National Physical Therapy Examination (NPTE) Practice Exam

What test finding is MOST consistent with a diagnosis of idiopathic pulmonary arterial hypertension?

1. VO2 max of 25 mL/kg/minute

2. Cardiac index of 0.8 L/minute/m2

3. Right atrial pressure of 15 mm Hg

4. Six-minute walk test result of 1640 ft (500 m)

The correct answer is: Right atrial pressure of 15 mm Hg

The most consistent test finding with a diagnosis of idiopathic pulmonary arterial hypertension (PAH) is a right atrial pressure of 15 mm Hg. In PAH, elevated right atrial pressure indicates increased resistance in the pulmonary circulation, which leads to right heart strain and ultimately dysfunction. This pressure reading reflects the hemodynamic changes associated with the disease and is a significant marker in the evaluation and diagnosis of pulmonary hypertension. In the context of pulmonary hypertension, particularly idiopathic forms, right atrial pressure is often elevated due to increased pressure in the pulmonary arteries, which results from vasoconstriction and vascular remodeling. As the right ventricle struggles to push blood through the narrowed pulmonary arteries, this contributes further to increased pressure within the right atrium. While a low cardiac index may suggest heart dysfunction, it is not specific enough to directly indicate PAH on its own. A VO2 max of 25 mL/kg/minute might reflect overall fitness levels or limited exercise capacity but does not specifically confirm pulmonary arterial hypertension. Similarly, a six-minute walk test result of 1640 ft (500 m) reflects exercise tolerance but can be influenced by many factors unrelated to PAH severity or presence. Therefore, the specific measurement of right atrial pressure