Asthma severity is more than just FEV1

n/a

It appears I haven’t done a proper “Breathing Basics” post in almost 8 years. I think this installment might fit under that category.

In browsing through some of the posts on various Asthma support groups, personal blogs, or in chatting with people who have asthma or COPD, I often hear someone refer to, or equate their FEV1 number to the severity of their particular disease. Heck, I even do it here on my own blog from time to time. After all, it’s just so much easier to label the entirety or severity of your disease with a percent sign, right. But really, I think we’re throwing the word around too much and placing too much importance on it.

While FEV1 is certainly a key parameter in determining lung function, lung mechanics alone doesnt paint a complete picture of the severity of ones lung disease, especially if that disease is asthma. Burden of disease issues such age, access to care, phenotype, severity of symptoms, hospitalizations, NFAs, medication side effects, the ability to exercise, mental health and quality of life issues are also major factors in disease severity. More about those later, but since were on the topic of FEV1, lets expand on that little more. Hopefully this post will make you think a little differently about yours, or someone else’s FEV1 and how it pertains to disease severity.

First, for those who might not know what the term FEV1 means, let me try to explain it as simply as I can.
FEV1 stand for “Forced Expiratory Volume in 1 second“. Basically, it’s a test to measure how fast and fully you can exhale in one second. Why do you need to know how fast you can exhale in one second? Well, because that’s crux of all obstructive lungs diseases, including asthma. Its not about having a hard time taking a breath in, but rather the inability to exhale the air out freely and completely. In asthma, it’s the “obstruction” or narrowing of the airway by the tightening of muscles that surrounds them, and/or inflammation and/or mucus on the inside of the airway that makes it difficult to exhale easily. If the “obstruction” gets bad enough, you start to wheeze when you exhale, cough, get short of breath… all the fun stuff. This difficulty in getting the air out then makes it more difficult to get the next breath in….. and so on and so on. Before you know it, you’re having a full on asthma exacerbation. Essentially the lower the number, the worse your lung function is. Anything below 50% is considered severe and anything below 30 % is extremely severe. On the opposite end,anything over 80% is considered normal.

The spirometry test itself goes something like this: you take a deep breath in and blow it out as hard and fast as you can, for as long as you can, into device called a Spirometer. As you’re blowing, the sensor attached to the mouthpiece of the device records and plots your effort and then extrapolates the first 1 second of that breath measuring how much you blew out. The result will be displayed in liters and also as a percentage of your predicted normal value, based on your age, body size and sex. For example on a recent spirometry test below, you can see my best effort for FEV1 was 0.9 liters or 32% of what would be predicted as normal for me based on my age and height.

The test was then repeated a few minutes later after inhaling 4 puffs of Albuterol to see if there was any change. You can see my FEV1 went up to 35%. Though not a huge increase, this uptick indicates that my airways are at least responding to the drug and that some reversibility is present. I should also mention that most people with mild to moderate asthma will have spirometry numbers that are normal or near normal in between flare ups, while those with more chronic severe asthma and who have significant airway remodeling (lung damage), will probably have numbers that are lower and that don’t improve significant, even relatively good breathing periods.

But that’s not all, on the graphic below you see there’s more being measured here than just FEV1. There are lots of other things being measured. Remember that first second of exhalation? Well how about if we measure the flow rates during the 2nd, 3rd, 4th, 5th or even 6th second into the exhalation? ( Yup it can take me that long to exhale all the air out of my lungs). The flow rates measured after the first second tends to come from the smaller airways in your lungs and is reflected by the FEV25-75%, which is basically the middle of your exhalation. The lower these numbers are, the more severe the obstruction and the less likely they will improve. You can see that my FEV25-75 is only 18% and doesn’t improve.

Weve just scratched the surface on what FEV1 and other Spirometry numbers can reveal, we also need to measure actual lung volumes to rule out other conditions that might either mimic asthma or that might be in addition too asthma. Unlike portable spirometers which are everywhere nowadays, these type of tests have to be done in a specially equipped PFT lab. There they can also measure how well oxygen and carbon dioxide are able to transfer between the lungs and the blood stream.

Below is one of the FULL PFTs I did during my Lung transplant evaluation in 2016. You can see there’s a quite a bit more info in a full test.

On the exercise front there are people I know with COPD who actually RUN marathons. Most are older and aren’t super fast, but they still run the. I know one guy with COPD who’s FEV1 is only 28% who not only runs marathons, but has also completed a Triathlon. As you’re aware, Ive completed several full marathons myself, my last one just 4 years ago. My average FEV1 during most of those races was 34%. But, big difference between myself and those “other” marathoners, is that I can’t run at all. Also, I have severe asthma, not classic COPD, so my disease triggers and tolerances to physical exertion are different. Attempting to sprint, or even racewalk more than 50 yards can throw me into severe bronchospasm and air trapping, of which I have a hard time recovering from, and which could put me in the hospital or worse. 4 years later, at 64 years old and a current FEV1 that hovers around 30%, I now struggle to walk just 7 miles without struggling to breath. On the bright side, unlike my COPD friends, my O2 sats rarely drop when I exercise. That’s because asthma is a disease of the airways, not the alveoli where oxygen transfer takes place. So again, even when were talking about exercise and the effects lung function, there’s definitely more involved just FEV1.

Back to those other factors that contribute to severity of one’s asthma. As mentioned earlier, is not just lung function or physiology that can make it really difficult to live with lung disease, it’s the way our bodies and minds tolerate it. Feeling short of breath or having symptoms all the time can really wear you down, both physically and mentally. When you can’t breath right, it’s difficult sleep, it’s difficult to work, concentrate, play etc. This then leaves your body even more tired and your immune system weaker. Likewise,the more symptomatic you are, the more medications you’ll probably have to take, and some of those meds have terrible side effects. And if the medications aren’t cutting it, you’re exacerbations or flare ups are likely to be more severe , and if they’re more severe, you’re more likely to end up in the hospital, and if they cant get your asthma flare under control there, then you could end up on a ventilator, and that could lead to secondary complications…..and well, I think you get the idea.

Any of these things, if they happen often enough, can affect your quality of life. And without a decent quality of life it doesn’t matter how high or low your FEV1 is. I know people who have near normal FEV1s, but their disease is bad in so many other ways, they can barely function . Conversely, I have horrible PFTs, and suffered just about every burden there is with this disease, but Im still able to function near normal when Im not sick and I still have a decent qualify of life. Clearly, everyone experiences their disease differently, regardless of their FEV1.

The post Asthma severity is more than just FEV1 appeared first on Breathinstephen.

http://breathinstephen.com/