Which patient has a better blood pressure, the patient with a blood pressure of 110/40 or the patient with a blood pressure of 90/60?
Mean arterial pressure (MAP) is generally considered to be the organ perfusion pressure in an individual. Because MAP requires an inconvenient calculation, we've all been taught...misled perhaps...into focusing on systolic blood pressure (SBP) as a marker of how well-perfused a patient is, and we tend to ignore the diastolic blood pressure (DBP).
It's important to remember, however, that we spend most of our lives in diastole, not systole. As a result, our organs spend more time being perfused during diastole than systole. The MAP takes this into account: MAP = (SBP + DBP + DBP)/3. DBP is more important than SBP!
So which patient is perfusing his vital organs better, the one with a BP of 110/40 or the one with a BP of 90/60? Do the MAP calculation...90/60 is better than 110/40!
