MAP | Mean Arterial Pressure
You learn all about the MAP, or mean arterial pressure, in nursing school. But when you go to work in the OR, you forget all about it just as you would if you chose to work elsewhere that didn’t have a high focus on the MAP. So, what exactly is the MAP and why is it important?
What is MAP?
The MAP is the average arterial pressure throughout one cardiac cycle (or from one heartbeat to the next). Cardiac output and the systemic vascular resistance play influence the MAP. A common MAP goal in (our) ICU is 65. A “normal” MAP is 70-100. A MAP at 60 or greater is considered sufficient to sustain organ perfusion. A MAP below 60 could mean that organs are not being perfused adequately and could result in tissue death. More often than not, the goal for a patients blood pressure is specific to MAP instead of systolic. I’ve seen a few blood pressures that I thought were concerning, but my preceptor would respond with “Well, the MAP is 67, so we’re good” (or something along those lines). I’ve learned to look at the MAP instead of the systolic/diastolic reading. The MAP can be calculated off of the automatic BP cuff or from an arterial line. If the patient has an ART line, you should be reading the MAP from the ART line (unless the accuracy is poor).
On the monitor the MAP can be displayed in a few different places (this image does not include all possibilities). The top line shows the NBP reading with the MAP in parenthesis. SYS/DIA (MAP). The next is the same order, but with the MAP under the reading. The last line shows the arterial line reading with the MAP next to it in parenthesis.
Calculating the MAP
Most monitors with automatically calculate the MAP, but if you’re ever in a pinch and need to calculate the formula is nice to know. To calculate the MAP you take the diastolic blood pressure, multiply it by two, add the systolic blood pressure, then take that sum and divide by three.
Follow your orders to keep you MAP at the goal or as close as possible. Next, I’ll discuss some of the medications, like Levophed and Cardene, I’ve learned to use over the last few weeks to get to the MAP goal.
