A couple of users have been interested in generating an alarm based on rate of change of heart rate because they have observed that increased heart rate is either a sign of an impending seizure or of a seizure itself.
I have generated a beta test version of the Android App that implements this functionality (V3.3.0a). If you would like to try it, you can download it from the github source code repository. If it gives you trouble, you can uninstall it, then install the latest public version from Google Play Store.
The way this alarm system works is it calculates an average heart rate over a given period (HR Rate Window). This is specified as the number of data points, which will normally be 5 seconds, so a window length of 12 corresponds to 12×5 = 60 seconds.
It then compares each heart rate measurement to the average and takes the difference. If the difference is greater than a specified threshold (HR Rate of Change Threshold) – say 10 bpm, it considers that an alarm condition. The main app screen now displays both the current and average heart rate so you can see how far it is off alarming.
If it detects an alarm condition for a given number of data points (HR Rate Duration) it raises an alarm with beeps and SMS text messages etc. It goes straight to Alarm, no warning first in this version.
The settings for this are visible if you select ‘Advanced Mode’ in the main settings screen, and select Seizure Detector Settings. You need to enable the Heart Rate alarm as well as the HR Rate of Change Alarm to use it.
Please let me know how you find it – I have guessed the default settings based on data for one seizure provided by a user, so it is not likely to be suitable for everyone – I am sure I could set it off if I run up the stairs. Please also share any settings that you find work for you, then I can decide where to set the defaults for the proper release.
Thanks! Graham (graham@openseizuredetector.org.uk)