ABSTRACT
BACKGROUND/OBJECTIVES: Bioelectrical impedance vector analysis (BIVA) is increasingly used in clinical research to assess soft tissue hydration. It is known that physical characteristics of electrodes, such as low intrinsic impedance, low electrode/skin contact impedance and type of gel, affect the reliability of noninvasive bioimpedance assessments. The aim of this study was to determine the effect of intrinsic impedance of electrode on the bioimpedance vector displacement in RXc graph. SUBJECTS/METHODS: The intrinsic impedance is measured in nine pregelled disposable Ag/AgCl electrodes usually used for bioimpedance measures. The BIVA method is performed on 35 healthy volunteers using a 50 kHz phase-sensitive bioimpedance analyzer (BIA 101 Anniversary) with the lowest intrinsic impedance electrode and highest. The individual bioimpedance vector is plotted on the bivariate normal interval of reference population. The differences in the mean bioimpedance vectors obtained with each electrode are plotted, with their 95% confidence ellipses, on the dRXc graph. The paired one-sample Hotelling's T2-test is used to compare the differences of the mean bioimpedance vectors. RESULTS: We found large variability in intrinsic resistance (11-665 Ω) and reactance (0.25-2.5 Ω) values of the electrodes analyzed and significant displacement (P<0.05) of bioimpedance vector positions in healthy adults according to the paired one-sample Hotelling's T2-test. CONCLUSIONS: A robust study of all physical characteristics of commercial Ag/AgCl electrodes is necessary to reach consensus on pregelled Ag/AgCl electrodes valid for bioimpedance measurement. This information will enable BIVA users to avoid systemic errors when performing BIVA assessments, specifically when these measurements are used for clinical interpretations.
Subject(s)
Body Composition/physiology , Body Water/physiology , Dehydration/diagnosis , Electric Impedance , Electrodes , Adult , Female , Gels , Healthy Volunteers , Humans , Male , Middle Aged , Silver , Silver CompoundsABSTRACT
In clinical practice, geriatric nutritional assessment usually includes nutritional screening, a simple anthropometric assessment, measurement of various biochemical parameters, such as serum albumin, and sometimes (not always) body composition analysis (BCA). However, there is a high prevalence of undiagnosed malnutrition in patients with dementia. Several factors contribute to this situation; probably, the most notable is the methodology used to assess body composition (BC). In this regard, for BCA, techniques are needed that are noninvasive, affordable, safe, simple and that require the minimum possible collaboration by the elderly patient. Consequently, body mass index (BMI) and waist circumference (WC) are widely used as indicators of overall and central adiposity, respectively; however, there is no consensus on the cutoffs for the elderly, and changes in BC (especially muscle-mass depletion) are masked by normal values of BMI and WC. Bioimpedance analysis is a simple, cost-effective and precise method for BCA, provided that cross-validated equations are used. Its main disadvantage is that it is highly sensitive to changes in body water (overhydration or dehydration), leading to substantial errors in BC estimates. However, using Bioelectrical Impedance Vector Analysis errors are minimized, as there is no need for the subject to be normally hydrated and it does not require the use of predictive models.
Subject(s)
Aging , Body Composition , Body Mass Index , Dementia/pathology , Waist Circumference , Aged , Body Water , Dementia/etiology , Electric Impedance , Geriatric Assessment , Humans , Malnutrition/complications , Malnutrition/pathology , Nutrition Assessment , Reference Values , Serum Albumin/metabolismABSTRACT
OBJECTIVE: To determine if there exist differences in the nutritional status of patients with dementia according to the type and severity of the disease. METHOD: In this cross-sectional study we carried out an assessment of the nutritional status (anthropometrical assessment, Mini Nutritional Assessment, Chang's protocol) in 83 institutionalized elderly diagnosed with dementia at evolutionary states of 5, 6, and 7 of GDS (Global Deterioration Scale) and FAST (Functional Assessment Stating). The results were analyzed by the Chi-squared, ANOVA, or Kruskal-Wallis tests, the Scheffé's posteriori contrasts, and the linear trend test. Significance was considered at p < 0.05. RESULTS: The mean age of the patients was 81.22 years. The BMI revealed that 21% of the sample were at risk for malnourishment and 14.5% were malnourished. However, by using the MNA, 56.6% of the patients were at risk for malnourishment and 41% were malnourished. According to the Chang's method, the percentage of malnourished patients was increased to 75.9%. None of these variables showed an association with the type of dementia. A significant association was observed between the evolutionary state of dementia and the BMI (p = 0.004), MNA (p = 0.002 and p = 0.006 for the score and the category, respectively), the muscle circumference of the arm (p = 0.043) and the calf circumference (p = 0.043) but not with the percentage of fat mass nor the nutritional diagnosis established by the Chang's method (degree and type of MN). The linear trend test confirmed that both the MNA and BMI scores and the muscle circumference of the arm and the calf circumference were lower in the more severe dementia states. CONCLUSION: Irrespective of the type of dementia, the presence of malnourishment in institutionalized elderly increases in parallel to the evolutionary degree of the dementia.
