Body Surface Area (BSA)

What is Body Surface Area?

Body Surface Area (BSA) is a calculated measurement that estimates the total surface area of the human body. It is an essential metric in various medical applications, including drug dosing, metabolic assessments, and cardiac output estimations. BSA is typically expressed in square meters (m²).

The DuBois and DuBois Formula

The most widely used method for calculating BSA is the DuBois and DuBois formula:

\[BSA = 0.007184 \times W^{0.425} \times H^{0.725}\]

Where:

• \(BSA\) = Body Surface Area in square meters (m²)
• \(W\) = Weight in kilograms (kg)
• \(H\) = Height in centimeters (cm)

Calculation Steps

Let's walk through an example calculation for a person weighing 70 kg and standing 170 cm tall:

1. Input the values:
   • \(W = 70\) kg
   • \(H = 170\) cm
2. Calculate \(W^{0.425}\): \[70^{0.425} \approx 3.9693\]
3. Calculate \(H^{0.725}\): \[170^{0.725} \approx 38.5254\]
4. Apply the formula: \[BSA = 0.007184 \times 3.9693 \times 38.5254\] \[BSA \approx 1.7958\, m^2\]

Visual Representation

To better understand BSA, consider the following diagram:

This diagram illustrates how BSA relates to the human body. The colored areas represent different body parts contributing to the total surface area.

Example and Interpretation

Let's interpret our calculated result:

• For a person weighing 70 kg and standing 170 cm tall, the BSA is approximately 1.80 m².
• This falls within the average range for adults (typically 1.6 - 1.9 m²).
• A doctor might use this BSA to determine appropriate dosages for certain medications or to assess metabolic function.