Pulmonary Function Tests measure how much air your lungs can hold, how much air moves in and out of them, and the lungs’ ability to exchange oxygen. These tests may be performed to potentially identify the cause of PH.
Computerized Tomography (CT) Chest Scan is a non-invasive test that uses small amounts of radiation to create many precise pictures of the structures in the chest, including the heart and lungs. Sometimes, a dye (also known as “contrast”) is injected into the arm to make the images of certain structures clearer. The test allows healthcare providers to see the lungs in far greater detail than with chest X-rays. Doctors can see the size of the lungs, larger blood vessels in the lungs, and lung tissue. The test looks for evidence of chronic lung diseases (Group 3 PH) or blood clots (Group 4 PH).
Nuclear Scan (Ventilation/Perfusion Scan or V/Q Scan) is a diagnostic tool which tests for blood clots in the lungs by producing a picture of air and blood flow to the lungs. A small dose of radioactive material is breathed in, and another small dose is injected via a blood vessel into the lungs. The doctor will review the images that are produced to evaluate the health of the lungs. This test is recommended to rule out CTEPH in all cases of PH. A Six-Minute Walk Test (6MWT) measures how far a patient can walk in six minutes. It also measures perceived exertion, heart rate, and oxygen saturation (how much oxygen is in the blood). Doctors compare test results from each clinic visit as one way to measure whether PH is improving or worsening.
Blood Tests check oxygen levels in the blood (i.e., with an arterial blood gas), observe liver and kidney function, and identify whether the patient has connective tissue disease (such as lupus or scleroderma), thyroid problems, or signs of infection or HIV. To help assess the function of the heart and to monitor response to treatment, a brain natriuretic peptide (BNP) test or an N-Terminalpro brain natriuretic peptide (NT-proBNP) may be conducted. Some centers measure NT-proBNP while others measure BNP, but both measure the same thing – heart function.
Sleep Studies are occasionally requested in patients at risk for obstructive sleep apnea or low oxygen levels overnight. These can be done at home with equipment to check for snoring and oxygen levels, or may require a complete polysomnogram, where a patient sleeps in a monitored sleep lab.