Severe anemia is proactively investigated and treated during ECMO support, since the oxygen-carrying capacity of blood depends on hemoglobin concentration. Although ELSO guidelines recommend maintaining hematocrit over 40% during ECMO (or, hemoglobin greater than approximately 13 g/dL), a recent systematic review showed no advantage of liberal transfusion strategies over restrictive transfusion thresholds for patients on VV- or VA-ECMO (ie, hemoglobin goal exceeding 7–10 g/dL). At our institution, hemoglobin <7 g/dL is the typical transfusion threshold for both pregnant and nonpregnant patients on ECMO support. If there is concern for inadequate tissue oxygenation despite attaining a target maternal Sao2 of 95%, cardiac output may be calculated using transthoracic or transesophageal echocardiography to determine whether a higher hemoglobin threshold is required to maintain desired oxygen delivery.
Thrombocytopenia is common during ECMO due to platelet activation by circuit components, systemic inflammation, medications, and underlying comorbidity.[73,76,77] Although infrequent, spontaneous intracranial hemorrhage during ECMO support can be a devastating complication relating to severe thrombocytopenia. ELSO guidelines recommend platelet transfusion to maintain a count >80,000 × 109/L; however, lacking robust evidence for this recommendation, other authors suggest lower platelet transfusion thresholds around 40,000 to 50,000 × 109/L.[73,78] In our practice, we typically maintain a platelet count >40,000 × 109/L to balance competing risks of thrombotic and hemorrhagic complications. Notably, hemostasis may yet be abnormal despite a numerically adequate platelet count, since exposure to circuit components causes qualitative platelet dysfunction in virtually all ECMO patients (ie, acquired von Willebrand disorder).[73,79]
Anesth Analg. 2022;135(2):277-289. © 2022 International Anesthesia Research Society