I’m confused. Last night my “events per hour” was 0.9, but my AHI was 6. Aren’t they sort of the same thing?
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It’s understandable to be confused, as “events per hour” and “AHI” (Apnea-Hypopnea Index) measure different things:
Events Per Hour: This shows the number of sleep events (apneas or hypopneas) detected per hour. In your case, 0.9 indicates less than one event on average during monitored hours.
AHI: This is calculated by taking the total number of apneas and hypopneas and dividing it by total sleep hours. An AHI of 6 suggests a higher average of combined events over your sleep time.
While both metrics relate to breathing during sleep, they reflect different calculations and should not be directly compared.
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I remain confused. I am on a BiPap machine. My last report from that machine for last night’s 7.5 hours of sleep was AHi of 32.7 Total AI 32.5. Obstructive of 0.5 and central of 0.5 According to your calculation, that seems to report less than 1 of each type event per hour. So the total combined number of obstructive and central apneas (less than one of each per hour for 7.5 hours) was less than 15. If you then divide that by the total number of sleep hours (7.5 ) you get 2, not 32.5. How might that happen and still be a correct report? Are there other types of apneas that would increase the AI t0 32.5? I did have a very large amount off leakage. Does the high leakage affect the calculations? Can there be a problem with this machine? Could there be a problem with my math?
Thanks
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Hi, It can be really frustrating when the numbers don’t seem to add up—especially when you’re trying to understand your own therapy data. You’re correct that, based on the obstructive and central counts you shared, the math doesn’t seem to match the total AI.
A few things could be going on here:
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Large leaks (like you mentioned) can definitely throw off the accuracy of event detection. When leaks are significant, the machine may overcount or misclassify events, which can make the AI look much higher than it really is.
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The total AI on your BiPAP might also include hypopneas or “unknown” apneas that don’t show up in the separate obstructive/central breakdown.
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In some cases, if the device can’t confidently classify an event because of leaks or signal issues, it may still count it in the total AI, which skews the results.
It’s worth working on getting those leaks under control first—sometimes a mask adjustment or refit can make a big difference. If you’re still seeing odd readings after that, I’d recommend checking in with your provider so they can pull the full report from the device and review it in detail. They’ll be able to confirm whether the machine is functioning correctly and help fine-tune your therapy settings. You’re already taking the right steps by asking questions and tracking your data—keep going, and you’ll get closer to the results you’re looking for 
Thanks for your prompt, informative answer. I will work on implementing you suggestions.
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You’re so welcome! I’m glad the information was helpful. I’m confident you’ll do great implementing those suggestions, and if anything comes up along the way, We’re here for you. Best of luck, and keep us posted on how things go! 