Bioelectrical impedance analysis before and after Novacor implantation.

In this study Bioelectrical Impedance Analysis was performed in 5 patients with end stage heart failure in whom a left ventricular assist device (Novacor) was successfully implanted. Whole body measurements of bioelectrical indices resistance and reactance were taken before surgery and 3, 7, 12, and 15 days after it. After surgery there was a significant decrease in reactance, indicating a shift of body fluids from intra- to extra-cellular space.     

Bioelectrical impedance changes during the menstrual cycle

Numerous physiological factors that may influence estimates of body composition based on bioelectrical impedance analysis (BIA) have been recognized. The two studies to date investigating changes in bioelectrical impedance during the menstrual cycle have produced conflicting results. Male control subjects were included in this study in an attempt to discern variations in bioelectrical impedance associated with the menstrual cycle in women from those due to other physiological variables affecting both sexes. Body weight and bioelectrical impedance (tetrapolar Holtain Analyzer; 50 kHz, 800 μA) were measured two to five times per week for one menstrual cycle (21–34 days) on 42 women (6 taking an oral contraceptive, OC), aged 19.0–34.4 years, and for 22–32 days on 28 men (18.9–24.1 years). Body weight in the non-OC women decreased significantly between menses and the late follicular phase, and increased significantly between the late follicular phase and the premenstruum (paired t test, P < 0.05). These changes were not correlated with matching bioelectrical impedance changes (linear regression, P > 0.05). Bioelectrical impedance in the non-OC women, and body weight and bioelectrical impedance in the OC women and the men, did not differ significantly over the measurement period. Likewise, estimated lean body mass (LBM) and total body water (TBW) derived from BIA remained stable. The intraobserver test-retest reliability (S_meas) of bioelectrical impedance was 12.3 ohm (2.8% of mean bioelectrical impedance) which produced as much as a 10–12% error in estimating LBM and TBW. Measurement error was reduced to 4 ohm in a subgroup where electrode positions were marked with indelible ink. These results indicate that body composition assessments based on BIA measured at 50 kHz are not affected by the menstrual cycle. Am. J. Hum. Biol. 9:155–161, 1997. © 1997 Wiley-Liss, Inc.     

Bioelectrical impedance analysis for measurement of body fluid volumes: a review

The need for a portable, inexpensive, accurate and safe method for measuring body composition is well established. Bioelectrical impedance analysis (BIA) has the potential to partially meet this need by estimating the water component of body composition. There are still a number of unresolved questions and limitations to the applications of BIA, however. This paper briefly reviews the theory of BIA, its application and its limitations. Recent progress in the development and validation of swept or multiple frequency BIA used to determine both extracellular water and total body water is discussed in detail.     

甘肃东乡族成人非脂肪组织体成分的生物电阻抗分析

目的利用生物电阻抗分析法,分析甘肃东乡族成人非脂肪组织体成分变化特点。方法采用横断面整群分层随机抽样方法,应用体成分分析仪,测量491例甘肃省东乡族自治县20岁以上东乡族成人非脂肪组织体成分指标。结果甘肃东乡族成年男性去脂体重、骨量、肌肉、蛋白质、体液量及构成比均高于女性(P0.01),且男性各年龄组的骨量、肌肉量、蛋白质、体液量均高于女性(P0.01)。骨量、肌肉量在同一性别中随年龄变化趋势相同,男性均在40岁年龄组达峰值后下降;女性先降后升,在40岁年龄组达峰值后又下降。男性的蛋白质在30岁年龄组达峰值后下降;女性的蛋白质呈持续下降状态。男女性的躯干肌肉量分别在50岁年龄组和40岁年龄组达峰值后下降。男女性的双上肢肌肉量、体液量均在40岁年龄组达峰值后逐渐下降。男性的双下肢肌肉量除在40岁年龄组稍有回升,总体呈下降趋势;女性的双下肢肌肉量呈持续下降状态。男女性的细胞内液量均先降后升,在40岁年龄组达峰值后又下降。男女性的细胞外液量分别在50岁年龄组和40岁年龄组达峰值后稍有下降。结论甘肃东乡族成年男性的非脂肪组织体成分高于女性。随着年龄的增长,非脂肪组织体成分均发生变化,除双上肢肌肉量、体液量、细胞内液外,其余体成分的变化趋势均存在性别差异。总体呈现出,东乡族成年女性非脂肪组织体成分量少于男性,部分无峰值呈持续下降或达峰值早,下降早,达峰值后下降趋势缓于男性的特点。     

