Supplemental parenteral nutrition improves immunity with unchanged carbohydrate and protein metabolism in critically ill patients: The SPN2 randomized tracer study

Abstract

Background & aims Individualized supplemental parenteral nutrition (SPN) providing measured energy expenditure from day 4 reduced infectious complications in a previous study including 305 intensive care (ICU) patients. The study aimed at investigating the metabolic, and immune responses underlying the clinical response of the previous trial.Methods Randomized controlled trial enrolling 23 critically ill patients on day 3 (D3) of admission to the ICU who were fed less than 60% of their energy target by the enteral nutrition (EN) alone: allocation to either continued EN or to SPN to a target validated by indirect calorimetry. Protein and glucose metabolism (primary endpoint) were investigated with tracer isotopes on D4 and D9. Secondary endpoints: 1) immune response, investigated in serum and in stimulated peripheral blood mononuclear cells (PMBC), by dosing a panel of cytokines (infectious complications were recorded), and 2) Muscle mass was assessed by ultrasound of the thigh.Results Comparable at baseline, the SPN group (n = 11) received more energy (median 24.3 versus 17.8 kcal/kg/day: p < 0.001) and proteins (1.11 versus 0.69 g/kg/day: p < 0.001) than the control group during the five days' intervention, resulting in a less negative energy balance by D9 (p = 0.0027). Net protein breakdown and Glucose kinetics on D9 did not differ, within or between groups. In agreement with a decrease in infection rate, immune response in the SPN group showed decreased serum IL-6 (p = 0.024), IL-1β, IL-10 levels and TNF-α secretion by PBMC (p = 0.018) at D9. Muscle mass loss from D4 to D15 tended to be less in the SPN group (-16% versus -23%: p = 0.06). Clinical course by D28 did not differ.Conclusions Feeding patients to cover an individualised measured energy target with SPN from D4 to cover needs, was associated with improved immunity, less systemic inflammation and a trend to less muscle mass loss.Clinical trial registry NCT02022813 at https://clinicaltrials.gov/.