Semi-elemental versus polymeric formula for enteral nutrition in brain-injured critically ill patients: a randomized trial

Background The properties of semi-elemental enteral nutrition might theoretically improve gastrointestinal tolerance in brain-injured patients, known to suffer gastroparesis. The purpose of this study was to compare the efficacy and tolerance of a semi-elemental versus a polymeric formula for enteral nutrition (EN) in brain-injured critically ill patients. Methods Prospective, randomized study including brain-injured adult patients [Glasgow Coma Scale (GCS) <= 8] with an expected duration of mechanical ventilation > 48 h. Intervention: an enteral semi-elemental (SE group) or polymeric (P group) formula. EN was started within 36 h after admission to the intensive care unit and was delivered according to a standardized nurse-driven protocol. The primary endpoint was the percentage of patients who received both 60% of the daily energy goal at 3 days and 100% of the daily energy goal at 5 days after inclusion. Tolerance of EN was assessed by the rate of gastroparesis, vomiting and diarrhea. Results Respectively, 100 and 95 patients were analyzed in the SE and P groups: Age (57[44-65] versus 55[40-65] years) and GCS (6[3-7] versus 5[3-7]) did not differ between groups. The percentage of patients achieving the primary endpoint was similar (46% and 48%, respectively; relative risk (RR) [95% confidence interval (CI)] = 1.05 (0.78-1.42); p = 0.73). The mean daily energy intake was, respectively, 20.2 +/- 6.3 versus 21.0 +/- 6.5 kcal/kg/day (p = 0.42). Protein intakes were 1.3 +/- 0.4 versus 1.1 +/- 0.3 g/kg/day (p < 0.0001). Respectively, 18% versus 12% patients presented gastroparesis (p = 0.21), and 16% versus 8% patients suffered from diarrhea (p = 0.11). No patient presented vomiting in either group. Conclusion Semi-elemental compared to polymeric formula did not improve daily energy intake or gastrointestinal tolerance of enteral nutrition.