Extracellular fluid and total body water changes in neonates undergoing extracorporeal membrane oxygenation.

After being placed on extracorporeal life support (ECLS), newborn patients typically weight 5% to 30% more than their birthweight. Recovery and eventual decannulation from ECLS is associated with a return to baseline weight or birthweight values after a pronounced diuresis. It has been assumed that the increases in weight in these patients are due to increases in extracellular fluid (ECF) and total body water (TBW). This study was undertaken to prove or disprove this hypothesis. ECF space was measured using the compound sodium bromide and TBW was determined with the use of deuterium oxide (nonradioactive heavy water). Fluid compartment measurements were made prior to the institution of ECLS, immediately after placement on bypass, approximately every other day while on bypass, and a final measurement was made once the patient was off bypass. Sodium bromide concentration was analyzed by high-pressure liquid chromatography, and deuterium oxide concentration was measured by the falling drop method. Eight newborns with respiratory failure were placed on either venoarterial (4 patients) or venovenous (4 patients) ECLS for an average of 106 hours (range, 71 to 219 hours). Pre-ECLS TBW was high in the neonates (87% of total body weight v the normal of 75% to 80%). Mean values for each fluid compartment were corrected for the additional volume of the bypass circuit when the patient was on bypass. ECF increased immediately after the institution of ECLS; however, both ECF and TBW decreased during the bypass run, and post-ECLS levels of ECF and TBW were similar to those found prior to ECLS.(ABSTRACT TRUNCATED AT 250 WORDS)     

Different pattern of fluid loss from the lower extremities in normohydrated and overhydrated stage 5 chronic-kidney-disease patients after haemodialysis

Aim: It is unclear whether fluid is lost from each body segment in a similar manner during haemodialysis (HD) in normohydrated (NH) and overhydrated (OH) patients. Methods: The authors measured changes in regional‐body fluid compartments using segmental multifrequency bioelectrical impedance analysis before and after HD in 26 stage 5 chronic‐kidney‐disease patients. Patients were divided into NH and OH groups. Correlation between ultrafiltration (UF) amount and per cent changes in extracellular fluid (ECF)/total body water (TBW) ratios measured in five body segments were analysed in NH and OH groups. Results: No differences were found between the two groups with respect to per cent decreases in body weight, TBW, or intracellular fluid levels. Correlation coefficients between UF amounts and per cent decreases in TBW, intracellular fluid and ECF were higher in the NH group than in the OH group. UF amounts were found to be correlated with per cent ECF/TBW decreases in all body segments in the NH group but, to be only correlated with per cent decreases in ECF/TBW_{Left arm} and ECF/TBW_Trunk in the OH group. Positive correlations were found between UF amounts and per cent ECF/TBW_{Right leg} decreases (r = 0.66, P = 0.01), regardless of age in the NH group only. Conclusion: NH and OH patients show different patterns of fluid loss from regional‐body fluid compartments. This may be useful for determining patient hydration status.     

Perioperative monitoring of total body water by bio-electrical impedance in children undergoing open heart surgery

Knowledge of the changes in total body water (TBW) following cardiac surgery (OHS) in children would be of value in fluid therapy and in researching the causes and management of capillary leak. We have validated a bioelectrical impedance technique (BEI) for non-invasive estimation of TBW in children after OHS. We report the use of this method in a longitudinal study. Twenty patients (mean age 4.7 years +/- 3.5 (SD), mean weight (WT) 16.2 kg +/- 1 kg) undergoing a variety of complex OHS procedures were studied from 1 day preoperatively to 4 days postoperatively. Anaesthetic and basic bypass (CPB) techniques were uniform. Six patients underwent CPB at less than 20 degrees C, 10 at 20 degrees - 25 degrees C and 4 at 26 degrees - 33 degrees C. TBW (BEI), core (ctemp) and peripheral (ptemp) temperatures and fluid balance (TFB) were recorded at frequent intervals. TBW (by BEI) rose (P less than 0.001) following CPB in all patients from 62% +/- 9% (SD) body weight preoperatively to 73% +/- 13% in the ICU (an increase of 11% +/- 5%). TBW remained significantly elevated until the 3rd postoperative day. Multivariate analysis (MVA) confirmed that TBW was significantly related to TFB, but not to ctemp or ptemp. MVA also revealed smaller patient size (height and weight), younger age and longer CPB time as incremental risk factors for the rise in TBW. Conclusions: (1) BEI permits the non-invasive study of TBW in children after OHS, when TBW variation may be considerable. (2) The smaller the child and the longer the CPB, the greater the rise in TBW. (3) The technique should be a valuable tool in researching the major water fluxes associated with CPB in children.     

