My dear pulmonologists, I have some bad news. Santa Claus isn't real. Neither is “ARDS.”
“ARDS” has traditionally been conflated with a specific histopathological form of lung injury: diffuse alveolar damage (DAD). Lectures, chapters, and articles typically juxtapose these two entities, promoting the concept that they're one and the same.
But they aren't.
The ability of “ARDS” criteria to identify patients with diffuse alveolar damage has always been limited. For example, an autopsy study in 2004 suggested that “ARDS” criteria were only 75% sensitive and 84% specific for diffuse alveolar damage.1 In 2012, the Berlin re-definition of “ARDS” broadened the definition of “ARDS” by including patients with less severe hypoxemia (P/F ratio between 200-300).2 This broadening of the definition made “ARDS” less specific for diffuse alveolar damage.
So “ARDS” isn't a disease, nor is it a pathological entity. “ARDS” is an arbitrarily defined syndrome. In practice, “ARDS” is a heterogeneous conglomeration of widely disparate patients who have a host of different pathologies. For example, “ARDS” includes patients with multi-lobar pneumonia, idiopathic pulmonary fibrosis exacerbation, aspiration pneumonitis, COVID… and dozens of other conditions.
“ARDS” is a messy syndrome, with a highly problematic definition. Some problems with the traditional definition of “ARDS” include:
- The P/F ratio ignores the effects of mean airway pressure on oxygenation. Depending on how the ventilator is set, patients may or may not meet the criteria for “ARDS.”
- There is poor inter-observer agreement with regards to what constitutes bilateral infiltrates on chest X-ray, with disagreement in about a third of cases.3
- Criteria for exclusion of heart failure are increasingly subjective.
To make matters worse, the misconception that “ARDS” is a disease actually causes a lot of harm. Let's explore two ways that harm is caused by the artificial construct of “ARDS:”
First, clinicians may mistakenly believe that “ARDS” is a diagnosis. This leads to premature diagnostic closure, wherein a clinician will diagnose a patient with “ARDS” – and then stop searching further for an underlying diagnosis. This deprives the patient of an adequate diagnostic evaluation, or appropriate therapy for the cause of their respiratory failure. Diagnosing a patient with “ARDS” gives the clinician a false sense of security that they know what is going on – when in fact they have no clue what the etiology of respiratory failure actually is.
Second, the misconception of “ARDS” as a real thing leads to futile and intellectually bankrupt research studies. For example, numerous trials have been performed to determine whether “ARDS” should be treated with steroids. In reality, some patients with “ARDS” have a disease that is steroid-responsive (e.g., eosinophilic pneumonia, bacterial pneumonia, underlying asthma). Other patients with “ARDS” have a disease that is steroid-resistant (e.g., exacerbation of idiopathic pulmonary fibrosis). Therefore, asking whether steroid is beneficial for “ARDS” is a naïve, flawed question that defies any accurate answer. Different studies will obtain conflicting results, depending on the specific patient populations they enroll. And if clinicians give steroid to a patient because they have “ARDS” – that’s dangerously over-simplistic, cookie-cutter medicine.
Recently, “ARDS” has been re-defined yet again, in an even broader fashion. This alone should be a sign that “ARDS” isn't real. Real things don't undergo radical re-definition every decade. If you re-define something frequently enough, then it actually means nothing.
The latest re-definition of “ARDS” makes it even more all-inclusive than the Berlin re-definition. Now, patients on high-flow nasal cannula or noninvasive ventilation are diagnosed as having “ARDS.” Patients without an arterial blood gas measurement may be diagnosed with “ARDS.” This will make “ARDS” even more nonspecific. My hope is that this new, ridiculously broad definition of “ARDS” will force clinicians to realize that “ARDS” isn't real.
It's easy to imagine a better nomenclature system. Patients with diffuse parenchymal lung disease (DPLD) could be sub-grouped based on acuity and severity. For example, “ARDS” could be replaced by acute, severe diffuse parenchymal lung disease (AS-DPLD). Chronic interstitial lung disease would be classified as chronic diffuse parenchymal lung disease (C-DLPD). Such a nomenclature system would eliminate confusion surrounding “ARDS” and “interstitial lung disease,” while providing a unifying structure to describe diffuse parenchymal lung disease.
Unfortunately, “ARDS” will persist for now. But once we realize that “ARDS” is an artificial, heterogeneous syndrome then it will cause less harm. We can smile and wave at it, the way we would wave at Santa Claus in a shopping mall. And then we will keep walking, because we have work to do – the patient needs a thorough investigation, specific diagnosis, and tailored therapy. Real, actual, adult things.
Photo credit: by Hoang-Mai Nguyen on Unsplash
references
- 1.Esteban A, Fernández-Segoviano P, Frutos-Vivar F, et al. Comparison of clinical criteria for the acute respiratory distress syndrome with autopsy findings. Ann Intern Med. 2004;141(6):440-445. doi:10.7326/0003-4819-141-6-200409210-00009
- 2.ARDS Definition Task Force, Ranieri V, Rubenfeld G, et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012;307(23):2526-2533. doi:10.1001/jama.2012.5669
- 3.Rubenfeld G, Caldwell E, Granton J, Hudson L, Matthay M. Interobserver variability in applying a radiographic definition for ARDS. Chest. 1999;116(5):1347-1353. doi:10.1378/chest.116.5.1347
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Not only ARDS but also Sepsis has same definition proplems
Agree, both have been re-defined a lot, to the point where their precise meaning is a little dubious. But I think sepsis is more of a real entity, whereas ARDS is an artificial syndrome that doesn’t correlate with any true natural phenomenon. My guess is that in 50 years we will still be using the term sepsis, but we will eventually eliminate the term ARDS.
