Long-Term Erythrocytapheresis Did Not Prevent Development of Severe Pulmonary Hypertension in Sickle Cell Disease
Authors: McCarty Grae Chambers , Knapp Esther Elise , Kurtz Joshua , Raj Ashok B. 
Published: December 2023

Background
The WHO classifies pulmonary hypertension into five different groups based on pathophysiology, clinical presentation, and therapeutic options. The development of pulmonary hypertension (PH) in sickle cell disease (SCD) is multifactorial and can cause devastating complications. Erythrocytapheresis is utilized in patients with SCD who have multiple comorbidities or are unresponsive to first-line treatments like hydroxyurea. It is hypothesized that treatment with long-term erythrocytapheresis (LTE) could slow the progression to pulmonary hypertension by modifying the pathophysiology of the disease process. However, limited clinical data supports this transfusion modality [1].
Case Description
The patient is a 17-year-old female with a history of SCD, obstructive sleep apnea (OSA), nocturnal hypoxemia, and recurrent pain crises maintained on LTE every four weeks for the past seven years. She had previously failed hydroxyurea therapy. She underwent a tonsillectomy and adenoidectomy seven years ago to treat OSA. The patient had an echocardiogram five years ago, which showed normal biventricular function and tricuspid regurgitation jet velocity. Recently she presented to the emergency department with cough, shortness of breath, fever, diarrhea, and nausea lasting for three days. Initial assessment revealed elevated liver enzymes, elevated BNP, hyperbilirubinemia, hemoglobin of 9.5 g/dL, and oxygen saturations in the 80's. Echo revealed right ventricular dysfunction and right atrial and ventricular enlargement with a tricuspid regurgitation jet velocity of 4.29 m/s and estimated right ventricular systolic pressure 90% systemic, as seen in figure 1. The patient was admitted to the PICU under concern of pulmonary hypertension crisis. She underwent a right cardiac catheterization three days into her admission and was diagnosed with severe pulmonary hypertension with a mean pulmonary artery pressure of 49 mmHg. Pulmonary capillary wedge pressure was 11 mmHg, and pulmonary vascular resistance was calculated to be 18 wood units x m 2 with 20 PPM of nitric oxide and 80% FiO2 the PVR decreased to 11 woods units x m 2 (figure 2). CTA showed subsegmental thrombosis and vascular surgery was consulted for evaluation for endarterectomy, but they decided she was not a surgical candidate. She was initiated on anticoagulation therapy with enoxaparin, sildenafil, and bosentan.
Conclusions
The cause of PH in this patient appears to be multifactorial. Possible etiologies include SCD-related, primary pulmonary hypertension, or subsegmental pulmonary embolism. Although LTE is increasingly used in the management of SCD, providers should not assume that a patient receiving this treatment will not progress to develop complications. Some patients on LTE may also develop progressive CNS vasculopathy and are still at risk for developing hypertension. Patients with SCD should be screened for PH if they are symptomatic or have comorbid conditions. This patient had a history of nocturnal hypoxemia and OSA, which some studies indicate are associated with pulmonary hypertension in adolescents with SCD. Screening for nocturnal hypoxemia and OSA is recommended in SCD to identify patients at high risk of PH development [2].
References
1. Estcourt LJ, Fortin PM, Hopewell S, Trivella M, Hambleton IR, Cho G. Regular long-term red blood cell transfusions for managing chronic chest complications in sickle cell disease. Cochrane Database Syst Rev. 2016 May;((5)):CD008360.
2. Mondal P, Stefek B, Sinharoy A, Sankoorikal BJ, Abu-Hasan M, Aluquin V. The association of nocturnal hypoxia and an echocardiographic measure of pulmonary hypertension in children with sickle cell disease. Pediatr Res. 2019 Mar;85(4):506-510. doi: 10.1038/s41390-018-0125-6. Epub 2018 Jul 24. PMID: 30135591.