Rollercoaster Blood Pressures

We are going crazy with Mom's blood pressure.  We cannot seem to get the dosage right.  She continues to be with a top number in the low 80s and we are trying to at least get it into the 90s.  I called Dr. Thomas ... and emailed both Dr. Plana and Dr. Thomas on Friday in hopes of getting a target blood pressure range and possibly some direction on how to adjust her medication.  She had a reading of 76 over something that scared us to death.  Since its the weekend there is little hope that we will hear from Plana.