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Abstract

Introduction: Limited studies supporting a hypocaloric feeding approach in critically ill obese patients have suggested differences in clinical outcomes, including decreased length of mechanical ventilation and intensive care unit (ICU) length of stay. Hypothesis: Hypocaloric parenteral feeding is associated with improvements in clinical outcomes, including reduced ICU length of stay and fewer days of mechanical ventilation. Methods: This retrospective chart review screened all obese (BMI > 30 kg/m2) adult patients receiving parenteral nutrition at goal rate for > 48 hours in three ICUs at our academic medical center over a 33 month period. The nutritional content of parenteral nutrition was quantified and patients were stratified by compliance with the guidelines ±10 percent on the basis of kcal/kg/day (actual and ideal body weights). Primary outcomes included net changes in albumin and prealbumin, ICU and hospital length of stay, and duration of mechanical ventilation. Statistical significance was tested using the Student’s t-test. Results: Twenty four patients were fed hypocalorically per the guidelines while 27 patients were fed with a modified hypocaloric approach that provided more kcal/kg per day than current guideline recommendations (13.79 ± 3.12 vs. 19.81 ± 2.78, p < 0.001). There were no statistically significant differences between the two feeding strategies in surrogate markers of nutrition support (except for prealbumin (p = 0.027)) and clinical outcomes, including days of mechanical ventilation, ICU length of stay, hospital length of stay, and in-hospital mortality. Subgroup analyses stratified by compliance to the protein recommendations and by kcal/kg adjusted body weight also failed to show an association between feeding strategy and outcomes. Conclusions: There was no association between parenteral hypocaloric feeding per the guidelines and a modified hypocaloric approach with regard to clinical outcomes in critically ill obese patients. Although well designed prospective studies are required to confirm, these results raise the possibility that a less strict hypocaloric feeding approach in this patient population does not impact meaningful clinical and nutritional outcomes.