Influence of peritoneal dialysis solution on measurements of fluid status by bioimpedance spectroscopy

Purpose and methods

The accurate estimation of volume status is a central problem in dialysis patients. Recently, a bioimpedance spectroscopy (BIS) device (BCM Body Composition Monitor FMC, Germany) has attained growing interest in this regard. By processing the raw data for extracellular water (ECW) and intracellular water (ICW) by means of a validated body composition model, this device allows a quantification of the individual fluid overload (FO) compared to a representative healthy population. In this study, we addressed the issue whether the presence of peritoneal dialysate has an impact on measurements of FO by BIS in PD patients.

Results

Forty-two BIS measurements using the BCM device were performed both in the absence (D?) and presence (D+) of peritoneal dialysate in 17 stable PD patients. Data for ECW, ICW and FO (D+; D?) were analyzed by paired t test and linear regression. Mean FO was 0.99 ± 1.17 L in D? and 0.94 ± 1.27 in D+ (p = n.s. paired t test). Linear regression demonstrated an excellent degree of conformity between FO (D?) and FO (D+) (r ² = 0.93).

Conclusion

The presence of peritoneal fluid in PD patients has a negligible influence on measurements of FO by BIS. The BIS measurements can be therefore conveniently and reliably done without emptying the peritoneal cavity; this may facilitate the use of BIS in this particular group of patients.     

Fluid volumes determination by impedance spectroscopy and hematocrit monitoring: application to pediatric hemodialysis

A method for extracting fluid volumes from multifrequency bioimpedance, which takes into account the body geometry and the presence of nonconducting elements, was tested on 12 young dialyzed patients against correlations for total body water volumes (TBW) from Watson et al. and Humes et al. Our calculations of TBW from impedance were found to overestimate Humes' values by 0.25 L (0.8%) postdialysis and by 2.08 L (6.5%) predialysis. Extracellular water (ECW) was found to contribute an average of 93% of ultrafiltered volume. Intracellular water volume (ICW) determination from impedance was found to be too imprecise to predict its variation during dialysis; therefore, ICW variations were calculated as the difference between ultrafiltration and ECW changes. The continuous recording of hematocrit by an optical device monitored changes in plasma and interstitial volumes. In most cases, ultrafiltration was compensated mainly by a contribution from interstitial fluid, and the drop in plasma volume was generally moderate.     

Comparison between standard single chamber versus dual chamber low glucose degradation product peritoneal dialysis fluids

Dual chamber (DC) peritoneal dialysis (PD) dialysates contain fewer glucose degradation products (GDPs), so potentially reducing advanced glycosylation end products (AGEs), which have been reported to increase inflammation and cardiovascular risk. We wished to determine whether use of DC dialysates resulted in demonstrable patient benefits. Biochemical profiles, body composition, muscle strength, and skin autofluorescence measurements of tissue AGEs (SAF) were compared in patients using DC and standard single chamber dialysates. We studied 263 prevalent PD patients from 2 units, 62.4% male, mean age 61.8 ± 16.1 years, 78 (29.7%) used DC dialysates. DC patients were younger (55.9 ± 16.4 vs. 64.2 ± 15.4 years), and more had lower Davies comorbidity score (median 1 (0‐1) vs. 1 (0, 2)), slower peritoneal transport (D/P creatinine 0.67 ± 0.12 vs. 0.73 ± 0.13), greater extracellular water‐to‐total body water (ECW/TBW) ratio (0.46 ± 0.05 vs. 0.42 ± 0.06), all P < .001, whereas there were no differences in the duration of PD (median (IQR) 19 (8‐32) vs. 14 (8‐23) months), residual renal function (Kt/V_urea 0.71 ± 0.71 vs. 0.87 ± 0.82), urine volume (642 (175‐1200) vs. 648 (300‐1200) mL/day), hand grip strength (26.9 ± 10.5 vs. 24.9 ± 10.7 kg), C‐reactive protein (4(1‐10) vs. 4(2‐12) mg/L), and SAF (median 3.60 (3.02, 4.40) vs. 3.50 (3.00, 4.23)) AU. In our cross‐sectional observational study, we were not able to show a demonstrable advantage for using low GDP dialysates over conventional glucose dialysates, in terms of biochemical profiles, residual renal function, muscle strength, or tissue AGE deposition. More patients using low GDP dialysates were slower peritoneal transporters with higher ECW/TBW ratios.     

Leptin in peritoneal dialysate from continuous ambulatory peritoneal dialysis patients.

The adipocyte-derived hormone leptin is the 16-kd product of the ob gene that regulates food intake and body weight. Plasma leptin level is elevated in patients with chronic renal failure, partly because of impaired clearance through the kidney. In this study, we examined whether leptin is cleared into peritoneal dialysate in patients with end-stage renal disease treated by continuous ambulatory peritoneal dialysis (CAPD). The subjects were 46 CAPD patients and 67 age- and gender-matched healthy subjects. Leptin concentration in peritoneal dialysate from CAPD patients was measurable by a sensitive enzyme-linked immunosorbent assay (ELISA), and the daily loss of leptin by the peritoneal route was estimated to correspond to the amount contained in approximately 2 L plasma. Dialysate leptin concentration correlated positively with plasma leptin level and with percent body fat measured by dual-energy X-ray absorptiometry. The dialysate-to-plasma (D/P) ratio of leptin concentration was twice higher than expected from its molecular weight. D/P ratios of beta2-microglobulin, albumin, and transferrin showed strong correlations with each other (r = 0.768 to 0.801), whereas the correlation between D/P ratios of leptin and beta2-microglobulin was less impressive (r = 0.378). This was also the case with the relationship between apparent peritoneal clearances of these macromolecules, suggesting that dialysate leptin had some origins other than passive transport of plasma leptin. To test the hypothesis that abdominal visceral fat may contribute to the unexpectedly raised peritoneal dialysate leptin concentration, multiple regression analysis was performed. Leptin concentration in peritoneal dialysate showed significant association with plasma leptin level and D/P ratio of beta2-microglobulin, and it also showed an independent association with abdominal visceral fat but not with subcutaneous fat assessed by ultrasonography. These results showed that peritoneal dialysate from CAPD patients contained a significant amount of leptin, which derived presumably from both plasma and local visceral fat tissue.     

Dialysis and Patient Factors Which Determine Convective Volume Exchange in Patients Treated by Postdilution Online Hemodiafiltration

Recent reports suggest a survival advantage for dialysis patients treated by postdilutional online hemodiafiltration (OL‐HDF) who achieve higher volume convective exchanges. As such, the factors associated with achieving higher convective volume exchange were determined. The convective exchange volumes during the midweek OL‐HDF session in a cohort of 653 patients with corresponding bio‐impedance measurements of volume status and sessional electronic records were audited. Mean patient age was 64.9 ± 14.9 years, 65.3% male, 47.7% diabetes, with 81.6% dialyzing using fistula access. Sessional substitution volume exchanged was 17.0 ± 3.5 L (83.8 ± 13.9 mL/min), with a filtration fraction of 23.3 ± 4.6%, sessional time of 3.8 ± 0.5 h, and blood flow 321 ± 28 mL/min. As expected, convection exchange volume achieved was associated with sessional time (β 3.24, P < 0.001), blood flow (β 0.03, P < 0.001), dialysate flow (β 0.03, P < 0.001), but also patient factors: postsessional intracellular water (ICW) (β 0.07, P = 0.002), and serum albumin (β 0.71, P = 0.011). In addition convective exchange was lower for diabetics (16.6 ± 3.0 vs. 17.3 ± 3.8 L, P < 0.01), and for patients with higher Davies co‐morbidity grades ( 16.6 ± 2.8 vs. 17.0 ± 3.6 vs. 17.9 ± 4.0 L), P = 0.01 respectively. As expected the convective volume exchanged with OL‐HDF was associated with sessional time and blood and dialysate flows. However, the convective volume exchange achieved was also associated with patient factors, including ICW, which is related to body cell mass and also co‐morbidity. Although some center practices can be modified to increase convective exchange, patient factors are not so readily remediable. As such, highly comorbid patients may not be able to achieve the higher volume convective exchanges reported to be associated with improved patient survival.     

Effect of gradually lowering dialysate sodium concentration on the interdialytic weight gain,blood pressure,and extracellular water in anuric hemodialysis patients

Background: The majority of hemodialysis (HD) patients are overhydrated and have high interdialytic weight gain (IDWG) which induces increased blood pressure (BP). The positive sodium balance resulting from a high sodium diet, a high dialysate sodium concentration (DNa), or a combination of both is major causes of this disease. We evaluated the effects of lowering DNa on IDWG, BP, and volume status in anuric HD patients with dietary sodium restriction. Methods: Thirty-two patients were enrolled in this study and the period was divided by phase 1 and 2 according to DNa which decreased from 140 to 135 mEq/L at a rate of 1 mEq/L per month; phase 1, 140 mEq/L; phase 2, 135 mEq/L. We compared the IDWG, BP, volume status measured by multifrequency bioimpedance spectroscopy, and adverse events such as intradialytic hypotension, cramps, and headache of both phases. Results: The IDWG was significantly reduced by 0.39?±?0.38?kg (p?=?0.000). Pre-dialysis BP showed significant reduction (systolic pressure 146?±?18 vs. 138?±?22?mmHg; p?=?0.012, diastolic pressure 80?±?10 vs. 75?±?11?mmHg; p?=?0.008). Pre-dialysis extracellular water (ECW) was reduced significantly by 0.13?±?2.22 L (p?=?0.02). There was no significant increase in adverse events (all p?>?0.05). Conclusions: This study showed that gradually lowering DNa could bring a significant reduction in pre-dialysis IDWG, BP, and ECW without increased adverse events. Large and crossover designed study will be needed to demonstrate the clear causal relationship.     

Diameter of inferior caval vein and impedance analysis for assessment of hydration status in peritoneal dialysis

In 19 stable peritoneal dialysis (PD) patients, hydration status was evaluated by measurement of vena cava diameter (VCD) and bioelectrical impedance analysis (BIA) variables: intracellular water (ICW), extracellular water (ECW), and total body water (TBW). We investigated whether BIA can replace VCD. VCD did not correlate with TBW but correlated moderately with ECW/TBW (r = 0.42; 0.025 < p < 0.05) and ICW/ECW (r = -0.47; p < 0.025). Patients with underhydration (n = 4; VCD <8 mm/m2) revealed limits for BIA variables as ICW/ECW (>1.50) and ECW/TBW (<0.40). The same held true for overhydration (n = 5; VCD >11.5 mm/m2): ICW/ECW (<1.50) and ECW/TBW (>0.40). Although the positive predictive value of ICW/ECW and ECW/TBW for both under- and overhydration was only 50% and 54%, respectively, there were no false negative values. Although BIA cannot replace VCD in PD patients, the reverse holds true as well. Combining BIA and VCD may lead to a better estimation of hydration status because both techniques provide complementary information.     

Changes in body composition of children with chronic renal failure on growth hormone

Body composition is altered in children with chronic renal failure (CRF) and contributes to the significant growth failure seen in these children. Recombinant human growth hormone (rhGH) has been used in the past several years to improve the somatic growth of children with CRF. To determine if the growth achieved in these children occurs concomitantly with body compositional changes, seven prepubertal (n=6) and pubertal (n=1) children with chronic renal insufficiency (n=4) and end-stage renal disease (n=3) underwent measurements of total body fat (FM), fat free mass (FFM), bone mineral density (BMD), total bone mineral mass (TBBM), total body water (TBW), and total body potassium (TBK) before and 6 months after initiation of subcutaneous recombinant human growth hormone (rhGH) at 0.35 mg/kg per week. The techniques used included dual- energy X-ray absorptiometry (for measurement of FM, BMD, and TBBM), total body potassium counting (for measurement of TBK), and deuterated water for assessment of TBW. Significant increases in both height and weight were seen following 6 months of rhGH therapy. These increases were accompanied by significant re- ductions in FM (4.4±1.4 kg vs. 3.6±1.2 kg, P=0.002) and percentage fat (18.6±3.9% vs. 14.5±3.4%, P=0.04), while FFM (17.9±3.0 kg vs. 20.7±3.6 kg, P=0.04) increased significantly as did TBBM (776±171 g vs. 844±177 g, P=0.001). Increases in TBK, a measure of body cell mass, were also seen. No difference in total BMD was observed. Thus, growth in CRF is occurring with repletion of the FFM and TBBM compartments. Despite these improvements, no change was observed in the body mass index (BMI). Measurement of BMI alone does not define the compartmental catabolic losses in FFM. Received: 20 September 1999 / Revised: 31 January 2000 / Accepted: 8 February 2000     

