Efficacy of Intravenous Almitrine in Reducing the Need for Mechanical Ventilation in Patients With Hypoxemic Acute Respiratory Failure Due to Covid-19-related Pneumonia

The COVID-19 outbreak is associated with a surge in ICU bed requirement and substantial mortality (estimated between 0.5% and 1%). Admission in the intensive care unit (ICU) and need for mechanical ventilation is reportedly associated with an estimated hospital mortality of more than 30%. Furthermore, the surge in ICU bed requirement is a worldwide-shared issue, leading to sub-optimal ICU management. In acute respiratory failure due to COVID-19-related pneumonia, vasoplegia with vascular enlargement inside the lung lesions and dilation of small vessels seen on chest CT scan largely account for severe hypoxemia whose physiological response is hyperventilation leading to hypocapnia. Almitrine, initially described to reduce intrapulmonary shunt by enhancement of hypoxic pulmonary vasoconstriction in combination with inhaled nitric oxide (iNO), redistributes pulmonary blood flow from shunt areas to lung units with normal ventilation/perfusion (VA/Q) ratio. Low dose of intravenous almitrine (2 µg.kg-1.min-1) alone also improves oxygenation (without combination with iNO) by selective pulmonary vasoconstriction of precapillary pulmonary arteries perfusing lung areas exposed to a hypoxic challenge with a slight increase in mean arterial pulmonary. Therefore, our hypothesis is that 5 days of low dose of almitrine therapy may improve the ventilation-perfusion (VA/Q) ratio at a relatively early stage of this specific lung disease and limit respiratory worsening and subsequent need for mechanical ventilation.