Body fluid compartments

The terms mole, molality, molarity, osmole, osmolality, osmolarity, osmolar gap and anion gap are defined and their clinical usefulness indicated. The following body fluid compartments are described: total body water (TBW), extracellular fluid (ECF), intracellular fluid (ICF), transcellular fluid TCF), plasma volume, red cell volume and interstitial fluid volume. Isotope-dilution techniques are briefly discussed and representative normal values for the various compartments according to sex and age are indicated. The physiological mechanisms that maintain the distinctive ionic compositions of the various fluid spaces are briefly outlined. New concepts of the function of the gel matrix and of the lymph drainage of the interstitium are presented. Opposing models to the sodium-potassium membrane pump are briefly described.     

Comparison of body fluid distribution between chronic haemodialysis and peritoneal dialysis patients as assessed by biophysical and biochemical methods.

BACKGROUND: The control of extracellular volume is a key parameter for reducing hypertension and the incidence of cardiovascular mortality in dialysis patients. In recent years bioimpedance measurement (BIA) has been proven as a non-invasive and accurate method for measuring intracellular and extracellular fluid spaces in man. In addition, plasma atrial natriuretic peptide (ANP) and cyclic guanosine monophosphatase (cGMP) concentrations have been shown to reflect central venous filling. Using these methods, we compared body fluid status between stable patients on haemodialysis and peritoneal dialysis. METHODS: Thirty-nine chronic haemodialysis patients, 43 chronic peritoneal dialysis patients and 22 healthy controls were included in the study. Multifrequency BIA was performed using the Xitron BIS4000B device (frequencies from 5 to 500 kHz were scanned and fitted) in patients before and after haemodialysis. Peritoneal dialysis patients were measured after drainage of the dialysate. Plasma ANP and cGMP levels were measured in plasma using a (125)I solid phase RIA. Serum albumin concentrations and serum osmolality were measured in all patients. The body fluid data were analysed in relation with the clinical findings. RESULTS: Total body water (TBW) was 0.471+/-0.066 l/kg before haemodialysis and 0.466+/-0.054 l/kg after haemodialysis. Peritoneal dialysis patients had a TBW (0.498+/-0.063 l/kg) that was greater than the before and after dialysis values of haemodialysis patients. The extracellular body fluid (V(ecf)) was increased pre-haemodialysis. It was even greater in peritoneal dialysis patients compared with patients both pre- and post-haemodialysis (pre 0.276+/-0.037 l/kg; post 0.254+/-0.034 l/kg; peritoneal dialysis 0.293+/-0.042 l/kg, P<0.05). However, plasma ANP concentrations (representing intravascular filling) in peritoneal dialysis patients were comparable with post-haemodialysis values (284+/-191 pg/ml vs 286+/-144 pg/ml). The correlation coefficient between sysRR and V(ecf) was r=0.257 in haemodialysis (P=0.057) and r=0.258 in peritoneal dialysis (P<0.05). A significant negative correlation was found between serum albumin and V(ecf)/TBW in peritoneal dialysis patients (r= -0.624). CONCLUSION: Body fluid analysis by BIA demonstrated that TBW and V(ecf) were increased in peritoneal dialysis patients, and were comparable or even greater than values found before haemodialysis. However, plasma ANP levels indicated that intravascular filling was not increased in peritoneal dialysis. The ratio of V(ecf) to TBW was correlated to systolic pressure and negatively to serum albumin in peritoneal dialysis patients.     

