Please explain MAP to me

  1. Mean Arterial Pressure ~= 1/3 * SBP + 2/3 * DBP

    What the heck is that number? Is it important? Should I record it?

    MAP is defined as the average arterial blood pressure during a single cardiac cycle.

    The reason that it is so important is that it reflects the haemodynamic perfusion pressure of the vital organs.

    A MAP of at least 60 is necessary to perfuse the coronary arteries, brain, and kidneys. Normal range is around 70 – 110 mmHg.
    A couple of questions:

    1. Do you check the MAP every time you take BP? Why (& what floor do you work in)?
    2. Do you report if MAP is below 60? How much below would warrant a call as opposed to further monitoring? How about if pt is asymptomatic?
    3. Could a MAP be considered too high? At what point?
    4. What was the lowest/highest MAP you have seen? How was the pt and what did you do?
    5. What else can you tell me about the MAP?
  2. 5 Comments

  3. by   mcleanl
    Most people don't record the MAP....unless you are in the ICU. We tend to look at MAPs in various situations like calculating CPP's and closely watching BP's

    MAP is particularly helpful with low bloodpressures.......

    so if you have a pt with a bp of 92/59, you know that your MAP is higher than 60. MAP is comprised of diastolic x2 + systolic divided by 3. In this insistance if you have call parameters for systolic < could call the doctor and let them know "hey, the bp is low but the MAP is good at 70." It may or may not effect the way the patient is treated.

    If you have a bp of 100/ you have a MAP of 54. Now you vitals organs may not be perfusing even though your systolic is at 100.

    Like every patient....low people tolerance to BP vary. So check the BP, assess the patient and call the doctor as needed. If the BP is low....knowing the MAP can be useful in deciding treatment.
  4. by   Perpetual Student
    1. do you check the map every time you take bp? why (& what floor do you work in)?

    our monitors display the map with every bp in our pacu.

    2. do you report if map is below 60? how much below would warrant a call as opposed to further monitoring? how about if pt is asymptomatic?

    the pacu is probably somewhat unique in that temporary changes in vs are expected. i will report considerable unexpected changes from the patient's pre-op, intra-op, and admission to pacu vitals. if the patient is asymptomatic i might give more fluids, provide stimulation, and recheck the bp. always consider the patient's baseline and report significant changes.

    3. could a map be considered too high? at what point?

    this would be patient specific. for example, if your patient just had a cardiac or vascular surgery you're going to want to keep the map in a somewhat narrow range.

    4.what was the lowest/highest map you have seen? how was the pt and what did you do?

    the lowest is 0. obviously resuscitation was attempted. if it is low you will need to figure out why it's low (hypovolemia, sepsis, whatever) and treat approrpiately w/ fluids and/or pressors. if the patient is pulseless start cpr absent a dnr order.

    i don't recall the highest map i've seen. i guess in the 150s. i medicated the patient for severe pain and also administered labetalol to bring him back down to his prescribed parameters. he did fine.

    5. what else can you tell me about the map?
    remember that it's a measure of blood pressure--you know what to do for low bp and high bp. some variation is to be expected. pay attention to baselines. "normal" values may be bad values for someone whose baseline is not normal and reflect a significant change in status.
  5. by   umcRN
    working in a NICU we primarily use MAPS, unless the kiddo has a whopping PDA & then we will go to systolics, but typically if we are running pressors we have an order for MAP to remains greater than whatever the appropriate number is depending on the size/age of the baby. For instance a 500gm 23 weeker should have a map >25, but a full term baby should have a map >45.

    If a map is too high, especially in a small preemie they are at increased risk for too much blood flow to the brain which can result in a brain hemmorrhage, too low, in any situation, and vital organs are left not getting perfused, which in babies can lead to things like NEC, renal and liver failure.
  6. by   Medic2RN
    Here is a past post regarding MAPs - papawjohn does an excellent job explaining it.
  7. by   Florence NightinFAIL
    Thanks everyone. That helps a lot.