Souvik Choudhuri, Banambar Ray and Dipika Mohanty
Depletion of nitric oxide (NO) in the microcirculation plays a central role in the pathogenesis of sickle cell disease (SCD) and acute chest syndrome (ACS). Various other mechanisms which are responsible for the sickle-cell vasoocclusive crisis are polymerization of sickle haemoglobin, platelet activation, endothelial damage and leucocyte adhesion. During the sickle cell crisis, the high rate of red blood cell (RBC) destruction leads to release of erythrocyte arginase (into the plasma), which thereby destroys arginine. Arginine, the substrate for NO synthase, once depleted, results in lower levels of NO in vessels, leading to vasoconstriction, pulmonary hypertension and ventilation perfusion mismatch. Increasing the availability of NO therefore has a central role in SCD, especially in cases of ACS. With the prevention of vasoconstriction by NO inhalation therapy in ACS, pain relief can be provided to the patients in sickle cell crisis. We present a report of 2 cases of sickle cell disease with ACS (Acute Chest Syndrome) in whom inhalation of NO through non-invasive ventilation (NIV) brought about pain relief and recovery from ACS.