Importance of Diastolic BP

[MarciL3001]

Anatomy newbie here. What does it really mean to have a low or high diastolic BP? I know the textbook definition (the pressure in the arteries between beats) , but I don't know the significance of it or why it's important. I would guess that blood flow during that period of rest contributes to organ/tissue perfusion. If someone has a high systolic and low diastolic (e.g. 140/55), why would this be concerning?

[Here.I.Stand, BSN, RN]

In many cases, a wide pulse pressure combined with the rest of the clinical picture can be indicative of a problem. In the case of neurotrauma or hemorrhagic strokes, a widening pulse pressure is part of Cushing's Triad which is a sign of impending herniation.

My son has a wider PP on his left arm; at his last appt with cardiology, Rt was 104/82, Lt was 114/40. He also has hyperdynamic flows through his aorta and gets quite tachycardic and c/o chest pain when dehydrated (found that out last month when he was pooping water for two days.) He's getting an MRI/MRA to check for an AVM or collaterals.

In critical care, vasopressive drips are dosed based on the MAP (mean arterial pressure), so a lower diastolic means more drug is needed, because it means a lower MAP.

Again with neurotrauma, you're watching cerebral perfusion pressures -- that's the MAP minus the ICP. So someone with a MAP in the low 60s but ICP in the teens might need help getting that BP up.

But then, some people naturally run lower. If clinically they look alright, we don't worry much about it.