Comparison of the Non-Invasive Methods Estimating Dry Weight in Hemodialysis Patients

Background. The treatment of deranged water homeostasis of hemodialysis (HD) patients needs focusing on an accurate assessment of dry weight (DW). However, the correct estimation of postdialysis DW is still a problem. Echocardiography of inferior caval vein diameter (ICVD) was recently considered as a reliable technique to estimate DWs of HD patients, whereas conductivity measurements and biochemical parameters remain controversial. In this study, we aimed to compare the noninvasive methods estimating DW in HD patients. Methods. We enrolled 60 patients: 30 hypervolemic (HV) (12 M, 18 F, with a mean age of 41.9 ± 13.6 years, mean HD duration of 38 ± 45 months) and 30 normovolemic (NV) patients (19 M, 11 F, with a mean age of 42.2 ± 14 years, mean HD duration of 62 ± 51.5 months) according to clinical sign and symptoms as well as the findings on chest x-ray. Furthermore, the DWs of patients were evaluated in post-HD period in terms of echocardiography parameters [ICVD and collapse index (CI) determined by Cheriex], plasma ANP (pANP) levels (RIA), and total body water (TBW) by bioelectrical impedance (BEI). Results. Forty-one of 60 patients had hypervolemic findings (68%) and 19 patients had normovolemia (32%) according to echocardiography parameters. Determination of “hypervolemia” by clinical acumen and pANP levels were not reliable, especially negative predictive values were lower as follows: sensitivity, specificity, positive predictive value, negative predictive values of clinical acumen and pANP levels: 63%, 69%, 87%, 50%, and 67%, 59%, 79%, 43%, respectively. TBW established by BEI did not correlate with ICVD and CI after HD (p > 0.05). The TBW of HV group according to echocardiography parameters was greater than NV group, but the difference was not statistically significant (27.4 ± 6.6 kg versus 26.4 ± 5.8 kg, respectively, p > 0.05). However, there was not any difference in the divided BSA values (1.58 ± 0.2 kg/m² versus 1.60 ± 0.2 kg/m², respectively, p > 0.05). Hypertension was seen in 37 (90%) of the echocardiographically hypervolemic patients, and the blood pressure was kept under control by previously given medication in only 7 (19%) patients. After the dry weight of the patients was corrected echocardiographically to normal limits, the blood pressure of 31 patients (86%) was normalized without antihypertensive treatment, but only in 6 patients remained the necessity of antihypertensive treatment. In addition, in 8 of 11 normotensive patients using antihypertensive drugs, assessment of their clinical and radiological findings showed normovolemia but ICVD > 11.5 mm/m²; however, the need for antihypertensive drugs disappeared when the ICVD reduced to 8–11.5/m². Conclusions. Clinical and radiological assessment, pANP levels, and TBW established by BEI appeared to be less valuable in interpreting DW's of HD patients. In accordance with the literature, echocardiography findings have proven to be reliable, and they are important noninvasive tools that can establish an effective and rational antihypertensive treatment.     

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.     

A new technique for establishing dry weight in hemodialysis patients via whole body bioimpedance

BACKGROUND: Quantitative techniques are necessary to achieve dry weight (DW) in patients with kidney failure. Bioimpedance spectroscopy (BIS) is a non-invasive method that determines the volume of body fluid compartments. The current work evaluates the use of BIS data in hemodialysis patients for the prediction of DW. METHODS: A new technique has been devised for the estimation of DW that involves the intersection of two slopes, slope normovolemia (SNV) and slope hypervolemia (SHV). These slopes characterize the variation in extracellular water (ECW) with body weight (BW) in the states of normovolemia and hypervolemia, respectively. SNV was established via measurements of ECW and BW in 30 healthy subjects. In a longitudinal study in new hemodialysis patients, successive reduction of post-dialysis weight (PDW) was attempted until clinical signs of normovolemia were presented. Measurements of ECW and BW that were acquired at the beginning of each treatment were used to determine SHV. RESULTS: SNV was found to be 0.239 L/kg and 0.214 L/kg for male and female healthy subjects, respectively. A significant DeltaPDW predicted by the new method (-4.98 kg) was highly correlated to the DeltaPDW achieved in the study (-5.85 kg, R = 0.839). Blood pressure was reduced (P < 0.001) and an 86% decrease in antihypertensive agents was achieved. CONCLUSION: The method of intersecting slopes (SHV with SNV) via BIS is a new method for the prediction DW. This approach will offer considerable improvement for the routine management of DW in the dialysis setting.     

