We have read the article" Prone Positioning and Survival in Mechanically Ventilated Patients With Coronavirus Disease 2019–Related Respiratory Failure "by Mathews et al., published in the critical care medicine journal in July 2021(1). We want to congratulate the authors for this successful publication and make some contributions. In the article, it has been mentioned in the conclusion that “In-hospital mortality was lower in mechanically ventilated hypoxemic patients with coronavirus disease 2019 treated with early proning compared with patients whose treatment did not include early proning”. The results showed that" Corticosteroids were used on ICU day one more often in proned versus nonproned patients (21.2% vs. 13.3%)". Reviewing the results and patient characteristics, we found unmatched patient populations in both groups that could potentially affect the results, hence the conclusion \cite{Mathews_2021}.  The evidence of steroids in COVID-19 pneumonia was published in the literature early in the COVID-19 pandemic. The Recovery trial, published in February 2021, showed that the in the dexamethasone group, the incidence of death was lower than that in the usual care group among patients receiving invasive mechanical ventilation (29.3% vs. 41.4%; rate ratio, 0.64; 95% CI, 0.51 to 0.81) \cite{2021}. A meta-analysis published in September 2020 looked at the association between administering corticosteroids compared with usual care or placebo and 28-day all-cause mortality. It showed the mortality benefit of using steroids (OR, 0.66 [95% CI, 0.53-0.82]); the mortality benefit was consistent with various types of steroids \cite{2020}. We conducted a recent meta-analysis of COVID-19 patients and found no mortality benefit of prone ventilation in intubated COVID-19 patient \cite{Fayed_2022,Fayed_2023}.  We addressed our concerns in other published studies \cite{Fayed_2023a,Fayed_2022a}.  In Mathews et al.'s study, in the prone early group, 149 patients received steroids out of 702 (21.2%), while in the no early prone group, 217 patients received steroids out of 1636 (13.3%). By using the Chi-square analysis, the p-value is < 0.00001. On further looking at the study Supplementary Digital Content, in reviewing table 5, titled "Multivariable Cox model for death among patients included in the target trial emulation of early proning initiation versus non-early proning initiation," when using steroids, the outcome of the study became insignificant with the result of the odds ratio of 1.07 (0.91-1.26) and survival favors non-early prone group. This result concurs with another published study on early-prone ventilation in COVID-19 patients. Among 6350 ICU patients with COVID-19, they found no association between early use of prone positioning and survival in patients on mechanical ventilation with severe hypoxemia on ICU admission \cite{Engerstr_m_2022}. We want to address and express our opinion regarding this limitation that could affect the outcome and the result of the study. The study should have included the difference between both groups in the limitation section. This difference would have affected Mathews et al.'s study outcome, and the conclusion should have been rectified.

We have read the article entitled ”Prone Positioning in intubated and mechanically ventilated patients with SARS-CoV-2” by Chen et al., published in the Journal of Clinical Anesthesia (2021 August) \cite{Chen_2021}[1]. We congratulate the authors for this successful publication and make some contributions.In the article, it has been mentioned in the conclusion that a prolonged prone position is a safe and feasible option to extend survival in patients with COVID-19. It was reported that among the patients that died within 14 days of intensive care admission, 11.8% received prolonged prone positioning, while 52.2% did not. The authors mentioned some study limitations, but it is incomplete.We have the following concerns regarding the methodology of the study. The authors clearly stated that patients who did not tolerate prolonged prone positioning were excluded from the study. The author should have mentioned how many patients were excluded, which could have affected the sample size distribution. Also, what was the definition of a prolonged prone position? What was the definition of intolerance to the prolonged prone position? Is it worsening oxygenation, hemodynamic stability, or other criteria? If exclusion were based on worsening oxygenation, hence prone position would have affected the outcomes and mortality. The authors did not mention if the patients excluded had an absolute or a relative contraindication to prone positioning. There are various terms used for proning in the study, prolonged proning, long-term proning, and persistent proning.During the early phase of the COVID-19 pandemic, with limited evidence of this novel disease. Many journals accepted borderline publications. Some journals didn't pay attention to major methodological concerns in published articles. We addressed our concerns in the published article addressing a similar topic \cite{Fayed_2022}. Our published meta-analysis on this topic showed no mortality benefit of prone ventilation. The study, as mentioned earlier by Chen et al., results were skewed compared to other published ones \cite{Fayed_2022a}.In conclusion, the excluded patients might have worse outcomes in the prone position. Hence, excluding these patients from the study might show results favoring the prone position, and hence there are favorable outcomes in the prone position. This should have been mentioned as a significant limitation of this study, and the conclusion should be cautiously drawn and rephrased.