[Factors influencing signal-averaged ECG parameters in hemodialysis patients]

The aim of the present study was to estimate the influence of hemodialysis process (HD) on the signal-averaged ECG (SAECG) parameters and to evaluate possible factors promoting SAECG parameters disturbances in the group of hemodialysis patients (HD-pts). 55 selected HD-pts entered the study. SAECG parameters (QRS duration, root-mean-square of the terminal 40 ms of the QRS--RMS40, low-amplitude signal duration--LAS40), were measured pre and postdialysis. Total (TBW), extracellular (ECW) and intracellular body water (ICW) calculated per kg of HD-pts body weight were estimated pre and postdialysis by using whole body bioimpedance. Two dimentional echocardiography was performed before HD. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha, CRP and intact parathormon were measured before HD. LP were found only before HD in 12.73% of patients. HD induced the decrease of LAS40 duration and the increase of RMS40 value in the of group of LP positive HD-pts (p<0.001 in both cases). The values of TBW and ECW calculated per kg of body weight as well as IL-6 and CRP levels were significantly higher in the LP positive in comparison with the LP negative patients (p=0.006 and 0.004 respectively). Induced by HD changes of RMS40 correlated with pre vs postdialysis values of TBW (r=0.499, p=0.001) and ECW (r=0.556, p<0.001) calculated per kg of body weight. Our study revealed that, that abnormal SAECG parameters and LP are frequently detected in HD-pts. The presence of LP in HD-pts in great part depends on the functional abnormalities (especially on the HD-pts hydration status) corrected by the HD process. The clinical significance of the proinflammatory factors (IL-6 and CRP) needs further investigation.

[Whole body versus segmental bioimpedance measurements (BIS) of electrical resistance (Re) and extracellular volume (ECV) for assessment of dry weight in end-stage renal patients treated by hemodialysis]

The precise estimation of the hydration status of the human body has a great meaning in the assessment of dry weight in end-stage renal disease patients treated by hemodialysis. The bioimpedance technique (BIS) is postulated as easy in use and as a non-invasive method in monitoring the size of hydrate space such as total body water (TBW) and extracellular volume (ECV). However, the precision of the method (Whole Body Bioimpedance Technique) has been questioned in several research papers. One of the problems lies in fluid transfer from peripheral spaces (limbs) to the central space (trunk) while changing the position of the body (orthostatic effect). This phenomena can be eliminated using segmental bioimpedance technique (4200 Hydra, Analyzer, Xitron, San Diego, CA, U.S.A.). The purpose of the study was to estimate the changes of electrical resistance (Re) the extracellular volume (ECV) at the time -pre, and -post 10 hemodialysis sessions using whole body bioimpedance technique (WBIS) in comparison to BIS measurements in specific segments of the body; arm (ECVarm), leg (ECVleg), trunk (ECVtrunk). The sum of changes in extracellular volume (ECV) in segments (2ECVarm+ ECVtrunk + 2ECVleg) was 13.26 +/- 1.861 L in comparison to 17.29 +/- 2.07 L (p < 0.01) as measured by WBIS technique at the time before HD. The changes in electrical resistance Re was of 558 +/- 68 W as calculated from the sum of segments versus 560 +/- 70 W (p < 0.05) as measured by WBIS. At the time after hemodialysis the sum of segmental ECV volume measurement was of 11.42 +/- 1.28 L in comparison to 14.84 +/- 1.31 (p < 0.001) from WBIS the whole body technique (WBIS) and changes in electrical resistance Re was of 674 +/- 67 W as calculated from the sum of segments versus 677 +/- 64 (p < 0.05) W respectively. The observed difference between the identical electrical resistance Re as measured by WBIS in comparison to the sum of segment measurements and important difference between ECV volume as measured by WBIS versus sum of segment ECV measurements can be partly explain by non-cylindric nature of human body composition. However, the segmental bio-impedance technique is a method which gives us more accurate data about the extracellular volume taken from each segment in the hemodialysis patient but the accuracy of trunk water assessment is still a problem.

Influence of the hepatocellular damage on the clinical usefulness of biochemical markers of bone metabolism and parathormon in haemodialysed patients

BACKGROUND

The present study was undertaken to determine if hepatitis C virus (HCV) and cytomegalovirus (CMV) infections, as well as biochemical indices of liver damage, can significantly influence the relationships occurring between markers of bone formation, resorption and PTH in hemodialysis patients.