Comparison of segmental with whole-body impedance measurements in peritoneal dialysis patients

Segmental impedance measurements were obtained using nine electrode configurations in 21 male patients undergoing peritoneal dialysis PD before and after the fluid drainage. For each segment we analyzed the impedance Z and the impedance divided by the height H of the patient Z/H. Our objective was to compare different segmental measurements with whole-body measurements in peritoneal dialysis. The Wilcoxon test was used to analyze the change in impedance produced by a PD session. Pearson or Spearman correlation coefficients were used for continuous or discrete variables, respectively. Statistical significance was set at P<0.05. Similar results were obtained for Z and Z/H. The correlation coefficients between the real R and imaginary X(c) parts of segmental impedances after drainage were within the expected range for healthy population (0.46-0.70), but not before drainage for the abdomen (0.34) and the upper part of the leg (0.24). The correlation between the real part of whole-body and the real part of longitudinal segments in the limbs was high (r=0.807-0.879). Furthermore, the imaginary part of whole-body showed a high correlation with the imaginary part of all longitudinal segments (r=0.856-0.931). The high contribution of arm and leg impedances in the whole-body impedance produced high correlation between whole-body and segmental measurements in legs and arms. In agreement with other previous studies, a significant increase of the arm resistance was detected after fluid drainage. The drainage of fluids in PD patients produced significant changes in the measured real parts of impedance in all measured segments, but only the measurement in the abdomen showed a significant positive correlation (r=0.533) with the extracted fluid volume. This low correlation indicates that the individual assessment of fluid volumes using segmental measurements will be highly inaccurate.     

数字化外科：生物电阻抗测量技术辅助临床外科的操作

背景：现代临床外科操作对减少创伤和提高精确度的要求日益提高,生物电阻抗测量技术能将人体组织的信息转化为数字化信号,识别不同组织、器官,进而达到辅助临床操作的目的。 目的：回顾分析生物电阻抗测量技术通过数字化转换辅助临床诊断、治疗以及手术等操作过程的情况。 方法：由第一作者检索 1999/2009 PubMed数据及万方数据库有关使用生物电阻抗测量技术辅助临床诊断、治疗以及手术等操作,通过数字化信号的采集和分析达到实时定位、定性、提高精度和疗效评估等方面的文献。 结果与结论：生物电阻抗测量技术以其无创、安全、可持续监控、多次测量和重复使用等优点,是一种理想的临床操作辅助手段。随着该技术新理论、新方法的不断发展,许多学者在此基础上对其辅助临床操作的应用进行了大量的研究和尝试,有理由相信其辅助应用的范围也将进一步扩大。     

Bioelectric impedance in the estimation of hemodynamic and fluid status in dialysis patients

