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Question

A large part of critical care and ICU management revolves around hemodynamic monitoring and support. But…..we typically don’t use traditional blood pressure (systolic and diastolic) numbers directly.

We use MAP!!!

1. What is MAP?
2. How do you calculate it?
3. Why is it a better variable to monitor when it comes to blood pressure and critical care?

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Answer

1. Mean Arterial Pressure (MAP)
2. It is calculated using the following formula:
   1. MAP = 1/3(SBP) + 2/3(DBP)
3. MAP has the greatest influence on blood flow autoregulation within the organs, as well as whole body hemodynamic homeostasis. It is superior to systolic pressure because it is the true driving pressure for peripherial blood flow and it does not change as the pressure waveform moves more distally.
   1. Bonus Pearl – MAP > 65 is a general ICU mantra as the minimum pressure pressure to maintain organ perfusion

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References

• Marino, PL. Arterial Pressure Monitoring. In: The ICU Book. 4th ed. 2014.
• The relevance of the mean arterial pressure. From: Deranged Physiology – Monitoring of Arterial Pressure. [Link]
• Mean Arterial Pressure. From: Cardiovascular Physiology Concepts. [Link]