Body Water Indices as Markers of Aging in Male Masters Swimmers

The association of age and weekly swim training distance with body water, lean tissue, fat mass and regional adiposity was examined in 27 male masters swimmers. Subjects ranged in age from 25.3 to 73.1 years (mean age = 47.7 ± 11.1 years). Weekly swim distances, estimated from self-reported swim logs, were from 3 400 to 17 500 m and averaged 10 016 ± 4 223 m. Total body water (TBW), and extracellular water (ECW) were predicted from multi-frequency bioelectrical impedance analysis and intracellular water was estimated by difference. Lean soft tissue, bone mineral content, fat mass, and percent body fat were estimated from dual-energy X-ray absorptiometry. Measures of skinfold thickness, waist circumference, and abdominal sagittal diameter provided an indication of regional adiposity. Total body water, ECW, and ICW mean values (ranges) were as follows: 47.4 ± 4.6 L (37.9-56.9 L), 19.6 ± 1.8 L., (16.4-24.8 L), and 27.8 ± 3.2 L (21.5-34.4 L). Mean percent body fat levels were 21.9 ± 6.6% and ranged from 10.3 to 34.9%. Age was negatively associated with ICW (p = 0.02) and with the ICW/TBW ratio (p = 0.00). Multiple-linear regression analysis backward method suggested that both lean tissue and fat mass were predictors of ICW although the association with fat mass did not reach statistical significance (p = 0.00 and p = 0.06 for lean and fat mass respectively). There was a tendency for greater lower abdominal thickness with increasing age (p = 0.08), but no other associations were observed between age or with swimming and body composition variables. Changes in ICW and the ration of ICW to TBW appeared to be the strongest marker of aging in this group of adult male competitive swimmers.

Key Points

• Subject age was negatively associated with the volume of intracellular water and with the intracellular-to-total body water ratio.
• There was a trend for age to be positively related to lower abdominal thickness.
• Weekly swim training distance was not associated with body water, lean tissue, fat mass or regional adiposity.
• Lean tissue mass appeared to be a strong positive predictor of total body water and the intra- and extracellular fractions.
• There was a trend for fat mass to be a negative predictor of intracellular water volume.

Key words: Total body water, intracellular water, exercise, body bomposition, dual-energy X-ray absorptiometry, bioelectrical impedance analysis     

Effects of icodextrin in automated peritoneal dialysis on blood pressure and bioelectrical impedance analysis.

BACKGROUND: Glucose absorption from glucose-based dialysis fluids limits ultrafiltration from the daytime dwell in automated peritoneal dialysis (APD). Icodextrin may allow greater ultrafiltration during the daytime period in APD, enhancing fluid control. METHODS: A 7.5% icodextrin dialysate was compared with a 2. 27% glucose dialysate for the daytime dwell in 14 subjects on APD. Blood pressure, weight and body water compartments estimated by multifrequency bioelectrical impedance (MFBIA) were determined in subjects using 2.27% glucose as the daytime dwell and then repeated 1 month after switching to icodextrin. RESULTS: Icodextrin resulted in symptomatic hypotension requiring reduction of antihypertensive medication in six of the 14 patients. Despite this reduction in treatment, systolic blood pressure fell from 142.4 (23.9) mmHg to 122.9 (17.7) mmHg, P<0.005, and diastolic blood pressure tended to fall from 82.8 (9.8) mmHg to 76.8 (10.1) mmHg, P=0.075. Change in systolic blood pressure significantly correlated with changes in weight (r=0.62, P<0.05) and MFBIA estimates of total body water (TBW) (r=0.56, P<0.05), extracellular water (ECW) (r=0.79, P<0.002), extra/intracellular water ratio (ECW/ICW) (r=0.72, P<0.01) and derived resistances R(ecf) of ECW (r=-0.69, P<0.01) and R(inf) of TBW (r=-0.66, P<0.02). Changes in diastolic blood pressure significantly correlated with changes in ECW (r=0.64, P<0.02) and ECW/ICW ratio (r=0.58, P<0.05), and almost significantly with R(ecf) (r=-0.51, P=0.08) and R(inf) (r=-0.52, P=0.07) estimated by MFBIA, but not with changes in weight or TBW. CONCLUSIONS: Use of icodextrin for the daytime dwell in APD results in improved fluid balance and blood pressure control compared with 2.27% glucose. MFBIA detected clinically important changes in fluid content in these patients.     

Nutritional aspects of body water dislocations in postoperative and depleted patients.

