Friend or Enemy?
Under normal conditions, the hemoglobin protein is stored in red blood cells and serves to carry oxygen in the blood. However, in the setting of critical illness, trauma, or blood transfusion, hemoglobin can be released from stressed RBCs into the bloodstream. This form is called CELL-FREE HEMOGLOBIN (CFH).
CFH damages the cells that line the blood vessels, and eventually damages other cells in the body too.
Patients with sepsis, major trauma, and those receiving blood transfusions have increased levels of CFH in their bloodstream, possibly leading to endothelial damage and increased permeability of the airways to fluid. Furthermore, CFH in the airways can damage epithelium in the setting of ARDS or pneumonia.
We are studying exactly how this happens, and what CFH does to lung cells in critically-ill patients in our hospital.