Body fluid compartment changes following neonatal surgery

The neonate is born with an excess of total body water (TBW) in the range of 75% to 85% of body weight (v 60% in the adult), which is due to a large extracellular fluid volume (ECF) of 40% to 50% of body weight (v 20% in the adult). In an attempt to define the changes that occur in TBW and ECF following neonatal surgery, the following prospective study was carried out. Twenty newborns with major congenital anomalies (gastroschisis, 10; esophageal atresia, 4; ileal atresia, 3; omphalocele, 2; and malrotation, 1) were studied weekly for 4 weeks following surgery while being maintained on a standard protocol of total parenteral nutrition (TPN). Total body water was measured using deuterium oxide, and extracellular fluid volume was assayed with sodium bromide; both were expressed as percent body weight (BW). Weight gain or maintenance was observed in all infants. TBW remained unchanged (from 85.4% to 83.0%), and ECF decreased from 51.2% to 36.7% during the observation period. The TBW in the ten gastroschisis infants decreased from 87.3% to 78.0% v the ten other newborns, in whom there was no change (84.0% to 85.0%). The ECF changes were more dramatic, decreasing from 51.6% to 32.3% in the gastroschisis infants, v 50.8% to 45.5% in the other neonates (P = .0156). There were no differences between the two groups in the intake and output of fluids. The following conclusions were drawn: (1) Following major surgery, newborns show a steady decrease in ECF and minimal change in TBW in spite of adequate weight gain while receiving TPN.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of extracellular fluid in cardiac surgery using cardiopulmonary bypass

Extracellular fluid (ECF) was assessed before and after the cardiac surgery using cardiopulmonary bypass (CPB), by means of a bioimpedance spectrum analyzer to see volumes of the fluid based on changes of the impedance to various frequencies. Difference between the levels before and after the operation was divided by body weight to study about a % BW. Simultaneously its relation to the lung compliance [tidal volume/(peak inspiratory pressure-end expiratory pressure)] was studied. Mean age of the 18 patients was 59.1 +/- 19 years old. ECF was assessed before to 24 hours after the operation continuously and once more after 48 hours. Mean CPB time was 165 +/- 52 minutes, and aortic cross clamp time was 121 +/- 4 minutes. A remarkable increase of ECF was noted immediately after the operation, which further increased gradually till arriving at the peak 4 hours after the operation (4.52 +/- 1.8% BW). Then it gradually decreased to 0.641 +/- 2.7% BW 48 hours later. Lung compliance measured at the same time showed the lowest level 6 hours after the operation. It was known that the bioimpedance spectrum analysis is a simple and non-invasive method, which enables to monitor the vital stable before and after the operation.     

Low arterial pressure during cardiopulmonary bypass in piglets does not decrease fluid leakage

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with increased fluid filtration occasionally leading to post-operative organ dysfunction. One of the factors determining fluid filtration is the capillary hydrostatic pressure which depends on arterial pressure, venous pressure and pre- to post-capillary resistance ratio. The purpose of this study was to assess whether lowering of the mean arterial pressure and/or the central venous pressure could reduce fluid extravasation during normothermic and hypothermic CPB. METHODS: Seven piglets were given nitroprusside to a mean arterial pressure of 35-40 mmHg during 60 min of normothermic and 90 min of hypothermic CPB (LP group). They were compared with a control group (C group, n = 7) without blood pressure interventions. Blood chemistry, net fluid balance, plasma volume, colloid osmotic pressure in plasma and interstitial fluid, intravascular protein masses, fluid extravasation rate and total tissue water content were measured or calculated. RESULTS: Mean arterial pressure was significantly lower in the LP group than in the C group during CPB. Plasma volume tended to increase in the LP group (P > 0.05), but remained essentially unchanged in the C group. Net fluid balance in the LP group was more positive than in the C group 30 min after CPB start [1.02 (0.15) vs. 0.56 (0.13) ml/kg/min (Mean (SEM) P < 0.05)]. Fluid extravasation rate tended to be higher in the LP group and total tissue water content of the gastrointestinal tract, left myocardium and skin was significantly elevated compared with the C group. CONCLUSION: During CPB, lowering of the mean arterial pressure using nitroprusside did not reduce fluid extravasation. On the contrary, the data may implicate an increase in edema formation during low pressure CPB.     