Ambulatory blood pressure monitoring in patients receiving long, slow home haemodialysis.

BACKGROUND: Good blood pressure (BP) control has been reported previously in haemodialysis (HD) patients receiving 8-h dialysis sessions. Home HD allows patients to dialyze for long periods, but there are few data on the BP control achieved by these patients. We studied BP control, using ambulatory blood pressure monitoring (ABPM), in our home-HD patients who were receiving long-hours dialysis. METHODS: Twenty-four patients aged 52.7+/-11 years underwent ABPM. They had been on home HD for 52.9+/-39 months and dialysed for 7.2+/-1.1 h thrice weekly. Two patients were taking antihypertensive drugs. Historical data on BP and weight gains were obtained from the patients' own records. Left ventricular (LV) mass was assessed by echocardiography and total body water (TBW) by bioelectrical impedance. RESULTS: The mean 24-h BP was 129+/-17 mmHg (systolic) and 83+/-14 mmHg (diastolic). The daytime BP was 131+/-17 mmHg (systolic) and 84+/-14 mmHg (diastolic), while the night-time BP was 126+/-22 mmHg (systolic) and 81+/-17 mmHg (diastolic). Six patients (25%) had a normal circadian BP rhythm, but the rest showed a subnormal fall or an increase in BP at night. Mean 24-h BP did not correlate significantly with time on dialysis, dialysis session length, Kt/V, haemoglobin, interdialytic weight gain, or TBW. Twenty-one patients (87%) had LV hypertrophy and 16 of these had diastolic dysfunction. LV mass index was inversely correlated with nocturnal BP fall (r=-0.54, P=0.03). Non-dippers had been treated longer than dippers (29 vs 59.2 months, P=0.03) but they were similar in respect to age, dialysis session length or Hb concentration. CONCLUSIONS: Long, slow haemodialysis at home provides satisfactory daytime BP control in the majority of patients without the need for antihypertensive drugs but abnormal circadian BP rhythm and LV hypertrophy remain common.     

Measurement of total body water with deuterium oxide in renal diseases

Total body water was measured by means of dilution technic with 99.8% deuterium oxide administration in normal subjects (controls), nephrotic (NS) patients with or without edema, and in longterm hemodialysis (HD) patients. Lean body mass (LBM) was calculated from height, body weight, and waist girth. Body fluid was evaluated according to the TBW/LBM ratio in HD patients. Effect of volume of body fluid on blood pressure was also investigated. Relationship among cardio-thoracic ratio (CTR), standard body weight (SW), and TBW were examined. SWTBW calculated from TBW and LBM, and SWCTR estimated mainly from CTR, blood pressure, were compared. The total body water to body weight ratios (TBW/BW) in controls, NS, and HD patients were 61.2 +/- 1.2%, 71.3 +/- 3.7% (with edema), 60.9 +/- 6.4% (without edema), 64.5 +/- 6.9% (pre-HD), 62.6 +/- 6.6% (post-HD) respectively. The mean TBW/BW of NS patients with edema was significantly greater than those of control, NS patients without edema, and post-HD patients. The TBM/LBM value above 0.78 was suggestive of overhydrated state in HD patients. The mean TBW/LBM in HD patients was 0.757, which was greater than that of controls. Hypotension during HD was seemingly induced by excess ultrafiltration regardless of the value of TBW/LBM. No relationship among CTR, SW, and TBW was observed in HD patients, but the mean TBW/LBM of patients with the CTR exceeding 55% was 0.786, which suggested as overhydrated state. It is useful to determine TBW/BW and TBW/LBM in order to evaluate of volume changes in body fluid of longterm HD patients.     