Measurements of plasma volume with 125I human serum albumin, extracellular water (ECW) with 82Br-minus, and total body water (TBW) with 3-H2O were made on 16 postoperative patients, 15 depleted patients, and three control subjects. Intracellular water (ICW) was calculated as the difference between TBW and ECW. The observed findings for the series as a whole showed no change in blood volume, an increase of 3.7 I in ECW, and a decrease of 1.5 I in ICW as compared to predicted values based on current weight. Compared to predicted values based on normal (pre-illness) weight, the observed body weight decreased 16% and ICW decreased 22%; this suggests that body weight consistently under-estimates the extent of nutritional depletion. Severe depletion seen in postoperative patients indicates that frequently earlier use of total parenteral nutrition would be beneficial. ICW was found to be the most reliable single index of moderate or severe nutritional depletion; errors in estimating normal values interfere with its use in mild depletion. The ratio of ECW:TBW best reflects distortion of body water composition; it is largely independent of weight, and is a more sensitive index than absolute values of ICW. Repeat measurements of body composition were made on 9 patients given total parenteral nutrition for an average period of 18 days. On the average, there was an ECW decrease of 1.8 I, a body weight increase of 2 kg, and an ICW increase of 3.2 I after parenteral nutrition. The increased ICW represents the repletion of half of the average initial deficit of 6.1 The initial ratio of ECW:TBW of 0.58 was reduced to 0.50, returning it about three-quarters of the way to the expected normal value of 0.48. Intravenous administration of 5% glucose as sole source of calories may be a factor in distortion of body water compartments.     

Comparison between serum free triiodothyronine levels and body fluid distribution in hemodialysis patients

Aim

Low free triiodothyronine (fT3) has been associated with the presence of malnutrition?Cinflammation syndrome in patients with end-stage renal disease (ESRD) and decreased overall survival in ESRD. Since thyroid hormone has a particular effect on body fluid status, we hypothesized that hemodialysis patients with low-T3 syndrome might have interstitial edema. In this study, we examined the relationship between levels of thyroid hormone and body composition parameters in Japanese hemodialysis patients.

Methods

The subjects were 52 patients on maintenance hemodialysis. Serum levels of thyroid hormone and atrial natriuretic peptide (hANP) were measured. Body composition parameters were measured using a bioimpedance body composition analyzer.

Results

Serum fT3 had positive correlations with body mass index (BMI), body fat mass (BFM), total body water (TBW) and intracellular water (ICW), and negative correlations with the ratio of extracellular water to total body water (ECW/TBW) and hANP. There were no correlations between serum fT4 and any body composition parameter. The 49 patients with data at baseline and after 1?year were divided into groups with increased (n?=?33) and decreased (n?=?16) fT3 after 1?year. ??BMI and ??BFM were significantly lower and ??TBW, ??ICW, ??ECW and ??ECW/TBW (changes over 1?year from baseline) were significantly higher in patients with decreased fT3 compared to those with increased fT3. There was no significant difference in ??hANP or ??cardiothoracic ratio between the two groups.

Conclusion

These results show that a decrease in fT3 might be associated with emaciation and interstitial edema in Japanese hemodialysis patients.     

Agreement Between 2 Segmental Bioimpedance Devices,BOD POD,and DXA in Obese Adults

This study examined the agreement between 2 segmental bioimpedance analysis (BIA) devices, air displacement plethysmography (BOD POD), and dual energy X-ray absorptiometry (DXA) for estimating body composition in obese adults. Fifty obese adults (25 men and 25 women; age = 34.20 ± 11.19 years; BMI = 36.14 ± 5.33 kg/m²) had their body fat percentage (BF%) and fat-free mass (FFM) evaluated with 2 segmental BIA devices (InBody 230 and InBody 720), BOD POD, and DXA (Lunar iDXA). Body composition via the BOD POD was determined using the Siri equation whereas manufacturer-based equations generated metrics (ie, BF% and FFM) for the InBody devices. The effect size of the mean differences for all BF% and FFM comparisons were trivial (Cohen's d < 0.20). The standard error of estimate (SEE), total error (TE), and 95% limits of agreement (LOAs) were low for both segmental BIA devices when compared to DXA (SEE < 2.26% and 2.35 kg; TE < 2.58% and 2.66 kg; 95% LOAs < ± 4.94% and 4.86kg). The error for BOD POD was also low when compared to DXA (SEE = 2.39% and 2.57 kg; TE = 2.34% and 2.56 kg; 95% LOAs = 4.63% and 5.06 kg). Validity statistics were slightly higher, but considered acceptable, when comparing the segmental BIA devices against BOD POD (SEE < 3.37% and 3.63 kg; TE < 3.44% and 3.79 kg; 95% LOAs < ± 6.62% and 7.19 kg). Lastly, the 2 segmental BIA devices produced nearly identical validity statistics when compared to each other. However, both BIA devices revealed proportional bias for BF% and FFM when compared to the BOD POD and DXA (all p < 0.05). The current study's findings indicate the InBody 230 is interchangeable with the InBody 720 in obese adults. Also, the trivial effect size, when compared against the BOD POD and DXA, suggest the InBody devices could be used for estimating group BF% and FFM. In contrast, the significant proportional bias demonstrates the BIA devices are not acceptable for individual estimates of body composition in an obese clinical population.     

