Evaluation of Appropriacy of Taking Water 2 Hour before Bioelectrical Impedance Analysis: Single-Frequency Bioelectrical Impedance Analysis Versus Multi-Frequency Bioelectrical Impedance Analysis

BACKGROUND: Bioelectrical impedance analysis (BIA) can be used to estimate body composition. To achieve the best results, the manufacturer's guidelines advise that individuals should restrict intake of food or caffeine, avoid vigorous exercise for 4 hours, and drink 2–4 glasses of water 2 hours before testing. We evaluated the appropriacy of drinking 2–4 glasses of water 2 hours before the BIA, as the validity of this indication has not been specifically demonstrated, by comparing intracellular water (ICW), extracellular water (ECW), total body water (TBW) in the fasting state, and after 1 and 2 hours of ingesting 500 mL of water.METHODS: Twenty-nine healthy adult men (n=10) and women (n=19) were recruited for the study. In the fasting state, the InBody 720 analyzer was used as multi-frequency (MF)-BIA and the output was recorded to determine the exact weight. Subsequently, Medinex BIA 450 analyzer was used as single-frequency (SF)-BIA, and the output was recorded. After drinking 500 mL of water 1 or 2 hours before assessment, the BIA tests were repeated as indicated above, and the ICW, ECW, TBW were compared by repeated measures ANOVA.RESULTS: SF-BIA measurements showed that compared to fasting state, the ICW decreased by approximately 0.56 L after 1 hour of drinking (P=0.001). The ECW was increased by about 0.62 L, 1 hour after drinking water compared to the fasting state (P=0.002). There were no significant differences between the results of BIA testing at 1 and 2 hours of fluid intake. The MF-BIA measurements indicated that testing after fasting, or 1 or 2 hours after fluid intake, did not result in significantly different ICW and ECW values. TBW showed no significant differences in the fasting state, or after 1 or 2 hours of fluid intake for both SF and MF.CONCLUSION: Several studies have shown that bioelectrical impedance should be measured in the fasting state. But not the food intake, drinking 500 mL of water may be permitted when measuring MF-BIA. However, for SF-BIA measurements, fluid intake resulted in an increase in the ECW level and a decrease in ICW.

Overhydration measured by bioimpedance analysis and the survival of patients on maintenance hemodialysis: a single-center study

BACKGROUND: Bioimpedance analysis (BIA) helps measuring the constituents of the body noninvasively. Prior studies suggest that BIA-guided fluid assessment helps to predict survival in dialysis patients. We aimed to evaluate the clinical usefulness of BIA for predicting the survival rate of hemodialysis patients in Korea. METHODS: We conducted a single-center retrospective study. All patients were diagnosed with end-stage renal disorder and started maintenance hemodialysis between June 2009 and April 2014. BIA was performed within the 1st week from the start of hemodialysis. The patients were classified into 2 groups based on volume status measured by the body composition monitor (BCM; Fresenius): an overhydrated group [OG; overhydration/extracellular water (OH/ECW) >15%] and a nonoverhydrated group (NOG; OH/ECW < or =15%). RESULTS: A total of 344 patients met the inclusion criteria. Of these, 252 patients (73.3%) were categorized into the OG and 92 patients (26.7%) into the NOG. Age- and sex-matching patients were selected with a rate of 2:1. Finally, 160 overhydrated patients and 80 nonoverhydrated patients were analyzed. Initial levels of hemoglobin and serum albumin were significantly lower in the OG. During follow-up, 43 patients from the OG and 7 patients from the NOG died (median follow-up duration, 24.0 months). The multivariate-adjusted all-cause mortality was significantly increased in the OG (odds ratio, 2.569; P = 0.033) and older patients (odds ratio, 1.072/y; P < 0.001). No significant difference of all-cause or disease-specific admission rate was observed between the 2 groups. CONCLUSION: The ratio of OH/ECW volume measured with body composition monitor is related to the overall survival of end-stage renal disorder patients who started maintenance hemodialysis.

RELATION BETWEEN BODY COMPOSITION AND PHYSICAL ATHLETIC PERFORMANCE OF LONG DISTANCE RELAY RUNNERS PRODUCED BY A FOUR WEEK WEIGHT LOSS PROGRAM / 体力科学

The purpose of this study was to examine the relation between body composition and athletic performance of long distance relay runners in a four week weight reduction program. Six male collegiate runners, aged 19.0 ± 0.9 years, participated in this study. Body water content and fat free mass (FFM) were measured by bioelectrical impedance spectroscopy.The weight loss by 4.1% of the initial body weight consisted of decreases in FFM and fat mass (54% and 46% respectively). Percentage of body fat did not change significantly by the end of the fourth week. The total body water (TBW) loss comprised of intracellular water (ICW) and extracellular water (ECW) at the end of the fourth week, and TBW loss and FFM loss were nearly the same values. Isokinetic muscular strength of right thigh, maximal oxygen intake (VO₂max) and total treadmill running time (maximal workout time) measured did not show any significant change. These results indicate (1) half of the weight loss consisted of decrease in FFM, (2) TBW loss was due to the reduction of ICW and ECW, (3) the content of FFM loss was considered to be body water, and (4) there was no impact on muscular strength of right thigh, VO₂max or maximal workout time.

RELATIONSHIP BETWEEN NUTRITIONAL STATUS AND FLUID DISTRIBUTION IN CONTINUOUS AMBULATORY PERITONEAL DIALYSIS PATIENTS / 营养学报

Objective: To investigate the relationship between nutritional status and body fluid distribution in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods: Sixty-six CAPD patients without edema were recruited in this study. Patients’ fluid status was measured by bioimpedance analysis (BIA) and nutritional status was assessed by subjective global assessment (SGA). Thirty-six age-matched healthy people served as controls. Results: As compared to the healthy control, CAPD patients had significant abnormal fluid distribution in the body with significantly decreased intracellular water (ICW) and little change in extracellular water (ECW). Malnutrition further aggregated the changes in body fluid distribution. Conclusion: Body fluid distribution is abnormal in CAPD patients and may be affected by patients’ nutritional status. The ratio of ICW/ECW can not be correctly used to evaluate hydration state when the patient is malnourished. Key word: intracellular water (ICW); extracellular water (ECW); bioimpedance analysis (BIA); malnutrition