Carboxyhemoglobin Elevation, a Marker for Hemolysis, Is Common in Veno-venous Extracorporeal Membrane Oxygenation

To the Editor: Giani et al.1 found low levels of carboxyhemoglobin (COHb) in a cohort of patients supported on veno-venous extracorporeal membrane oxygenation (VV ECMO) at their center. It is noteworthy that even on ECMO support, COHb values were below average levels found in general intensive care unit population (1.3–1.9%) without extracorporeal support.2 Moreover, in observational studies of VV ECMO, severe hemolysis occurs between 10% and...