About 14вЂ‰days post-admission, she experienced a gradual increase in RR (from 25 to 30вЂ“40вЂ‰bpm), tidal volume (VT, from 410 to 480вЂ‰ml ), and MV (from 10 to 12вЂ“15вЂ‰L/min), accompanied by an increased PaCO 2 (from 39 to 47вЂ“60вЂ‰mmHg) and decreased oxygenation (arterial partial pressure of oxygen /fraction of inspired oxygen, from 127 to 74вЂ“100вЂ‰mmHg FiO 2, from 0.5 to 0.7). She was supported in pressure control mode: inspiratory pressure 15вЂ“18 cmH 2O and positive end-expiratory pressure (PEEP) 6вЂ“8 cmH 2O. A tracheotomy was performed 6вЂ‰days post-admission. On admission, she had severe dyspnea (respiratory rate, 40вЂ‰bpm) and acute hypoxemic respiratory failure (oxygen saturation 45% with oxygen flow 12вЂ‰L/min) and underwent endotracheal intubation immediately. To explain these pathophysiological features and discuss the ventilatory strategy during the late phase of severe ARDS in COVID-19 patients, we first used a metabolic module (COVX module GE Healthcare, Helsinki, Finland) on a General Electric R860 ventilator (Engstrom Carestation GE Healthcare, USA) to monitor parameters related to gas metabolism, end-expiratory lung volume (EELV), physiological dead space, ventilatory ratio (VR), and lung mechanics in two COVID-19 patients.Д¬ase 1: A 70-year-old woman (BMI, 21.5вЂ‰kg/m 2) with acute respiratory failure caused by COVID-19 was transferred to Tongji Hospital (Wuhan, China) on February 26, 2020. We also found that many mechanically ventilated COVID-19 patients recovering from severe ARDS experienced gradual increases in CO 2 retention and minute ventilation (MV). Recently, several articles have reported that the early acute respiratory distress syndrome (ARDS) caused by coronavirus disease 2019 (COVID-19) significantly differ from those of ARDS due to other causes, such as mismatch between changes in respiratory mechanics and severity of impaired oxygenation, significantly decreased ventilation efficiency, and lower lung recruitability. As of April 29, 2020, the number of total confirmed cases has exceeded 3 million, associated to 207,973 deaths worldwide. Tidal volume (8вЂ“9вЂ‰ml/kg) could be increased appropriately under the limited plateau pressure however, barotrauma should still be kept in mind.ДЄn ongoing outbreak of coronavirus disease 2019 (COVID-19) is spreading globally. ConclusionДuring the recovery period of ARDS among mechanically-ventilated COVID-19 patients, attention should be paid to the monitoring of physiological dead space and metabolism. We found that remarkably decreased ventilatory efficiency (e.g., the ratio of dead space to tidal volume 70вЂ“80%, arterial to end-tidal CO 2 difference 18вЂ“23вЂ‰mmHg and ventilatory ratio 3вЂ“4) and hypermetabolism (oxygen consumption 300вЂ“400вЂ‰ml/min, CO 2 elimination 200вЂ“300вЂ‰ml/min) may explain why these patients experienced more severe respiratory distress and CO 2 retention in the late phase of ARDS caused by COVID-19. To explain these pathophysiological features and discuss the ventilatory strategy during the late phase of severe ARDS in COVID-19 patients, we first used a metabolic module on a General Electric R860 ventilator (Engstrom Carestation GE Healthcare, USA) to monitor parameters related to gas metabolism, lung mechanics and physiological dead space in two COVID-19 patients.

However, the underlying mechanics remain unclear. Actually, we newly observed that some mechanically ventilated COVID-19 patients recovering from severe ARDS (more than 14вЂ‰days after invasive ventilation) often experienced evidently gradual increases in CO 2 retention and minute ventilation. Recently, several articles have mentioned that the early acute respiratory distress syndrome (ARDS) caused by COVID-19 significantly differ from those of ARDS due to other causes. An ongoing outbreak of coronavirus disease 2019 (COVID-19) is spreading globally.

Dead space lungs