Daily Dietary Energy and Macronutrient Intake and Anthropometric Measurements of the Peritoneal Dialysis Patients

Introduction: This study was planned to investigate the relation between dietary macronutrient status and anthropometric measurements in peritoneal dialysis (PD) patients. Materials and methods: A total of 28 clinically stable patients were enrolled in this study. All patients were taken a dietary therapy according to the guidelines of the American Journal of Kidney Foundation for 12 weeks. The anthropometric measurements were taken by bioelectrical impedance analyzer. The daily macronutrient intakes of the patients were calculated by the food consumption records. Results: The mean age was 48.3 ± 13.10 years [56.3 ± 7.41 years for males (n = 14) and 40.3 ± 12.84 years for females (n = 14)]. There were significant changes in fat percentage (%), total body water (TBW; %, L), extracellular water (ECW; %, L), basal metabolic rate over body weight (BMR/BW), and body fat mass index (BMFI) in males (p < 0.05), but there was no change in females (p > 0.05). The daily dietary energy and protein intakes were under the recommended level in the study period. Conclusion: Patients undergoing PD frequently have low intakes of protein and energy. It is recommended that individuals undergoing PD periodically maintain 3-day dietary records followed by dietary interviews conducted by a dietitian.     

Salt and Fluid Intake in the Development of Hypertension in Peritoneal Dialysis Patients

Background. Although fluid overload contributes to hypertension in CAPD patients, less attention has been paid to the role of excess salt and fluid intake. Therefore, we investigated the role of salt and fluid intake in the development of hypertension in CAPD patients. Methods. A total of 165 stable CAPD patients were included into this study. Based on the blood pressure in three consecutive months, they were divided into three groups: persistent hypertensive (PH; n = 33), intercurrent hypertensive (IH; n = 58) and persistent normotensive (PN; n = 74). The IH group was further divided into two phases: normotensive and hypertensive. Fluid status was evaluated by clinical assessment and bioimpedance analysis (BIA). Results. There were no differences in age, gender, and duration of dialysis among groups. Patients were more fluid overloaded in the PH group. Extracellular water (ECW), total body water (TBW), and normalized extracellular water by height (NECW) were higher in the PH group than the PN group (16.77 ± 3.62 L vs. 14.61 ± 2.92 L for ECW, p < 0.01; 32.22 ± 8.23 L vs. 28.98 ± 6.00 L for TBW, p < 0.05; and 10.28 ± 1.86 L/m vs. 9.08 ± 1.63L/m for NECW, p < 0.01). However, patients in the PH group also had more total fluid removal (TFR) and total sodium removal (TSR) compared with the PN group (1346.82 ± 431.27 mL/d vs. 1139.28 ± 412.65 mL/d for TFR, p < 0.05; and 141.52 ± 61.57 mmol/d vs. 102.42 ± 62.51 mmol/d for TSR, p < 0.01). The same trend was demonstrated when compared values of hypertensive and normotensive phase in IH group; patients had higher ECW, TBW, NECW, TSR, and PNa when they were in hypertensive phase than in the normotensive phase. Conclusions. This study confirmed that fluid overload was closely associated with the development of hypertension in CAPD patients. It also showed that hypertensive patients were in general more fluid overloaded despite a higher fluid and sodium removal as compared with normotensive patients.     

Effect of Two‐Year Caloric Restriction on Bone Metabolism and Bone Mineral Density in Non‐Obese Younger Adults: A Randomized Clinical Trial

