How to relate physio files to log files (fmri)?

My project involves related logfiles with physio. I've downsized my frequency for physio data from 50 Hz down to 25 Hz. But now I don''t know how to relate the logfile intervals (CTO, CHB, BSE) to physio data. I heard their are toolboxes and such but if someone can please help me in any way I would appreciate it.