Robert F. Kushner

Comparison of two bioelectrical impedance analysis models for total body water measurement in children

We compared two bioelectrical impedance analysis models, the right-sided tetrapolar method and an experimental cylindrical method, to total body water (TBW) determined by isotopic dilution in 37 prepubertal children aged 5-9 years, who were divided into development and cross-validation groups. Despite its theoretical advantage, no improvement in predicted TBW was seen with the experimental method. The best predictive equation, using the tetrapolar method, was TBW (kg) = 1.84 + 0.45 (height square/resistance) +0.11(weight); r2 = 0.98; SEE = 0.62 kg.

Errors in estimating peritoneal fluid by bioelectrical impedance analysis and total body electrical conductivity.

Whole-body bioelectrical impedance analysis (BIA) and total body electrical conductivity (TOBEC) have been used to estimate body composition and generalized changes in total body water (TBW). The sensitivity of these methods to measure small, rapid, localized changes in body water has not been fully evaluated. We compared the prediction of TBW by whole-body and segmental BIA and TOBEC with deuterium oxide dilution (D2O) in 10 control subjects and 7 renal failure patients receiving continuous ambulatory peritoneal dialysis (CAPD) prior to and after dialysate infusion. Using D2O as the reference method, there was no significant mean residual error between TBW predicted by BIA and TOBEC in controls (-1.2 +/- 1.5 and -0.9 +/- 1.0 kg) and CAPD patients pre-infusion (-1.0 +/- 2.0 and 0.29 +/- 2.01 kg). After infusing 1.9 +/- 0.18 kg dialysate, the mean residual error between change in body weight and the three methods was -0.44 +/- 0.53 kg for D2O (p < 0.1), -1.7 +/- 0.25 kg for BIA (p < 0.0001), and 1.2 +/- 0.4 kg for TOBEC (p < 0.001). Segmental BIA detected a 7.6% reduction in trunkal resistance with no significant change across the limbs, consistent with abdominal fluid accumulation. It is concluded that whole-body BIA underpredicts and TOBEC overpredicts small changes in peritoneal fluids.

Total parenteral nutrition-associated metabolic acidosis

To prevent acid-base disturbances, a patient receiving intravenous nutritional solutions must excrete the daily metabolic production of acid. These hydrogen ions are generated from external (infused) sources and internal metabolic processes. Patients with normal respiratory and renal organ function are capable of excreting these volatile and nonvolatile acids, respectively, and maintaining acid-base balance. However, increased renal or gastrointestinal loss of bicarbonate, diminished renal excretion of acid, or increased acid production may all result in a metabolic acidosis. This article reviews the mechanisms of hydrogen ion production associated with total parenteral nutrition and the variety of disease states leading to development of a metabolic acidosis.

Determination of body fluids by the impedance technique

For the purposes of determining body composition, the body can be viewed as the sum of two components, fat and fat-free mass, the latter including water, protein, and minerals. Current methods for determining the size of these various components of the body are either inexact, invasive, or dependent on expensive or slow instrumentation. Bioelectrical impedance, which is rapid, noninvasive, and relatively inexpensive is examined as an alternative method for measuring body composition. The potential for the impedance technique arises from the very different electrical properties of the body components. The theory of bioelectrical impedance analysis is briefly presented, and human applications are discussed. The results of studies validating the method are cited.<<ETX>>

Endoscopic, Radiographic, and Clinical Response to Prolonged Bowel Rest and Home Parenteral Nutrition in Crohn's Disease

Total parenteral nutrition is widely used as a therapeutic measure in patients with severe, active Crohns disease unresponsive to conventional medical management. We have reviewed our experience with 10 patients with nonfistulous Crohns disease treated by home parenteral nutrition (HPN) and bowel rest (nothing-by-mouth) assessing the nutritional, radiologic, endoscopic, and clinical responses. After a mean of 4.1 months of treatment, all patients had a marked improvement in nutritional status and resolution of gastrointestinal symptoms; 90% reduced their corticosteroid dose. Eight of nine patients had endoscopic and/or radiographic evidence of mucosal healing. Although 60% of patients were able to avoid surgery and tolerate refeeding, all six patients continue to require steroids to control symptoms. Our study suggests that HPN and bowel rest is a useful therapeutic approach to selected patients with active Crohns disease, which permits a reduction in corticosteroid dosage and partial healing of mucosal lesions in most. Further studies are required to determine which patients should receive HPN and its optimal duration.

Intense Nutritional Support in Inflammatory Bowel Disease: A Review

We have reviewed the value of intense nutritional support in inflammatory bowel disease (IBD), relying mostly on the limited uncontrolled studies that have been performed. In most circumstances, nutritional restitution and a short-term clinical remission are accomplished when this support is provided. In some patients, particularly those with Crohns disease who undergo surgery, intense nutritional support probably decreases morbidity and mortality. Children with IBD can undergo linear growth rates with nutritional supplementation. There is a great need for additional controlled studies.

Metabolic Acidosis: Development in Two Patients Receiving a Potassium-Sparing Diuretic and Total Parenteral Nutrition

Two patients developed a metabolic acidosis associated with a normal undetermined anion concentration while receiving a potassium-sparing diuretic and total parenteral nutrition. In both cases the metabolic acidosis resolved within one week after discontinuing administration of the diuretic. The use of potassium-sparing diuretics in a patient receiving total parenteral nutrition requires caution and continued monitoring for this potential drug-nutrient interaction.