients
00:26:28
Speaker
that you're gonna be using this low tidal volume in all of them and maybe even lower in some, you can decrease it all the way to four mLs per kg predicted body weight to get that plateau pressure down.
00:26:44
Speaker
But that's gonna decrease your minute ventilation and that's gonna decrease your alveolar ventilation and that's going to decrease
00:26:54
Speaker
your ph so we're going to go into permissive hypercapnia you can increase the ventilator rate to compensate for some of that low tidal volume but you may need to accept ph's i feel comfortable with 725 or more sergio with some exceptions you don't want a high pa co2
00:27:21
Speaker
with increase intracranial pressure or perhaps even severe pulmonary hypertension.
Oxygenation and Saturation Targets
00:27:27
Speaker
But you should anticipate in most patients willingness to accept a 72573 or less.
00:27:38
Speaker
And for the PAO2, we typically use saturation targets of
00:27:50
Speaker
88% are higher in more severe ARDS and less severe ARDS where you can build in a little safety cushion for mucus plugging.
00:28:01
Speaker
You might want to run it more in the 94, 96 if you can do that with reasonable oxygen FiO2.
00:28:16
Speaker
So I think those are very important parameters.
00:28:18
Speaker
And I think that, like you said, you mentioned esophageal and pressure monitoring, but that is not commonly done, might be something that in some situations
Effective Use of Mechanical Ventilation
00:28:27
Speaker
might be useful.
00:28:27
Speaker
But for most of our providers practicing in the community, by following the
00:28:33
Speaker
plateau pressure, making sure that they have the right tidal volume based on predictive body weight, following the driving pressure, and then following the gas, you can really, I mean, target your mechanical ventilation very adequately, and I think that that's what we should be doing in every patient.
00:28:50
Speaker
Let me ask you a little bit.
00:28:51
Speaker
We talked about people a little bit, Dr. Dellinger.
00:28:54
Speaker
You talked about that incremental increase by a factor of two, trying to find the sweet spot with the driving pressure.
00:29:02
Speaker
What about recruitment maneuvers?
00:29:04
Speaker
Where do we stand today with recruitment maneuvers?
00:29:07
Speaker
Yeah.
00:29:09
Speaker
So I think, you know, I was a, I'm a big fan of ESPN 30 for 30.
00:29:17
Speaker
And I must admit, for years, I was a big fan of the 40 for 40 recruitment maneuver, which was applying 40 centimeters of water CPAP
00:29:31
Speaker
for 40 seconds to try to open up atelectatic lung and then find the PEEP that holds that.
00:29:41
Speaker
There was a study published in 2017 that used much more exaggerated recruitment pressures and times repeatedly that produced worse outcome when PEEP was set with recruitment
00:29:58
Speaker
maneuvers, but these were really dramatic, sustained, high pressures.
00:30:05
Speaker
I think when you take the approach of, I'm going to go with my fixed low tidal volume, I'm going to go to eight a peep and leave it there for three to five minutes if you can.
00:30:23
Speaker
and then I'm going to look at driving pressure, and then I'm going to go to 10 for three to five minutes and look at driving pressure and oxygenation, and then 12 and then 14.
00:30:31
Speaker
You know, that is allowing the incremental increase in PEEP to do your recruitment for you.
00:30:42
Speaker
And I also, you mentioned that, you know, we're really,
00:30:48
Speaker
Figuring the bedside practitioner that maybe doesn't treat a lot of ARDS will be listening to this podcast.
00:30:57
Speaker
And if you say, you know, all this driving pressure stuff is just too darn confusing for me, is there an alternative that's simpler?
00:31:08
Speaker
And the alternative would be just to use the ARSnet PEEP table and look at where your
00:31:17
Speaker
your PAO2 is and where your FiO2 is and see if you're in a box.
00:31:27
Speaker
And if you're not in a box, then you're either too high or too low and you just look for, you adjust PEEP to get your FiO2 down.
00:31:40
Speaker
And that's been done in some of the ARGNET trials.
00:31:43
Speaker
So there's certainly nothing wrong with that approach.
00:31:48
Speaker
There are two PEEP tables, one for patients that have the moderate or severe ARDS, that's called the higher PEEP table, and a PEEP table for the mild ARDS, that's called the standard PEEP table.
00:32:04
Speaker
But you can just find whether you're on the right PEEP by finding yourself in these tables.
00:32:14
Speaker
So I think that we will add those tables to the show notes, but I think that...
Review of PEEP Strategies: Maneuvers and Adjustments
00:32:20
Speaker
It's a great point that you talked about the ART trial that was published last year that really showed significant increase in mortality with these very aggressive and very prolonged recruitment maneuvers, which is really not what most people are doing in the clinical setting today.
