Abstract
Background:The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO).Methods:We prospectively analyzed the effects of PP on respiratory mechanics from continuous data with over a thousand time points during 16-h PP sessions in patients with COVID-19 and ARDS under VV-ECMO conditions. The evolution of respiratory mechanical and oxygenation parameters during the PP sessions was evaluated by dividing each PP session into four time quartiles: first quartile: 0–4 h, second quartile: 4–8 h, third quartile: 8–12 h, and fourth quartile: 12–16 h.Results:Overall, 38 PP sessions were performed in 10 patients, with 3 [2–5] PP sessions per patient. Seven (70%) patients were responders to at least one PP session. PP significantly increased the PaO2/FiO2 ratio by 14 ± 21% and compliance by 8 ± 15%, and significantly decreased the oxygenation index by 13 ± 18% and driving pressure by 8 ± 12%. The effects of PP on respiratory mechanics but not on oxygenation persisted after supine repositioning. PP-induced changes in different respiratory mechanical parameters and oxygenation started as early as the first-time quartile, without any difference in PP-induced changes among the different time quartiles. PP-induced changes in driving pressure (−14 ± 14 vs. −6 ± 10%, p = 0.04) and mechanical power (−11 ± 13 vs. −0.1 ± 12%, p = 0.02) were significantly higher in responders (increase in PaO2/FiO2 ratio > 20%) than in non-responder patients.Conclusions:In patients with COVID-19 and severe ARDS, PP under VV-ECMO conditions improved the respiratory mechanical and oxygenation parameters, and the effects of PP on respiratory mechanics persisted after supine repositioning.
Highlights
The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO)
We included all consecutive patients under mechanical ventilation with the following inclusion criteria: (i) presence of ARDS according to the Berlin definition [12]; (ii) VV-ECMO implantation for patients with severe ARDS meeting one of the following criteria: [1] arterial oxygen partial pressure (PaO2)/inspired fraction of oxygen (FiO2) ratio less than 50 mmHg for longer than 3 h or [2] PaO2/FiO2 less than 80 mmHg for longer than 6 h, or [3] arterial pH < 7.25 with arterial carbon dioxide partial pressure (PaCO2) greater than or equal to 60 mmHg for longer than 6 h with respiratory rate of 35 breaths/min and mechanical ventilation settings adjusted to maintain plateau pressure (Pplat) less than or equal to 32 cm H2O [7]; and (iii) positive COVID-19 real-time reverse transcriptase-polymerase chain reaction assay in nasal swabs or pulmonary samples
Between March 1, 2020 and June 1, 2021, 261 patients with COVID-19 and ARDS were admitted in our intensive care unit (ICU), and 24 (9%) required VV-ECMO: 18 (75%) of the patients were men, and two (8%) were immunocompromised (Table 1)
Summary
The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO). Most severe cases of respiratory involvement can lead to acute respiratory distress syndrome (ARDS), with high mortality of up to 60% [1,2,3]. The effects of PP are characterized by homogenization of transpulmonary pressure and distribution of total pulmonary stress and strain. These effects lead to decrease in alveolar overdistension of non-dependent pulmonary areas and reduction in cyclic opening-closing phenomena in dependent pulmonary areas [5]. PP is associated with lower patient mortality regardless of its effects on oxygenation [6]
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