In order to estimate the hemodynamic and fluid changes, "dry body weight" and intradialytic stability, electric bioimpedance cardiography was performed in 37 dialysis patients during dialysis procedure, i.e. before, at 2 h and after dialysis. The following parameters were estimated: systemic vascular resistance index-fl. Ohm/m2 (SVRI), mean arterial pressure-Torr (MAP), thoracic fluid conductivity/Ohm (TFC), cardiac index-L/min/m2 (CI), left cardiac work index-kg m/m2 (LCWI) and ejection fraction % (EF). Results were compared with changes in total body water estimated by the urea kinetic model (UKM). The patients were divided into three groups: normotensive (n = 12), hypertensive (n = 15) and hypotensive (n = 10). EF was increased in all the three groups, but only in hypotensives this change was significant (from 40.5 +/- 9.1 to 50.2 +/- 5.41, p < 0.01). The changes in other hemodynamic parameters (CI, LCWI, SVRI) did not reach statistical significance. TFC decreased significantly in all the three groups: normotensive from 0.056 +/- 0.009 to 0.048 +/- 0.009 (p < 0.001), hypotensive from 0.043 +/- 0.009 to 0.035 +/- 0.058 (p < 0.001) and hypertensive from 0.054 +/- 0.016 to 0.045 +/- 0.014 (p < 0.001). These changes were accompanied by a significant decrease in total body water (TBW): from 34.05 +/- 4.19 to 32.72 +/- 4.51 in the hypotensive group, from 34.06 +/- 7.18 to 32.91 +/- 7.27 in the normotensive group, and from 38.92 +/- 7.06 to 37.59 +/- 7.04 in the hypertensive group. The technique was found to be simple, noninvasive and helpful for the estimation of individual hemodynamic changes during dialysis procedure.     

Influence of ionic shifts during dialysis on volume estimations with multifrequency impedance analysis

During dialysis the ion concentrations in many body fluids change significantly. The influence of these changes on the accuracy of volume measurements with bioimpedance spectroscopy is investigated by the following procedure: Plasma ion concentrations and impedance spectra (5–500 kHz) are measured during six standard haemodialyses. Intracellular ion concentrations are estimated using a multi-compartment model. Intra-(ICV) and extracellular (ECV) volumes are calculated using a fluid distribution model (FDM) based on Hanai's mixture theory. The input variables of the FDM are intra-and extracellular resistance data that have been fitted from impedance spectra with a Cole-Cole model. Resistivity changes (RCs) due to concentration changes of Na⁺, K⁺ Cl⁻, HCO₃ ⁻ and unspecified intracellular ions are estimated. The FDM is corrected for the Rcs. Corrected ICVs and ECVs are calculated and compared with uncorrected values. The range of relative RCs between the start and end of the dialyses is −3.2% to 1.4% in the ECV and −3.7% to 1.7% in the ICV. From the RCs, volume estimation errors of −1.0% to 1.9% (ECV) and −1.2% to 2.1% (ICV) relative to the initial values have been calculated. At the end of dialysis, the percentage of the error with respect to the volume change is <15% for the ECV but >20% for the ICV. Consequently, a correction of the FDM for RCs is necessary to obtain more reliable ICV data.     

Sildenafil in dialysis patients

Some of the highest rates of erectile dysfunction are seen in patients with renal failure, especially those on dialysis. The treatment of erectile dysfunction has been revolutionized in the last decade by the introduction of sildenafil. The literature on sildenafil in dialysis patients is here reviewed. Sildenafil seems to be both safe and effective in the treatment of sexual dysfunction in the dialysis population.     

Hypertension in dialysis patients

Hypertension is a major risk for cardiovascular complications in dialysis patients. The pathogenesis of hypertension is multifactorial and is not completely understood. Hypervolemia has always been considered a major pathogenetic factor. In addition, a disturbed hormone profile with an activated renin angiotensin system, increased catecholamine, vasopressin and endothelin, and perhaps decreased nitrous oxide activity seem to play a role in the high incidence of hypertension in dialysis patients. The influence of autonomic dysfunction on blood pressure control in hemodialysis patients is not clear. The frequent use of erythropoietin during the last decade may have contributed to the increased incidence of hypertension in the dialysis population. Data from the First Report on Dialysis and Transplant in Sicily showed that hypertension is the cause of end-stage renal disease in 8% of dialysis patients and that the incidence of hypertension, as a cause of end-stage renal disease, increased with age.     

