A metabolic cart is a device used to measure the oxygen consumed when someone performs maximal or sub-maximal workouts, leading to calculations that measure the amount of energy expended during the workout, according to the Department of Health and Exercise Sciences at Skidmore College. Metabolic carts are used in human research and to analyze nutritional needs of patients.
A metabolic cart works by attaching head gear to a subject while the person breathes a specific amount of oxygen over a period of time. The machine is calibrated before the apparatus is placed on the subject and then a computer makes calculations, according to class resources from San Diego State University.
One critical measurement found by metabolic carts is the resting energy expenditure, or REE. Medscape explains that this data can help doctors determine how much food and nutrition ICU patients should receive while in critical care. A metabolic cart measures both oxygen intake and carbon dioxide outtake, thereby leading to calorimetry calculations for patients.
Metabolic carts are just one way to determine a patient's energy needs. An article in the Journal of Trauma indicates that mathematical formulas and weight-based calculations can be used alongside metabolic carts to determine nutritional requirements. One study found a metabolic cart was able to determine ICU patients' energy needs just as well as formulas and calculations.