00:32:37
Speaker
But it seems that as of now, your preference, Dr. D, and what the literature would support is either an incremental raise and peep
00:32:46
Speaker
using driving pressure and other parameters to find the sweet spot, or simply recurring to the ARDS net PEEP table and just making sure that for the given PAO2, FiO2, you have the right PEEP.
00:33:00
Speaker
Is that correct?
00:33:02
Speaker
That is correct.
00:33:03
Speaker
And the old logic was that there's probably some lung that you can only open up
00:33:13
Speaker
with much higher pressures than you're going to get to with the incremental recruitment where PEEP is the recruitment.
00:33:23
Speaker
When I trained, there was no recruitment maneuver.
00:33:30
Speaker
No one talked about recruitment maneuver, but we were recruiting just by increasing the PEEP with fixed title volume.
00:33:38
Speaker
You continue to raise your end inspiratory pressure
00:33:43
Speaker
through the raising the end expiratory pressure with fixed tidal volume.
00:33:48
Speaker
And is there still a place for some patients in whom you would do the 40 of CPAP for 40 seconds?
00:33:55
Speaker
Or that's really something that you have walked away from?
00:33:59
Speaker
No, I'll still do it.
00:34:01
Speaker
I'll do it when I get a fresh ARDS patient that's trying to die from hypoxemia.
00:34:09
Speaker
You know, I'll just go straight to a
00:34:13
Speaker
40 for 40 recruitment maneuver or in a patient that's already has high plateau pressures, I would even be willing to do 50 for 40.
00:34:24
Speaker
Just for when I feel like I've got just so much boggy atelectatic lung that's trying to take my patient down and I just want to do something to open it up and then go to a higher peak than I would typically
00:34:41
Speaker
use with the incremental PEEP recruitment.
00:34:43
Speaker
So I might do 40 for 40, get a big bang boost in my oxygenation and just throw a PEEP of 12 or 14 in to see if I can hold it.
00:34:56
Speaker
And I think that it's probably good advice also for our audience to realize that this has potential complications.
00:35:05
Speaker
You want to talk a little bit about the dangers of high PEEP, of a high recruitment maneuver, Dr. D?
00:35:10
Speaker
Yeah, so we've always realized that PEEP is a huge offender for increasing intrathoracic pressure because we spend most of our respiratory cycle in expiration.
00:35:22
Speaker
So when you raise expiratory pressure, has a major effect on intrathoracic pressure.
00:35:29
Speaker
So as you increase intrathoracic pressure, you increase the right atrial pressure
00:35:38
Speaker
because of pleural pressure.
00:35:40
Speaker
So it goes, intrathoracic pressure, pressure goes to pleural space, pleural space wraps around the mediastinum.
00:35:49
Speaker
That raises the right atrial pressure because it's thin walled.
00:35:54
Speaker
And therefore your downstream pressure for right heart filling is decreased.
00:35:59
Speaker
So you decrease venous return to the right heart by increasing intrathoracic pressure with PEEP.
00:36:08
Speaker
Luckily, in ARDS, lungs are poorly compliant, so you don't get as much of that intrathoracic pressure transferred to the right atrium because the ARDS actually protects the transmission to the pleural space.
Complications of High PEEP and Maneuvers
00:36:29
Speaker
But you certainly get some, and often you're dealing with septic shock and you're dealing with bad ARDS.
00:36:37
Speaker
And as you crank up the PEEP, you anticipate you're going to need to compensate for that by increasing the pressure in the large veins outside the thorax, which is the upstream pressure for blood return to the right heart by giving fluid.
00:36:56
Speaker
So it may be PEEP increased fluid, PEEP increased fluid, PEEP increased fluid.
00:37:03
Speaker
Inseptic shock.
00:37:05
Speaker
Now, if the patient's not in septic shock, you don't need to be as vigilant, but you would need to recognize that if the blood pressure goes down, not only do you need to think of pneumothorax, but you also need to think of decreased blood return to the heart and how fluid might be the next step.
00:37:31
Speaker
So what about... And recruitment... Go ahead.
00:37:33
Speaker
Recruitment is just...
00:37:35
Speaker
is a really big increase.
00:37:38
Speaker
When PEEP increases intrathoracic pressure, adding a high end inspiratory pressure just further increases intrathoracic pressure, and you worry about a recruitment maneuver being even a bigger insult than would incremental increases in PEEP.
00:38:02
Speaker
and you worry about pneumothorax with the hyperinflation.
