In the Swinamer equation, which variable is multiplied by 945?

• A. Body surface area
• B. Age
• C. Temperature
• D. Breaths per minute

Answer: (A)

Metabolic rate scales with body size, and body surface area is a practical measure of that size because it reflects the amount of tissue exposed and the energy required to maintain it. In the Swinamer equation, daily energy expenditure is calculated by multiplying body surface area in square meters by 945, giving an estimate in kilocalories per day. The constant 945 is a scaling factor chosen to convert BSA into kcal/day with the units used. So the variable being multiplied by 945 is body surface area. For example, a person with a BSA around 1.7 m^2 would have an estimated expenditure of about 1,600 kcal/day from this equation, illustrating how larger surface area leads to higher energy needs. Other factors like age, temperature, or breaths per minute influence energy requirements in broader contexts but are not the multiplier in this formula.