An adult patient who weighs 62 kg (132 lb) requires a minute ventilation of 15 L/min to maintain a PaCO2 of 36 mm Hg while receiving mechanical ventilation. Which of the following could explain these ventilatory requirements?

The requirement for a minute ventilation of 15 L/min in this patient can be explained by excessive caloric intake. When a patient consumes more calories than their body needs, especially in the context of mechanical ventilation, metabolic demands increase. This leads to an elevated production of carbon dioxide (CO2) as a byproduct of metabolism. To maintain a normal arterial carbon dioxide tension (PaCO2) in the context of increased metabolic demand, the ventilatory requirements must be adjusted upward to achieve sufficient carbon dioxide removal from the body.

In this case, the elevated minute ventilation of 15 L/min suggests that the respiratory system is working harder to eliminate excess CO2 resulting from potential overfeeding or excessive caloric intake, which requires a proportional increase in minute ventilation to maintain normocapnia (normal levels of CO2 in the blood).

Other factors such as increased dead space ventilation, a febrile state, or increased pulmonary shunt could contribute to elevated minute ventilation, but they are not as directly tied to caloric intake. For instance, increased dead space would typically require compensation but is generally less directly related to caloric needs, while fever can increase metabolic rate but not necessarily to this extreme unless combined with caloric input. Increased pulmonary shunt