MAP Formula Explained
Understanding the Mean Arterial Pressure calculation and its clinical significance.
The MAP Formula
MAP = Mean Arterial Pressure
SBP = Systolic Blood Pressure
DBP = Diastolic Blood Pressure
PP = Pulse Pressure (SBP - DBP)
Why This Formula?
The cardiac cycle spends about 2/3 of its time in diastole (relaxation phase) and 1/3 in systole (contraction phase). Therefore, the diastolic pressure is weighted twice as heavily as the systolic pressure in the calculation.
This weighted average more accurately represents the average arterial pressure throughout the entire cardiac cycle.
Step-by-Step Calculation
Measure Blood Pressure
Obtain systolic (SBP) and diastolic (DBP) blood pressure readings. For example: SBP = 120 mmHg, DBP = 80 mmHg
Multiply DBP by 2
DBP × 2 = 80 × 2 = 160 mmHg
Add SBP to the Result
SBP + (2 × DBP) = 120 + 160 = 280 mmHg
Divide by 3
280 ÷ 3 = 93.3 mmHg
Interpret the Result
MAP of 93.3 mmHg is within the normal range (70-100 mmHg)
Example Calculations
Normal Blood Pressure (120/80)
NormalMAP = (120 + 2 × 80) ÷ 3 = 93.3 mmHg
Hypertension (150/95)
ElevatedMAP = (150 + 2 × 95) ÷ 3 = 113.3 mmHg
Hypotension (90/60)
Low-NormalMAP = (90 + 2 × 60) ÷ 3 = 70 mmHg
Severe Hypotension (80/50)
CriticalMAP = (80 + 2 × 50) ÷ 3 = 60 mmHg
Clinical Significance
Why MAP Matters
- •Represents the average arterial pressure throughout the cardiac cycle
- •Better indicator of organ perfusion than systolic or diastolic BP alone
- •Critical for managing blood pressure in shock, sepsis, and hypertension
- •Used to guide vasopressor therapy in critical care
Organ Perfusion Thresholds
MAP below 60 mmHg is associated with inadequate organ perfusion
- Brain: Requires MAP ≥ 60 mmHg
- Kidneys: Require MAP ≥ 60 mmHg
- Heart: Requires MAP ≥ 60 mmHg
- Sepsis target: MAP ≥ 65 mmHg
Medical Disclaimer: This tool is for informational reference only and is not intended to provide medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional. Learn more