Lung Recruiting Effect of Prone Positioning in Spontaneously Breathing Patients with COVID-19 Assessed by Electrical Impedance Tomography

A 72-year-old male known for having obesity (body mass index of 38 kg/m(2)) and for smoking was admitted to the ICU for acute respiratory failure. A chest computed tomography scan revealed interstitial lung infiltrates with subpleural and posterior lung condensation (Figure 1). Coronavirus disease 19 (COVID-19) pneumonia was confirmed by a positive result of real-time RT-PCR from nasal and pharyngeal swab. The patient had a rapid decrease in the ROX (respiratory rate-oxygenation) index (1) (respiratory rate: 28 breaths/min; pulse oximetry: 91%; oxygen flow rate: 5 L/min) and was invited to initiate prone positioning combined with conventional oxygen therapy as the first-line ventilation strategy according to the routine practice in our center (2). Prone positioning was maintained according to patient tolerance for a total duration of 290 minutes. Global and regional ventilation patterns were checked using electrical impedance tomography (Draeger Pulmovista 500). After the start of prone positioning, electrical impedance tomography revealed a constant improvement in global and regional delta end-expiratory lung impedance that predominated in the posterior area of the lungs (Figure 1). At the same time, the respiratory rate decreased from 28 to 20 breaths/ min, and the pulse oximetry increased from 91 to 97%, whereas the oxygen flow rate was reduced from 5 L/min to 3 L/min. Finally, intubation was avoided, and the patient was discharged from the ICU. Prone positioning combined with conventional oxygen therapy could be proposed in patients with severe COVID-19 to avoid intubation (2) by promoting alveolar recruitment in the lung area lacking hypoxic vasoconstriction (3, 4).