The hemoglobin level impact on arterial oxygen saturation during venous-venous-extracorporeal membrane oxygenation support of acute respiratory distress syndrome patients: a mathematical marginal approach

Hemoglobin (Hb) levels in the range of 7 14g/dL have been targeted in extracorporeal membrane oxygenation (ECMO)-supported acute respiratory distress syndrome (ARDS) patients. There is an association between low Hb levels and prolonged duration of mechanical ventilation and bleeding episodes. In contrast, higher Hb levels are associated with lower ECMO blood flow, increased hemolysis, and increased costs. Current transfusion strategies are mostly based on individual judgment, derived mainly from oxygen delivery (DO2) /consumption rationale (VO2).(1) High volume ECMO centers are used to more restrictive Hb strategies, although there is no consensus on a definitive transfusion approach.(2) Conversely, some experienced centers use higher Hb thresholds for transfusion and accept oxygen arterial saturation (SatO2) as low as 70% with excellent clinical outcomes.(3) Critical illnesses are related to cellular dysfunction due to reduced DO2 to tissues. Oxygen delivery depends on cardiac output (CO), Hb level, oxygen arterial partial pressure (PaO2), and SatO2 as in equation 1.(4)