From the Research
Mean arterial pressure (MAP) can be calculated using the formula: MAP = [(2 × diastolic blood pressure) + systolic blood pressure] ÷ 3. For example, if a patient has a blood pressure of 120/80 mmHg, the MAP would be [(2 × 80) + 120] ÷ 3 = 280 ÷ 3 = 93.3 mmHg. This formula works because diastole typically lasts twice as long as systole during each cardiac cycle, making diastolic pressure more influential on the average pressure. MAP is clinically important because it represents the average pressure driving blood through the systemic circulation during the cardiac cycle and is a better indicator of perfusion to vital organs than systolic pressure alone. A normal MAP ranges from 70-100 mmHg in adults, as suggested by various studies including 1. In critical care settings, automated monitors often display MAP directly, but manual calculation is still valuable for quick bedside assessment. MAP below 60 mmHg generally indicates inadequate organ perfusion, while sustained MAP above 110 mmHg may indicate hypertensive crisis requiring intervention. The calculation of MAP is crucial in managing patients with shock, including septic shock, where vasopressors such as norepinephrine are used to maintain adequate blood pressure, as discussed in 2 and 3. Additionally, other studies like 4 and 5 highlight the importance of MAP in different shock states and the use of various vasopressors to achieve target blood pressures. However, the most recent and highest quality study 1 provides the most relevant information for calculating MAP and its importance in clinical practice. Key points to consider when calculating MAP include:
- Using the correct formula: MAP = [(2 × diastolic blood pressure) + systolic blood pressure] ÷ 3
- Understanding the normal range of MAP: 70-100 mmHg in adults
- Recognizing the importance of MAP in critical care settings
- Being aware of the potential consequences of low or high MAP, such as inadequate organ perfusion or hypertensive crisis.