Mean Arterial Pressure (MAP)
Calculates mean arterial pressure.
When to Use
- The Mean Arterial Pressure can be calculated in all patients in which blood pressure values are obtained.
- Blood pressure targets have been shown to improve outcome in a number of conditions. These include sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.
- Clinical guidelines may use either SBP or MAP as a blood pressure goal.
- The Mean Arterial Pressure (MAP) is derived from a patient’s Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP).
- MAP is often used as a surrogate indicator of blood flow and believed to be a better indicator of tissue perfusion than SBP as it accounts for the fact that two thirds of the cardiac cycle are spent in diastole.
- A MAP of 60 mmHg or greater is believed to be needed to maintain adequate tissue perfusion.
- Since MAP is a product of Cardiac Output (CO) and Systemic Vascular Resistance (SVR) [MAP = CO x SVR], variations in SVR make the relationship between MAP and CO often unreliable (for example, a patient with a poor CO but high SVR such as a patient in cardiogenic shock may have an acceptable MAP but a CO that is too low to provide adequate perfusion to tissues).
The MAP should be calculated when the clinical scenario mandates a blood pressure adjustment based on MAP rather than SBP, as well as for the management of patients with acute conditions where there is a concern for appropriate organ perfusion.