Abstract
INTRODUCTION: Acute chest syndrome (ACS) is a leading cause of mortality in Sickle Cell Disease (SCD), often characterized by rapid respiratory decline and acute pulmonary hypertension (PH). While exchange transfusion is the standard of care for severe cases, delayed access to hemoglobin (Hb) electrophoresis often hinders real-time monitoring of therapeutic efficacy. We propose that POCUS guided assessments of pulmonary arterial pressures via tricuspid regurgitation jet velocities can serve as a real-time hemodynamic tool to direct serial exchange transfusions thereby preventing right heart failure and mortality in severe acute chest syndrome. CASE PRESENTATION: A 20-year-old male patient with HbSS (baseline HbS 28.7%, on hydroxyurea) presented with shortness of breath, severe hip/back pain and acute hemolysis (Hb 8.3 g/dL, bilirubin 7.4 mg/dL, LDH 484 U/L). Despite treatment for ACS and an initial exchange transfusion, his oxygen requirements escalated from simple nasal cannula to high-flow nasal cannula. Repeated imaging showed worsening infiltrates, and Point-of-Care Ultrasound (POCUS) revealed acute PH (TR jet velocity > 4 m/s). MANAGEMENT AND OUTCOME: Following the second exchange transfusion, the patient's tachycardia, dyspnea, and oxygen requirements rapidly improved. Follow-up Point-of-Care Ultrasound (POCUS) demonstrated an improved and now trace tricuspid regurgitation. Subsequent electrophoresis confirmed the first exchange only reduced HbS to 49%, while the second achieved a therapeutic level of 20.9% (recommended target HbS of <30% by American Society of Hematology). DISCUSSION/CONCLUSION: This case demonstrates that acute elevations in pulmonary artery pressure can serve as a critical surrogate marker for ongoing sickling when electrophoresis results are delayed. The patient's TRV of 3.74 m/s placed him in a high-mortality cohort (P < 0.001). Given that POCUS provides high diagnostic accuracy (AUC 0.87), it may be utilized as a real-time hemodynamic monitor to guide the necessity of serial exchange transfusions in the absence of immediate HbS% quantification. In severe ACS, achieving a target HbS ≤ 30% is vital, and bedside echocardiography may identify patients requiring immediate repeat exchange transfusion to prevent right heart failure and death.