Diagnostic Tests and Assessments
WITHIN THE GENERAL MEDICAL COMMUNITY the lack of clinical knowledge of PF remains a concern. This is further complicated by the fact that there are more than 200 different types of ILD. Limited awareness of the causes and an inadequate understanding of disease progression have resulted in misdiagnosis of many of the ILDs. In fact, a recent study showed that more than 50% of patients with IPF might have been initially misdiagnosed.7
It was not until 1999 that the American Thoracic Society (ATS and the European Respiratory Society (ERS), in collaboration with the American College of Chest Physicians (ACCP), described specific clinical and pathological characteristics of IPF.14 In 2011 the ATS, ERS, Japanese Respiratory Society (JRS), and the Latin American Thoracic Society (ALAT) defined evidence-based guidelines for the diagnosis and management of IPF, helping to standardize IPF diagnosis and treatment.2 In general, the diagnosis of IPF requires three factors:14
- Exclusion of other known causes of ILD.
- The presence of a UIP pattern on high-resolution computed tomography (HRCT) in patients not subjected to surgical lung biopsy.
- Specific combinations of HRCT and surgical lung biopsy pattern in patients subjected to surgical lung biopsy.
Your care provider will use a series of diagnostic tests and assessments to help determine if you have PF. To determine if you have PF, and the type of PF, you may require multiple tests. Additionally, the exclusion of known causes of fibrotic lung disease requires a careful history and physical examination focusing on comorbidities, medication use, environmental exposures, and family history.
Multiple care providers from a variety of specialties, including pulmonologists, radiologists, rheumatologists, and pathologists,can help determine your diagnosis. Providers who are experienced in the diagnosis of PF can improve the accuracy of your diagnosis. To find a medical center near you with specific expertise in PF call 888.733.6741 or visit www.pulmonaryfibrosis.org/medicalcenters.
The tests outlined below may be used in the diagnosis of PF. If you have already been diagnosed with PF, many of these tests will be used to follow your lung health.
DIAGNOSTIC TESTS AND ASSESSMENTS
History and Physical Exam: A detailed medical history and examination to learn if there were any environmental, occupational, familial, or other medical conditions that could have contributed or predisposed a person to the disease’s development. When listening to the lungs with a stethoscope, the physician may hear “crackles” or Velcro-like sounds. These are “opening” sounds made by the small airways during inspiration.
Chest X-Ray: A routine chest X-ray may be used as a screening test. However, 5–15% of patients with significant scarring will have a normal chest X-ray and IPF cannot be diagnosed from a chest X-ray alone.
High-Resolution Computerized Tomography (HRCT): A detailed image of the lungs to help physicians more clearly identify certain radiographic patterns in the lung tissue that may indicate disease. A radiologist may identify a “honeycombing” pattern that suggests lung scarring and damage to the air sacs, or “ground-glass opacity” that refers to the hazy appearance of lung tissue that is most associated with inflammation.
Pulmonary Function Tests: Breathing tests that measure the total amount of air in the lungs and assess the flow of air in and out of the lungs. There are two important components to pulmonary function tests: (1) spirometry that measures inspired and expired lung volumes and the rate at which this occurs and (2) diffusion capacity,or DLCO, that measures the ability of oxygen to diffuse into the bloodstream. These tests are usually done in a hospital or clinical laboratory and consist of breathing into a spirometer; they are sometimes done sitting inside a large plastic enclosure that resembles a glass telephone booth.
Pulse Oximeter: A device placed on the finger or earlobe that indicates the amount of oxygen saturation in the blood. Normal ranges are 95–100% on room air. Pulse oximetry does not measure carbon dioxide levels, so a blood gas level measurement may be necessary in some patients.
Arterial Blood Gas (ABG): Direct arterial puncture to measure arterial pH, oxygen saturation (PaO2), and carbon dioxide content (PCO2). Arterial blood has been oxygenated by the lungs and thus indicates how much oxygen is available to the body.
Bronchoscopy: Examination of the main airways of the lungs through the use of a small, flexible tube called a bronchoscope. Bronchoscopy helps to evaluate lung problems or blockages and provides a means to sample tissue or fluids. Unfortunately, the lung tissue samples obtained through bronchoscopy are small and usually inadequate for a definitive diagnosis.
Bronchoalveolar Lavage (BAL): A way to remove a tiny sampling of cells from the lower respiratory tract using a bronchoscope. A small amount of saline is injected through the bronchoscope and, when withdrawn, removes a sample of cells from the respiratory tract. Usually this is not helpful in making the diagnosis of IPF, but may be beneficial in other clinical situations.
Surgical Lung Biopsy: Surgical lung biopsy can be an important diagnostic tool in the evaluation of patients suspected of having a fibrotic lung disorder and is generally considered the “gold standard” for diagnosis. A lung biopsy in conjunction with an HRCT can also help determine how far the disease has progressed. Usually the biopsy can be performed by a minimally invasive procedure using video assisted thoracoscopic surgery (VATS). VATS is usually well tolerated, but it may not be recommended for all individuals.
Exercise Testing: A measure of how well the lungs function during exertion. Methods vary from hospital to hospital, but usually include the use of a stationary bike or treadmill. The most common method of exercise testing is the six-minute walk test, where the distance a patient can walk in six minutes is measured. Blood pressure, electrocardiogram, and oxygen saturation levels are monitored during exercise testing.
Esophogram: An X-ray examination of the esophagus (the tube that carries food to your stomach). This exam will help to determine if you suffer from GERD.
Echocardiogram (ECHO): A test that uses sound waves to create a picture of your heart, providing information about your heart function and screening for the presence of pulmonary hypertension.
This information has been approved by Gregory P. Cosgrove, MD (September 2012)