Awake prone positioning for COVID-19 patients with acute respiratory failure: unknown appropriate duration

Zeng, G., Wang, L

 Intensive Care Med (2024). https://doi.org/10.1007/s00134-024-07637-8

In a recent issue of Intensive Care Medicine, we read with great interest the article by Liu et al. [1] who conducted a trial to explore whether prolonged awake prone positioning (APP) would reduce the rate of intubation at 28 days when compared with a shorter period of APP in non-intubated patients with coronavirus disease 2019 (COVID-19)-related acute hypoxemic respiratory failure (AHRF). They reported that prolonged APP of patients with COVID-19-related AHRF reduces the intubation rate without significant harm. We applaud the authors for their work. However, several factors potentially affecting their results should be discussed.

First, the pathophysiology of COVID-19 pneumonia characteristics will change over time. The protocol of the study suggested that the trial recorded blood biochemical indicators and blood gas analysis of the two groups of patients at day 1, day 3 and day 7. However, this information is not presented in the article, which is not conducive to assess the patient's baseline situation and disease progression, such as inflammation. These are all factors affecting the prognosis of patients. In addition, the characteristics of the two groups of patients were similar, such as comorbidities, glucocorticoids, antiviral drugs and other variables. However, vaccination history, an important variable in reducing severe disease or death in COVID-19 patients, was not considered.

Second, the trial was unblinded. Participants, research teams, and physicians were aware of which group they had been assigned to, and the introduction of bias was inevitable. There are many factors that affect patients’ acceptance of prolonged APP, which may be related to the patient’s cognition, degree of cooperation and severity of the disease. Patients receiving prolonged APP have the lowest risk of intubation. The possibility of confounding is that patients would benefit more from extended APP or that patients who tolerate prolonged APP are less likely to have clinical deterioration themselves.

Third, the results of the subgroup analyses of tracheal intubation and death caught our attention. Receiving prolonged APP appeared to reduce intubation rates in patients receiving high few nasal cannula (HFNC) and noninvasive ventilation (NIV) from intensive care units/intermediate care units, but not in patients receiving standard oxygen therapy and from general wards. These findings are consistent with those of a previous meta-analysis [2]. However, it is noteworthy that prolonged APP, although reducing intubation rate in this population, did not reduce mortality. Therefore, whether prolonged APP will lead to delayed intubation and missed the rescue opportunity needs to be vigilant.

AHRF is complex, can be caused by different etiologies, has significant heterogeneity, and is a dynamic process. The optimal duration of the APP largely depends on the individual response to ventilation-perfusion regulation and disease progression. Therefore, continuous evaluation and adjustment during APP is essential to ensure its continued suitability for the patient’s evolving condition. Future directions should consider a combination of the patient’s phenotype and the patient’s disease progression to preserve opportunities for personalized treatment, such as APP for an appropriate duration.