Updated: Apr 9
Prone positioning ventilation (PPV) has been a valuable rescue therapy for patients with severe hypoxemia and ARDS, offering benefits in oxygenation and reducing mortality. In the context of COVID-19, PPV has become a standard of care for many intensivists. However, there is limited knowledge about the optimal duration patients should be kept in this position.
A recent retrospective trial in CHEST aimed to determine whether a prolonged (24 or more hours) PPV strategy improved mortality in intubated COVID-19 patients compared to intermittent (∼16 hours with daily supination) PPV. This multicenter, retrospective cohort study included consecutively admitted intubated COVID-19 patients treated with PPV between March 11 and May 31, 2020. Total of 157 underwent prolonged PPV compared 110 patients with intermittent PPV. The initial prone session duration was longer for patients undergoing prolonged PPV compared to those receiving intermittent PPV (median, 40 hours versus 17 hours; P < .001). Results showed that patients undergoing prolonged PPV had reduced 30-day and 90-day mortality compared to intermittent PPV, particularly in patients with Pao2/Fio2 ≤ 150 at the time of pronation. Prolonged PPV was associated with fewer pronation and supination events and a small increase in rates of facial edema. The study concludes that prolonged PPV is a safe and effective strategy for reducing mortality in intubated COVID-19 patients .
The study presents several potential benefits of choosing prolonged PPV over intermittent PPV in COVID-19 patients. Physiological benefits of PPV, such as improved compliance of the respiratory system and reduced lung strain, increase continuously over 24 hours of prone ventilation. Repeated supination may lead to atelectotrauma and ventilator-induced lung injury, potentially contributing to mortality. Prolonged PPV requires fewer healthcare personnel to implement, reducing resource utilization.
The findings raise questions about the relationship between PaO2/FiO2 ratio and mortality. No differences in the change in PaO2/FiO2 ratio were found based on PPV strategy, and it did not explain the association with improved mortality seen with prolonged PPV. Further research is necessary to determine how prolonged PPV affects ventilation inhomogeneity during acute respiratory distress syndrome (ARDS) and its contribution to the associated improvement in mortality.
The study has several strengths, including a multicenter design and minimization of selection bias. However, the retrospective nature of the study introduces potential limitations, such as unmeasured confounding factors. Future randomized controlled trials are necessary to confirm these findings and investigate the applicability of the PPV strategy to other causes of acute respiratory failure.
The study raises several questions, including the precise mechanism associated with the time dependency of PPV's effect on mortality and whether patients undergoing prolonged PPV may benefit from specific ventilatory settings. Furthermore, as COVID-19 ARDS presents unique characteristics, it's essential to consider whether the mortality reduction is specific to certain patient groups. Future research should focus on understanding the physiological aspects of prolonged PPV and personalizing strategies based on individual patient phenotypes.
While the study discussed above focuses on the benefits of prolonged PPV in COVID-19 ARDS patients, its implications for non-COVID ARDS patients should be considered with caution. There are key differences between COVID-19 ARDS and non-COVID ARDS, such as the diffuse involvement of the endothelium, heterogeneous response to positive end-expiratory pressure, and significant V/Q mismatch in COVID-19 ARDS patients.
However, the insights provided by the study may be used to guide further research into the potential benefits of prolonged PPV in non-COVID ARDS patients. The findings may encourage clinicians to investigate the time-dependent effects of PPV on mortality, ventilatory settings, and lung protective strategies in non-COVID ARDS.
It is important to note that a personalized approach based on the specific patient's phenotype is encouraged when treating ARDS patients, whether they have COVID-19 or not. More research is needed to determine the potential benefits of prolonged PPV in non-COVID ARDS patients and how these strategies can be tailored to individual patients.
Overall, these findings suggest that prolonged proning position offers additional benefits, which should be considered in clinical practice.
1. Daniel Okin et al. CHEST 2023 163533-542DOI: (10.1016/j.chest.2022.10.0343 163533-542DOI: (10.1016/j.chest.2022.10.034