Awake prone positioning in acute hypoxaemic respiratory failure.

Awake prone positioning (APP) of patients with acute hypoxaemic respiratory failure gained considerable attention during the early phases of the coronavirus disease 2019 (COVID-19) pandemic. Prior to the pandemic, reports of APP were limited to case series in patients with influenza and in immunocompromised patients, with encouraging results in terms of tolerance and oxygenation improvement. Prone positioning of awake patients with acute hypoxaemic respiratory failure appears to result in many of the same physiological changes improving oxygenation seen in invasively ventilated patients with moderate-severe acute respiratory distress syndrome. A number of randomised controlled studies published on patients with varying severity of COVID-19 have reported apparently contrasting outcomes. However, there is consistent evidence that more hypoxaemic patients requiring advanced respiratory support, who are managed in higher care environments and who can be prone for several hours, benefit most from APP use. We review the physiological basis by which prone positioning results in changes in lung mechanics and gas exchange and summarise the latest evidence base for APP primarily in COVID-19. We examine the key factors that influence the success of APP, the optimal target populations for APP and the key unknowns that will shape future research.

Epidemiology and outcomes of early-onset AKI in COVID-19-related ARDS in comparison with non-COVID-19-related ARDS: insights from two prospective global cohort studies.

BACKGROUND: Acute kidney injury (AKI) is a frequent and severe complication of both COVID-19-related acute respiratory distress syndrome (ARDS) and non-COVID-19-related ARDS. The COVID-19 Critical Care Consortium (CCCC) has generated a global data set on the demographics, management and outcomes of critically ill COVID-19 patients. The LUNG-SAFE study was an international prospective cohort study of patients with severe respiratory failure, including ARDS, which pre-dated the pandemic. METHODS: The incidence, demographic profile, management and outcomes of early AKI in patients undergoing invasive mechanical ventilation for COVID-19-related ARDS were described and compared with AKI in a non-COVID-19-related ARDS cohort. RESULTS: Of 18,964 patients in the CCCC data set, 1699 patients with COVID-19-related ARDS required invasive ventilation and had relevant outcome data. Of these, 110 (6.5%) had stage 1, 94 (5.5%) had stage 2, 151 (8.9%) had stage 3 AKI, while 1214 (79.1%) had no AKI within 48 h of initiating invasive mechanical ventilation. Patients developing AKI were older and more likely to have hypertension or chronic cardiac disease. There were geo-economic differences in the incidence of AKI, with lower incidence of stage 3 AKI in European high-income countries and a higher incidence in patients from middle-income countries. Both 28-day and 90-day mortality risk was increased for patients with stage 2 (HR 2.00, p < 0.001) and stage 3 AKI (HR 1.95, p < 0.001). Compared to non-COVID-19 ARDS, the incidence of shock was reduced with lower cardiovascular SOFA score across all patient groups, while hospital mortality was worse in all groups [no AKI (30 vs 50%), Stage 1 (38 vs 58%), Stage 2 (56 vs 74%), and Stage 3 (52 vs 72%), p < 0.001]. The time profile of onset of AKI also differed, with 56% of all AKI occurring in the first 48 h in patients with COVID-19 ARDS compared to 89% in the non-COVID-19 ARDS population. CONCLUSION: AKI is a common and serious complication of COVID-19, with a high mortality rate, which differs by geo-economic location. Important differences exist in the profile of AKI in COVID-19 versus non-COVID-19 ARDS in terms of their haemodynamic profile, time of onset and clinical outcomes.