Optimizing Nitrogen Balance Is Associated with Better Outcomes in Neurocritically Ill Patients

Abstract

Marked protein catabolism is common in critically ill patients. We hypothesized that optimal protein supplementation using nitrogen balance might be associated with better outcomes in the neurointensive care unit (NICU) patients. A total of 175 patients admitted to the NICU between July 2017 and December 2018 were included. Nitrogen balance was measured after NICU admission and measurements were repeated in 77 patients. The outcomes were compared according to initial nitrogen balance results and improvement of nitrogen balance on follow-up measurements. A total of 140 (80.0%) patients had a negative nitrogen balance on initial assessments. The negative balance group had more events of in-hospital mortality and poor functional outcome at three months. In follow-up measurement patients, 39 (50.6%) showed an improvement in nitrogen balance. The improvement group had fewer events of in-hospital mortality (p = 0.047) and poor functional outcomes (p = 0.046). Moreover, improvement of nitrogen balance was associated with a lower risk of poor functional outcomes (Odds ratio, 0.247; 95% confidence interval, 0.066-0.925, p = 0.038). This study demonstrated that a significant proportion of patients in the NICU were under protein hypercatabolism. Moreover, an improvement in protein balance was related to improved outcomes in neurocritically ill patients. Further studies are needed to confirm the relationship between protein balance and outcomes.

Keywords: catabolism; critical illness; neurointensive care; nitrogen balance; protein.

Figure 1

Kaplan–Meier curves for outcomes according to the nitrogen balance. Patients with an improvement in protein balance had fewer events of neurological worsening (p = 0.030) (A) and lower in-hospital mortality (p = 0.068) than those without an improvement or aggravation in protein balance (B).