Critical Lung Care in ARDS

To start: The ARDS Task Force paper from 2012 that revised the definition of Acute Respiratory Distress Syndrome from the 1994 American European Consensus Conference (AECC). The paper is most impressive as it approached definitions of illness by applying them to quantifiable outcomes. This idea bridges the gap between the clinical definitions we use to standardize medical communication with relevant prognostic information we can use to communicate with our patients and colleagues about the progression of a disease. An analogous process was used in the JNC-8 guidelines for the management of high blood pressure, the paper is a great example of where we should be moving toward when creating and revising definitions of medical diseases.

Here they re-defined ARDS as 3 mutually exclusive categories based on degree of hypoxemia: mild (PaO2/FIO2 ≤ 300 mm Hg), moderate (PaO2/FIO2 ≤ 200 mm Hg), and severe (PaO2/FIO2 ≤ 100 mm Hg). Importantly, these distinctions matter as mortality increases with severity of disease by this definition

Next, a review from NEJM about ventilator-induced lung injury. The article provides a great overview about the changes in ventilation when a patient is intubated and uses this as a basis to understand why mechanical ventilation can cause lung injury.  Concepts such as barotrauma and atelectrauma were reviewed, along with how we can utilize different modes of mechanical ventilation to  minimize potential lung injury by addressing the pulmonary pathology present.

They reviewed ARDS treatment as well –

1.Tidal Volume 6ml/kg (of ideal body weight).

2. Higher PEEPs seem to help, but more studies are needed.

3. High-Frequency Oscillatory Ventilation failed to show improvement in mortality in 2 recent trials.

4. If P/F ratio is <150, consider prone positioning and neuromuscular blockade.

5. Great Vent pathway on page 8 of this article.

By Dr. Sukhi Bains and Dr. Andrew Grock

Special thanks to Dr. Ashika Jain

References

Slutsky AS et al. (2013). Ventilator Induced Lung Injury. NEJM; 369: 2126-36

The ARDS Task Force. (2012). Acute Respiratory Distress Syndrome: The Berlin Definition. JAMA;307(23): 2526-33.

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