Immuno-nutrients for ARDS: An Update Essay

Abstract

interrupted by lung injury, causing excess fluid in both the interstitium and alveoli. Consequences include impaired gas exchange, decreased compliance, and increased pulmonary arterial pressure. Patients with ARDS tend to progress through three relatively discrete pathologic stages: the exudative stage, proliferative stage, and fibrotic stage. More and more possible causes of ARDS have been identified and other potential causes continue to emerge as adverse pulmonary reactions to new therapies are observed. However, only a few common causes account for most cases of ARDS. Most current therapies for ARDS are supportive, aimed at improving gas exchange and preventing complications while the underlying condition that precipitated the ARDS is addressed. Nutrition support refers to the enteral or parenteral provision of calories, protein, electrolytes, vitamins, minerals, and fluids.Enteral nutrition is the preferred method for feeding critically ill patients with functioning gastrointestinal tract. Enteral nutrition improves several clinical outcomes like infectious complications and ICU or hospital length of stay. Indeed, enteral nutrition seems to play a role in the modulation of the immune system of critically ill patients. Several specific substrates with immunological effects have been added, alone or in combination, to standard diets trying to modify the immune response of the patients. The number of these key nutrients, also called immunonutrients, is now increasing but arginine, glutamine, nucleotides and omega-3 polyunsaturated fatty acids seems to play a primordial role in the regulation of immunological and inflammatory responses in critically ill patients. ARDS are associated with disease states characterized by a hypermetabolic response. Clinical states such as sepsis, pancreatitis, aspiration pneumonia, and severe trauma are associated with marked hypermetabolism secondary to the inflammatory process. Providing nutritional support to these patients early in their disease course is essential in order to minimize the loss of lean body mass and to provide adequate energy for metabolic support. Enteral nutrition is the preferred nutritional support method due to its reduced septic risk, lower cost, and role in maintaining the gastrointestinal barrier function. Energy requirements among ARDS patients vary considerably based on the underlying clinical state. Indirect calorimetry (IC) is the most accurate method for measuring energy expenditure in hospitalized patients. Despite its superiority, IC use in ARDS has its limitations.