APRV for ARDS – What’s the Evidence?

Written by Seth Walsh-Blackmore

Spoon Feed
Evidence does not yet support airway pressure release ventilation (APRV) as an alternative to conventional lung-protective ventilation in acute respiratory distress syndrome (ARDS). However, this approach is plausible and warrants continued investigation.

Why does this matter?
Lack of evidence for significant improvements in ARDS outcomes with adjuncts to the cornerstone low-tidal volume continuous mandatory ventilation (CMV) has generated interest in open-lung ventilation to maximize alveolar recruitment at lower peak pressures (1,2). APRV is an open lung technique that utilizes standard ventilators, demonstrates positive results in animal models, and has a basis for human benefit (3). Is the hype real?

Stay open-minded to an open-lung
In this expert opinion article, two critical care physicians review the eight published RCTs examining APRV in ARDS. Individually, none of the RCTs demonstrate a statistically significant mortality benefit with APRV vs. CMV.  Ventilator-free days and barotrauma incidence were without significant differences, but these data don’t tell the full story.

Only one trial was designed for a primary mortality outcome. Half the trials had no formally defined primary outcome. Three trials did not report safety outcomes. Most trials were underpowered. Three trials stopped early. One stoppage was due to higher rates of hypercapnic respiratory failure with APRV, the others for futility and low enrollment. Only half the trials were in active ARDS; others were at-risk patients. The variability in trial protocols underscores a principal issue in researching APRV; its clinical novelty raises uncertainty about how to study it. It needs a flagship trial to build a greater body of high quality evidence to guide formal recommendations for routine clinical application. The theoretical benefit of APRV warrants this level of investigation, but until we have it, the authors conclude APRV remains an ARDS intervention best restricted to experimental settings.

Comment from JF peer reviewer, Dr. Meghan Breed: “A few thoughts…this is not a mode of ventilation that is commonly used from the start, but rather a rescue mode when hypoxia persists despite more conventional modes of ventilation. Mean airway pressure and FiO2 are the two ways that we are really able to affect oxygenation on the ventilator, so this mode capitalizes on the mean airway pressure. Hypercarbia is a side effect of this mode, but often if you are to the point of needing to try this mode of ventilation, a degree of hypercarbia is tolerated. I agree that more robust clinical trials are warranted, but this will not change my use of APRV in the ICU, particularly if patients are not candidates for more aggressive therapies such as ECMO.”

Another Spoonful
EMCrit has written extensively on APRV – the nuts of bolts of the mode and how to use it, when to use it, and its limitations. Please read more on their site.

Source
Caution-Do Not Attempt This at Home. Airway Pressure Release Ventilation Should Not Routinely Be Used in Patients With or at Risk of Acute Respiratory Distress Syndrome Outside of a Clinical Trial. Crit Care Med. 2023 Jan 20. doi: 10.1097/CCM.0000000000005776. Epub ahead of print.

Works Cited

1. Fan E, Brodie D, Slutsky AS. Acute Respiratory Distress Syndrome: Advances in Diagnosis and Treatment. JAMA. 2018;319(7):698–710. doi:10.1001/jama.2017.2190
2. Habashi, Nader M. MD, FACP, FCCP. Other approaches to open-lung ventilation: Airway pressure release ventilation. Critical Care Medicine 33(3):p S228-S240, March 2005. | DOI: 10.1097/01.CCM.0000155920.11893.37
3. Jain SV, Kollisch-Singule M, Sadowitz B, et al. The 30-year evolution of airway pressure release ventilation (APRV). Intensive Care Med Exp. 2016;4(1):11. doi:10.1186/s40635-016-0085-2