Between mean arterial pressure (MAP) and blood pressure (BP), which do you use when prescribing hemodialysis to instruct a hold on additional ultrafiltration should the value become too low?  

I believe the data on systolic blood pressure and outcomes is better than the other values of blood pressure measurement. As such I use the systolic blood pressure mainly to decide on ultrafiltration, medications and other therapy. Of course patient symptoms are also very important.