Abstract
Background:Airway Pressure Release Ventilation (APRV) is a pressure controlled intermittent mandatory mode of ventilation characterized by prolonged inspiratory time and high mean airway pressure. Several studies have demonstrated that APRV can improve oxygenation and lung recruitment in patients with Acute Respiratory Distress Syndrome (ARDS). Although most patients with COVID-19 meet the Berlin criteria for ARDS, hypoxic respiratory failure due to COVID-19 may differ from traditional ARDS as patients often present with severe, refractory hypoxemia and significant variation in respiratory system compliance. To date, no studies investigating APRV in this patient population have been published. The aim of this study was to evaluate the effectiveness of APRV as a rescue mode of ventilation in critically ill patients diagnosed with COVID-19 and refractory hypoxemia.Methods:We conducted a retrospective analysis of patients admitted with COVID-19 requiring invasive mechanical ventilation who were treated with a trial of APRV for refractory hypoxemia. PaO2/FIO2 (P/F ratio), ventilatory ratio and ventilation outputs before and during APRV were compared.Results:APRV significantly improved the P/F ratio and decreased FIO2 requirements. PaCO2 and ventilatory ratio were also improved. There was an increase in tidal volume per predicted body weight during APRV and a decrease in total minute ventilation. On multivariate analysis, higher inspiratory to expiratory ratio (I: E) and airway pressure were associated with greater improvement in P/F ratio.Conclusions:APRV may improve oxygenation, alveolar ventilation and CO2 clearance in patients with COVID-19 and refractory hypoxemia. These effects are more pronounced with higher airway pressure and inspiratory time.
Highlights
The novel Coronavirus Disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) has become a global health emergency and has created unprecedented challenges to health care systems worldwide
The aim of this study was to assess the physiological changes in patients with severe Acute Respiratory Distress Syndrome (ARDS) secondary to COVID-19 undergoing a trial of Airway Pressure Release Ventilation (APRV) for refractory hypoxemia
Our results demonstrated that APRV resulted in significant reduction in the ventilatory ratio indicating a reduction in dead space ventilation
Summary
The novel Coronavirus Disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) has become a global health emergency and has created unprecedented challenges to health care systems worldwide. The inverse ratio ventilation facilitates lung recruitment, increases the respiratory system compliance, and improves gas exchange and oxygenation when compared to a traditional, non-inverse-ratio ventilatory strategy.[2] the lack of standardized protocols and the scarcity of clinical evidence from prospective studies have made APRV an infrequently used mode of ventilation that is mostly reserved as a rescue ventilatory strategy in patients with refractory hypoxemia and acute respiratory distress syndrome (ARDS). Methods: We conducted a retrospective analysis of patients admitted with COVID-19 requiring invasive mechanical ventilation who were treated with a trial of APRV for refractory hypoxemia. Conclusions: APRV may improve oxygenation, alveolar ventilation and CO2 clearance in patients with COVID-19 and refractory hypoxemia. These effects are more pronounced with higher airway pressure and inspiratory time
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