Although caloric restriction (CR) could delay biologic aging in humans, it is unclear if this would occur at the cost of significant bone loss. We evaluated the effect of prolonged CR on bone metabolism and bone mineral density (BMD) in healthy younger adults. Two‐hundred eighteen non‐obese (body mass index [BMI] 25.1 ± 1.7 kg/m²), younger (age 37.9 ± 7.2 years) adults were randomly assigned to 25% CR (CR group, n = 143) or ad libitum (AL group, n = 75) for 2 years. Main outcomes were BMD and markers of bone turnover. Other outcomes included body composition, bone‐active hormones, nutrient intake, and physical activity. Body weight (–7.5 ± 0.4 versus 0.1 ± 0.5 kg), fat mass (–5.3 ± 0.3 versus 0.4 ± 0.4 kg), and fat‐free mass (–2.2 ± 0.2 versus –0.2 ± 0.2 kg) decreased in the CR group compared with AL (all between group p < 0.001). Compared with AL, the CR group had greater changes in BMD at 24 months: lumbar spine (–0.013 ± 0.003 versus 0.007 ± 0.004 g/cm²; p < 0.001), total hip (–0.017 ± 0.002 versus 0.001 ± 0.003 g/cm²; p < 0.001), and femoral neck (–0.015 ± 0.003 versus –0.005 ± 0.004 g/cm²; p = 0.03). Changes in bone markers were greater at 12 months for C‐telopeptide (0.098 ± 0.012 versus 0.025 ± 0.015 μg/L; p < 0.001), tartrate‐resistant acid phosphatase (0.4 ± 0.1 versus 0.2 ± 0.1 U/L; p = 0.004), and bone‐specific alkaline phosphatase (BSAP) (–1.4 ± 0.4 versus –0.3 ± 0.5 U/L; p = 0.047) but not procollagen type 1 N‐propeptide; at 24 months, only BSAP differed between groups (–1.5 ± 0.4 versus 0.9 ± 0.6 U/L; p = 0.001). The CR group had larger increases in 25‐hydroxyvitamin D, cortisol, and adiponectin and decreases in leptin and insulin compared with AL. However, parathyroid hormone and IGF‐1 levels did not differ between groups. The CR group also had lower levels of physical activity. Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ～31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span. Further long‐term studies are needed to determine if CR‐induced bone loss in healthy adults contributes to fracture risk and if bone loss can be prevented with exercise. © 2015 American Society for Bone and Mineral Research.     

Exploration of Fluid Dynamics in Perioperative Patients Using Bioimpedance Analysis

Introduction

Perioperative fluid restriction is advocated to reduce complications after major surgeries. Current methods of monitoring body fluids rely on indirect volume markers that may at times be inadequate. In our study, bioimpedance analysis (BIA) was used to explore fluid dynamics, in terms of intercompartmental shift, of perioperative patients undergoing operation for hepato-pancreato-biliary (HPB) diseases.

Methods

A retrospective review was conducted, examining 36 patients surgically treated for HPB diseases between March 2010 and August 2012. Body fluid compartments were estimated via BIA at baseline (1 day prior to surgery), immediately after surgery, and on postoperative day 1, recording fluid balance during and after procedures. Patients were stratified by net fluid status as balanced (≤500 mL) or imbalanced (>550 mL) and outcomes of BIA compared.

Results

Mean net fluid balance volumes in balanced (n?=?16) and imbalanced (n?=?20) patient subsets were 231.41?±?155.44 and 1050.18?±?548.77 mL, respectively. Total body water (TBW) (p?=?0.091), extracellular water (ECW) (p?=?0.125), ECW/TBW (p?=?0.740), and intracellular water (ICW) (p?=?0.173) did not fluctuate significantly in fluid-balanced patients. Although TBW (p?=?0.069) in fluid-imbalanced patients did not change significantly (relative to baseline), ECW (p?=?0.001), ECW/TBW (p?=?0.019), and ICW (p?=?0.012) showed significant postoperative increases.

Conclusion

The exploration of fluid dynamics using BIA has shown importance of balanced fluid management during perioperative period. Increased ECW/TBW in fluid-imbalanced patients suggests possible causality for the development of ascites or fluid collections during postoperative period in patients undergoing HPB operations.

     

Does a reduction in dialysate sodium improve blood pressure control in haemodialysis patients?

