The role of segmental bioelectrical impedance technique in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients.

OBJECTIVE: To investigate the role of segmental bioelectrical impedance technique (SBIA) in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients. METHOD: We selected the patients at the Department of Nephrology of the First Affiliated Hospital of Zhengzhou University and measured the segmental bioelectrical impedance by a German Fresenius body composition analyzer (the Fresenius whole body composition measurement (BCM) machine was used as a segmental machine in this study). An alternating current (5 kHz, 0.05-0.7 mA) was continuously released during the measurement. The released current penetrated the peritoneal cavity on both sides of the body, from which the segmental resistance at a frequency of 5 kHz was obtained from the multifrequency data (R5/Ω). Baseline BIA measurements were initiated after the patient entered the supine position for 5-10 min, then dialysate was instilled into the peritoneal cavity. BIA measurements were performed at 10-min intervals during the retention of dialysate in the abdomen and finally ended when dialysate drainage was complete. Real-time intraperitoneal volume estimated by SBIA (IPVSBIA)and ultrafiltration volume estimated by SBIA(UFVSBIA) was calculated. At the same time, the actual ultrafiltration volume at the end of peritoneal dialysis was weighed and measured (UFVMEA). RESULTS: A total of 30 patients were included in the study, 9 patients withdrew from the study due to subjective factors during the measurement process, and 21 patients completed the study. The correlation coefficient R2 of UFVSBIA and UFVMEA was 0.21 (p < 0.05). Bland-Altman analysis showed that the bias of UFVSBIA to the actual UFVMEA was 0.12 L, and the 95% agreement limit was between -0.5 L and 0.74 L, which confirmed that UFVSBIA measured by electrical impedance method and UFVMEA measured by weighing method were in good agreement. The time required to reach the maximum ultrafiltration volume (UFVSBIA) was 108 ± 68 min, and the mean value of the maximum ultrafiltration volume (Max UFVSBIA) was 1.16 ± 0.60 L. CONCLUSION: The segmental bioelectrical impedance technique can be used to assess the intraperitoneal ultrafiltration volume of peritoneal dialysis patients in real-time and effectively. This method may guide the dialysis fluid retention time and the maximum ultrafiltration volume in PD patients.

Comparison of bioimpedance equations and dual-energy X-ray for assessment of fat free mass in a Chinese dialysis population.

PURPOSE: Bioelectrical impedance analysis (BIA) is simple, noninvasive, inexpensive and frequently used for estimating fat free mass (FFM). The aims of this study were to evaluate the applicability of different BIA equations on FFM in Chinese subjects, and to compare the difference in hemodialysis and peritoneal dialysis patients with healthy controls respectively. METHODS: Dialysis patients and healthy adults were enrolled in this study, and the subjects were matched by age, gender, and the minimum sample size in each group was calculated using PASS. FFM estimated by BIA was calculated using equations of Kyle, Sun SS and Segal, and TBW/0.73. Dual-energy X-ray absorptiometry (DXA) method was set as reference method. Pearson's correlation and Bland-Altman analysis were used to test the validity of the BIA equations. RESULTS: 50 hemodialysis (HD) patients, 52 peritoneal dialysis (PD) patients and 30 healthy adults aged 22-67 y were included in this study. Age, height, weight, BMI and gender did not differ significantly among HD, PD patients, and healthy controls (p > 0.05), but BIA parameters were quite different (p＜0.01). Bland-Altman analysis showed that in healthy volunteers, all equations showed good agreement with DXA measured. For dialysis patients, the FFM predictions of different equations showed differences between HD and PD patients, and the equations seemed more applicable for HD patients. CONCLUSION: The equations developed by healthy subjects might be not appropriate for dialysis patients, especially peritoneal dialysis patients. It is recommended to develop a specific BIA equation from dialysis population.

The geriatric nutritional risk index may predict healthcare costs and health transitions during hemodialysis in China.

BACKGROUND AND OBJECTIVES: The aim of the present study was to retrospectively analyze the relationship between the Geriatric Nutritional Risk Index (GNRI) at baseline and healthcare costs of three-month as well as the risk of quality-of-life score at the 6-month follow-up for Chinese hemodialysis patients. METHODS AND STUDY DESIGN: One hundred patients who had been on maintenance hemodialysis were enrolled in this study. The general characteristics, laboratory test results and GNRI of the patients at baseline were recorded. The healthcare costs and quality-of-life scores were determined at the follow-up examination. RESULTS: Patients were divided into two groups according to their median GNRI at baseline: a lower GNRI group (GNRI <86.4) and a higher GNRI group (GNRI >86.4). The patients in the lower GNRI group exhibited reduced hemoglobin (74.7±13.1 g/dL vs 82.3±15.2 g/dL, p<0.05) and albumin (27.4±3.3 g/L vs 34.5±4.0 g/L, p<0.05) as well as reduced body weight (62.7±9.5 kg vs 68.0±9.2 kg, p<0.05) at baseline. The medication cost at follow-up was higher in the lower GNRI group (RMB 3,238±1,534 vs RMB 2,378±1,048, p<0.05). And a lower GNRI at baseline was associated with increased future medication costs and worse health in hemodialysis patients. CONCLUSIONS: The present study suggests that a lower GNRI in hemodialysis patients may be associated with an increased risk of higher future healthcare costs as well as worse health.

Assessment of extracellular fluid volume and fluid status in hemodialysis patients: current status and technical advances.

The assessment of extracellular fluid volume (ECV) and fluid status is both important and challenging in hemodialysis patients. Extracellular fluid is distributed in two major sub-compartments: interstitial fluid and plasma. A variety of methods are used to assess the ECV, with tracer dilution techniques considered gold standard. However, ECV defined as the distribution space of bromide, sodium, chloride, and ferrocyanide appears to be larger than the distribution volume of inulin and sucrose, suggesting a partial distribution into the intracellular volume. Relative blood volume monitoring, measurement of inferior vena cava diameter by ultrasound and biochemical markers are indirect methods, which do not reflect the ECV and fluid status accurately. Bioimpedance spectroscopy (BIS) techniques enable assessment of ECV and intracellular volume. Currently, BIS appears to be the most practical method for assessing ECV volume and fluid status in dialysis patients.