Knowing your patient’s Mean Arterial Pressure (MAP) is far more important than their blood pressure. This is because MAP represents the average arterial pressure during an entire cardiac cycle. Here’s some MAP basics to get your neurons firing!
Mean Arterial Pressure
Calculating Mean Arterial Pressure (MAP)
There are many different formulas for calculating MAP, but the one I use is simple (simple enough that Siri on my iPhone can do the math for me, if I’m busy). So here’s the formula:
MAP = ((Diastolic BP x 2)+Systolic BP) ÷ 3
So if we have a patient with a BP of 120/80, it would look something like this:
MAP = ((80 x 2) + 120) ÷ 3
MAP = (160 + 120) ÷ 3
MAP = 280 ÷ 3
MAP = 93
The reference range for MAP in a healthy individual is 70-110, meaning that the patient above is A-OK! You want to be sure to keep your patient’s MAP >65 to ensure adequate organ perfusion.
Yes, I know that most cardiac monitors with non-invasive blood pressure (NIBP) monitoring capability will automatically calculate MAP for you, but I wanted to cover this for times when manual BP assessment is required. Please remember that this is just an easy method to approximate MAP using NIBP measurement. If you have invasive monitoring capability, there is a much better way; but that discussion will have to wait for another time.
Photo Credit “How To Take Your Cat’s Blood Pressure” by Mark Turnauckas is licensed under CC by 2.0