The Application of Awake-Prone Positioning Among Non-intubated Patients With COVID-19-Related ARDS: A Narrative Review

Abstract

The coronavirus disease (COVID-19) pandemic has significantly increased the number of patients with acute respiratory distress syndrome (ARDS), necessitating respiratory support. This strain on intensive care unit (ICU) resources forces clinicians to limit the use of mechanical ventilation by seeking novel therapeutic strategies. Awake-prone positioning appears to be a safe and tolerable intervention for non-intubated patients with hypoxemic respiratory failure. Meanwhile, several observational studies and meta-analyses have reported the early use of prone positioning in awake patients with COVID-19-related ARDS (C-ARDS) for improving oxygenation levels and preventing ICU transfers. Indeed, some international guidelines have recommended the early application of awake-prone positioning in patients with hypoxemic respiratory failure attributable to C-ARDS. However, its effectiveness in reducing intubation rate, mortality, applied timing, and optimal duration is unclear. High-quality evidence of awake-prone positioning for hypoxemic patients with COVID-19 is still lacking. Therefore, this article provides an update on the current state of published literature about the physiological rationale, effect, timing, duration, and populations that might benefit from awake proning. Moreover, the risks and adverse effects of awake-prone positioning were also investigated. This work will guide future studies and aid clinicians in deciding on better treatment plans.

Keywords: ARDS; COVID-19; SARS-CoV-2; awake prone position; non-invasive respiratory support.

Figure 1

Schematic diagram of the pathophysiological mechanism of prone position treatment in ARDS. (A) and (C) represent the natural form of alveoli without the effect of gravity. (B) Under the gravitational gradient and pleural pressure, the alveolar volume in the dorsal area is significantly smaller than that in the ventral area, thus the changes caused by ARDS will be more significant. (D) In the prone position, the effect of the gravitational gradient or pleural pressure is reversed, i.e., the volume of the ventral alveoli decreases while that of the dorsal alveoli increases. (E) In the supine position, the ventral transpulmonary pressure (PTP) significantly exceeds the dorsal PTP. (F) Prone positioning reduces the difference between the ventral and dorsal PTP, making ventilation more homogeneous. (G) The previously dependent lung continues to receive the majority of the blood flow as alveoli reopen. (H) The newly dependent lung continues to receive the minority of the blood flow as alveoli begin to collapse. (I) In the supine position, the bronchial drainage is limited. (J) Prone positioning improves bronchial drainage.