Serial changes in body composition in patients with chronic renal failure on peritoneal dialysis]

Nutritional status is one of the most important factors affecting mortality and morbidity in chronic dialysis patients. There are, however, few data on serial body composition changes in these patients. To investigate serial changes in body composition in patients on peritoneal dialysis, we measured intracellular fluid volume(ICF), extracellular fluid volume(ECF), body protein volume(BPV), body fat volume(BFV) and bone mineral content(BMC) using multifrequency bioelectrical impedance analysis (MF-BIA). MF-BIA was performed in 35 patients, consisting of 21 men and 14 women with a mean age of 51.3 +/- 10.9 years, before and after one year of observation. At the baseline in male patients, ICF was 37.0 +/- 3.4%, ECF 19.7 +/- 1.6%, BPV 20.7 +/- 1.7%, BFV 18.1 +/- 6.6% and BMC 4.5 +/- 0.4% of body weight, and in female patients ICF was 34.4 +/- 2.6%, ECF 17.8 +/- 1.9% BPV 19.0 +/- 1.6%, BFV 24.4 +/- 6.2% and BMC 4.5 +/- 0.4% of body weight. In the group of patients whose body weight increased more than 3 kilograms(n = 9), the increase rate of BFV was 32.3 +/- 20.2%, significantly higher than that of the other segments(p < 0.001). On the other hand, in the group of patients whose body weight decreased more than 3 kilograms(n = 5), each segment showed the same extent of decrease and there was no significant difference in the decrease rates among each segment. In the group of patients whose body weight was stable(n = 21), changes in each body composition segment were extremely small. It could be concluded that the body weight increase is due mainly to increase in BFV and body weight decrease results from a concurrent decrease in each body composition segment in peritoneal dialysis patients.     

Retrograde autologous priming: is it useful in elective on-pump coronary artery bypass surgery?

BACKGROUND: The effect of reduced cardiopulmonary bypass (CPB) prime volume by retrograde autologous priming (RAP) was studied. METHODS: Twenty patients undergoing elective coronary artery bypass grafting were randomized to either standard prime (SP) volume (1,602 +/- 202 mL crystalloid prime, n = 10) or RAP (395 +/- 150 mL). RAP was performed by draining crystalloid prime from the arterial and venous lines into a recirculation bag before CPB. Cardiac index, pulmonary vascular resistance index, systemic vascular resistance index, alveolar-arterial oxygen tension difference, pulmonary shunt fraction, extravascular lung water (EVLW), plasma colloid osmotic pressure (COP), crystalloid fluid balance, body weight, and clinical parameters were evaluated perioperatively. RESULTS: Demographic data and operative parameters were equal for patients in both groups. During CPB, COP was reduced by 55% in the SP group (9.8 +/- 2.0 vs 21.4 +/- 2.1 mm Hg) and by 41% in the RAP group (12.4 +/- 1.1 vs 20.9 +/- 1.8 mm Hg) (p = 0.008, SP vs RAP group). Compared with preoperatively, EVLW was unchanged in the RAP group 2 hours post-CPB, but it was elevated by 21% in the SP group (p = 0.002, SP vs RAP group). End-CPB crystalloid fluid balance was significantly reduced in the RAP group (1,857 +/- 521 vs 2,831 +/- 637 mL). Postoperative (day 2) weight gain in the SP group (1.5 +/- 1.2 kg, p = 0.021) was absent in the RAP group (0.1 +/- 0.9, NS). Postoperative time to full mobilization was shorter in the RAP group. Postpump cardio-respiratory function did not differ among groups. CONCLUSIONS: This small-scale pilot study indicates that by reducing crystalloid fluid administration and fall of COP during CPB, RAP reduces postpump EVLW accumulation and weight gain in uncomplicated coronary artery bypass graft patients with no associated effects on cardio-respiratory function.     