MATERIAL/METHODS

76 HD patients were tested for anti-HCV and anti-CMV antibodies. Serum intact PTH osteocalcin, total and bone isoenzyme of alkaline phosphatase, and plasma tartrate-resistant acid phosphatase were determined as bone metabolism indices. Serum alanine aminotransferase (ALT) and gamma-glutamyl transferase (gamma-GT) were measured as markers of hepatocyte function. The patients were divided into subgroups according to serological and enzymatic status.

RESULTS

37 patients were anti-HCV positive, 61 were anti-CMV positive, and 35 were both anti-HCV and anti-CMV positive. 13 patients were free of viruses. Elevated ALT and gamma-GT activity was found in 26 and 15 patients respectively. Indices of bone formation, resorption and PTH values showed no significance differences in the respective subgroups. Markers of bone formation significantly correlated with one another, as well as markers of bone resorption and intact PTH in all patients. In the subgroup of patients with increased gamma-GT activity, significant differences were found in the slopes of the regression lines occurring in most of the estimated correlations in comparison with all other subgroups.

CONCLUSIONS

In renal osteodystrophy, hepatocellular damage indicated by an increase of gamma-GT influences the relationship between the biochemical markers of bone metabolism and parathormon levels, but the presence of anti-HCV and anti-CMV antibodies does not.

The obtention of vascular access on the arm for hemodialysis

The chronic dialysis is the way of replacing the lost kidney function. Well functioning vascular access is the prerequisite for chronic hemodialysis treatment. The arteriovenous fistulas are the optimal form of vascular access. In patients, in whom the usual sites for fistula have been exhausted the vascular fistula on the arm was placed. 53 dialysis accesses were performed on the arm between 1989 and 1999. All subcutaneous fistulas were created by the junction of the cephalic vein with brachial artery, just above the cubital fossa on the anterior surface of the arm. All anastomoses were created in the operating room under local anesthesia. The preferred route for exposure of cephalic vein was making the single incision along the arm. When the distal part of cephalic vein has been ligated and divided, the adequate space for the graft in the tunnel was performed. End-to-end anastomosis between the distal end of vein and side of brachial artery was completed using the suture material. In 50 hemodialysed patients the regular flow through the arteriovenous fistula was observed. Fistula thrombosis occurred in 2 cases. In 4 examined patients we observed blood extravasation in the subcutaneous tissue, where the tunnel was created. In 5 patients the local cellulitis was noted. The late vascular complications were evaluated in 15 cases. Aneurysms were revealed clinically in 3 patients and false aneurysm occurred in 2 patients. The described late complications required no surgical correction. The anterior side of the arm is the best place for arteriovenous access used for hemodialysis, in patient without the possibilities of surgical creation of the forearm's fistula.

[Chronic venous occlusion in hemodialysis-related fistula: diagnosis and endovascular treatment]

The main reasons of fistula dysfunction are stenosis and thrombosis. There are two kinds of thrombosis: acute and chronic. Acute thrombosis is total fistula occlusion while chronic occlusion is partial venous occlusion with collateral veins, which lead to impair fistula's function. 450 dialysis fistulas were referred to US (ultrasound) examination. Among 392 patients with fistula dysfunction, 71 presented chronic venous occlusion in hemodialysis shunt. 35 patients were qualified to endovascular recanalization. The mean length of the occluded segment was 3-35 cm (subclavian vein 2-4 cm). 38 patients underwent angiography (35 before endovascular treatment). Technique of recanalization included antegrade venous puncture, insertion guidewire (0.021'), catheter (5 Fr), balloon catheter (5-8 mm) and in 2 cases stent placement. Colour Doppler allowed to diagnose 34 (97%) cases of chronic venous occlusion in hemodialysis shunt. Decrease of mean flow volume in brachial artery--709 +/- 395 ml/min. (50-1500 ml/min) was statistically significant (p = 0.0015). Normal mean flow volume was 1242 +/- 641 ml/min. 20 of 35 recanalization procedures were performed successfully. The main reason of failure was perforation or false channel. Mean primary patency was 75% after 3 months. Mean cumulative was 85% (10/12) after 6 months. Chronic venous occlusion is often present in hemodialysis shunt and reduces flow volume. