So you’re interested in learning more about flow volume loops obtained from a pulmonary function test (PFT). What we have here are some PFTs from my asthma past accompanied by a brief explanation of what you are seeing. You can consider this a brief flow volume loops 101 course for asthmatics.

This is a flow volume loop. By looking at the shape of the loop a doctor can determine how well air is moving through the air passages of your lungs. If the expiratory side of the loop is concave, this is a sign of airway (airflow) obstruction, which is indicative of either asthma or COPD.

In this loop, the dotted line represents normal lung function. The solid line represents a patient with asthma before given a bronchodilator. You can see the PEFR (Peak Expiratory Flow Rate) and FVC (Forced Vital Capacity) are reduced, and the expiratory side of the curve is concave. This is normal when expiratory flow from the airways is obstructed.

(Note: Some of the following flow volume curves go in the opposite direction as the one in my example above. However, the same principle applies.)

Here is a PFT I did on January 16, 1985, seven days after I was admitted to National Jewish Hospital/ National Asthma Center (Now called National Jewish Health) with high-risk asthma. You can see my first flow volume loop shows an FEV1 of 51%, which means my lung function was only 51%. This is a sign that I have airflow obstruction. After I was given a breathing treatment with Alupent (Metaproterenol), my lung function improved. This is a sign that my airflow obstruction is reversible with appropriate treatment. This PFT shows that I my lungs meet both criteria for diagnosing asthma: airflow obstruction that is reversible with appropriate treatment.

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Here is a PFT done on me on January 27, 1985, after I was on systemic steroids for 10 days. You can see my lung function greatly improved. This is a classic case of how PFTs can be used to not only monitor lung function, but also course of therapy. This PFT was done after I had been on systemic steroids for 10 days. It shows that the current course of therapy was working. It shows that my asthma responds well to systemic corticosteroids. You’ll note here my FEV1 improved from 51% on January 16 to 111%. That’s a remarkable improvement in only 10 days.

Another thing you can do with a PFT is diagnosing exercise- induced asthma (EIA). Clearly you can see here my PFT values decreased with exercise, yet improved after a breathing treatment with Alupent (Metaproterenol).

Another thing that can be done with PFTs is to determine what medicine works best as a pre-treatment that can be done before exercising to prevent EIA. Here is a PFT where my doctor had me take two puffs of Albuterol prior to exercising. You can see those two puffs did not stop my EIA from occurring. A PFT I did later showed that I did respond well to a pre-treatment of Cromolyn (Intal).

And here you can clearly see that even after almost three months on the best asthma medicines in the world, my baseline FEV1 was still only 77%, which improved post bronchodilator. According to my physician, this PFT confirmed for him I had mild obstructive airway disease with hyperinflation and air trapping and with significant reversal after inhaled Alupent (Metaproterenol). The doctor notes that my baseline airflow was lower than my previous PFT, however I do believe I had been weaned off systemic steroids at this time. So once again you can see that a PFT can be used to track the course of asthma treatment.

Here, just before I was discharged from the asthma hospital, my July 6, 1985, PFT showed my FEV1 was 89%, and my lung function had markedly improved since I was admitted on January 1985.

For the record, in case you’re curious, the following are the medications I was on when I was discharged from the asthma hospital. I was trialed on other meds too, but this is what I ended up on in the end. I was completely weaned off systemic corticosteroids.

Cromolyn (Intal): This was a mast cell stabilizer and anti-inflammatory. It’s still used but not as often as in 1985. Today there are better medicines.

Theodur (Theophylline): This is a bronchodilator that relaxed the smooth muscles surrounding my bronchial tubes. It was a very common and front-line medicine to treat both asthma and COPD. I was actually chronically addicted to this medicine until I was put on Serevent (which is in Advair) a few years ago. I took my last Theophylline pill in December 2007. Prior to that, my asthma doctor told me that when he started as a doctor most of his asthma and COPD patients were on this medicine, and that I was one of only three of his patients left on it. Well, now he has only two patients on it.

Alupent (Metaproterenol): This was the rescue medicine before Albuterol gained fame. I took it four times a day and also used it when needed. It had a greater cardiac effect than Albuterol, and it often left me with a bounding pulse that sometimes scared me. Albuterol makes me shaky, but it doesn’t make my heart bound unless I overuse it. Still, even when Albuterol affects my heart, it doesn’t even come close to what Alupent did. I believe Alupent was just recently discontinued.

Azmacort (triamcinolone): This was the inhaled steroid that seemed to work best for me, however I had to take 4 puffs 4 times a day which ultimately turned out to be hard to be compliant with when I was discharged. Today I’m on Flovent (which is in Advair), which is stronger and only needs to be taken twice a day. It’s way easier to be compliant with Advair than Azmacort.

Zanax (Alprazolam): This was to ease my anxiety from being in the asthma hospital 3,000 miles away from my home in Michigan. One of my sources that currently work for National Jewish Health told me homesickness was one of the major problems with kids who were admitted to the asthma hospital, and ultimately this is what led to the child asthma program being completely changed from when I was an inpatient.

Drixoral (dexbrompheniramine and pseudoephedrine): This is a combination antihystamine and decongestant to treat my allergies. I don’t think I got much relief from it, but it was the best that was available back in 1985. When I left the asthma hospital, while my asthma was controlled, my allergies continued to irritate me until a few years ago when I was put on Singulair.

Atropine: This medicine is an anti-cholinergic that sits on the receptor sites of acetylcholine to prevent it from causing your airways to constrict. It is referred to as a back door bronchodilator. I was later put on Atrovent and then taken off it all together. Atrovent is sometimes used to manage hardluck asthma, but mainly it is no longer considered a front line therapy for asthma. Atropine is no longer used for asthma.

Here is a PFT I did on myself at work December 14, 2009. On my initial FVC my FEV1 was 87%. After a breathing treatment of Ventolin, my FEV1 improved to 109%. So this proves I still have some obstruction and some air trapping, and it is obviously reversed with a bronchodilator. It also proves that my current course of asthma therapy of Advair, Singulair and Ventolin is working. Excuse my artwork. I had to trace this off the monitor considering the printer isn’t working. (Our loops run the opposite direction from my PFTs done 24 years ago, but the idea is still the same.)

You also may have noticed that the bronchodilator of choice on all the PFT from 1985 was Alupent. This medicine has since been phased out in favor of Ventolin (Albuterol), which has way fewer side effects. Xopenex is a newer bronchodilator that some studies show has fewer side effects than Ventolin, although it costs a lot more and therefore is less often prescribed. I think the same principle applied in 1985, in that Albuterol was the newer drug with fewer sided effects, yet because it costs more Metaproterenol was the bronchodilator most often prescribed.

There, now you know everything an asthmatic needs to know about flow volume loops obtained from a PFT.