An intensive-care study used oxygen consumption and carbon dioxide production to estimate resting energy expenditure at several sedation depths. The investigators measured metabolic activity and assigned sedation scores as separate steps.
Seventy-four mechanically ventilated patients were assessed in a prospective self-controlled design. Mean estimated resting energy expenditure was 1,347 kcal/day at mild sedation, 1,236 at moderate sedation and 1,140 at deep sedation. Oxygen consumption and carbon dioxide production both declined with deeper sedation. The respiratory quotient showed no statistically significant difference.
Measurements on the same patient reduce the influence of differences between patients, while sedation depth and midazolam dose changed together in this design. The calorimetry estimate applies to the conditions during measurement. It does not quantify nutrition needs across an entire day or identify a universal relationship between a midazolam concentration and metabolic rate.