Nutrition in dialysis patients

Malnutrition is a common clinical problem in dialysis patients, which is multifactorial in origin. It is most often found in a patient of chronic renal failure (CRF) during the period when the glomerular filtration rate (GFR) falls below 10 ml/min, but dialysis is yet to be started. The loss of proteins, aminoacids and other essential nutrients during the procedure of dialysis may further aggravate the malnutrition. Poor nutrition in dialysis patients is associated with increased morbidity and mortality in the form of delayed wound healing, malaise, fatigue, increased susceptibility to infection and poor rehabilitation. In view of the above consequences, all patients on dialysis must undergo nutritional assessment. It is very vital to maintain good nutritional status in-patients on dialysis by adequate protein and calories intake, appropriate supplementation of iron, calcium, minerals and water-soluble vitamins and, of course, the supplementation should be individualised. Nutritional needs are enhanced in presence of stresses like infection or surgery to limit excessive tissue catabolism and therefore, these are the situations, which demand intensive nutrition therapy. Total parenteral nutrition (TPN) may be required for patients on dialysis in intensive care unit, using a central venous catheter. However, enteral route is always preferred to parenteral ones, whenever possible. Even after adequate dialysis has been given, dietary counselling is often required for both hemodialysis and peritoneal dialysis patients to ensure that they ingest the recommended amount of protein, calories and essential micronutrients.     

腹膜透析治疗老年慢性肾功能衰竭的临床分析

目的 分析持续性腹膜透析(PD)治疗老年慢性肾功能衰竭(CRF)患者的临床效果,探讨PD在老年CRF患者中的应用经验.方法 回顾性分析89例老年CRF患者接受PD(简称老年PD组)治疗后的临床表现和生化指标、主要并发症、存活率、死亡原因等,并与53例非老年PD组相比较.结果 老年PD组的原发疾病以糖尿病(37.08%)、原发性高血压(30.34%)为主,而非老年PD组则以肾小球肾炎(54.72%)为主.两组患者的1年与3年存活率差异无统计学意义,腹膜炎仍是两组患者退出PD的主要原因.老年组的病死率明显高于非老年组,感染与心脑血管病是两组患者的主要并发症和死亡原因.低钾血症在老年PD患者中非常普遍.结论 腹膜透析在老年CRF患者的治疗中有效,但长期存活仍受腹膜炎、心脑血管病并发症的影响,老年PD患者的低钾血症应引起足够的重视.     

腹膜透析治疗老年慢性肾功能衰竭的临床分析

目的分析持续性腹膜透析(PD)治疗老年慢性肾功能衰竭(CRF)患者的临床效果,探讨PD在老年CRF患者中的应用经验。方法回顾性分析89例老年CRF患者接受PD(简称老年PD组)治疗后的临床表现和生化指标、主要并发症、存活率、死亡原因等,并与53例非老年PD组相比较。结果老年PD组的原发疾病以糖尿病(37.08%)、原发性高血压(30.34%)为主,而非老年PD组则以肾小球肾炎(54.72%)为主。两组患者的1年与3年存活率差异无统计学意义,腹膜炎仍是两组患者退出PD的主要原因。老年组的病死率明显高于非老年组,感染与心脑血管病是两组患者的主要并发症和死亡原因。低钾血症在老年PD患者中非常普遍。结论腹膜透析在老年CRF患者的治疗中有效,但长期存活仍受腹膜炎、心脑血管病并发症的影响,老年PD患者的低钾血症应引起足够的重视。     

Prostatic adenomectomy in dialysis patients

A case of a 55-year old patient is presented with terminal renal insufficiency and a massive prostatic adenoma causing urinary tract obstruction. The case history of the patient on mandatory dialysis was complicated by recurrent, therapy resistant urinary tract infections accompanied by septic fever outbreaks and anemic relapses. Following suprapubic transvesical adenomectomy, no fever episodes, negative urine cultures and improvement in the anemic condition were all noted. Due to the fact that the upper age limit for acceptance into a hemodialysis program and possible kidney transplantation has been raised, it is important to note that patients with prostatic adenomas may be frequently encountered. Dialysis patients require successful treatment of urinary tract obstructions prior to transplantation. Immunosuppressive therapy which follows transplantation increases risk of infection which can endanger the graft and the patient's life.