Your Lung Function Test Questions Answered by Wilmington Family Doctors

According to the Office of Disease Prevention and Health Promotion (ODPHP), over 25 million Americans have asthma.

Moreover, 14.8 million Americans currently suffer from COPD. Public health researchers estimate that 12 million more people are struggling with undiagnosed lung disease.

Chronic lung conditions are no joke. Lower respiratory disease is the 6th leading cause of death in the United States. Many patients face barriers to effective diagnosis and treatment of pulmonary disease.

Lung function tests give physicians accurate, objective data about your lung health.

This is invaluable when making a diagnosis and monitoring disease management. Learn how these tests work, why you might need one, and how they can improve your approach to treating your respiratory condition.

What Is a Pulmonary Function Test?

Lung function tests help diagnose respiratory illness, and they can help determine the severity of lung disease. These tests take a few different measurements, including:

  • Airflow
  • Lung volume
  • Lung capacity

A pulmonary function test (PFT) is another term for a lung function test. Most PFTs require patients to inhale and exhale into a spirometer.

An Arterial Blood Gas (ABG) test is the only test that does not analyze a patient’s breath directly.

When Is a Lung Function Test Required?

A family physician or primary care doctor may order a lung function test if a patient has symptoms of lung disease. Symptoms often include:

  • Low blood-oxygen concentration
  • Shortness of breath
  • Cough
  • Phlegm or sputum production
  • Wheezing
  • Labored breathing
  • Fatigue
  • History of smoking

Physicians commonly use lung function tests to help diagnose asthma, bronchitis, or COPD. More rarely, the test may indicate interstitial lung disease, lung cancer, or a different respiratory infection.

What Types of Pulmonary Function Test Might You Need?

Different devices can run different pulmonary function tests. The four main tests used to measure lung function are:

  • Spirometry
  • Body Plethysmography
  • Respiratory Pressure Meter (peak flow)
  • Arterial Blood Gas (ABG)

Spirometry is the most common diagnostic test, and some family doctors and other primary care physicians may offer it in their office. Your family physician is more likely to order a peak flow or spirometry lung function test if you have respiratory distress.


Spirometry tests measure lung volume and airflow, by different metrics.

During a spirometry test, you breathe into a mouthpiece connected to a machine. You wear a nose clamp during the test, so you exhale and inhale entirely through your mouth.

Most patients take a spirometry test sitting upright. Physicians may ask you to take the test lying down to diagnose conditions that impact diaphragm function.

You will be asked to take as deep a breath as you can during the test. Then, you will be asked to exhale as forcefully and as quickly as you can. You will also be asked to exhale for as long a duration as possible.

Spirometry tests are typically repeated three times, with breaks in between. This allows your physician to eliminate any results that may be an outlier.

In some cases, a patient will take albuterol or some similar medication between the second and third tests. This can demonstrate the effect of fast-acting medications on your lung function.

Body Plethysmography

A body plethysmography test is similar to a spirometry test. Like the spirometry test, you breathe into a mouthpiece attached to a machine. Unlike a spirometry test, body plethysmography is in an enclosed, airtight box.

Body plethysmography tests measure many of the same things spirometry tests do, but they also measure residual air volume, which is how much air is left in your lungs after you exhale.

Respiratory Pressure Meter

A respiratory pressure meter is also called a “peak flow” meter. This test is portable. It takes less than five minutes.

You can take this test sitting or standing.

It is more limited than other tests, as it only tells you about airflow. It cannot assess lung volume or capacity.

Arterial Blood Gas (ABG)

An arterial blood gas (ABG) test measures the ratio of oxygen and carbon dioxide in your blood. It also measures the pressure of those gasses and the pH balance of the blood.

In this test, you sit or lie down, while a provider draws blood.

ABG tests are used in emergencies to determine if someone is expelling CO² effectively, or not. These test can also help diagnose enzyme-related lung dysfunction.

How Long Do Lung Function Tests Last?

Lung functions tests take less than an hour to complete and obtain results. The typical spirometry test takes about 30 minutes. An ABG test also takes about 30 min for testing and results.

A body plethysmography test typically takes about 15 minutes. Peak flow meter tests are portable, and they take only five minutes.

Understanding Your Lung Function Test Results

Lung function tests determine if your condition is largely restrictive or obstructive.

Restrictive lung conditions make it hard for a patient to completely expand their lungs and fill them with air. Obstructive conditions make it hard to push out all the CO² in your lungs when you exhale.

