Nutrition in Clinical Practice

Biochemical relationships between oxidative stress, antioxidant nutrients, and chronic diseases are complicated and often conflicting. Basic research supports the concept that reactive oxygen species precipitate changes that result in oxidative damage to lipid, protein, and DNA biomolecules. Oxidative stress is implicated in the development of cancer, cardiovascular disease, diabetes, sepsis, various eye diseases, and neurologic conditions. Supplementation with antioxidant nutrients seems plausible to counter the effects of oxidative stress, but the preferred mode of delivery for these nutrients may be through the patient's diet rather than as supplements to the diet. In fact, evidence supporting consumption of at least 5 servings of fruits and vegetables continues to grow. To better understand the role of antioxidant nutrients in disease promotion or prevention, this review will discuss basic nutritional biochemistry relating to oxidative stress and antioxidant defense systems, followed by a discussion of the metabolism (vitamins E, C, A) and interrelationships of select antioxidant nutrients.

An essential component in developing the nutrition support plan for hospitalized patients is evaluating energy requirements. Assessing energy expenditure (EE) and identifying requirements in the critically ill patient present the clinician with a challenge; how to prevent overfeeding and minimize underfeeding? Both under- and overfeeding have been associated with increased morbidity and mortality. It is known that critical illness alters EE. This alteration is hormonally mediated and is characterized by changes in metabolic processes. Methods used by clinicians to assess EE in the critically ill patient vary significantly. It is the purpose of this review to outline the various methods for evaluating EE in critical illness with emphasis on their benefits and limitations.

The administration of enteral nutrition in intensive care unit (ICU) patients is largely managed by nurses. However, the degree of knowledge, interest, and training in this field can differ considerably among nurses and among ICUs. Such differences may lead to variations in the way in which enteral nutrition is used. To investigate these issues, a questionnaire survey was sent to the nursing staffs of 5 ICUs in Belgium. The response rate was 68%. Although theoretical knowledge of enteral nutrition was globally poor, its advantages over parenteral nutrition were usually known. Responses to questions related to practical issues associated with enteral feeding showed more institution-specific answers than interindividual differences.

A retrospective analysis of 55 mechanically ventilated critically ill patients was conducted to determine adequacy of nutritional support (total parenteral nutrition or enteral nutrition) according to requirements established by indirect calorimetry. Patients who received 90% to 110% of the established energy requirements as measured by indirect calorimetry were defined as adequately fed. At the time of the indirect calorimetry measurements, all patients were receiving their targeted nutritional support, as assessed by the unit dietitian, who used predictive formulas to assess patients. Indirect calorimetry results showed that 25% of the patients were overfed (receiving >110% of energy requirements), 35% were underfed (receiving <90% of energy requirements), and 40% were adequately fed (receiving 90% to 110% of energy requirements). We determined that critically ill patients with a body mass index <20 kg/m² were the most likely group to be assessed inappropriately by available regression equations. If indirect calorimetry measurement is unavailable, we suggest using an empiric formula of 37 kcal/kg for critically ill patients with a body mass index <20 kg/m².

Background: Nutritional support is an important link between the response to injury and recovery in critical illness. Objective: Our goal was to evaluate energy and substrate metabolism in septic and nonseptic critically ill patients in the resting state and during the administration of standardized total parenteral nutrition. Design: This was a prospective, clinical cohort study of 25 consecutively admitted critically ill patients either with (n = 14) or without (n = 11) sepsis who received total parenteral nutrition. Resting energy expenditure was measured on days 0, 2, and 7 by indirect calorimetry. Energy and substrate balances were calculated on days 2 and 7. Results: Resting energy expenditure was not significantly different between septic and nonseptic patients on day 0 (2.65± 0.49 and 2.36 ± 0.56 kJ × min^–1 × m^–2, respectively). Energy balances were positive for both groups on days 2 (0.68 ± 0.4 and 0.74 ± 0.6 kJ × min^–1 × m^–2, respectively; NS) and 7 (0.65 ± 0.3 and 0.78 ± 0.5 kJ × min^–1× m^–2, respectively; NS). Substrate balances were not significantly different between groups on days 0, 2, and 7. Resting energy expenditure on day 0 was negatively correlated with the severity of illness in septic patients only (r = –0.58, P < 0.05). Conclusions: Metabolic changes were not significantly different between septic and nonseptic critically ill patients during the administration of standardized total parenteral nutrition. A disease-specific macronutrient composition of total parenteral nutrition formulas does not seem to be necessary in either septic or nonseptic critically ill patients.

Objective: The objective was to review retrospectively all patients undergoing bariatric surgery at a large university medical center. Methods: Ten adolescents 17 years or younger underwent gastric bypass surgery; 7 of 10 adolescents had severe obesity-related morbidities. Follow-up> 1 year was present in 9 of 10 adolescents. Results: The average weight before surgery was 148 ± 37 kg. Postoperative recovery was uneventful in all adolescents; 9 of 10 adolescents had weight loss in excess of 30 kg (mean weight loss was 53.6 ± 25.6 kg). Obesity related morbidities resolved in all adolescents. Five adolescents had mild iron deficiency anemia, and 3 adolescents had transient folate deficiency. Late complications requiring operative treatment occurred in 4 of the adolescents. Conclusion: Gastric bypass surgery was an effective method for weight reduction in morbidly obese adolescents. The procedure was well tolerated, with few unanticipated side effects. Gastric bypass remains a last resort option for severely obese adolescents for whom other dietary and behavioral approaches to weight loss have been unsuccessful.

Hypothesis: Immediate enteral feeding following major abdominal surgery reduces postoperative complications and mortality when compared with parenteral nutrition. Design: A prospective multicenter randomized trial. Setting: A university hospital department of digestive surgery. Patients and Interventions: Two hundred forty-one malnourished patients undergoing major elective abdominal surgery were randomly assigned to receive, after surgery, either enteral (enteral nutrition group: 119 patients) or parenteral nutrition (total parenteral nutrition group: 122 patients). The patients were monitored for postoperative complications and mortality. Results: The rate of major postoperative complications was similar in the enteral and parenteral groups (enteral nutrition group: 37.8%; total parenteral nutrition group: 39.3%; P was not significant), as were the overall postoperative mortality rates (5.9% and 2.5%, respectively; P was not significant). Conclusions: The present study failed to demonstrate that enteral feeding following major abdominal surgery reduces postoperative complications and mortality when compared with parenteral nutrition.