Nutrition in Clinical Practice

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) represent points on a spectrum of acute hypoxic respiratory failure that are distinguished by the severity of associated hypoxemia. The hallmark of ALI/ARDS is an increase in pulmonary capillary permeability resulting from epithelial and endothelial injury; a variety of inflammatory mediators are involved in the pathogenesis, including toxic oxygen radicals, cytokines, and eicosanoids. Patients with ALI/ARDS are at high risk for malnutrition because the underlying disease increases caloric expenditure and promotes the loss of lean body mass; this, in turn, has adverse effects on pulmonary and immune function. The type of fatty acids (FA) that comprise the cell membrane of alveolar macrophages and neutrophils is influenced by dietary fat intake; this, in turn, impacts on the nature of eicosanoid mediators produced during ALI/ARDS. Diets high in linoleic acid (LA) promote an inflammatory response by stimulating production of arachidonic acid and its derived eicosanoids. Nutritional supplementation with ω-3 FA can lessen the inflammatory response and be of therapeutic benefit in patients with ALI/ARDS. This article reviews the pathology and pathophysiology of acute hypoxemic respiratory failure, summarizes animal and human studies that delineate the effects of modified FA solutions, and provides clinical recommendations for the nutrition support of patients with ALI/ARDS.

The incidence of type 2 diabetes mellitus and one of its risk factors, obesity, are increasing at rapid rates in all age groups. Good glycemic control has been proven to reduce debilitating complications. Diabetes Medical Nutrition Therapy (MNT) in the United States focuses on encouraging “complex” over “simple” carbohydrates and the quantity of carbohydrates consumed. In a number of countries worldwide, a quality marker for carbohydrates, the glycemic index, is promoted. This glycemic index (GI) quantifies a carbohydrate's expected impact on the blood glucose response postprandially. Lack of agreement exists among scientists in the United States as to the clinical benefits and patients' ability to comprehend GI. Many factors alter GI, including processing, ripening, and plant varieties. Modest clinical benefits on lipid and glucose levels have been documented. There are simple or complex approaches to enhance individualized MNT with GI in the management of this chronic disease.

Celiac disease (CD) occurs in genetically predisposed individuals who demonstrate a permanent intolerance to gluten, found in wheat, barley, and rye. This leads to the development of an autoimmune enteropathy, resulting in the malabsorption of critical vitamins, minerals, and calories. Signs and symptoms of the disease classically include diarrhea, short stature, iron-deficient anemia, and chronic abdominal pain. However, patients may present with another autoimmune disease (such as type I diabetes) or a family history of the disease, with no gastrointestinal symptoms. Serum antibodies can be used to screen for CD. However, the keys to confirming the diagnosis remain a small intestinal biopsy and the patient's clinical response to a gluten-free diet. Clinicians in the United States must maintain a high index of suspicion for CD, because it is significantly underdiagnosed in this country.

In pediatric hospitals, several factors interfere with the delivery of parenteral nutrition (PN). The purpose of this study was to assess the impact of a customized system of PN ordering on PN delivery, using a retrospective chart review before (n = 40) and after (n = 43) implementation of the system. No difference was observed in the proportions of children who did not receive the ordered amount of dextrose and amino acids (30% versus 23%, p = .49). Before customization, the subjects were more likely to receive intralipids (42% versus 19%, p = .02), and micronutrients (67% versus 9%, p < .0001) out of range. These results remained unchanged after adjustment for age, hospital unit, other fluids, and presence of a central line. Our findings highlight the discrepancy between ordered and received PN in pediatric patients. Customized PN ordering was associated with improved delivery of intralipids and micronutrients.

A variety of methods are used to estimate whether a gastric residual volume is excessive during enteral feedings. In this study, mathematical models of gastric volume during continuous or bolus feedings were developed to evaluate the relevance of measuring residual volumes. The validity of common threshold values of residual volumes that are used to monitor the safety of enteral feeding in infants and adults was tested. A mathematical representation of gastric volume was established using standard integration methods. Assuming an exponential rate of gastric emptying, continuous feedings result in a steady state volume that is proportional to the half-emptying time of the stomach and the rate of addition of endogenous and exogenous fluids. During bolus feedings, a steady state volume will be achieved that is proportional to the volume of the bolus and a rate constant calculated using the half-emptying time and the bolus interval. Based on these models, it can be predicted that threshold values commonly used to monitor feedings do not accurately predict residual volume. In both infants and adults, the threshold values often will overestimate residual volumes at shorter half-emptying times and underestimate residual volumes at longer half-emptying times. Because of the complex relationship between infusion volume, gastric emptying, and gastric volume, evaluation of the volume of gastric contents is an unreliable method for monitoring feeding tolerance.

Objective: The usefulness of skin level gastrostomy tubes (button systems) for maintaining nutrition support after primary insertion of percutaneous endoscopic gastrostomy (PEG) is widely accepted. Technical and usability problems have forced the development of new systems. The experience with a newly developed skin-level gastrostomy system (Freka-Button Gastrostomy) in oncological patients is described. Methods: In a cohort study we prospectively evaluated for ease of use, complications, and time to failure, a modified balloon button system based on the MIC-Key type. It differs from other systems by its application mode and balloon design. Since February 1998, 18 systems were applied in 15 patients (median age 56 years, 42 to 72 years, 14 men, 1 woman). Results: Correct application of the 18 buttons in 15 individuals was easy and fast to perform (median intervention time 10.8 minutes). During follow-up (median 201, range 2 to 590 days) 1 button was removed because of the patient's decision, 2 others had to be renewed because of technical problems, and no major complication occurred. Conclusions: The new Freka-button system provides an easy-to-use, safe, and feasible alternative for long-term use of skin-level gastrostomy tubes in oncological patients.

SUMMARY FROM ORIGINAL ARTICLE: Continuous infusion into the superior vena cava of hypertonic nutrient solutions containing large amounts of nitrogen, calories, and vitamins and required amounts of electrolytes can be accomplished safely for long periods of time with meticulous attention to preparation and administration of the solution. With the exclusive use of parenteral hyperalimentation, weight gain, positive nitrogen balance, growth, and development have been regularly achieved. This technique allows adequate metabolic support of patients with severe nutritional debility or prolonged disability of the gastrointestinal tract and adds a valuable tool to the repertoire of the surgeon and investigator. Dudrick SJ, Wilmore DW, Vars HM, Rhoads JE. Ann Surg 169:974–984, 1969.