Daily systemic energy expenditure in the acute phase of aneurysmal subarachnoid hemorrhage

Background: Patients with subarachnoid hemorrhage often have impaired consciousness and cannot regulate nutritional intakes themselves. Previous studies have demonstrated elevated energy expenditure in the acute phase, but it is not known whether the energy demand is constant during the first week after onset of the disease. In this study, we performed daily measurements of energy expenditure with indirect calorimetry during the first 7 days after aneurysmal subarachnoid hemorrhage in mechanically ventilated patients. Methods: Metabolic measurements were performed daily with indirect calorimetry in 26 patients with aneurysmal subarachnoid hemorrhage. All patients were intubated and mechanically ventilated. The measured value was compared to the predicted values from the Harris–Benedict equation and the Penn State University 1998 equation. Urinary nitrogen excretion was measured daily. Results: There was a significant increase in energy expenditure during days 2–3 compared to days 5–6. The Harris–Benedict equation underestimated metabolic demand. The Penn State 1998 equation was closer to the measured values, but still underestimated caloric need. Urinary nitrogen excretion increased throughout the first week from initially low values. Conclusions: There is a dynamic course in energy expenditure in patients with aneurysmal subarachnoid hemorrhage, with increasing metabolic demand during the first week of the disease. Indirect calorimetry could be used more often to help provide an adequate amount of energy.