Heart rate reading

i HAVE Always relied on my oxi meter to keep pulse in check. It has been very good to me and let me know i Need to go to er running in the 150’s so my confusion is my finger meter and I have several to check and have checked batteries show about a 20 to 25 difference in reading, Normally I have to adjust meds due to fluctuating heart rate. But the sonon the finger shows normal 61 to 80 my Sono lately is showing 76 to 110 to 140 flucuates all over. So I dont know which one is the accurate one to go on, in the past they would both show when it went high now it dose not , Sono much highter, any feed back would be apprecitated

have you tried other leads (hand to wrist, leg or chest) and see what readings you are getting? I notice that I need to hold the device firmly between my hands to get a consistent rate. Loosing my grip gets me different reading rates. You might want to look as the manual is you have not all ready done so at https://support.sonohealth.org/support/solutions/articles/60000672445-user-manual-full