Effect of increased enteral nutrition on ICU-acquired infections: a multicenter observational study

Introduction

The objective of this study was to evaluate the effect of increasing enteral nutrition (EN) adequacy on acquired infection in the ICU.

Methods

Prospective, multicenter, observational study in three medical/surgical ICUs. We enrolled consecutive patients within 24 hours of admission to the ICU who were expected to stay for more than 24 hours. For this analysis, we excluded patients who were not mechanically ventilated in the ICU for more than 72 hours and who received parenteral nutrition. No interventions. Charts were reviewed to determine nutritional adequacy and clinical outcomes. Suspected infections were adjudicated by two or more clinicians to determine the presence or absence of infection (rated as either probable or possible infection).

Results

A total of 598 patients were enrolled in the overall study; 206 were included in this analysis. The average patient age was 62.2 years; APACHE II score was 23.3; BMI 28.6; and 73% were medical. Overall, patients received 48.8% (range 0 to 120%) of their energy and 45.0% (range 0 to 120%) of their protein requirements from EN. On average, patients remained ventilated for 9.1 days (interquartile range (IQR) 6 to 11), in the ICU for 13.5 days (IQR, 7 to 14) and 25.2% and 21.8% developed an infection after 72 and 96 hours, respectively. Overall 28-day mortality was 29.1%. In the overall analysis, greater amounts of energy and protein were consistently associated with a reduction in infection but only achieved levels near statistical significance when considering the incremental effect of 1,000 kcal/day and 30 g/day on patients with at least one probable infection after >96 hours (odds ratio (OR) 0.32, 95% confidence interval (CI), 0.10 to 1.03, P = 0.055 and OR 0.41, 95% CI 0.19 to 0.89, P = 0.024 for energy and protein, respectively). In all cases, the OR was lower when considering infections that developed after 96 hours compared with infections that developed after 72 hours and when considering probable infections compared with all infections. There was a trend towards a reduction in pneumonia that developed after 96 hours with increasing amounts of energy (OR 0.40, 95% CI 0.10 to 1.53, P = 0.18) and protein (OR 0.42, 95% CI 0.16 to 1.09, P = 0.076).

Conclusions

Increased EN adequacy was associated with a reduction in infectious complication, particularly after 96 hours of ICU admission.