Within the past year, two major societies have released guidelines on ARDS: the ATS (American Thoracic Society) and the ESICM (European Society of Intensive Care Medicine). Don’t be fooled by their names – both of these organizations are fundamentally international in scope. Some authors on the ATS document were from Europe, and similarly some authors on the ESICM document were from America.
So, we have two high-quality guidelines written by international groups of smart people within a narrow time-frame. What happens when we line them up? They disagree. A lot.
nobody knows what ARDS is
To begin with, there’s no clear definition of exactly what ARDS is. Recently, a new global ARDS definition was proposed that doesn’t require that the patient is intubated. However, the global ARDS definition has yet to receive widespread acceptance. To date, no major trials have been performed utilizing the global ARDS definition as inclusion criteria. This leaves everyone in a very uncomfortable position – sandwiched between a newer and unvalidated definition, and an older definition.
I couldn’t find a clear definition of ARDS in either guideline. The ATS guideline doesn’t seem enthralled with the global definition of ARDS, stating that the definition of ARDS “has evolved over time, with a recent suggestion that it be expanded to include intubated and nonintubated patients.”
The ESICM guideline includes a debate about how to define ARDS, without any definitive conclusion. Unlike the ATS document, the ESICM guideline contains considerable discussion about noninvasive ventilation and high-flow nasal oxygen, so the authors seem to implicitly endorse the global definition of ARDS.
guidelines disagree on the basics
ARDS has always been a controversial topic. However, one would expect that two evidence-based guidelines should agree on basic aspects of ARDS care. Shockingly, these guidelines really don’t. For example:
- Paralysis: ATS guidelines suggest paralysis in patients with early severe ARDS. ESICM guidelines recommend against the routine use of continuous infusions of paralytics in patients with moderate-to-severe ARDS.
- PEEP: ATS guidelines recommend using higher PEEP values. ESICM guidelines were unable to make a recommendation for or against routine PEEP titration with a higher PEEP/FiO2 strategy versus a lower PEEP/FiO2 strategy.
- High-flow nasal oxygen & noninvasive ventilation: The ESICM makes numerous recommendations regarding this, whereas the ATS ignores this topic entirely.
this is an embarrassment to our field
It’s 2023. Other fields have increasingly precise definitions of their diseases, facilitating accurate and personalized care. For example, there are five types of myocardial infarction, all of which are clearly delineated in an international guideline. Oncologists are increasingly defining tumor types down to a molecular level. Infectious disease specialists are using PCR to rapidly identify pathogens and predict their antibiotic sensitivity profiles.
Meanwhile, pulmonary/critical care physicians have failed to reach any clarity about what ARDS is. In the absence of any clear definition, guidelines regarding ARDS management remain confused and conflicting. Among individual practitioners, the amount of practice variation and confusion about ARDS is even worse.
It’s unclear where to go from here. ARDS isn’t actually a disease, but rather it is a poorly constructed syndrome (which is highly problematic, as explored further here). It might be ideal to completely abandon the construct of ARDS and just start over with something new that has a concrete definition (e.g., “acute diffuse parenchymal lung disease”). Alternatively, everyone needs to agree on what ARDS actually is, and then study it using that definition – to create a cohesive and consistent body of literature.
Either way, the current state of affairs in ARDS is embarrassingly shambolic and needs to be fixed.
going further & references
- “ARDS” is not a real thing
- ESICM guidelines: Grasselli G, et al. European Society of Intensive Care Medicine Taskforce on ARDS. ESICM guidelines on acute respiratory distress syndrome: definition, phenotyping and respiratory support strategies. Intensive Care Med. 2023 Jul;49(7):727-759. doi: 10.1007/s00134-023-07050-7 [PubMed]
- ATS guidelines: Qadir N, et al. An Update on Management of Adult Patients with Acute Respiratory Distress Syndrome: An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2023 Nov 30. doi: 10.1164/rccm.202311-2011ST [PubMed]
Opening image credits: Photo by Ricardo Viana on Unsplash
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Nice analysis. Do you know why the recommendation for prone positioning is now reduced to 12 hrs ?
Sorta looks like prone positioning is falling out of favor again: Too much work for staff, or loss of a sense of belief? https://journals.lww.com/ccmjournal/abstract/2023/11000/declining_use_of_prone_positioning_after_high.10.aspx
Personally, I rather like “acute diffuse parenchymal lung disease”. ARDS definitions have been bouncing around since at least the 1980s. At least back then, since we really didn’t know what we might be treating, we could have diverse definitions and protocols. We have a better idea today, and a recent example of a pandemic’s worth of diffuse changes leading to intubation and controlled ventilation. And we discovered in the process that our practice might not be achieving what we’d hoped. Yeah, it’s time for a change.
The seminal paper describing the syndrome was by Ashbaugh in 1967 and was more specific in its description than the modern definitions, linking the clinical syndrome to the presence of hyaline membranes on histology.
Subsequent efforts have prioritised easy bedside diagnosis over precision. The central problem is this: without a specific treatment, routine lung biopsy cannot be justified, and without routine lung biopsy, we are stuck with an imprecise diagnostic process that considers aspiration of pond water to be the same disease as pulmonary vasculitis.
Tens of thousands of ventilated patients recruited in different ARDS studies over the years and we still read “we suggest”, “further studies are warranted”, “we can’t make statement”.
sounds discouraging, Josh. my brother is a pulm-crit guy in Virginia… just sent him your blog. thanks, as always
tom fiero, merced