Preoperative Assessment of Body Fluid Disturbances in Patients with Obstructive Jaundice

Postoperative renal dysfunction in obstructive jaundice (OJ) patients has been associated with hypovolemia and depletion of the extracellular water compartment (ECW). The aim of the study was to evaluate the preoperative status of body compartments in OJ patients measured by two methods. In a prospective study 39 OJ patients (11 benign and 28 malignant obstructions) were investigated, with 15 healthy subjects used as a control group (CG). Bioelectrical impedance analysis (BIA) determinations and values derived from anthropometric measurements were used to assess body compartment status. The coefficient of variation of BIA was below 4% in both OJ and CG subjects. No differences were found in intracellular water. However total body water (TBW) and ECW were reduced in OJ patients (50.5 ± 4.6 vs. 56 ± 8% body weight, p= 0.05; and 21 ± 4.5 vs. 23.8 ± 2.5% body weight, p < 0.05, respectively). There were no differences between benign and malignant obstructions. Seventy four percent of OJ patients had an ECW volume below the mean ± 2 SD in the CG subjects. Anthropometric and BIA determinations correlated closely for TBW measurements in both CG (r= 0.92, p < 0.001) and OJ patients (r= 0.91, p < 0.001). Bland-Altman analysis also showed that for TBW the BIA was in agreement with anthropometry. In the present study, BIA offered a good correlation with anthropometric determinations and was a reliable method for body fluid disturbances assessment in jaundiced patients.     

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.

     

Cyclosporine enhances salt sensitivity of body water composition as assessed by impedance among psoriatic patients with normal renal function.

OBJECTIVE: Cyclosporine (CsA) therapy may be accompanied by a significant increase in blood pressure, either sodium (Na+) independent or Na+ dependent. The relationship between Na+ intake and body water distribution among patients treated with CsA has not been evaluated. We report the study, by bioelectrical impedance analysis (BIA), of water composition changes after dietary salt manipulations both before and during CsA treatment of psoriatic patients. METHODS: Ten normotensive psoriatic patients, ages 37 +/- 12 years (range, 19 to 54), with normal renal function were included. Each patient was assessed by BIA in 2 phases, before (phase 1) and during (phase 2) CsA therapy (3 mg/kg/day). In both phases, each patient was assessed in basal conditions (basal1 and basal2), on day 7 of a low-sodium diet (LS1 and LS2; 20 mEq/day) and on day 7 of a high-sodium diet (HS1 and HS2; 350 mEq/day). Plasma creatinine (Pcr), urinary volume excretion (Uv), urinary sodium (UNa+), urinary potassium (UK+), urinary osmolality (UOsmo), weight (Wt), resistance (R), reactance (Xc), total body water (TBW), extracellular water (ECW), intracellular water (ICW), Na:K exchangeable (Nae:Ke), phase angle (PA), and body cell mass (BCM) were evaluated. Blood pressure was monitored during 24 hours on the last day of each diet. Paired Student's t-test was used to analyze the different phases. RESULTS: Before CsA treatment, Wt, TBW and Nae:Ke were lower during LS1 than during basal1, whereas TBW was higher during HS1 than during LS1. During CsA, Wt, TBW, ECW, and Nae:Ke were lower during LS2 than during basal2, whereas ICW and PA were higher during LS2 than during basal2. HS2 showed higher TBW, ECW, and Nae:Ke and lower ICW, PA, and BCM than during LS2. Systolic blood pressure was higher during HS2 than during LS2 or HS1. In addition, diastolic blood pressure was higher during HS2 than during HS1. CONCLUSION: Body hydration status was more sensitive to dietary salt fluctuations during CsA treatment than without CsA, and a high-sodium diet seemed to enhance the CsA-induced hypertension side effect. Moreover, patients on low sodium intake under CsA treatment displayed neither any disturbance of body water composition nor any blood pressure change. Our data suggest that a low sodium intake might be very useful in preventing undesirable pressure and volume changes brought about by CsA treatment.     

