If the boards give you a question describing a patient with decrease saturation (orthodeoxia) and dyspnea (playpnea) while in the upright position and he also have liver disease then this is certainly HepatoPulmonary syndrome.
They have platypnea and orthodeoxia because there's increased pulmonary vasodilation (for unknown reason) which results in ventilation perfusion mismatch (shunt) because more blood is going than there's alveoli to exchange oxygen with. This shunt increases in the upright position.
They have platypnea and orthodeoxia because there's increased pulmonary vasodilation (for unknown reason) which results in ventilation perfusion mismatch (shunt) because more blood is going than there's alveoli to exchange oxygen with. This shunt increases in the upright position.