Awake Prone Positioning for Acute Hypoxaemic Respiratory Failure in COVID-19

Prone positioning has been demonstrated to significantly reduce mortality in invasively ventilated patients with moderate to severe acute respiratory distress syndrome through several physiological mechanisms, including optimization of ventilation and perfusion and a reduction in ventilator-associated lung injury. The marked increase of hospitalisation rates of patients with acute hypoxaemic respiratory failure during the COVID-19 pandemic, and associated strain on healthcare resources, led to interest in the use of prone positioning in conscious self-ventilating, or “awake”, patients, as an adjunct to the provision of oxygen therapy and respiratory support. The adoption of this technique was with the intent of reducing the likelihood of progressive respiratory failure and thus the need for invasive mechanical ventilation. In this review we summarize the background, physiological mechanisms and current evidence for the use of awake prone positioning in both COVID-19 related hypoxaemic respiratory failure and that attributed to other aetiologies. Whilst several studies note an improvement in respiratory parameters including oxygenation, the effect on clinically important outcomes such as rates of intubation and mortality remain unclear. The evidence base beyond COVID-19 related respiratory failure remains constrained and there is a paucity of evidence to help identify those most likely to benefit from this therapy. There remains no agreed consensus on how to implement awake prone positioning and significant variation exists in practice. Several clinical questions should be the focus for future research studies of this treatment modality including how to identify early responders and non-responders to therapy.