Letter to the editor: “Clinical characteristics, physiological features, and outcomes associated with hypercapnia in patients with acute hypoxemic respiratory failure due to COVID-19---insights from the PRoVENT-COVID study”

[...]lung protective ventilation using lower tidal volume and higher respiratory rate is the cornerstone of the management of patients with severe ARDS, including that attributable to Covid-19, with the potential consequence of hypercapnia. [...]ventilatory ratio, defined as [minute ventilation (ml/min) × partial pressure of arterial CO2 tension (mm Hg)]/(predicted body weight × 100 × 37.5), is a simple bedside index of assessing the efficiency of mechanical ventilation [6]. [...]hypoxemia, quantified by the ratio of partial pressure arterial oxygen tension and fraction of inspired oxygen concentration (PaO2/FiO2), does not necessarily assess the alveolar ventilation and physiological dead space which reflect the overall efficacy of the lungs to eliminate the CO2 load.