Markers only in limited sections
The automatic marker placement often goes wrong if there is either a shift in the signal, or a calibration phase in the same file. In the image below, we have both. This leads the software to fail and it places markers on specific sections, but not others. Reduce the data range by selecting the data from beginning to end of the focus area, then save selection as a new file and take the blood pressure calculations from there.
The shift in the data is unavoidable. If the exclusion of the calibration period does not improve the situation, the signal needs to be processed manually. Two options are available:
Place flags on all systole peaks, then use find cycle to place systole markers where flags are. Clear flags and repeat for diastoles.
Clear all existing markers from the BP signal, then use find cycle for a peak detection. This option can be challenging because the BP signal has the systole peak, followed by a smaller peak and the software may place markers on all second peaks. However, it can be faster to remove all of these incorrect systole markers than performing option 1.
In this particular case, removing the calibration period did not improve the signal detection:
To use option 2., we have to use a threshold to find the peaks. This means that everything above the threshold will be considered as a systolic peak. You have to try different threshold. The ideal threshold will differ between participants and sessions, depending on the blood pressure and variability at the time.
Try a different threshold:
The result using a threshold of 85:
Now we have the problem described above; the small peak after the systole is incorrectly identified as a systole in each BP cycle. These have to be manually removed using the flag removing tool.
After the removal, your signal will look like this:
The diastoles are also tricky. In this case, the threshold of 75 or higher creates more diastoles than necessary, so here we go again, removing all of those.