Assessment of total body water and lean body mass from anthropometry, Watson formula, creatinine kinetics, and body electrical impedance compared with antipyrine kinetics in peritoneal dialysis patients

Background. Indirect methods such as anthropometry (A), Watson formula (W), creatinine kinetics (CK), and body electrical impedance (BEI) are increasingly applied to determine total body water (TBW) and lean body mass (LBM) in dialysis patients. These methods share the disadvantage that they have been validated for healthy men only. We studied which of these four commonly applied methods can best be used routinely in CAPD patients. Methods. TBW estimates obtained from A, W, CK, and BEI were compared with those obtained by a gold standard (antypirine distribution volume, ADV) in eight CAPD patients. In addition, several BEI equations to derive lean body mass (LBM) were compared with LBM estimated by ADV in order to determine which equation is the most valuable for the assessment of LBM by BEI in CAPD patients. Results. TBW as ADV was 41.4±6.6 (mean±SD) L. TBW estimated by W, A and CK underestimated ADV by a mean±SD of 2.3±13, 5±8.4 and 12.3±10.9% respectively. TBW as measured by BEI overestimated ADV by 2.5±8.8%. The correlation coefficients between ADV-TBW and TBW estimated by the indirect methods were r=0.88 (A), r=0.87 (BEI), r=0.82 (CK), and 0.68 (W). LBM estimated by ADV was 56.7±8.9 (mean±SD) kg; LBM by different BEI equations ranged from 49.9±7 to 58.1±10.7 kg. The correlation coefficient between LBM by ADV and LBM according to the various BEI equations ranged from 0.81 to 0.93. Conclusions. A and BEI: can be used to estimate TBW, but the considerable SD (or inaccuracy) makes individual predictions hazardous. Considering the correlation coefficients and difference between LBM by ADV and LBM according to different BEI equations, Deurenberg's formula can be advocated for use in the estimation of LBM by BEI.     

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.     

Effects of antihypertensive medication on left ventricular function during electroconvulsive therapy: study with transthoracic echocardiography

STUDY OBJECTIVE: To characterize the effects of antihypertensive medications on cardiac function using transthoracic echocardiography during electroconvulsive therapy (ECT). STUDY DESIGN: Randomized, double-blind study set at a university hospital. PATIENTS: 30 American Society of Anesthesiologists (ASA) physical status I and II patients undergoing ECT. INTERVENTIONS: Patients were given thiopental sodium (two mg/kg) and succinylcholine (one mg/kg), and mask ventilation was initiated with 100% oxygen before bilateral ECT. Patients received a bolus injection of one of several different antihypertensive medications: 0.08 mg/kg alprenolol, 0.01 mg/kg nitroglycerin, 0.02 mg/kg nicardipine, or saline immediately after anesthesia induction and before electrical shock. MEASUREMENTS: Cardiac function was examined through transthoracic echocardiography before anesthesia induction, throughout the ECT procedure, and for 10 minutes after the seizure. MAIN RESULTS: Electrical shock resulted in a significant change in fractional area change when compared with the awake condition. Further fractional area change at one minute after ECT was significantly higher in patients who received nicardipine than in the other groups (means +/- SD): control group, 43% +/- 10%; nitroglycerin group, 46% +/- 8%; nicardipine group, 65% +/- 6% (P < 0.05 vs the other three groups); and alprenolol group, 51% +/- 7%. Systolic blood pressure/end-systolic area-end-diastolic area at one minute after the electrical shock was higher in the control, nitroglycerin, and alprenolol groups but not in the nicardipine group when compared with the awake condition (means +/- SD): control group, 39 +/- 8 mmHg/cm(2) (P < 0.05 vs the other three groups); nitroglycerin group, 32 +/- 9 mmHg/cm(2); nicardipine group, 29 +/- 7 mmHg/cm(2); alprenolol group, 31 +/- 6 mmHg/cm(2). CONCLUSIONS: Specific antihypertensive drugs produced different hemodynamic effects during ECT. Our data suggest that alprenolol was the most appropriate agent for minimization of changes in heart rate and transthoracic echocardiographic variables after ECT.     

