Possible sleepyhead or respironics system one bug
Good day!
Tested this in Sleepy head versions:
SleepyHead v1.0.0-beta-2 (Windows 10)
SleepyHead v0.9.8-0 (testing) (Ubuntu 16.04 LTS)
Please see the zoomed out sleepyhead daily chart below. It shows an OA of 255 seconds! Of course waveform shows no apnea at all. May be this is a problem with either SystemOne or SleepyHead. 255 is familiar as it could be -1 interpreted as 8 bit unsigned int.
Thanks,
sskblr
07-30-2017, 08:24 AM
(This post was last modified: 07-30-2017, 08:31 AM by Sleeprider.)
RE: Possible sleepyhead or respironics system one bug
The event flags are set by the CPAP, not Sleepyhead. The software only reports what is in the data provided by the machine. The period shown is one of low tidal volume, but I agree it is respiration and should not have been flagged as OA unless this flow is less than 20% of normal. Compare this to a period of normal breathing to determine if it may be a hypopnea, or your normal respiration. Remember there may be some respiration during apnea and it still meets the definition used by Respironics: An apnea is detected when there is an 80% reduction in airflow from a baseline for at least 10 seconds if there is no airflow detected for 10 seconds. During the apnea, one or more pressure test pulses are delivered by the device. The device evaluates the response of the patient to the test pulse(s) and assesses whether the apnea has occurred while the patient has a clear airway or an obstructed airway. The airway is determined to be clear if the pressure test pulse generates a significant amount of flow; otherwise the airway is determined to be obstructed. When the airway is obstructed then an Obstructed Airway Apnea event is recorded. I believe the hypopnea threshold is less than 40% of normal.
RE: Possible sleepyhead or respironics system one bug
Thanks SleepRider. That is an excellent description of how events are flagged.
I compared the graphs around the event to the ones when there are no apneas. Everything looks identical. The reason I was concerned to begin with was the duration of the event - 255 seconds! May be a spurious event then. I will keep an eye if anything similar is flagged in future.
Thanks again
sskblr