COMMENTARY

Few Eligible ARDS Patients Receive Low Tidal Volume Ventilation

Aaron B. Holley, MD

Disclosures

August 30, 2017

A Critical Care Clinician Survey Comparing Attitudes and Perceived Barriers to Low Tidal Volume Ventilation With Actual Practice

Weiss CH, Baker DW, Tulas K, et al
Ann Am Thorac Soc. 2017 Aug 3. doi: 10.1513/AnnalsATS.201612-973OC. [Epub ahead of print]

Background

Acute respiratory distress syndrome (ARDS) is associated with a high mortality rate. Few specific interventions will affect outcomes. Neuromuscular blockade (NMB),[1] prone positioning,[2] and low tidal volume ventilation (LTVV)[3] have all shown a mortality benefit. Although the randomized controlled trial that proved efficacy showed that NMB wasn't associated with critical care weakness,[1] the phenomenon is well described and NMB is a risk factor.[4] Prone positioning requires institutional buy-in, specific beds, and is associated with risk for extubation and other errors. LTVV has the longest track record and broadest impact (it's not isolated to severe ARDS [PaO2/FiO2 < 100]). It's low-cost and easy to achieve. There's even a push to use LTVV in patients without ARDS.[5] With rare exceptions, if there's one thing we should be doing for our ARDS patients, it's LTVV.

The Study

This recent survey published in the Annals of the American Thoracic Society found that most physicians agree about the benefits of LTVV. They see few barriers to use. Data from their hospitals, however, revealed that only 7.4% of eligible patients received LTVV. This represents a striking disconnect between what physicians think versus what they do. Data from the survey didn't identify major drivers of this disconnect. Physicians generally felt that ARDS was quickly and easily diagnosed and saw few difficulties with ordering or implementing LTVV.

In their discussion, the authors hypothesized two categories of barriers to explain the low LTVV rates: inappropriate LTVV strategies and unperceived barriers. Examples of inappropriate LTVV strategies are using plateau pressure but not tidal volume limits, and calculating tidal volume using actual instead of ideal body weight. Unknown perceived barriers are numerous, but cited examples are role ambiguity (physicians think respiratory therapists are managing ventilator settings) and respiratory therapists or nurses failing to implement LTVV orders due to perceived danger to the patient.

Viewpoint

This isn't the first study to show us that we physicians aren't as good as we think we are. What's striking to me is the magnitude of the discrepancy between thought and action. The survey doesn't give us clues for fixing the problem. Based on what we know about human behavior, and on the authors' hypotheses, we should probably start with the basics. Our ICU already uses checklists and closed-loop communication, but ARDS diagnosis and ventilator settings aren't part of our current protocols. Add LTVV to the growing list of evidence-based strategies that are underutilized.

Abstract

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