Preoperative Weight Loss as a Predictor of Long-term Success Following Roux-en-Y Gastric Bypass

BACKGROUND: All patients undergoing gastric bypass surgery at this institution are recommended to achieve a goal of 10% total body weight (TBW) loss prior to surgery. The objective of this study was to determine whether preoperative TBW correlated with 3- and 4-year weight loss outcome. METHODS: This study was conducted prospectively at a large teaching hospital. All adult patients with 3- and 4-year follow-up data since the start of the study in 1998 to September 2007 were included. All data are expressed as mean +/- SD. Pairwise correlation and ordinary least squares regression analysis was used to determine the strength of association between preoperative TBW loss and weight loss at 3 and 4 years. RESULTS: One hundred fifty patients (120 females), age 45.3 +/- 8.9 years, were included. Their body mass indexes (BMIs), preoperatively and after 3 years, were 52.2 +/- 9.8 and 35.4 +/- 8.2 kg/m(2), respectively. There was a significant correlation between preoperative and 3-year TBW lost (9.5 +/- 6.8% vs 31.9 +/- 11.7%, r = 0.302, p = 0.0002) and between excess body weight (EBW) lost preoperatively and after 3 years (16.1 +/- 11.3% vs 55.1 +/- 20.2%, r = 0.225, p = 0.006). Ninety five patients had follow-up data available at 4 years. Their mean preoperative BMI was 52.6 +/- 9.7 kg/m(2) and decreased to 37.5 +/- 9.0 kg/m(2). The TBW loss prior to and after surgery (10.0 +/- 6.5% vs 29.4 +/- 11.5%) was significantly correlated (r = 0.247, p = 0.015). The EBW loss preoperatively and after 4 years correlated positively (17.1 +/- 11.1% vs 50.8 +/- 19.8%, r = 0.205, p = 0.046). CONCLUSION: There is a significant correlation between weight loss attained preoperatively and sustained weight loss at 3 and 4 years.     

Suppression of the renin-angiotensin-aldosterone axis with erythropoietin therapy by a negative feedback loop.

To investigate the pathophysiology of hypertension in patients receiving recombinant human erythropoietin (rHuEpo) we studied its effects on the renin-aldosterone axis of chronic haemodialysis (HD) patients not receiving antihypertensive drugs. Nine severely anaemic normotensive HD patients received rHuEpo 50 U/kg bodyweight, thrice weekly after each HD. The dose was increased by 25 U/kg bodyweight every 4 weeks to a maximum of 100 U/kg or until an increase of Hb or Hct of 2 g/dl or 7% was achieved. Blood samples were taken after 30 min supine rest and while seated 10 min later after gentle ambulation. Results expressed as mean +/- SEM: therapy in normotensive HD patients by a negative feedback loop, before the development of hypertension.     

The Effect of Strict Volume Control on Cognitive Functions in Chronic Hemodialysis Patients

Cognitive dysfunction is a well-known complication of chronic renal failure that is evident in 30% of hemodialysis (HD) patients. However, the pathogenesis of this dysfunction is unknown. Left ventricular hypertrophy could develop in hypertensive HD patients without establishing normovolemia. Our aim was to evaluate the effect of strict volume control by salt restriction and ultrafiltration on cognitive functions in HD patients. This cross-sectional study was composed of 22 HD patients who were normotensive by applying a strict volume control, 24 HD patients who were normotensive by receiving anti-hypertensive drugs, and 20 healthy controls. The strict volume control was defined as managing of blood pressure control by strict salt restriction and insistent ultrafiltration. P300 recording as an indicator of cognitive disfunction was measured when blood pressures were reached at target level at the end of six-month follow-up period. In all patients, dimensions of the heart were evaluated with echocardiography on an interdialytic day. The cardiothoracic ratio and echocardiographic dimensions were significantly lower in patients with strict volume control. P300 amplitudes were significantly lower in patients on antihypertensive drugs than in patients with strict volume control (9.5 ± 5.1 versus 11.3 ± 5.4 μV). P300 latency was longer in patients on antihypertensive drugs than in the control group and patients with strict volume control (359.9 ± 39.6 versus 345.6 ± 36.7 ms). Our results suggest that hypervolemia may be one of the causal and potentially modifiable factors of cognitive dysfunction. Strict volume control may have beneficial effects on cognitive functions in hemodialysis patients.     

