NBRC Normal Values TMC Practice Test

Cardiac index standardizes cardiac output for body size. It’s calculated as CO divided by body surface area, so the units are L/min per m^2. With typical CO around 4–8 L/min and a body surface area about 1.7–2.0 m^2, the normal CI falls roughly in 2.5–4.0 L/min/m^2. The range 2.5–4.0 best fits this, making it the normal reference. Values below about 2.5 suggest reduced pumping capacity, while values above about 4 indicate high-output states.