Platypnoea after pneumonectomy caused by a combination of intracardiac right-to-left shunt and hypovolaemia. Relief of symptoms on restitution of blood volume.

A patient developed platypnoea about a month after pneumonectomy. The symptoms proved to be due to a combination of an atrial right-to-left shunt and hypovolaemia. Blood volume substitution did not change the direction of the shunt, but the symptoms were relieved. The physiological background to this may be a less pronounced venous desaturation and thereby a less marked influence of the shunt on the arterial oxygen saturation.