Energy and substrate metabolism in patients with chronic extensive graft-versus-host disease

BACKGROUND: Allogeneic stem cell transplantation is frequently complicated by graft-versus-host disease (GVHD). Weight loss is one of the characteristic features of GVHD. The etiology of weight loss in GVHD is not completely understood. METHODS: We measured resting energy expenditure (REE) and substrate oxidation rates by indirect calorimetry in patients with stable chronic extensive GVHD under immunosuppressive therapy (n=13) and sex-, age-, height-, and weight-matched healthy controls (n=13) in order to evaluate metabolic changes in these patients. Measurements were done on day 518+/-261 after allogeneic stem cell transplantation in the postabsorptive state. Serum concentrations of glucagon, norepinephrine, tumor necrosis factor-alpha, interleukin-6, and free fatty acids were determined. RESULTS: Patients showed a maximum weight loss of 22% during their course of GVHD; nevertheless, they regained 15% of total body weight (TBW) during successful treatment of GVHD. Indirect calorimetry showed an increase in REE per kilogram of TBW (patients, 21.8+/-3.1 kcal/kg TBW/day; controls, 19.9+/-2 kcal/kg TBW/day; P<0.05). Respiratory quotient (patients, 0.79+/-0.04, controls, 0.86+/-0.04; P<0.005) and non-protein respiratory quotient (0.78+/-0.05 and 0.87+/-0.05, respectively; P<0.005) were decreased in patients. GVHD patients had elevated serum glucagon and norepinephrine concentrations, whereas tumor necrosis factor-alpha and interleukin-6 were in the normal range. CONCLUSIONS: Patients with chronic extensive GVHD show an increase in REE and alterations in fat and carbohydrate oxidation rates. These changes seem to be the result of increased action of glucagon and norepinephrine.     

Parathormon, calcium, phosphorus, and left ventricular structure and function in normotensive hemodialysis patients

Clinical and experimental data suggest that Parathormon (PTH), calcium, and phosphorus participate in left ventricular hypertrophy (LVH) and affect myocardial contractility in end-stage renal disease. Cellular calcium overload and interstitial fibrosis induced by PTH may lead to impairment of left ventricular diastolic function. Hyperphosphatemia is an independent risk of cardiovascular mortality in dialysis patients. The aim of the study was to estimate the influence of PTH and calcium-phosphorus metabolism on left ventricular structure and function in hemodialysis patients, without hypertension and antihypertensive drug therapy (SBP = 126.2 +/- 11.1 DBP = 75.8 +/- 6.5 mmHg). Echocardiographic findings in a group of 22 normotensive HD patients had been compared to 43 hypertensive HD patients. Relationships between PTH, calcium-phosphorus metabolism and echocardiography in normotensive group were then evaluated. Left ventricular mass index (LVMI) was lower in normotensive patients: 128.3 +/- 46.2 versus 165.8 +/- 46.7 (p < 0.01). The prevalence of LVH was 55% in normotensive HD patients compared to 86% in hypertensive group (p < 0.01). In normotensive group we found correlation between PTH and LVMI (r = 0.44; p < 0.05). There were also significant relationships between calcium and posterior wall thickness (r = -0.44; p < 0.05), phosphorus and LVMI (r = 0.47; p < 0.05). A significant correlation was observed between both phosphorus, calcium x phosphorus product and E/A ratio: r = -0.47 and r = -0.43, respectively (p < 0.05 both). Disturbances of calcium-phosphorus metabolism and secondary hyperparathyroidism contributes to left ventricular hypertrophy, and impaired left ventricular diastolic function in normotensive hemodialysis patients.     

