"Red blood cells (RBCs) play a key role in microcirculation and oxygen delivery to organ and tissues. This role is determined by their ability to deform and to pass through the vessels that are even smaller than RBC size. There is a close relationship between RBC deformability and its unique disc shape. Under different circumstances, RBC may change their shape and undergo echinocyte, stomatocyte or spherocyte transformation. Echinocytes or stomatocytes are potentially capable to restore the disc shape if they are put in favorable environment (e.g. fresh normal plasma), whereas the spherocyte transformation is considered to be irreversible. In-vitro studies using micropore filtration technique demonstrated that normal RBCs (discocytes) have an optimum shape for the flow in microvessels. In contrast to discocytes, stomatocytes and echinocytes produced by adding chlorpromazine or sodium salicylate, respectively, to normal RBCs demonstrated altered passage through circulation. Mechanisms of microcirculatory disorders in critical conditions such as trauma-hemorhagic shock, sepsis or burn have been under investigation for decades. Mechanisms of microcirculatory disorders in critical conditions such as trauma-hemorhagic shock, sepsis or burn have been under investigation for decades. (Sergey B Zaets- Do We have Enough Direct Evidence to Postulate that Abnormally Shaped Red Blood Cells Impair Microvascular Blood Flow in Critical Conditions?)."