The Therapeutic Role of Almitrine and Inhaled Nitric Oxide (INO) As Rescue Therapy in Patients of Acute Respiratory Distress Syndrome (ARDS) Due To Covid-19-A Narrative Review

COVID-19 is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), leading to acute respiratory distress syndrome among suffered patients manifested through severe hypoxemia and ventilation-perfusion VA/Q mismatch. This study aims to evaluate the effectiveness of INO, Almitrine and INO + Almitrine combined in terms of improvement in PaO2/FiO2 (mmHg) ratios and arterial or venous blood gases profile were analyzed before and after rescue therapy. Various databases were searched for collection studies and only 18 studies of interest were included in this review. Initially, baseline parameters (PaO2/FiO2 ratios, pH, PaCO2, PaO2, SpO2 and echocardiographic parameters like velocity-time integral of the left ventricular outflow tract (VTI LVOT), Cardiac index, Tricuspid regurgitation (TR) peak velocity, Left Ventricular (LV) eccentricity index and finally RV/LV surface ratio) were assessed. They were compared after INO (10 ppm), Almitrine alone (2,4,8 and 12 µg/kg/min) and INO (10 ppm) + Almitrine (8 µg/kg/min) combined. After rescue therapy significant rise of PaO2/FiO2 (mmHg) ratios from 146 mmHg to 255 mmHg in one study and 79 mmHg to 117 mmHg in another was observed and arterial or venous blood gases profile was also improved from baseline of value (pH= 7.30, PaCO2= 48 mmHg, PaO2= 102 mmHg, bicarbonate=28 mmol/L and So2= 97%) to (pH= 7.32, PaCO2= 46 mmHg, PaO2= 180 mmHg, bicarbonate=28 mmol/L and So2= 99%) after INO and Almitrine combined therapy. Similarly, the cardiac parameters on echocardiography were also under normal reference values after rescue therapy validating the effectiveness of rescue therapy (INO + Almitrine) in treating COVID-19 induced ARDS.