Chemical paralysis reduces energy expenditure in patients with burns and severe respiratory failure treated with mechanical ventilation.

Abstract

Predictive formulas often overestimate energy requirements, particularly in patients being treated with mechanical ventilation, resulting in significant overfeeding. The purpose of this study was to quantify the effect of chemical paralysis on energy expenditure in patients with burn injuries receiving ventilation treatment, and compare measured energy expenditure with estimates of energy expenditure based on predictive formulas. The study was a retrospective review of 14 patients with burn injuries treated with mechanical ventilation that required chemical paralysis to reduce inspiratory pressures or improve oxygenation. Indirect calorimetry was performed before, during, and after paralysis. Measured energy expenditure (MEE) was compared with the energy predictions of the Harris-Benedict (HBEE) and Curreri (CEE) estimates. During paralysis, mean MEE was significantly lower than pre- or postparalysis (19.65 +/- 1.65 versus 26.00 +/- 2.42 and 29.49 +/- 2.83 kcal/kg/24 hr, respectively). Mean HBEE (2031 +/- 145 kcal/24 hr) approximated MEE pre-(1989 +/- 350 kcal/24 hr) and postparalysis (2237 +/- 269 kcal/24 hr), but overestimated MEE during paralysis (1532 +/- 208 kcal/24 hr; p < 0.05). Mean CEE (2957 +/- 229 kcal/ 24 hr) estimates significantly overestimated MEE before, during, and after paralysis (1989 +/- 350, 1532 +/- 208, and 2237 +/- 269, respectively p < 0.05). Predictive formulas significantly overestimate measured energy requirements in these patients. Indirect calorimetry should guide nutrition support in patients requiring prolonged mechanical ventilation.