Physiologic Effects of the Awake Prone Position Combined With High-Flow Nasal Oxygen on Gas Exchange and Work of Breathing in Patients With Severe COVID-19 Pneumonia: A Randomized Crossover Trial. (14th December 2022) - Lehingue, Samuel
Abstract : OBJECTIVES: To determine the effect of the awake prone position (APP) on gas exchange and the work of breathing in spontaneously breathing patients with COVID-19–associated acute hypoxemic respiratory failure (AHRF) supported by high-flow nasal oxygen. DESIGN: Prospective randomized physiologic crossover multicenter trial. SETTINGS: Four ICUs in Marseille, France. PATIENTS: Seventeen patients with laboratory-confirmed COVID-19 pneumonia and Pao 2 /Fio 2 less than or equal to 300 mm Hg while treated with high-flow nasal cannula oxygen therapy. INTERVENTIONS: Periods of APP and semirecumbent position (SRP) were randomly applied for 2 hours and separated by a 2-hour washout period. MEASUREMENTS AND MAIN RESULTS: Arterial blood gases, end-tidal CO2 . and esophageal pressure were recorded prior to and at the end of each period. Inspiratory muscle effort was assessed by measuring the esophageal pressure swing (∆PES ) and the simplified esophageal pressure–time product (sPTPES ). The other endpoints included physiologic dead space to tidal volume ratio (VD /VT ) and the transpulmonary pressure swing. The APP increased the Pao 2 /Fio 2 from 84 Torr (61–137 Torr) to 208 Torr (114–226 Torr) ( p = 0.0007) and decreased both the VD /VT and the respiratory rate from 0.54 (0.47–0.57) to 0.49 (0.45–0.53) ( p = 0.012) and from 26 breaths/min (21–30 breaths/min) to 21 breaths/min (19–22 breaths/min), respectively ( p = 0.002). These variables remained unchanged during the SRP. The ∆PES and sPTPES per breath were unaffected by the position. However, the APP reduced the sPTPES per minute from 225 cm H2 O.s.m –1 (176–332 cm H2 O.s.m –1 ) to 174 cm H2 O.s.m –1 (161–254 cm H2 O.s.m –1 ) ( p = 0.049). CONCLUSIONS: In spontaneously breathing patients with COVID-19–associated AHRF supported by high-flow nasal oxygen, the APP improves oxygenation and reduces the physiologic dead space, respiratory rate, and work of breathing per minute.