Less O2 saturation in blood is seen in: September 2006

Ans. A: R-L shunt Shunting of blood from the right side to the left side of the circulation (right-to-left shunt) is a powerful cause of hypoxemia. The shunt may be intracardiac or may be intrapulmonary. It has been traditionally thought that this cause could be readily distinguished from the others as the only cause that cannot be corrected by the administration of 100% oxygen.