Early ICU energy deficit: Is it a risk factor for ventilator-associated pneumonia?

Background and objectiveBetter comprehension of the interactions between pathogens and host nutritional status offers an attractive field of research to optimize preventive strategies against VAP and to guide optimal selection of the initial antibiotic regimen taking into consideration that ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in mechanically ventilated patients hospitalized in the ICU. Therefore, we aimed to investigate the pattern of energy balance in mechanically ventilated patients who experienced VAP.Subjects and methodsFifty adult patients intubated at ICU admission and mechanically ventilated ⩾96h before a first VAP episode were included in our study for analysis. Systematic precise nutritional intake was calculated from ICU admission to the day of BAL to assess the early level of energy balance and its impact on the pathogenesis of VAP. VAP microbiology was assessed with quantitative cultures of BAL. Energy balance was expressed as cumulated (kcal or kcal/kg) from ICU admission to day of BAL and was calculated on the time of BAL as follows: cumulated energy delivered – cumulated REE.ResultsAmong the 50 BAL cultures, 25 contained Staphylococcus aureus (methicillin-susceptible S. aureus [MSSA], n=16; methicillin-resistant S. aureus [MRSA], n=9) whereas 10 grew P aeruginosa, 2 grew Enterobacteriaceae, 3 Streptococcus pneumoniae, 2 Acinetobacter baumannii. Six polymicrobial BAL cultures contained other pathogens: Enterobacteriaceae (n=5), S. pneumoniae (n=6), H. influenzae (n=4). Patients with S. aureus VAP had a significantly higher mean energy deficit than those S. aureus-negative BAL cultures (−10707.56±1988.47 vs −9337.48±835.69, P=0.002). However, Energy balance was not statistically significantly associated with the methicillin resistance of S. aureus strains (−10611.56±1865.8kcal for 16 patients with MSSA VAP vs −10607.65±1976.7kcal in nine patients with MRSA VAP, P=.879).ConclusionEarly negative energy balance is an independent determinant of S. aureus VAP in mechanically ventilated patients. Feeding prescriptions based on limiting the energy deficit during the first week of ICU stay could be a way to optimize S. aureus VAP prevention