Nutrition
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The availability and widespread use of TPN enables physicians to help patients in a way that had not been possible in the past. However, in order to best utilize this modality, we must be aware of potential hazards and metabolic complications. Many patients receiving TPN, particularly those receiving perioperative TPN, are malnourished to various extents, and careful monitoring of glucose metabolism is warranted to avoid malnutrition-associated reactive hypoglycemia.
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Case Reports
Clinical and biochemical aspects of thiamine treatment for metabolic acidosis during total parenteral nutrition.
We encountered six cases of total parenteral nutrition (TPN)-associated lactic acidosis during the 6-y period of 1988-1993. The patients were characterized by severe disease of the digestive organs, minimal food intake before surgery, and postoperative TPN with no food intake and with no vitamin supplements. Within 4 wk of TPN, they developed hypotension (< or = 80/60 mmHg), Kussmaul's respiration, and clouding of consciousness, as well as abdominal pain not directly related to the underlying disease. ⋯ Thiamine replenishment at intravenous doses of 100 mg every 12 h resolved lactic acidosis and improved the clinical condition in 3 patients. This article includes a review of 11 relevant reports published from 1982-1992 and a discussion of the biochemical mechanism of onset of thiamine deficiency-associated lactic acidosis. We emphasize the needs (1) to supplement TPN with thiamine-containing vitamins for the patients whose food intake does not meet nutritional requirements; (2) to monitor the patients routinely measuring serum thiamine concentration and erythrocyte transketolase activity during TPN; and (3) to intravenously replenish using high-dose thiamine simultaneously with the manifestation of signs and symptoms of lactic acidosis.
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Whereas macronutrient intake has been extensively investigated in an attempt to unravel the pathogenesis of human cholesterol gallstones, theoretical considerations and animal models suggest that deficits in micronutrient antioxidants may be more relevant. We report a pilot study of this aspect. The plan was to obtain 7-d weighed food inventories over a 6-mo period from equal numbers of patients who had not consciously changed their diets, patients who were on low-fat diets and age- and gender-matched controls. ⋯ Furthermore, the lower daily intake of alpha-tocopherol and linoleic acid by these patients persisted when results were expressed relative to total fat consumption. The results support the hypothesis that insufficiency of dietary antioxidants, particularly alpha-tocopherol, may be germane to human gallstone disease; they also suggest that low intakes of linoleic acid and essential amino acids may be relevant. Because of the small sample sizes, however, these deductions should be regarded as tentative, pending confirmation by biochemical analysis of blood and especially of hepatic bile.
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Randomized Controlled Trial Comparative Study Clinical Trial
Response of severely malnourished patients to preoperative parenteral nutrition: a randomized clinical trial of water and sodium restriction.
Preoperative parenteral nutrition (PPN) may be beneficial for severely malnourished patients who are candidates for a major elective surgical procedure. The response to PPN, however, has not been thoroughly investigated. Expansion of the extracellular water compartment may occur in some patients, producing a further decrease in the serum albumin concentration and increasing the postoperative complications. ⋯ Weight changes correlated with water (r2 = 0.46, P = 0.001) and sodium (r2 = 0.62, P = 0.0001) balances. Inappropriate responses to PPN in both groups (expansion or depletion of the extracellular water compartment) were associated with a significant increase in pulmonary postoperative complications. During PPN, extracellular water expansion--as determined by increasing weight and lowering of the serum albumin concentration--and aggressive fluid therapy to treat water and sodium depletion seem crucial to the development of postoperative respiratory complications.