Acute stroke patients are being underfed: a nitrogen balance study

Patients with acute neurological illness may be hypercatabolic. The Harris-Benedict Equation (HBE) is used to estimate energy needs in acute stroke. A "stress factor" for stroke does not exist, and it is not known if the HBE accurately estimates the energy expenditure needs in acute ischemic or hemorrhagic stroke. We sought to assess nitrogen balance in patients with acute stroke and to determine the variables associated with negative nitrogen balance.

This was a case series, single-center study. Eligibility criteria included acute stroke requiring enteral nutrition, tolerating tube feedings at goal, normal urine output, and no underlying catabolic illness. Enteral feeding was adjusted to meet HBE requirements. After 24 hours of goal feeding, a 12-hour urine collection for nitrogen excretion was done. We determined if any of the following variables were associated with negative nitrogen balance: gender, glucose 6.6 mmol/L or more, age 80 years or older, National Institutes of Health Stroke Scale (NIHSS) 20 or higher, mechanical ventilation, and diabetes mellitus.

We studied 27 patients (10 with intracranial hemorrhages and 17 with ischemic strokes) during an 18-month period. The median age was 80 (range: 48-90), and the median NIHSS was 19 (range: 4-38). The median time to feeding was 2 days (range: 1-8), the median time from onset to nitrogen balance was 5 days (range: 2-11), and the median interval between initiation of feeding and nitrogen collection was 2 days (range: 1-5)Negative nitrogen balance was seen in 12 of 27 (44%) patients. There was no relation between age, NIHSS, stroke type, admission glucose, history of diabetes, and mechanical ventilation use and nitrogen balance. Only 11 of 27 patients were anabolic.

Critically ill stroke patients are being underfed using the current methods to estimate caloric needs. Hypercatabolism is common in acute stroke; clinical variables do not seem to allow prediction of this catabolic state.