Nutrition in the intensive care unit — you must breathe what you eat

• The imprecision in prescribing of enteral nutrition in critically ill patients must result in occasions of overfeeding as well as underfeeding. • Overfeeding could cause increased CO2 production and thus increased work of breathing and prolonged ventilator dependence. This possibility is supported by the limited relevant literature. • We examined this possibility mathematically using the data in The Augmented versus Routine Approach to Giving Energy Trial (TARGET) feasibility study and in its main study protocol. • Patients in the energy-dense feeding arm will receive 50% more calories and produce 52% more CO2 than patients in the standard feeding arm. • The full TARGET study is ideally positioned to answer the practical clinical question of whether increased feeding in critically ill patients can be delivered without prolonging ventilator dependence.