Supine versus Prone Positioning in COVID-19 Pneumonia: Comment.

To the Editor:

Prone positioning is a simple method to improve oxygenation in ventilated patients with acute respiratory distress syndrome (ARDS).[1] Potential explanations are reduction of ventilation/perfusion mismatch, a more homogeneous distribution of transpulmonary pressure along the ventral-to-dorsal axis, and recruitment of nonaerated dorsal lung regions of the lung, with an increase in lung volume.[2] Many of these mechanisms could also apply to awake patients with ARDS by COVID-19.[3]

Here, we present an image (fig. 1) from a computed tomography performed in a 71-yr-old woman with ARDS from COVID-19 in both supine and prone positioning during awake spontaneous ventilation. Arterial blood gas analysis in the supine position with high-flow nasal cannula oxygen therapy (50% concentration; flow rate, 50 l/min) showed Pao2/fractional inspired oxygen tension (Fio2) of 130, with an improvement in prone positioning (Pao2/Fio2, 238). Bilateral, multifocal, and asymmetric lung disease was present in the supine computed tomography, with a “crazy paving” pattern (ground-glass opacities associated with smooth interlobular thickening) in the upper lobes, and peripheral, heterogeneous, and ill-defined consolidations in the lower lobes. An increase in total lung volume, mainly due to a significant expansion of both lower lobes (fig. 1, black arrows), was detected in the prone position (2,749 ± 31 ml) compared to supine (2,418 ± 30 ml). This change was accompanied by a moderate decrease in the attenuation of the lesions in the lower lobes (fig. 1, blue arrows), the vast majority showing a ground glass attenuation. These findings support the hypothesis of functional lung tissue recruitment in the prone position in awake patients with ARDS by COVID-19.

Fig. 1.

Chest computed tomographic image of an awake 71-yr-old patient with pneumonia by COVID-19 in supine (A and C) and prone positioning (B and D). Sagittal computed tomography (A and B) shows a slight decrease in attenuation of some of the lung lesions in prone study (blue arrows) and an increase in lung volumes of the right lower lobe (black arrow; B) compared with the supine study (A). Axial computed tomography (C and D) shows an increase in lung volumes of the left lower lobe (black arrow) with decrease in attenuation in the prone study (blue arrows; D) compared with the supine study (C). The prone studies (B and D) show a partial recovery of the aerated lung parenchyma in the left (B) and right (D) inferior lobe.

Competing Interests

The authors declare no competing interests.