function calculateMAP() {
var sbp = parseFloat(document.getElementById('systolicBP').value);
var dbp = parseFloat(document.getElementById('diastolicBP').value);
var resultDiv = document.getElementById('map-result-area');
var display = document.getElementById('map-display');
var statusMsg = document.getElementById('map-status-msg');
if (isNaN(sbp) || isNaN(dbp) || sbp <= 0 || dbp <= 0) {
alert("Please enter valid positive numbers for both Systolic and Diastolic pressure.");
return;
}
if (sbp <= dbp) {
alert("Systolic pressure must be higher than diastolic pressure.");
return;
}
// Formula: MAP = [SBP + (2 × DBP)] / 3
var map = (sbp + (2 * dbp)) / 3;
var roundedMap = map.toFixed(1);
display.innerText = roundedMap;
resultDiv.style.display = 'block';
var status = "";
var color = "";
if (map = 70 && map 100 && map < 110) {
status = "Slightly Elevated";
color = "#f39c12";
} else {
status = "High (Hypertension)";
color = "#c0392b";
}
statusMsg.innerText = status;
statusMsg.style.color = color;
resultDiv.style.backgroundColor = color + "10";
}
Understanding Mean Arterial Pressure (MAP)
Mean Arterial Pressure (MAP) is a critical cardiovascular metric that represents the average pressure in a person's arteries during one full cardiac cycle. Unlike standard blood pressure readings (systolic and diastolic), MAP provides a single value that clinicians use to determine how well vital organs—such as the brain, kidneys, and heart—are being perfused with blood.
The Mathematical Formula for MAP
The calculation of MAP is based on the fact that the heart spends approximately two-thirds of the cardiac cycle in diastole (relaxation) and one-third in systole (contraction). Therefore, the formula weights the diastolic pressure more heavily:
MAP = [Systolic BP + (2 × Diastolic BP)] / 3
Alternatively, it can be calculated using pulse pressure:
MAP = Diastolic BP + 1/3(Systolic BP – Diastolic BP)
Why is MAP Important?
In medical settings, especially in intensive care and emergency medicine, MAP is often considered a more accurate indicator of organ perfusion than systolic blood pressure alone. A MAP of at least 60 mmHg is generally required to maintain adequate blood flow to the vital organs. If the MAP falls below this threshold for an extended period, organs may become ischemic (deprived of oxygen), leading to organ failure or shock.
Interpreting the Results
MAP Value (mmHg)
Interpretation
Below 60
Dangerously Low: Risk of organ damage/shock.
70 to 100
Normal: Ideal range for healthy individuals.
Above 100
High: Indicates high pressure which can cause long-term vascular damage.
Example Calculation
Let's look at a realistic example for a standard healthy adult with a blood pressure of 120/80 mmHg:
Systolic (SBP): 120
Diastolic (DBP): 80
Calculation: [120 + (2 × 80)] / 3
Step 1: 120 + 160 = 280
Step 2: 280 / 3 = 93.33
Result: The MAP is 93.3 mmHg, which falls perfectly within the normal range.
Clinical Considerations
While the MAP calculator is a useful tool, it is important to remember that "normal" can vary based on individual health conditions. For example, patients with certain types of brain injuries or kidney disease may require a higher MAP to maintain adequate health. Conversely, patients with certain cardiac conditions might be managed at a lower MAP to reduce the workload on the heart. Always consult with a healthcare professional regarding blood pressure management.