Which patient population may have a lower than average Cardiac Index?

A lower than average Cardiac Index is often observed in obese individuals due to several physiological factors. In this population, there is frequently an increased body mass, which means that the heart must pump blood over a larger volume of tissue. As weight increases, the demand on the cardiovascular system may not correspondingly escalate, leading to a situation where the heart's output isn't adequately matched to the increased body surface area or metabolic demands.

In obese individuals, there can also be related complications such as reduced cardiovascular efficiency and potential heart dysfunction, which can impact overall cardiac performance. Therefore, even if their stroke volume may remain relatively normal, the total cardiac output may be spread thin over an increased body mass, resulting in a lower Cardiac Index when calculated.

In contrast, elite athletes typically exhibit a higher cardiac index due to enhanced cardiac efficiency and increased stroke volume as a result of training. Young children may possess higher cardiac indices relative to their size as their bodies are still developing and maneuvering higher metabolic demands. Adolescents often have cardiac outputs that are more aligned with adult values, as their cardiovascular systems are maturing.