Peripheral<unk>  improves with oxygen therapy. Conversely, central<unk>  does not respond to oxygen therapy because of the underlying intrapulmonary or intracardiac shunt which is responsible for mixing the nonoxygenated  venous blood  and oxygenated arterial blood. All causes of central<unk>  may cause peripheral<unk> .
Cyanosis diagnostic study of choice
Cyanosis other diagnostic studies
Cyanosis echocardiography or ultrasound
Methemoglobinemia diagnostic study of choice
Pulmonary hypertension diagnostic study of choice
Cardiomyopathy other diagnostic studies
Diabetic foot other diagnostic studies
Pulmonary hypertension other diagnostic studies