Breathing is something most of us take for granted—until it becomes difficult. When symptoms like shortness of breath, chest tightness, or chronic cough arise, doctors often recommend a pulmonary function test (PFT) to understand how well your lungs are working.

This comprehensive guide explains what pulmonary function testing involves, how long it takes, and what the capillary pulmonary wedge pressure measurement can reveal about your heart and lung health.

Pulmonary function testing (PFT) refers to a group of noninvasive tests that measure how well your lungs move air in and out, and how efficiently they deliver oxygen to your bloodstream. These tests are commonly used to diagnose or monitor conditions such as:

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Pulmonary fibrosis
• Heart failure or lung-related heart conditions
• Preoperative lung evaluation

A PFT can help your doctor identify whether breathing problems are caused by airway restriction, reduced lung volume, or poor oxygen exchange.

Pulmonary function testing is typically performed in a doctor’s office, clinic, or hospital respiratory lab. The entire process usually takes 30 to 60 minutes, depending on the type and number of tests your doctor orders.

You’ll be asked to sit upright, wear a nose clip, and breathe through a mouthpiece connected to specialized equipment. The technician may ask you to:

• Take deep breaths and exhale forcefully into the device
• Hold your breath for a few seconds
• Repeat breathing patterns several times for accurate results

In some cases, a bronchodilator (an inhaled medication that opens airways) may be given mid-test to see how your lungs respond.

While standard pulmonary function tests measure airflow and lung volume, capillary pulmonary wedge pressure (PCWP) offers insight into how your heart and lungs work together.

The capillary pulmonary wedge pressure is measured during a special procedure called right heart catheterization. A thin, flexible tube is inserted into a vein—usually in the neck or groin—and gently guided into the heart and pulmonary arteries. From there, doctors can measure the pressure in the small pulmonary capillaries that reflect the left side of the heart’s function.

This test is especially useful in diagnosing or evaluating:

• Heart failure – Elevated wedge pressure can indicate that the left side of the heart is struggling to pump blood efficiently.
• Pulmonary hypertension – High pressure in the pulmonary arteries can strain both the heart and lungs.
• Fluid buildup in the lungs – Abnormal wedge pressure may explain symptoms such as shortness of breath or fatigue caused by fluid congestion.

Although it sounds complex, this test is performed under careful monitoring by a cardiologist and provides valuable information for tailoring treatment.

While the basic PFT is completed in under an hour, the capillary pulmonary wedge pressure measurement takes a bit longer because it involves heart catheterization. The procedure itself typically lasts 30 to 60 minutes, but preparation and recovery can extend your total time to two to three hours.

You’ll be awake but sedated during the process. Most patients go home the same day after observation and are advised to rest for 24 hours.

Whether you’re experiencing ongoing shortness of breath or managing a chronic heart or lung condition, pulmonary function testing offers a clearer picture of your respiratory health. Measuring capillary pulmonary wedge pressure helps physicians distinguish whether breathing difficulties stem from the lungs, the heart, or both.

This insight allows for more accurate diagnoses and personalized treatment plans—ensuring you get the right care at the right time.

Pulmonary function testing is a safe, effective way to evaluate lung performance and detect underlying heart or lung issues early. When combined with measurements like capillary pulmonary wedge pressure, it becomes an even more powerful tool for understanding how your heart and lungs interact.

At Modern Family Medicine, we believe in proactive, patient-centered care. Our team partners with families and individuals to identify respiratory or cardiovascular concerns and develop comprehensive treatment strategies that promote long-term health and well-being.

If you’ve been experiencing breathing difficulties or persistent fatigue, talk to your healthcare provider about whether pulmonary function testing could help uncover the cause—and guide you toward better breathing and better living.