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Prone position in non-intubated patients with COVID-19 related acute respiratory failure

Background. Although pronation is mostly used as a treatment option in intubated patients with severe acute respiratory distress syndrome (ARDS), COVID-19 health emergency has led to a revaluation of this technique also in patients undergoing non-invasive ventilation (NIV). Objectives. The main study outcome was to assess oxygenation level for patients kept in prone position by comparing partial pressure of oxygen on fractional concentration of oxygen in inspired air (PO2/FiO2 ratio) changes before pronation and one hour after resupination. Method. In this retrospective single centre study, 20 patients over 18 years with a confirmed diagnosis of COVID-19 related pneumonia and receiving helmet-CPAP or NIV were enrolled from Villa Scassi Hospital (Genoa, Italy) between March and May 2020. Data regarding blood gas measurements, respiratory rate and dyspnoea severity were collected immediately before pronation (T0), during pronation (T1) and one hour after resupination (T2). Patients were responding if their PO2/FiO2 ratio had improved by at least 20% comparing T0 and T2. Results. In patients undergoing helmet-CPAP the PO2/FiO2 ratio improved significantly comparing data at T0 and T1 (p-value < 0.0001) and even when the supine position was resumed (p-value < 0.0001). The slopes of PO2/FiO2 ratio from T0 and T1 between the two groups of responders and not-responders also differed significantly (p-value = 0.004). Discussion. Our results show that pronation improves oxygenation in awake patients with COVID-19-related pneumonia receiving helmet-CPAP, and this effect is maintained even one hour after re-supination. The significant difference in the slope of the PO2/FiO2 ratio from T0 and T1 between the two groups shows that a lack of substantial increase in the ratio between supine and prone position could predict a failure of this technique. Conclusions. In a health emergency such a global pandemic where available resources are limited, pronation should always be attempted in patients with COVID-19 pneumonia in ARDS undergoing helmet-CPAP.