Myths and Misconceptions of Airway Pressure Release Ventilation: Getting Past the Noise and on to the Signal

Abstract

In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): “Scientific orthodoxy kills truth”. In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of “lung protective” ventilation. Unfortunately, inadequacies of the current conceptual model–that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the “baby lung” - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV’s clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.

Effects of airway pressure release ventilation on lung physiology assessed by electrical impedance tomography in patients with early moderate-to-severe ARDS

“…Second, we didn’t focus on the effects of spontaneous breathing on APRV. The effects of APRV with or without spontaneous breathing on ARDS patients are still being debated [ 14 ]. Third, EIT only provides a cross-sectional lung-region analysis, which may differ from whole-lung evaluation.…”

Airway Pressure Release Ventilation in COVID-19-Associated Acute Respiratory Distress Syndrome—A Multicenter Propensity Score–Matched Analysis

“…5 In contrast to the studies, 12,14,19 demonstrating significantly higher tidal volumes beyond the limits of lung-protective ventilation in APRV, the present study showed similar tidal volumes per PBW as well as peak pressure values compared to the matched LTV control group that followed ARDSnet recommendations. 23 However, regardless of the ventilation mode, the aim of lung protective ventilation less than or equal to the “magic number” 27 of 6 mL/kg PBW was missed in a considerable number of patients (compare Figure 1). However, there is an ongoing debate whether the ARDSnet tidal volume limitations should be applied to the APRV release volume or whether concepts of a mandatory mode of ventilation (ARDSnet) are mistakenly transferred to the paradigm of a spontaneous ventilation mode.…”

Management of refractory hypoxemia using recruitment maneuvers and rescue therapies: A comprehensive review

“…Accordingly, time rather than pressure controls the end-expiratory lung volume. Continuous analysis of the expiratory flow curve is therefore necessary as respiratory mechanics change during ventilation, in order to accurately and independently set and adjust T High and T Low ( 100 , 104 ). If hypoxemia is present, an increase of P High then of T High are warranted.…”

“…Therefore, in the absence of a large, multicenter, randomized controlled trial demonstrating a patient outcome benefit compared to low-tidal volume ventilation in patients with ARDS, a definitive recommendation for the use of APRV cannot be made ( 5 , 101 , 102 ). There have been many criticisms of APRV, regarding the difficulty of mastering this mode, the assumed risk of barotrauma, increased right ventricular afterload, or uncontrollable auto-PEEP and dynamic hyperinflation ( 104 ). However, a recent review highlighted the fact that some authors' beliefs about APRV are often based on little clinical experience with its use, and are generally not supported by rigorous studies.…”

“…However, a recent review highlighted the fact that some authors' beliefs about APRV are often based on little clinical experience with its use, and are generally not supported by rigorous studies. Although APRV has not yet shown to be superior to low-tidal volume ventilation in multicenter randomized controlled trials, the reverse is equally valid ( 104 ).…”