Using Peak Flow Meter
Hello, I hope you're doing alright. I've recovered from my last severe attacks in July and I started work and am back in school. Work isn't good for my asthma as there are lots of triggers, so I'm applying for a different job, but I am hanging in there.
I recently got a peak flow meter and the instructions to use it seem simple enough, blow as hard as I can into the tube and read the numbers to determine each zone for me. However,, the hardest part for me is blowing as hard as possible, when that's not usually possible for me. My lungs are usually already decreased in capacity which is why I need my inhalers so when I blow as hard as I can, it's not very hard unless I force myself and that's usually quite painful.
When I breathe hard letting all the air out of me, it reads between 320 and 380 L/min and that's on a good day before my inhaler. When I force myself, I reach between 400 and 500 L/min which seems to be a normal reading for someone around 5'2 and 115lbs. I'm just not sure why I get below normal when I simply breathe out as best I can, but when I force myself I get "normal" readings and am wheezing and I usually feel worse than when I started. When I take my inhaler I see some improvement, but I have to wait before I breathe out all at once so I don't hurt myself even more after my inhaler.
I'm not sure why this is, maybe I'm not doing it right? I just noticed I have decreased lung capacity and wheezing beforehand and usually have difficulty talking before I take my inhaler. The inhaler allows me to get better readings, but in order to go from a low reading to a good one, I have to force myself to blow all the air out as fast as I can, which isn't usually possible for me. I was barely able to successfully exhale rapidly when I first got my PFT.
I'm kind of frustrated I must measure my breathing as hard as I can when I can't even breathe well in the first place so I don't get good readings unless I hurt myself trying. I was just wondering if I'm doing doing right or if there's anything I need to do differently.
Thank you!
-Thyme
Hi Thyme - thanks for your post - this is a very interesting topic! The purpose of a peak flow meter is, as you suspect, to measure one's peak flow RATE during a forceful exhalation. This helps to determine the patency of one's airways. In other words, the peak flow rate helps determine how open one's lungs are and, if there is some obstruction (based on the asthma diagnosis). Just as you said, the peak flow meter at home, is somewhat representative of a full fledged pulmonary function test (PFT), which measures one's lung volumes, capacities and flow rates. The adequacy of one's results for this type testing device is actually effort dependent. If a patient is compromised, the results are also compromised.
I thought you might gain some additional insight for your concern, from this article, which focuses on peak flow meters in general: https://my.clevelandclinic.org/health/articles/4298-peak-flow-meter. It is a reference from the Cleveland Clinic. I do hope you find the information is helpful in a practical way.
Wishing you well,
Leon (site moderator asthma.net)Oh wow, that's interesting. I've noticed that my lungs are not very open before I take any inhaler, so I cannot exhale very fast at all. In other words, a "normal" reading or green zone for me is how well I breathe after 2 puffs, and anything before I inhale reads far below where I should be and I've strained myself when my lungs have already decreased in capacity without medicine.
Whenever I scrape 400 without my daily inhaler, I wheeze loudly and my throat hurts a lot, and the air starts forceful but results in my lungs shrinking and I struggle to breathe out. I also depend on my daily inhaler to breathe normally, I can't breathe normally without it, so I may have to take my daily inhaler before using the peak flow meter so that the readings might not be compromised. "Normal" to me is using my daily inhaler (and/or a nebulizer) like I'm supposed to each day and then monitoring my breathing throughout the day to notice any changes. It seems safer to me than struggling to get a good reading with already deflated lungs without my daily medicines.
Thank you!Hi again, Thyme, and thanks for your response and further explanation. Have you ever had an opportunity to discuss this with your physician? I am curious as to what your doctor's comments might be about this.
Regards,
Leon (site moderator asthma.net)
I also think it would be good to invite
into this conversation as she has written some great stuff on peak flow meters in her family. I am not an expert but just do the best you can, Thyme -- that's the point, to see what you can do. Nobody wants you keeling over in the name of higher numbers, aye? -Melissa, asthma.net team
Hi Melissa - you make a good point! We actually do have a wealth of information published, right here on asthma.net, which focuses on peak flow meters. For's (and everyone else's benefit) - here are links to several of those articles:
Here is one from Andrea, in which she refers to peak flow rates: https://asthma.net/living/asthma-sounds.
Next, this one from our own, which is pretty comprehensive: https://asthma.net/clinical/peak-flow-meter-questions.
And finally, this one from Theresa Cannizzaro: https://asthma.net/living/lets-talk-peak-flows-peak-flow-meters.
I do hope that Andrea has the time to chime in, too, and share her thoughts here.
All the best,
Leon (site moderator asthma.net)
Hello again! I know it's been a while, I got locked out of my account then got a new phone. My pulmonolgist says it's alright to. I'm going to have to in order to get a more accurate reading without harming my lungs.
Hi Thyme, and welcome back - it's nice to 'see' you here again, re-engaging with the community! I hope the previous year has treated you well.
I am glad to hear you are under the care of a pulmonologist. For the physician to advise you that everything is all right - that is a vote of confidence in how you are doing. Am I understanding this correctly?
Warm regards,
Leon L (author / moderator)