00:38:09
Speaker
So I think that we covered, Dr. D, a lot of territory in terms of what we believe every patient with ARDS should receive in terms of initial mechanical ventilation.
00:38:20
Speaker
We talked about some of the parameters that the clinician should be following at the bedside, the things that we should be worried about.
00:38:27
Speaker
But refractory hypoxemia will be the
00:38:31
Speaker
The topic of a future episode, because I think we could talk about that for another hour.
00:38:37
Speaker
But I do want to just ask you, in terms of those patients, that we maximize the low tidal ventilation, we optimize PEEP.
00:38:48
Speaker
We have them on the ARDS network protocol and are still either having severe hypoxemia, high plateau pressures, or persistent respiratory acidosis.
00:39:02
Speaker
What are the next steps that you would consider in terms of step two and three based on evidence right now?
00:39:10
Speaker
Yeah.
00:39:11
Speaker
So two things.
00:39:14
Speaker
Yeah.
00:39:15
Speaker
One is I follow the, not surprisingly, I follow the surviving sepsis campaign guidelines.
00:39:24
Speaker
So I use neuromuscular blockers in all patients with a PaO2, FiO2 ratio of less than 150 or maybe 150 or less.
00:39:45
Speaker
And I do that to take the patient's inspiratory effort away to avoid overinflation, which is the potential proposed mechanism for why two days of neuromuscular blockers in one large study did improve outcome.
00:40:07
Speaker
So until there's contrasting evidence, I will use
00:40:11
Speaker
neuromuscular blockers for two days.
00:40:17
Speaker
And I use prone positioning in that same patient group with the PAO2-FIO2 ratio of 150 or less.
00:40:29
Speaker
And do you do the prone positioning, Dr. D, after you do the neuromuscular blockers?
00:40:35
Speaker
I would.
00:40:37
Speaker
And how long would you prone somebody?
00:40:39
Speaker
I would.
00:40:41
Speaker
You know, first time, typically 16 hours, 16, 18 hours.
00:40:48
Speaker
And then by 16 to 18 hours, you would anticipate that there would be sustained improvement.
00:40:56
Speaker
Well, the first thing is, if I prone the patient, I'll only leave them prone if it improves oxygenation.
00:41:03
Speaker
And certainly, if it worsens oxygenation, as can't happen, I flip them back in a hurry.
00:41:09
Speaker
But assuming it improves oxygenation, I'll leave them 16, 18 hours and then put them back supine.
00:41:15
Speaker
You know, sometimes just one proning session, they fly.
00:41:22
Speaker
But if they slowly deteriorate again, then they're headed back for another 16 to 18 hour proning session.
00:41:32
Speaker
And I think it's important for the audience to also understand that both of these interventions that you have referred as being things you utilize in patients who are moderate to severe ARDS with low PAO2, 502 ratios have been shown in large randomized trials to improve mortality.
00:41:48
Speaker
Right.
00:41:49
Speaker
So these are evidence-based interventions that as far as we know from literature that has looked at this are not probably applied to the full extent of what they could.
00:42:01
Speaker
So I think the penetration is still suboptimal.
00:42:06
Speaker
And I think a lot of clinicians are jumping to less proven therapies before they go through these steps, which I think is an important take-home message.
00:42:17
Speaker
That's correct.
Role of Steroids in ARDS Treatment
00:42:18
Speaker
I agree totally, Sergio.
00:42:20
Speaker
We'd like to also get your thoughts on adjunctive therapies for ARDS and what are some other things that we should be considering in these patients.
00:42:29
Speaker
Obviously, steroids, very similar to the story with steroids and septic shock and sepsis, seems to be a pendulum that goes back and forth with every couple of years.
00:42:39
Speaker
But where do you stand today on steroids in ARDS?
00:42:43
Speaker
What do you recommend based on the literature?
00:42:46
Speaker
Yeah.
00:42:47
Speaker
It's controversial.
00:42:49
Speaker
You know, it's still a good pro-con at a national meeting.
00:42:54
Speaker
I personally do not use steroids empirically in ARDS.
00:43:06
Speaker
There are some people that do.
00:43:08
Speaker
I think the evidence is somewhat conflicting from physiologic improvement.
00:43:17
Speaker
It's been shown to worsen outcome in influenza ARDS.
00:43:24
Speaker
I think it makes me, if I don't know what's causing my ARDS, I certainly would be very vigilant to look for steroid-responsive causes of ARDS.
00:43:37
Speaker
And if I have something to suggest a steroid-responsive cause, like
00:43:44
Speaker
eosinophilic pneumonia or some type of vasculitis or something.
00:43:50
Speaker
But I don't just give it for severe hypoxemic ARDS.
00:43:58
Speaker
And I think that you mentioned specific populations where it's been shown to actually worse outcomes, and one of those is viral influenza or viral pneumonias.
00:44:09
Speaker
Also, there seems to be some concern about rapid tapering being a problem.
00:44:15
Speaker
Any comments on that, Dr. Dellinger?
00:44:18
Speaker
Well, I think the Lazarus trial, which was when steroids were given for late ARDS,
00:44:25
Speaker
and shown not to benefit.
00:44:29
Speaker
Some people believe the reason that trial did not show benefit was the rapid taper of steroids, because a lot of those patients came off the ventilator faster, but then went back on the ventilator and ended up having bad outcomes.
00:44:46
Speaker
So, you know, if I do use steroids and ARDS, which I don't, but if I started tomorrow,
00:44:54
Speaker
I would be very cautious about how rapidly I tapered.
00:44:59
Speaker
You've also had a lot of experience research-wise and obviously clinically with inhaled nitric oxide and vasodilators.
Inhaled Nitric Oxide and Vasodilators for Severe ARDS
00:45:08
Speaker
Any role for that today in ARDS?
00:45:12
Speaker
Yeah, I guess I'm historically prominent in showing that empiric use of
00:45:21
Speaker
inhaled nitric oxide does not improve outcome in ARDS.
00:45:27
Speaker
Therefore, relegating it to patients that are dying from hypoxemia despite everything else you're doing.
00:45:36
Speaker
And I have used it for that on
00:45:40
Speaker
quite a few occasions when you just, they're just dying from hypoxemia, you've done everything else.
00:45:45
Speaker
You should have proned them by then.
00:45:47
Speaker
They should be on neuromuscular blockers, should be on ARSnet protocol.
00:45:52
Speaker
You should have looked for the sweet spot PEEP, but if you still can't get the PAO2 up, then a selective inhaled vasodilator, either inhaled nitric oxide or epoprostenol,
00:46:09
Speaker
epoprostenol i think is the choice for many institutions because it's cheaper but that's what uh that's circumstances where i would use an inhaled uh selective pulmonary vasodilator it makes sense i mean you're you're sending something that'll dilate the blood vessels in the area where you're ventilating so you
00:46:36
Speaker
You send it down to the alveolites that are open and it diffuses across and attracts the blood flow as a vasodilator.
00:46:50
Speaker
One thing that does bother me is I see a lot of patients that I pick up that have been shotgunned when they first
00:47:02
Speaker
came to the ICU trying to die from ARDS, they got everything, and they got it sort of in a cocktail and their own selective inhaled pulmonary vasodilator.
00:47:15
Speaker
And I find one of the first things I do is make sure it's making a difference.
00:47:20
Speaker
And then I just titrate that down as an isolated variable.
00:47:24
Speaker
And often I find that it's not producing
00:47:29
Speaker
significant effect, probably 40% of the time I'd say.
00:47:32
Speaker
Yeah, and I think in an era, and obviously we definitely in our practice are very conscious of providing value, so improved outcomes at lower cost, using costly therapies that provide no value is probably not a good idea.
00:47:47
Speaker
I agree totally
Fluid Restriction Approach in ARDS
00:47:48
Speaker
Sergio.
00:47:48
Speaker
Well, finally in terms of adjunctive therapies for ARDS, any comments on fluid management?
00:47:57
Speaker
Yeah, I think it's, there's reasonable evidence that a fluid conservative, fluid restrictive approach in patients that aren't in shock and don't have tissue hypoperfusion improves clinical outcomes such as getting patients off the ventilator quicker, getting them out of the ICU quicker, and it makes
00:48:27
Speaker
As we were just talking, it makes economical sense to do it.
00:48:32
Speaker
Of all the evidence-based literature, I think it's the least currently practiced in our ICUs, maybe even less than prone positioning, which is to try to minimize fluids, even to the point of giving Lasix.
00:48:54
Speaker
You know, now we don't have as many CBPs in our ICU patients, but getting the CBP down to values of very low, four or less, as long as the BUN creatinine tolerates it and urine output and blood pressure gets patients off the ventilators.
00:49:16
Speaker
And a lot of these people got a lot of fluid early.
00:49:19
Speaker
It's sort of a de-resuscitation.
00:49:21
Speaker
Sergio, I remember once,
00:49:24
Speaker
I had a patient that we were talking withdrawal of support on Friday afternoon.
00:49:30
Speaker
You came in on Saturday morning, started giving a bunch of Lasix to my patients, and I think you dried out their brain, and all of a sudden their neurologic exam perked up.
00:49:43
Speaker
Yeah.
00:49:43
Speaker
Like they say, rather be lucky than good, right?
00:49:46
Speaker
Sometimes those things work.
00:49:48
Speaker
But I think that these are all very
Applying Proven ARDS Treatment Strategies
00:49:50
Speaker
valid points.
00:49:50
Speaker
And what's very interesting from my perspective is that everybody in critical care is always very interested and concerned with the next thing that's coming down the road.
00:50:00
Speaker
Yet there is
00:50:01
Speaker
ample opportunity to implement more effectively all the things we talked about that are proven to make a difference as of the current evidence that we have today.
00:50:11
Speaker
Studies have shown that the penetration of low tidal volume in recognized ARDS patients is still
00:50:20
Speaker
So a third of patients don't get low tidal volumes and plateau pressures at below 30.
00:50:26
Speaker
So I think that all these things that we talked about today should be our first and foremost concern in making sure that we provide what really works first.
00:50:35
Speaker
And I think that, Dr. D, that we will have another opportunity to talk more about refractory hypoxemia and things that are maybe more experimental in the future.
00:50:43
Speaker
But this has been, I think, a wonderful conversation.
00:50:47
Speaker
And one of the things that we like to do at Critical Matters is also tap into the wisdom of our guest and really ask them a couple of questions that are outside of the confines of the specific topic we're discussing.
00:50:59
Speaker
Would that be okay?
00:51:01
Speaker
That would be fine.
00:51:02
Speaker
So the first question relates to books.
00:51:05
Speaker
And I would like to know what book or books have influenced you the most or what book have you gifted most often to others?
00:51:13
Speaker
I think the book that I remain impressed with to this day, because I so much enjoyed reading it and the message was the last book in the Douglas Adams Hitchhiker's Guide to the Galaxy, the book So Long and Thanks for All the Fish, which is what the dolphins said to Earth as they blasted off in a spaceship as the true
00:51:40
Speaker
supremely intelligent beings on earth realizing that the humans had sent the world to hell in a handbasket.
00:51:50
Speaker
So I like that one.
00:51:52
Speaker
Well, that's a great book.
00:51:53
Speaker
And I think that it also, this is a question that we've asked several guests.
00:51:57
Speaker
And I think that what it really always reminds me is that we learn from stories.
00:52:03
Speaker
And some of those stories are fictional stories and others are non-fictional, but there's still a tremendous amount to be learned from fictional stories as they apply to life.
00:52:14
Speaker
So we'll include a link to the book in the show notes.
00:52:17
Speaker
The second question, Dr. D., is,
00:52:21
Speaker
What do you believe to be true in medicine or in life that most other people don't believe?
00:52:25
Speaker
That if you show compassion as a physician, that it will do as much for you as it does for the patient and their family.
00:52:44
Speaker
And I think that that's an important, important lesson that sometimes in this burnout critical care environment, people tend to forget.
00:52:52
Speaker
No, it can make your day.
00:52:57
Speaker
The last question is, what would you want every intensivist that's listening to this podcast to know?
00:53:03
Speaker
Could be a quote or a fact.
00:53:06
Speaker
Yeah.
00:53:07
Speaker
So I, you alerted me to this one in advance and
00:53:14
Speaker
You know, there's a thousand.
00:53:18
Speaker
And it's easier for me just to go to something that I would want every person in the world to think about, and particularly professionals and particularly physicians that get a chance to make a difference in so many different areas.
00:53:44
Speaker
I'm a huge fan of Martin Luther King, as you know, and Gandhi.
00:53:52
Speaker
And Martin Luther King said, the ultimate test of a man or woman is not where he stands in moments of comfort and moments of convenience, but where he or she stands in moments of challenge and controversy.
00:54:12
Speaker
And I think that those are wonderful words.
00:54:14
Speaker
And like you said, I mean, definitely apply to a lot of what we do in the ICU, but to life in general.
00:54:21
Speaker
And I think that this would be a perfect place to stop.
00:54:25
Speaker
Dr. D, I would be remiss if I didn't thank you first for all you have done for my career, for my learning and critical care, and for many others.
00:54:35
Speaker
So first of all, thanks for being such a wonderful mentor and teacher for so many critical care providers, including myself.
00:54:43
Speaker
And second, thank you for the time and the willingness to share your knowledge with our audience.
00:54:48
Speaker
And we hope to have you back on Critical Matters soon.
00:54:53
Speaker
Thank you, Sergio.
00:54:54
Speaker
It was indeed my pleasure.
00:54:58
Speaker
Thanks again for listening to Critical Matters.
00:55:01
Speaker
Make sure to subscribe to this podcast on iTunes or Google Play.