WHO class-specific equations using height for predicting body weight: crude indicator for dry weight in haemodialysis patients

AIM: Body weight (BW) might be related to total body water, and the difference between a patient's actual BW and ideal BW (IBW) might be the volume marker. However, there has been no information about the association between IBW and dry weight (DW) in haemodialysis (HD) patients. METHODS: First, we analysed the relationship between DW and IBW in 51 HD patients. The IBW was calculated by 21 x Height (Ht)(2). Weight status was analysed by the WHO classification. Second, in 12 436 controls, linear equations using Ht(2) were sought to predict the BW in each sex and WHO class. Third, using these equations, predicted BW (PW) was compared with DW in each WHO class at the initiation and after 1 year in 619 new HD patients, retrospectively. RESULTS: Among 51 HD patients, 38 were normal weight in whom there was no difference between DW and IBW. In each sex and WHO class of the 12 436 controls, linear equations using Ht(2) were developed to predict BW. These equations were applied to 619 new HD patients. In males, there were no differences between PW and DW in underweight (UW), overweight (OW), obese (OB) and extremely obese (EOB) patients at the initiation of the HD. In females, there were no differences between PW and DW in OW patients. Despite no statistical differences, there were wide ranges of distribution from -6 to 6 kg between PW and DW. CONCLUSIONS: BW had a linear relationship with Ht(2) and might be predictable by the WHO class-specific equation using Ht(2). These equations might be useful as a crude indicator of DW in HD patients.     

Comparison of anthropometric equations for estimation of total body water in peritoneal dialysis patients.

BACKGROUND: Several formulae exist for estimating total body water (TBW). We aimed to assess their validity in peritoneal dialysis patients by comparison with TBW estimated by deuterium oxide dilution (TBW(D)). METHODS: We compared the equations of Chertow (TBW(Cher)), Chumlea (TBW(Chum)), Hume and Weyers (TBW(HW)), Johansson (TBW(J)), Lee (TBW(L)), Watson (TBW(W)) and TBW as 58% of body weight (TBW(0.58Wt)) with TBW(D) in 31 peritoneal dialysis (PD) patients and 32 controls. Estimates were compared with TBW(D) using Bland and Altman comparison. Extracellular water (ECW) was also estimated by sodium bromide dilution. RESULTS: In PD patients, mean TBW(D) was 35.04 (SD 7.84) l. Estimates were greater for TBW(Cher), TBW(Chum), TBW(HW), TBW(J) and TBW(0.58Wt). Mean TBW(L) and TBW(W) did not differ from TBW(D). Ninety-five percent limits of agreement (LOA) compared with TBW(D) (as a percentage of the mean) were similar for all of the different equations in PD patients (between +/-15.4 and +/-17.3%) except TBW(0.58Wt), which was far greater (+/-26.4%). In controls, mean TBW(D) was 37.03 (SD 6.63) l. Estimates were greater for TBW(Cher), TBW(Chum), TBW(HW), TBW(J) and TBW(0.58Wt). Mean TBW(L) and TBW(W) did not differ from TBW(D). Ninety-five percent LOA compared with TBW(D) (as a percentage of the mean) were similar for all equations in the controls, and closer than in PD patients (between +/-9.1 and +/-11.5%) except TBW(0.58Wt), which was again far greater than the other equations (+/-28.1%). TBW(HW) - TBW(D) correlated with mean TBW (r=-0.412, P<0.05 in PD and r=-0.383, P<0.05 in controls). TBW(W) - TBW(D) (r=-0.539, P<0.005) correlated with mean TBW in PD. TBW(0.58Wt) - TBW(D) correlated with body mass index (BMI) (r=0.624, P<0.0001 in PD and r=0.829, P<0.0001 in controls) and ECW/TBW (r=0.406, P<0.05 in PD and r=0.411, P<0.02 in controls). CONCLUSIONS: Predictive equations were less accurate in PD than controls. TBW(0.58Wt) was most inaccurate, with systematic overestimation of TBW with increasing BMI and ECW/TBW. There were no differences in LOA with TBW(D) for the other equations within each group.     

