Discussion
ACS is one of the leading causes of mortality and morbidity in patients with SCD.6 Given the propensity of pulmonary disease in patients with SCD, any infectious process including SARS-CoV-2 can exacerbate ACS and lead to life threatening refractory hypoxemic ARDS as seen in our case through the sequestration of sickled RBCs. With limited data detailing SARS-CoV-2 in children with SCD, our case illustrates key elements that provide a treatment strategy for ECMO support which allowed this patient to recover but also allowed for rehabilitation to improve his candidacy for LTx.
As the ECMO circuit can exacerbate sickling and hemolysis, we believe aggressive management of the HbS level maintaining a level ≤15% while on ECMO was critical in our management and contributed to the positive outcome for this patient as we believe it prevented end organ damage from vaso-occlusive events from further sickling. Pro-active and pre-planned changes of oxygenator or circuit based on fibrin deposit burden and the free plasma hemoglobin level also prevented further hemolysis leading to end organ dysfunction or disastrous circuit failure. We also maximized the hydroxyurea therapy to increase the level of anti-sickling HbF level, in an attempt to minimize overall blood transfusion requirements, thereby lowering risk of allosensitization, should he later require LTx. The hydroxyurea-induced increase in HbF level also allowed liberalization of his exchange transfusion requirement to maintain HbS levels <30% upon discharge. The patient has returned home but continues to require chronic mechanical ventilation and is only tolerating a very prolonged wean from mechanical ventilation. He participates in physical rehabilitation without need for re-hospitalization, which enhances his potential for full recovery or makes his future candidacy for LTx more favorable as pre-transplant hospitalizations is associated with increased morbidity and mortality post-LTx.7