Spirometry and peak flow tests give you measurements of lung health. These include:

  • Volume
  • Capacity
  • Expiratory flow

ABG tests also tell you about expiratory flow, indirectly. ABG test readings tell you your:

  • Blood pH
  • Oxygen, CO² saturation
  • Oxygen, CO² pressure

If possible, your family physician or primary care physician will try to establish your baseline lung function so they can compare your test results to that baseline.

In 2019, the American Thoracic Association updated its standards and guidelines for assessing spirometry test results. The standards factor patient age, weight, height, and birth sex into lung volume assessments.

Your primary care doctor can help you understand your test results in terms of percentiles. You can ask your doctor to explain how reduced volume, capacity, or flow impacts your day-to-day life.

How Can Direct Primary Care Help Patients With Lung Issues?

Lung conditions can be chronic, and some very serious. Direct primary care practices like Promina Health offer an affordable and more personalized way to get help managing lung conditions.

At Promina Health, appointments are not time-limited. Your family physician will take time to really listen to you, understand your respiratory quality of life, and track the progress of your lung treatment.

Test As Often As Needed

At a direct primary practice like Promina Health, spirometry lung function tests are offered at no-cost; they are included in your monthly membership. Any visits that you need are also included in the membership plan, so you won’t have the added expense of paying a co-pay or paying for each visit to help manage your condition.

The medical non-profit Choosing Wisely recommends taking a lung function test every 4-6 weeks after an asthma or COPD diagnosis, until test results show function has improved, so these expenses can add up in a traditional, non-direct primary care practice.

Save on Medication

Promina Health also offers significant savings on respiratory medications, conveniently dispensed right from the office. If there’s a medication that’s not available in the the office, your family doctor will help you find a pharmacy with the best price. This is true both for long-term allergy and asthma treatments, and for medications prescribed to treat infections.

Certain lung conditions can cause individuals to be more vulnerable to infection. For example, patients with underlying respiratory conditions, and those who are moderately immunocompromised, face a higher risk of HSV-1 infections in the lungs. In this case, primary care physicians may prescribe Valtrex to treat the HSV-1. However, this treatment isn’t always affordable. At a typical pharmacy, patients pay $232 for Valtrex. At Promina Health, patients only pay approximately $25. That’s 90% off the pharmacy price.

Patients with other lung conditions will see similar savings on many other respiratory medications filled at Promina Health Direct Primary Care.

Address Environmental Factors

A family physician in a direct primary care practice like Promina Health, have more time to spend with you than most conventional primary care physicians, and can help identify environmental factors such as mold, dust mites, certain gases, and particulate pollutants that may be exacerbating your lung condition.

The Environmental Protection Agency publishes instructions and checklists to improve your home’s indoor air quality (and your lung function).

Your family doctor at Promina Health will review the recommendations, and help you determine how best to improve your lung function.

Your family physician at Promina Health can also treat your entire family, using a similar membership plan. Meeting with the entire household is a good way to help identify environmental factors that may be exacerbating lung conditions. It is easier to eliminate household pollutants when everyone is on the same page.

See What’s Included in Your Direct Primary Care Membership

A direct primary care membership with Promina Health offers incredible benefits. Whether you’re struggling to manage a chronic condition, or you need reliable, low-cost care, Promina Health can help.

Membership includes unlimited appointments with a board-certified family physician; visits are never rushed. It’s easy to make appointments for same day or next day, and you can contact your doctor by phone or text at any time.

Promina Health members never pay a co-pay for appointments, and many treatments and diagnostic assessments are also included at no extra cost.

Wellness, nutrition, and chronic disease management services are included in the membership, and patients can purchase prescription medications at a steep discount, right from the office.

See the complete list of services included in membership on the Member Benefits page.

View Pricing

Promina Health membership starts at $49/month for a single young adult. Families can also include children in their membership at a discounted rate. Patients pay a one-time enrollment fee of $100 ($150 for family). After enrollment, members are charged monthly. To enroll as a new patient at Promina Health, visit the Pricing page.

Chronic Disease Management With Direct Primary Care: Join Now

With Promina Health Direct Primary Care, you can cut through the barriers that get in the way of getting the diagnosis, treatment, and management you need.

With direct pricing, patients save up to 80% on diagnostic procedures—whether that’s a lung function test, a blood panel, or EKG. For many patients, those savings transform the impossible into the affordable.

Promina Health patients never pay copays or deductibles, and pricing is always transparent. Join now to get personalized healthcare you can afford (and deserve!).