改良股动、静脉插管体外循环中器官灌注效果的实验研究

目的比较改良股动、静脉插管体外循环(CPB)与常规CPB在相同流量灌注时对脑、肺、肝、肾、肠等重要器官灌注的效果。方法将20条犬(体重10～15kg)随机分为两组,每组10条。胸腔镜组:改良股动、静脉插管后建立CPB,经电视胸腔镜施行手术;常规开胸组:常规建立CPB手术。两组建立CPB后以相同的流量灌注,分别在无名动脉、左颈总动脉、肠系膜上动脉、肾动脉、对侧腘动脉、同侧腘动脉及其所有相伴行的静脉留置套管针,连接测压管道,于麻醉诱导后即刻(T1)、主动脉阻断前(T2)、主动脉阻断15min(T3)、主动脉开放15min(T4)、CPB结束后20min(T5)记录动、静脉压,并在以上时间点抽取相应部位静脉血测定静脉血氧饱和度(SvO2)。结果除了胸腔镜组同侧腘动脉灌注压明显低于常规开胸组(P<0.01)外,两组其余动脉的动脉灌注压比较差异均无统计学意义。主动脉阻断前、主动脉阻断15min、主动脉开放15min,胸腔镜组肾静脉、肠系膜上静脉、对侧腘静脉和同侧腘静脉的静脉压明显高于常规开胸组(P<0.05);胸腔镜组肾静脉、肠系膜上静脉、对侧腘静脉和同侧腘静脉SvO2低于常规开胸组(P<0.05)。结论改良股动、静脉插管与常规CPB相同流量灌注时其动脉灌注压相近,经股动、静脉插管下腔静脉平面以下的静脉压较常规开胸手术略高,因此,对小儿胸腔镜CPB的器官保护提供了理论依据。     

Body fluid spaces and blood pressure in hemodialysis patients during amelioration of anemia with erythropoietin

Blood pressure (BP) may increase in hemodialysis patients during treatment of anemia with recombinant human erythropoietin (r-HuEPO). Since fluid volume is a determinant of BP in dialysis patients, changes in body fluid spaces during r-HuEPO therapy could affect BP. Thus, 51Cr-labeled red blood cell (RBC) volume, inulin extracellular fluid (ECF) volume, and urea total body water (TBW), as well as cardiac output, plasma renin activity (PRA), and plasma aldosterone concentration were determined postdialysis before and after r-HuEPO therapy in patients in whom changes in BP could be managed by ultrafiltration alone. Eleven patients entered the study: one had a renal transplant and two required addition of antihypertensive drug therapy and were excluded; eight, of whom two required antihypertensive drug therapy following the study, were included in the analyses. Results revealed an increase in predialysis hemoglobin from 67 to 113 g/L (6.7 to 11.3 g/dL) (P = 0.001) during 18 +/- 6 weeks of therapy. Predialysis diastolic BP increased from 80 to 85 mm Hg (P = 0.07), while postdialysis diastolic BP was unchanged at 73 mm Hg. 51Cr-RBC volume increased, from 0.7 to 1.3 L (P = 0.004). ECF tended to decrease, from 13.7 to 10.8 L (P = 0.064), while TBW decreased to a similar extent, but not significantly, 34.3 to 31.2 L (P = 0.16). Postdialysis ECF volume was positively correlated with mean arterial BP at baseline (r = 0.89, P = 0.007) and after therapy (r = 0.74, P = 0.035). However, the regression lines for this relationship were different (P = 0.022) before and after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparing different methods of assessing body composition in end-stage renal failure

BACKGROUND: Accurate measurement of nutritional status in patients with end-stage renal disease is important because of its clear association with prognosis. Total body water (TBW) has additionally been recently recognized as an independent prognostic value because of its relationship with hypertension and cardiac morbidity. The current study was designed to assess the utility of surrogate markers of nutritional state and TBW in patients with end-stage renal disease. METHODS: Fifty-four patients with renal disease were studied. TBW obtained using the deuterium dilution technique was compared with estimates derived from anthropometric measures of TBW, including 58% body weight, Watson equations, and bioelectrical impedance analysis (BIA). Anthropometrically derived fat-free mass (FFM) was compared with BIA-derived estimates. Total body nitrogen (TBN) measurements were correlated with TBW estimates and BIA-derived resistance. RESULTS: TBW was significantly underestimated by the Watson equation (mean difference, -1.751 L, P = 0.01) and the 58% body weight approximation significantly overestimated it (mean difference, 1.792 L, P = 0.04). The Kushner BIA estimation of TBW did not significantly differ from that of the gold standard determined from D2O dilution (mean difference, -1.221 L, P = 0.12) and was also the method that showed the best agreement with the D2O estimate. However, the limits of agreement were large. Accurate prediction equations for FFM (FFM = -21.768 + 0.001 x ht2 + 6630.669 x 1/R + 0.312 x wt, R2 = 0.95) and TBN (TBN = -668.324 - 3.963 x age + 10.133 x wt + 0. 045 x ht2 + 32141.457 x 1/R, R2 = 0.91) were derived from BIA obtained resistance. CONCLUSIONS: The estimation of TBW varies significantly depending on the method of calculation. BIA is the most accurate surrogate marker for the measurement of both TBW and other parameters of body composition.     

