What is the upper limit of the normal cardiac index range?

What is the upper limit of the normal cardiac index range?

• A. 5.0 L/min/m2
• B. 4.0 L/min/m2
• C. 6.0 L/min/m2
• D. 3.5 L/min/m2

Answer: (A)

Cardiac index is cardiac output adjusted for body surface area, letting us compare heart performance across different body sizes. Because it normalizes for size, the upper end of a normal range in children and infants can be higher than adults, reflecting their higher metabolic demands. The upper limit commonly cited for pediatric cardiac index is around 5.0 L/min per square meter, so a CI of 5.0 is considered the high end of normal. For example, a cardiac output of about 6 L/min with a body surface area of 1.2 m^2 gives CI = 6 / 1.2 = 5.0, illustrating the upper boundary. Values like 6.0 would exceed typical normal, while 4.0 or 3.5 fall within or below the range but do not represent the upper limit.

Cardiac index is cardiac output adjusted for body surface area, letting us compare heart performance across different body sizes. Because it normalizes for size, the upper end of a normal range in children and infants can be higher than adults, reflecting their higher metabolic demands. The upper limit commonly cited for pediatric cardiac index is around 5.0 L/min per square meter, so a CI of 5.0 is considered the high end of normal. For example, a cardiac output of about 6 L/min with a body surface area of 1.2 m^2 gives CI = 6 / 1.2 = 5.0, illustrating the upper boundary. Values like 6.0 would exceed typical normal, while 4.0 or 3.5 fall within or below the range but do not represent the upper limit.