Proposed diagnostic workup algorithm for hypoxemia in patients with SCD. Proposed algorithm for evaluation of hypoxemia in patients with SCD and other hemoglobinopathies. BIPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; OPSG, overnight polysomnogram. Echocardiography should be performed while the patient is clinically stable. All or some of the proposed studies may be obtained depending on the patient presentation and clinical suspicion for the underlying cause of hypoxemia.