If the patient moves a finger during the scan, the real-time graph will reflect this and the patient can be still again and the graph will return to normal. It is acceptable for this to happen a few times during the scan (but better if the patient remains still for the entire scan). The software will filter this data out of the scan, interpreting it as noise due to patient motion rather than the HRV signal.
If the patient moves too many times, however, too much data will be lost and the scan will not be valid. At the end of a scan, if the myINSiGHT detects that too much data has been lost due to patient motion, the system will include a warning on the scan summary that you should re-scan this patient: