The presurgical management with erythrocytapheresis of a patient with a high-oxygen-affinity, unstable Hb variant (Hb Bryn Mawr).

BACKGROUND: Hemoglobin (Hb) Bryn Mawr is an unstable Hb variant resulting in congenital hemolytic anemia. This variant Hb also has an increased affinity for oxygen. The perioperative transfusion management of this disorder is described, and the first genomic analysis of this Hb variant is given. CASE REPORT An 1 1 -year-old boy, heterozygous for Hb Bryn Mawr, was referred for cholecystectomy. Sequence analysis of genomic DNA confirmed that the patient was heterozygous for a T+C transition in the codon for amino acid 85, causing a substitution of serine for phenylalanine in the P-globin chain. On the basis of whole-blood 0, dissociation studies, projected tissue 0, delivery would have been suboptimal during general anesthesia; therefore, a partial red cell exchange transfusion was performed to lower variant Hb and prevent tissue hypoxia during surgery. The red cell mass to be exchanged (50%) was determined from the calculated increase in 0, delivery capacity required to maintain an 0, extraction of 4 to 5 mL of 0, per dL of whole blood. The,p5O of whole blood from the patient immediately after the exchange transfusion was 16.0 torr. At the time of surgery, the p50 was normai (25.9 torr). The patient's whole blood 2,3 DPG levels were 4.70 mmol per mL of red cells (before transfusion) (normal range = 4.8 i 0.3 mmol/mL red cells), 4.07 mmol per mL of red cells (immediately after transfusion), and 4.55 mmol per mL of red cells (48 hours after transfusion). CONCLUSION: This patient with Hb Bryn Mawr was prepared for surgery with a partial exchange transfusion to prevent tissue hypoxia during anesthesia. Decreased 2,3 DPG levels immediately after transfusion resulted in increased 0, affinity of whole blood; however, 48 hours after exchange transfusion, a normal p50 (due to both removal of variant Hb and regeneration of 2,3 DPG) was observed. Partial exchange transfusion is useful in the preoperative management of patients with Hb variants characterized by increased 02, affinity.