Why Critically Ill Patients Are Protein Deprived

Abstract

Critical illness dramatically increases muscle proteolysis and more than doubles the dietary protein requirement. Yet surprisingly, most critically ill patients receive less than half the recommended amount of protein during their stay in a modern intensive care unit. What could explain the wide gap between the recommendations in clinical care guidelines and actual clinical practice? We suggest that an important aspect of the problem is the failure of guidelines to explain the pathophysiology of protein-energy malnutrition and the ways critical illness modifies protein metabolism. The difficulty created by the lack of a framework for reasoning about appropriate protein provision in critical illness is compounded by the many ambiguous and often contradictory ways the word malnutrition is used in the critical care literature. Failing to elucidate these matters, the recommendations for protein provision in the guidelines are incoherent, unconvincing, and easy to ignore.

Clinical Outcomes of Inadequate Calorie Delivery and Protein Deficit in Surgical Intensive Care Patients

“…No difference in in-hospital or 30-day mortality was detected between low-and high-calorie deficit groups. (14) 3 (8) 3 (8) 5 (14) 9 (24) 36 (97) 1891 (396) 98 (15) 1154 (462) 51 (21) 737 (544) 47 (24) 8467 (5058) 523 (210) 62 (22) 56 (20) 15 (8)(9)(10)(11)(12)(13)(14)(15) 15 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) 14 (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)…”

Protein requirement in critical illness

“…These considerations strongly predict that generous protein provision can improve clinical outcomes in protein-catabolic states. The recommended protein intake for normal people is 0.8 g/kg per day, whereas the commonest official recommendation in critical illness is 1.5 g/kg normal dry body weight per day (Ziegler 2009;Hoffer and Bistrian 2013a). A large amount of metabolic data, and some preliminary clinical trial evidence, suggests that the early provision of 1.5-2.5 g protein/kg per day could be optimal (Hoffer andBistrian 2012, 2013b;Hoffer and Bistrian 2014).…”

“…Actually they did not, because they are flawed by a serious design problem: they focused on the wrong nutrient. All therapeutic trials -especially nutritional ones, given their variety and complexity -should be founded on physiologically sound premises (Tonelli et al 2012;Hoffer and Bistrian 2013a). The physiologically implausible premise of all the RCTs whose results are being cited to justify the recommendation that "less nutrition is better in the ICU" is that calories are the only important macronutrient in critical illness.…”

“…I suggest 2 explanations: the first is a complacent ignorance of the details of nutritional physiology, perhaps justified by the misconception that since physiological insight is not "evidence" it can be disregarded when designing clinical trials (Tonelli et al 2012;Hoffer and Bistrian 2013a); the second is cognitive bias. One such bias arises from a process of stereotypical thinking that regards "calories" as a synonym for "nutrition".…”

Underfeeding versus full enteral feeding in critically ill patients with acute respiratory failure: a systematic review with meta-analysis of randomized controlled trials

“…Cytokine and stress hormones predispose patients to high protein catabolism due to muscular proteolysis, allowing the synthesis of acute-phase protein (1). As a result of this stress response, critically ill patients are bound to develop protein and energy deficits, added by total or partial inability of oral feeding.…”