Background
Optimal nutritional support for critically ill patients remains a contentious topic in intensive care medicine. While malnutrition is associated with poor outcomes, the risks of overfeeding—particularly in patients with shock—are increasingly recognized. The NUTRIREA-3 trial originally compared low versus standard calorie and protein intake in mechanically ventilated adults with shock. This post hoc analysis specifically examines the impact of these nutritional strategies on renal function, a critical consideration given the high prevalence of acute kidney injury (AKI) in this population.
Study Design
The analysis included 3036 patients from the multicenter NUTRIREA-3 randomized controlled trial. Participants were adults receiving mechanical ventilation for shock (septic, cardiogenic, or hypovolemic) within 48 hours of ICU admission. Patients were randomized to either:
– Low group: 6 kcal/kg/day and 0.2-0.4 g protein/kg/day
– Standard group: 25 kcal/kg/day and 1.0-1.3 g protein/kg/day
Nutrition was delivered via enteral or parenteral routes for the first 7 ICU days. The primary outcome was acute kidney disease (AKD) incidence during ICU stay (up to discharge or day 90). Secondary outcomes included renal replacement therapy (RRT) need, urea levels, and mortality.
Key Findings
Primary Outcome
AKD occurred in 44.6% of low-group patients versus 46.1% in the standard group (HR 0.97, 95% CI 0.88-1.07, P=0.53). This non-significant difference persisted across pre-specified subgroups including patients with early kidney dysfunction or chronic kidney disease.
Biomarker Differences
Despite similar AKD rates, the low group showed:
– Lower peak urea levels (P=0.002)
– Lower urea at ICU discharge (P=0.002)
This suggests reduced nitrogen waste accumulation with restricted feeding.
Safety and Mortality
No significant differences were found in:
– RRT requirements (11.8% vs 12.9%)
– ICU mortality (32.7% vs 31.8%)
– 90-day mortality (42.3% vs 40.9%)
Expert Commentary
These findings challenge the traditional ‘more is better’ approach to critical care nutrition. The urea reduction in the low group may reflect reduced renal metabolic workload, though this didn’t translate to structural kidney protection. Importantly, the study demonstrates that short-term underfeeding doesn’t exacerbate renal injury—a reassuring finding for clinicians managing shock with concurrent AKI.
Conclusion
For ventilated shock patients, 7-day low-calorie/protein feeding showed equivalent renal safety to standard nutrition. The results support cautious nutritional approaches in early critical illness, particularly when renal function is compromised. Future research should explore longer-term outcomes and optimal protein timing.
Trial Registration
ClinicalTrials.gov Identifier: NCT03573739 (NUTRIREA-3)