<unk>  is due to either hepatopulmonary syndrome or an anatomical cardiovascular defect increasing positional right-to-left shunting (bloodflow from the right to the left part of the circulatory system) such as a patent foramen ovale. These defects include rare syndromes in which the venous blood from the liver does not pass through the lungs, or if venous blood from the portal circulation reaches the inferior vena cava without passing through the liver (Abernethy malformation, type 1).
Platypnea
Periodic breathing
Tachypnea
Trepopnea
Apnea
Bradypnea
Shallow breathing
Bendopnea