İs sepsis directly related to microbiologic agent ? if so Everyone meets with microbiologic agent must be critical ill patient Perhapse due to immunopathology infectıon is secondary can’t be ?
That’s what I have thought for a while now. I’m just waiting for the inevitable “Surviving ARDS” campaign to happen, with one hour non-evidence based bundles of care that we must follow or face disciplinary actions.
Great summary. I learned a lot about this very topic when I saw my first ARDS patient years back, and staff couldn’t agree with what we had, much less how to treat, or set the vent. And it didn’t get better over time. COVID didn’t help in the debate.
Could not Disagree more. Clear diagnostic criteria are important, Take a trip to the ICU and look around.
I think you may have missed the point. Read the article again slowly?
Can you elaborate a little more? outside of the coders and billers, there is no reason for a diagnostic criteria to exist at all in my opinion. Pneumonia doesn’t become a different disease just because the P:F ratio falls past some arbitrary point.. are you really are making management decisions based on a PF of 305 vs 297? because to me that’s what it sounds like you are saying?
Can’t agree more Josh! In my mind it’s always just acute lung injury, and then try to determine the compliance and heterogeneity to figure out the management.
Thanks for the newsflash. The S in ARDS stands for syndrome, not disease. We have been treating underlying causes for many years. if some people aren’t looking for underlying causes, they need more than a reminder.
If you really want to help, Please tell everyone that Long Covid really, really, really isn’t a disease.
I couldn’t agree more, long covid is not a thing. It could be anything.
“Sententious” doesn’t get enough play these days.
interesting that a lot of the dissenting comments here are from retired / current pulmonologists, who naturally would be the least inclined to view a heterogenous group of respiratory pathologies as a single entity. this article is not meant as an attack on you! but as a warning to my generation of practitioners against simplifying this common presentation in critically ill patients, which is warranted and necessary – I have witnessed this occur in many settings and have undoubtedly done so myself. lung protective ventilation is important but not enough on its own – we must seek and treat the… Read more »
that is below the belt. age has nothing to do with it. please. ARDS is a thing, just like Sepsis is a thing. but like most things. diseases don’t read text books, and maybe they don’t always create the same pathology either. we aren’t as smart as we think, but words are all we have.
All syndromes are not a “real thing.” They all are just an arbitrary pattern of clinical behavior that does not encompass an individual patient’s pathologies.
Well said!
This is the hill I will die on for “hypertensive emergency”. Just because someone has some numbers that all fit a pattern that has an ICD 10 code, doesnt mean we HAVE TO treat them differently. Patients with uncontrolled HTN for 45 years, will someday have an AKI or an NSTEMI. Sometimes they even get fluid overloaded. crazy stuff I know. It doesnt become a different disease just because the numbers pass some arbitrary cutoff. If I started parading around diagnosing everyone with a GCS less than 12 calling them “coma syndrome” and blanketing them with narcan, modafinil and thiamine… Read more »
I thought Covid was the true ards did you all not see the same?? Most of my pts died
I was a Chief Financial Officer who enjoyed traveling and rebuilding cars. However, when I was diagnosed with Idiopathic pulmonary fibrosis (IPF) and discovered I could no longer fulfill my responsibilities at work. I realized my condition was quickly worsening. I and my husband lived on the second floor of an apartment complex,i was out of breath when i got to the front door, i didn’t have the energy to hug my husband then. My condition was severe and my next step would be a lung transplant, began to look into using Madiba herbs treatment instead. Ever since my herbal… Read more »
agreed
So true. I have started using the phrase lung failure as a go to diagnosis for extreme hypoxemia that seems parenchymal/alveolar in nature. And then I go from there to make a diagnosis. And we should check compliance in everyone and always assume that the patient is at risk of VILI. I’ve seen intensivists call lung failure “ARDS” even if the x ray is notable for effusions/arelectasis only. I think the term lung failure is fair because it forces us to get more specific. ARDS is only helpful as a “diagnosis” in that it encourages lung protective ventilation. On that… Read more »
I have to write a paper on a guidelines development and challenge its validity, links to evidence based medicine and such for my paramedic honours and this has made me want to challenge the guidelines for ARDS.
Thanks Josh for all your work towards educating and sharing the knowledge with the community of intensivists. I agree the way we look at ARDS has to be clear. It’s a manifestation of an underlying issue and treatment of which is primarily for the underlying problem, while being considerate of the manifestation as well. I see these definition helps me to label a situation as ARDS which alerts the intensivists to realise the gravity of the situation, explicit in planning and optimise the treatment strategy for hypoxemia, while treating or puzzling the underlying cause. I admire your words of looking… Read more »