The use of iso-shunt lines for control of oxygen therapy

The concept of "virtual shunt" is presented as a practical means for determining the optimal inspired oxygen concentration for patients with hypoxaemia due to pulmonary venous admixture. The approach permits a reduction in the number of blood-gas analyses needed. Its limitations have been explored and its validity assessed from a series of 44 observations made on 4 patients. © 1973 John Sherratt and Son Ltd.