Blood gas tension Blood gas tension Blood gas tension refers to the partial pressure of gases in blood. There are several significant purposes for measuring gas tension; the most common gas tensions measured are oxygen tension (PO), the carbon dioxide tension (PCO) and carbon monoxide tension (PCO). The subscript "x" in each symbol represents the source of the gas being measured; ""a"" meaning arterial, ""A"" being alveolar, ""v"" being venous, ""c"" being capillary. Blood gas tests (such as arterial blood gas tests) measure these partial pressures. PO – Partial pressure of oxygen at sea level (765 mmHg) in arterial blood is between 75
Fetal hemoglobin round to sickle-shaped. These defective red blood cells have a greater tendency to stack on top of one another and block blood vessels. These invariably lead to so-called "painful vaso-occlusive episodes", which are a hallmark of the disease. If fetal hemoglobin remains the predominant form of hemoglobin after birth, the number of painful episodes decreases in patients with sickle-cell disease. Hydroxyurea promotes the production of fetal hemoglobin and can thus be used to treat sickle-cell disease. The fetal hemoglobin's reduction in the severity of the disease comes from its ability to inhibit the formation of hemoglobin aggregates within red blood