Fig. 4

Individual functional response to prone positioning. Fourteen mechanically-ventilated patients with COVID-19 were evaluated in the supine and prone positions. Herein we describe the response to prone positioning in terms of change in arterial oxygenation (expressed as the ratio of the arterial tension to the inspiratory fraction of oxygen [PaO₂:FiO₂]) (n = 14) (A), respiratory system compliance (n = 14) (B), and carbon dioxide tension (PaCO₂) for the same minute ventilation (n = 13) (C), in descending order. Each bar refers to one patient. The same letter in the three panels refers to the same patient. Please note that patient D, present in other figures, did not undergo prone positioning and is absent from this figure. FiO₂ was decreased in the prone position in patient K and patient F, and increased in patient G. The impact of prone positioning on PaCO₂ could not be assessed in patient L because his minute ventilation was increased during prone positioning. Finally, patient N had a baseline PaO₂:FiO₂ of 273 mmHg; the decision to prone him was based on the detection of large ventral lung hyperinflation at the CT taken in the supine position (please refer to the main text for other details)