Introduction: There has been debate as to the value of lower sodium dialysates to control blood pressure in haemodialysis patients, as sodium is predominantly removed by ultrafiltration. Methods: Re‐audit of clinical practice following reduction in dialysate sodium concentration. Results: Overall dialysate sodium concentration decreased from 138.9 ± 1.7 to 137.8 ± 1.7 mmol/L (mean ± standard deviation), resulting in a reduction in pre‐ and post‐dialysis mean arterial pressure (MAP) of 4 mmHg (from 100.6 ± 15.6 to 97.1 ± 15.6, P < 0.01 and from 91.7 ± 15.6 to 87.1 ± 14.6, P < 0.001 respectively), yet fewer patients were prescribed antihypertensives (49.6 vs 60.6%), and less antihypertensive medications/patient (mean 0.86 vs 1.05), ultrafiltration requirements (2.8% vs 3.2% body weight, P < 0.001), and symptomatic intradialytic hypotension (0.19 vs 0.28 episodes per week, P < 0.001). A multivariable model showed that for a dialysate sodium of 136 mmol/L, younger patients had higher MAP than older patients (0.35 mmHg lower MAP/year older; but with a dialysate sodium of 140 mmol/L, there was minimal association of MAP with age (0.07 mmHg higher MAP/year older). Conclusion: Change in clinical practice, amounting to a modest reduction in dialysate sodium was associated with a reduction not only in pre‐ and post‐dialysis blood pressures, but also ultrafiltration requirements and symptomatic intradialytic hypotension. However, this effect on blood pressure was most marked for older patients and women, within minimal effects for younger patients, and lesser effects for men, suggesting that dialysate sodium reduction alone may help improve blood pressure control, but requires additional factors such as dietary sodium restriction to be effective in younger male patients.     

Bioimpedance analysis and intradialytic hypotension in intermittent hemodialysis

BACKGROUND: Intradialytic hypotension (IDH) is one of the most severe complications during hemodialysis. Its appearance is caused in part by rapid fluid removal with concomitant failure in blood pressure regulation but also by other dialytic-dependent and independent factors. PATIENTS AND METHODS: We investigated total (TBW), extracellular (ECW) and intracellular water (ICW) in chronic intermittent hemodialysis dialysis hypotension-prone (CRF-HP, n = 11) and nonhypotension-prone (CRF-NHP, n = 10) patients with end-stage renal disease before, every 30 minutes during, as well as after dialysis and within onset of intradialytic hypotension by multifrequent bioimpedance analysis (BIA). Additionally, intradialytic time course of BIA in patients with acute renal failure (ARF) and septic shock (n = 10) was observed. RESULTS: IDH occurred in 72.1% of CRF-HP and in 80% of ARF patients. In CRF-HP and CRF-NHP, ECW significantly decreased by -12.44 +/- 4.22% in CRF-HP and -9.0 +/- 6.2% in CRF-NHP comparing pre- and post-dialysis values (each p < 0.01). Conversely, ICW increased by +11.5 +/- 11.3% in CRF-HP and +18.4 +/- 25.2% in CRF-NHP (each p < 0.05). In patients with ARF no significant changes could be detected. Calculated ECW/ICW and ECW/TBW ratio significantly decreased in CRF patients with a higher rate in CRF-HP patients (p < 0.05). Neither ECW/ICW nor ECW/TBW ratio correlated with mean arterial pressure. The onset of intradialytic hypotension (n = 35) did not differ intraindividually compared to normotensive periods (n = 411). Fluid removal in CRF patients seems to be mainly from the extracellular space. The reduced decreases in ECW/ICW and ECW/TBW ratios in CRF-HP compared to CRF-NHP may indicate an insufficient refilling from intra- to extracellular compartment in CRF-HP. CONCLUSION: In conclusion, multifrequent BIA is not capable to predict hypotension in the individual patient during a particular dialysis session.     

Effect of Dialysate Sodium Reduction on Body Water Volume,Blood Pressure,and Inflammatory Markers in Hemodialysis Patients — A Prospective Randomized Controlled Study

Accumulating evidence suggests an association between body volume overload and inflammation in chronic kidney diseases. The purpose of this study was to evaluate the effect of dialysate sodium concentration reduction on extracellular water volume, blood pressure (BP), and inflammatory state in hemodialysis (HD) patients. In this prospective controlled study, adult patients on HD for at least 90 days and those with C-reactive protein (CRP) levels ≥ 0.7 mg/dL were randomly allocated into two groups: group A, which included 29 patients treated with reduction of dialysate sodium concentration from 138 to 135 mEq/L; and group B, which included 23 HD patients not receiving dialysate sodium reduction (controls). Of these, 20 patients in group A and 18 in group B completed the protocol study. Inflammatory, biochemical, hematological, and nutritional markers were assessed at baseline and after 8 and 16 weeks. Baseline characteristics were not significantly different between the two groups. Group A showed a significant reduction in serum concentrations of tumor necrosis factor-α, and interleukin-6 over the study period, while the BP and extracellular water (ECW) did not change. In Group B, there were no changes in serum concentrations of inflammatory markers, BP, and ECW. Dialysate sodium reduction is associated with attenuation of the inflammatory state, without changes in the BP and ECW, suggesting inhibition of a salt-induced inflammatory response.