tetano
Editor, Senior Moderator
Ann Intensive Care
. 2025 Mar 31;15(1):46.
doi: 10.1186/s13613-025-01452-0. Time-dependent effects of prone position on ventilation-perfusion matching assessed by electrical impedance tomography in patients with COVID-19 ARDS: sub-analysis of a prospective physiological study
Yuxian Wang[SUP] #[/SUP][SUP] 1 [/SUP], Yaxiaerjiang Muhetaer[SUP] #[/SUP][SUP] 1 [/SUP], Xin Zheng[SUP] #[/SUP][SUP] 1 [/SUP], Wei Wu[SUP] 1 [/SUP], Jiale Tao[SUP] 1 [/SUP], Ling Zhu[SUP] 1 [/SUP], Jieqiong Song[SUP] 2 [/SUP], Zhanqi Zhao[SUP] 3 4 5 6 [/SUP], Ming Zhong[SUP] 7 8 [/SUP]
Affiliations
Background: Prone positioning (PP) has been shown to improve oxygenation in patients with acute respiratory distress syndrome (ARDS); with a focus on its early physiological effects. However, the time-dependent effects of PP on ventilation-perfusion (V/Q) matching have not been fully investigated. In this study we aimed to investigate the longitudinal effects of PP on regional V/Q matching and the distribution of ventilation and perfusion in patients with coronavirus disease 2019 (COVID-19)-associated ARDS.
Methods: This study analyzed patients with COVID-19 ARDS who were mechanically ventilated and underwent their first PP treatment. V/Q mismatching was assessed using electrical impedance tomography (EIT). At five intervals during the initial PP session PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB] measurements and EIT evaluations were performed including: before the initiation of PP while in the supine position (SP), 1 h after PP (PP[SUB]1[/SUB]), 3 h after PP (PP[SUB]3[/SUB]), 16 h after PP (PP[SUB]end[/SUB]), and 3 h after reverting to the supine position (RE-SP[SUB]3[/SUB]).
Results: In this study eighteen COVID-19 ARDS patients were enrolled. In comparison with SP, PP led to significant improvements in oxygenation, with PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB] consistently increasing at each PP time point and peaking at PP[SUB]end[/SUB]. Dorsal ventilation significantly increased at PP[SUB]1[/SUB] (P = .047), and steadily rose during PP, with a higher increase at PP[SUB]end[/SUB] than PP[SUB]1[/SUB] (P < .001). Dorsal perfusion remained unchanged during the first three hours of PP; however, significantly increased by PP[SUB]end[/SUB]. Ventilation and perfusion returned to their baseline levels at RE-SP[SUB]3[/SUB]. PP increased normal V/Q (%), and decreased non-perfused (%), low V/Q (%), particularly in the dorsal lung regions, compared with SP. At RE-SP[SUB]3[/SUB], there was a marked increase in the non-ventilated (%), low V/Q (%), and non-perfused (%) compared with PP. The global inhomogeneity (GI)-V/Q ratio was noted to have decreased during PP and correlated with an increase in PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB].
Conclusions: In COVID-19-induced ARDS patients, prone positioning initially improves oxygenation and V/Q matching by enhancing ventilation distribution and decreasing low V/Q (%). Over time, perfusion changes further improve V/Q matching, but these benefits diminish once the patient returns to the supine position, leading to increased V/Q mismatch. Trial registration Clinical Trials.gov, NCT04725227. Registered 25 January 2021, https://clinicaltrials.gov/study/NCT04725227?cond=NCT04725227&rank=1.
Keywords: Acute respiratory distress syndrome; Electrical impedance tomography; Mechanical ventilation; Prone positioning; Pulmonary perfusion; Ventilation-perfusion matching.
. 2025 Mar 31;15(1):46.
doi: 10.1186/s13613-025-01452-0. Time-dependent effects of prone position on ventilation-perfusion matching assessed by electrical impedance tomography in patients with COVID-19 ARDS: sub-analysis of a prospective physiological study
Yuxian Wang[SUP] #[/SUP][SUP] 1 [/SUP], Yaxiaerjiang Muhetaer[SUP] #[/SUP][SUP] 1 [/SUP], Xin Zheng[SUP] #[/SUP][SUP] 1 [/SUP], Wei Wu[SUP] 1 [/SUP], Jiale Tao[SUP] 1 [/SUP], Ling Zhu[SUP] 1 [/SUP], Jieqiong Song[SUP] 2 [/SUP], Zhanqi Zhao[SUP] 3 4 5 6 [/SUP], Ming Zhong[SUP] 7 8 [/SUP]
Affiliations
- PMID: 40163279
- DOI: 10.1186/s13613-025-01452-0
Background: Prone positioning (PP) has been shown to improve oxygenation in patients with acute respiratory distress syndrome (ARDS); with a focus on its early physiological effects. However, the time-dependent effects of PP on ventilation-perfusion (V/Q) matching have not been fully investigated. In this study we aimed to investigate the longitudinal effects of PP on regional V/Q matching and the distribution of ventilation and perfusion in patients with coronavirus disease 2019 (COVID-19)-associated ARDS.
Methods: This study analyzed patients with COVID-19 ARDS who were mechanically ventilated and underwent their first PP treatment. V/Q mismatching was assessed using electrical impedance tomography (EIT). At five intervals during the initial PP session PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB] measurements and EIT evaluations were performed including: before the initiation of PP while in the supine position (SP), 1 h after PP (PP[SUB]1[/SUB]), 3 h after PP (PP[SUB]3[/SUB]), 16 h after PP (PP[SUB]end[/SUB]), and 3 h after reverting to the supine position (RE-SP[SUB]3[/SUB]).
Results: In this study eighteen COVID-19 ARDS patients were enrolled. In comparison with SP, PP led to significant improvements in oxygenation, with PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB] consistently increasing at each PP time point and peaking at PP[SUB]end[/SUB]. Dorsal ventilation significantly increased at PP[SUB]1[/SUB] (P = .047), and steadily rose during PP, with a higher increase at PP[SUB]end[/SUB] than PP[SUB]1[/SUB] (P < .001). Dorsal perfusion remained unchanged during the first three hours of PP; however, significantly increased by PP[SUB]end[/SUB]. Ventilation and perfusion returned to their baseline levels at RE-SP[SUB]3[/SUB]. PP increased normal V/Q (%), and decreased non-perfused (%), low V/Q (%), particularly in the dorsal lung regions, compared with SP. At RE-SP[SUB]3[/SUB], there was a marked increase in the non-ventilated (%), low V/Q (%), and non-perfused (%) compared with PP. The global inhomogeneity (GI)-V/Q ratio was noted to have decreased during PP and correlated with an increase in PaO[SUB]2[/SUB]/FiO[SUB]2[/SUB].
Conclusions: In COVID-19-induced ARDS patients, prone positioning initially improves oxygenation and V/Q matching by enhancing ventilation distribution and decreasing low V/Q (%). Over time, perfusion changes further improve V/Q matching, but these benefits diminish once the patient returns to the supine position, leading to increased V/Q mismatch. Trial registration Clinical Trials.gov, NCT04725227. Registered 25 January 2021, https://clinicaltrials.gov/study/NCT04725227?cond=NCT04725227&rank=1.
Keywords: Acute respiratory distress syndrome; Electrical impedance tomography; Mechanical ventilation; Prone positioning; Pulmonary perfusion; Ventilation-perfusion matching.