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.     

冠状动脉搭桥术后血浆可溶性Fas及其配体的变化

目的比较在心肺转流（CPB）或非CPB下冠状动脉搭桥术（cABG）后可溶性Fas（sFas）和可溶性Fas配体（sFasL）的血浆浓度变化。方法19例病人分别在CPB（CPB组，n=9）或非CPB（非CPB组，n=10）下行择期cABG。术前、术毕和术后取血测定白细胞介素-6（IL-6）、中性粒细胞弹性蛋白酶、sFas、sFasL血浆浓度。结果术毕、术后4h的IL-6和术毕、术后4、12h的中性粒细胞弹性蛋白酶非CPB组明显低于CPB组（P〈0．05或P〈0．01）。CPB组的sFas在术后4、12h明显升高（P〈0．05或P〈0．01），非CPB组在术后12h明显升高（P〈0．01），术后24h恢复至术前水平。两组的sFasL在术毕和术后4、12h均明显升高（P〈0．05或P〈0．01），术后24h恢复至术前水平；其中术后12h非CPB组明显低于CPB组（P〈0．05）。结论CPB或非CPB下行cABG均导致sFas和sFasL血浆浓度升高，但CPB的应用使sFasL血浆浓度升高得更多。sFasL血浆浓度可反映机体炎性反应的程度。     

Assessment of total body water from anthropometry-based equations using bioelectrical impedance as reference in Korean adult control and haemodialysis subjects.

BACKGROUND: Several indirect prediction equations to estimate total body water (TBW) with simple demographic and anthropometric data are commonly used by researchers and dialysis units. These equations are largely based on observations in subjects of the Western hemisphere. The purpose of this study was to investigate the possible application of anthropometry-based TBW equations to a Korean adult control population and maintenance haemodialysis (HD) patients using multifrequency bioelectrical impedance analysis (BIA) as reference. METHODS: We performed BIA and anthropometric measurements in 67 healthy adults and 101 HD patients. Four anthropometry-based equations were used: 58% of actual body weight (TBW-58), the Watson formula (TBW-W), the Hume formula (TBW-H), and the Chertow formula (TBW-C). Multifrequency BIA was performed at fasting state in controls and after HD. RESULTS: TBW-BIA was 34.6+/-6.9 l in control and 29.9+/-5.1 l in HD patients. TBW-58 and TBW-C gave significantly greater TBWs than TBW-BIA in both control and HD subjects. The correlation coefficients of TBW-BIA with calculated TBWs were lowest in TBW-58 (0.754 in control and 0.856 in HD subjects), and highest in TBW-C (0.944 in control and 0.916 in HD subjects). Mean prediction error was greatest in the Chertow formula for control and HD patients. Mean prediction error, limits of agreement, and root mean square error were lowest between TBW-BIA and TBW-H in control and between TBW-BIA and TBW-W in HD subjects. The correlation coefficient in the Bland-Altman plot was closer to zero and parallel with TBW-W than TBW-H in control and HD subjects. CONCLUSION: Currently available TBW equations overestimate TBW in both Korean normal control subjects and HD patients. Among them, the Watson formula appears to be the closest to TBW and to have the least bias. Based on this analysis, it is reasonable to use the Watson formula for the calculation of TBW in Korean adult control and HD subjects until an Asian-based TBW equation is available.