Urea space and total body water measurements by stable isotopes in patients with acute renal failure

BACKGROUND: Knowledge of urea volume of distribution (Vurea) in patients with acute renal failure (ARF) is critical in order to prescribe and monitor appropriate dialytic treatment. We have recently shown that in ARF patients, Vurea estimation by urea kinetic modeling is significantly higher than total body water (TBW) by anthropometric estimation. However, these estimates of Vurea and TBW have not been validated by isotopic methods, considered as reference measurement standards. METHODS: In this study, we measured Vurea by [13C]urea and TBW by deuterium oxide (D2O) in 21 patients with ARF (14 males, 7 females, age 62.0 +/- 10.6 years old, 83% Caucasian, 17% African American) at three different centers. These measurements were compared to TBW estimates from anthropometric and bioelectrical impedance (BIA) measurements. RESULTS: Our results show that Vurea by [13C]urea (51.0 +/- 11.7 L) is significantly higher than TBW estimated by all other methods (TBW by D2O: 38.3 +/- 9.8 L, P < 0.001; TBW by BIA: 45.7 +/- 15.7 L, P= 0.08; TBW by Watson formula: 38.3 +/- 7.3 L, P < 0.001; TBW by Chertow formula: 39.3 +/- 7.8 L, P= 0.002, all versus Vurea). Despite significant overestimation of the absolute value and considerable variation, Vurea significantly correlated with TBW by BIA (r= 0.66, P < 0.01) and TBW by D2O (r= 0.5, P= 0.04). There was also significant correlation between D2O and BIA determined TBW (r= 0.8, P < 0.001). CONCLUSION: In terms of useful guidelines to prescribe a specific dose of dialysis in patients with ARF, conventional estimates of TBW as surrogates for Vurea should be used with caution. We propose that these conventional estimates of TBW should be increased by approximately 20% (a factor of 1.2) to avoid significant underdialysis.     

Association between extracellular water, left ventricular mass and hypertension in haemodialysis patients.

BACKGROUND: Hypertension and left ventricular hypertrophy (LVH) are present in the majority of patients undergoing haemodialysis (HD). These two pathologies persist after dialysis onset, and pharmacological therapy is often required for adequate control of blood pressure (BP). Although fluid overload is a determinant of hypertension, clinical assessment of this parameter remains difficult and unsatisfactory. Bioimpedance analysis (BIA) spectroscopy and the relative determination of extracellular water (ECW%) may provide a simple and inexpensive tool for investigating fluid overload. We studied 110 patients on thrice-weekly HD to determine whether ECW body content correlates with hypertension and LVH in this patient population. METHODS: Hypertension was determined according to the WHO criteria (office BP >/= 140/90 and/or the use of antihypertensive therapy). Twenty-four hour BP monitoring and echocardiography were performed on midweek inter-HD days. Blood chemistries, dialysis dose (spKt/V) and bioimpedance were analysed on midweek HD days. RESULTS: Hypertension was present in 74.5% of patients. There were no differences for age, spKt/V, haemoglobin, serum creatinine and residual renal function between normotensive and hypertensive patients. Twenty-four hour systolic BP (SBP), 24 h diastolic BP and 24 h pulse pressure were higher in hypertensive patients, in spite of antihypertensive therapy. LVH was present in 61.8% of patients. BIA revealed that ECW% was increased in LVH+ patients (LVH+ = 47.5 +/- 7.9%, LVH- = 42.4 +/- 6.2%, P = 0.01) and in hypertensive patients compared with normotensives (46.5 +/- 7.7% vs 43 +/- 7.2%, P = 0.02). Dry body weights and inter-HD body weight increases did not differ between hypertensive and normotensive patients nor between patients with or without LVH. ECW was correlated with SBP (r = 0.35, P < 0.01) and with left ventricular mass index (LVMi(g/sqm)) (r = 0.49, P < 0.001). A stepwise multiple linear regression model revealed that LVMi(g/sqm) was significantly correlated with ECW%, SBP and male gender (r = 0.65, P < 0.001). CONCLUSIONS: LVH and hypertension are present in a majority of HD patients and they are closely correlated with one another. We found associations between fluid load, measured by BIA and expressed as ECW, and BP and LVM.     

