Normal cardiac index is

Experiments have shown that the cardiac output increases approximately in propoion to the surface area of the body. Therefore, cardiac output is frequently stated in terms of the cardiac index, which is the cardiac output per square meter of body surface area. The average human being who weighs 70 kilograms has a body surface area of about 1.7 square meters, which means that the normal average cardiac index for adults is about 3 L/min/m2 of body surface area. Ref: Guyton and Hall textbook of medical physiology 13th edition. Page:245 clinical impoance useful marker of how well the hea is functioning as a pump by directly correlating the volume of blood pumped by hea with body suface area. Normal range is 2.6 to 4.2 L/min/m2 CI less than 2.2L/min/m2 is seen in cardiogenic shock.