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.     

Continuous extracorporeal fluid removal in children with low cardiac output after cardiac operations

Eleven hypervolemic and oliguric children with low cardiac output after cardiac operations were treated by slow continuous ultrafiltration or continuous arteriovenous hemofiltration. A mean negative fluid balance of 1.63 +/- 0.37 ml/kg/hr (standard error of the mean [SEM]) significantly improved the hemodynamic status within 59 +/- 6.1 hours (SEM). Although the central venous pressure decreased significantly from 15.2 +/- 0.84 to 8.8 +/- 0.92 mm Hg (p less than 0.0001), the mean arterial pressure increased significantly from 41.5 +/- 2.54 to 53.5 +/- 2.21 mm Hg (p less than 0.001). In addition, pH increased significantly from 7.31 +/- 0.01 (SEM) to 7.43 +/- 0.001 (SEM) (p less than 0.001) and oxygenation index (arterial oxygen tension/inspired oxygen fraction) from 119 +/- 15.2 (SEM) to 214 +/- 27.0 (SEM) (p less than 0.001). Hemodynamic improvement during slow continuous extracorporeal fluid removal allowed a significant decrease of the catecholamine infusion rate. After normovolemia had been achieved, continuous arteriovenous hemofiltration had to be continued in four children because of persistent anuria. Eight patients could be weaned from artificial ventilation and vasopressor support. Two patients died without recovery of renal function and one with restored renal function. Slow continuous ultrafiltration and continuous arteriovenous hemofiltration improve the cardiovascular function in children with low cardiac output by optimizing the preload conditions of the failing heart. In addition, they improve acid-base balance and pulmonary gas exchange.     

Hemodialysis with high-calcium dialysate impairs cardiac relaxation

BACKGROUND: During hemodialysis (HD), serum ionized calcium is directly related to the dialysate calcium concentration. We have recently shown an acute induction of hypercalcemia to impair left ventricular (LV) relaxation. In the current study we sought to establish whether changes in serum Ca++ also affect LV function during HD. METHODS: We echocardiographically examined the LV relaxation and systolic function of 12 patients with end-stage renal disease before and after three HD treatments with dialysate Ca++ concentrations of 1.25 mmol/liter (dCa++1.25), 1.5 mmol/liter (dCa++1.50), and 1.75 mmol/liter (dCa++1.75), respectively. Age- and sex-matched healthy controls were also examined echocardiographically. RESULTS: The LV posterior wall thickness and the interventricular septum thickness, and the LV end-diastolic dimension and the end-systolic dimensions were significantly greater in the patients when compared with the controls, and the LV fractional shortening, the ratio of peak early to peak late diastolic velocities (E/Amax), and the isovolumic relaxation time (IVRT) showed impairment of LV relaxation and systolic function in the patients. Serum ionized calcium increased significantly during the dCa++1.5 HD (1.24 +/- 0.10 vs. 1.34 +/- 0.06 mmol/liter, P = 0. 004) and dCa++1.75 HD (1.19 +/- 0.10 vs. 1.47 +/- 0.06 mmol/liter, P = 0.002), and plasma intact parathyroid hormone decreased significantly during the dCa++1.75 HD (medians 8.2 vs. 2.7 pmol/liter, P = 0.002). LV systolic function was not altered during any of the treatments. The changes in E/Amax and IVRT suggested impairment of relaxation during all sessions, but only during the dCa++1.75 HD was the impairment statistically significant (E/Amax 1. 153 +/- 0.437 vs. 0.943 +/- 0.352, P < 0.05; IVRT 147 +/- 29 vs. 175 +/- 50 msecond, P < 0.05). CONCLUSION: HD with high-calcium (dCa++1. 75 mmol/liter) dialysate impairs LV relaxation when compared with lower calcium dialysate (dCa++1.25 and dCa++1.5 mmol/liter) treatments.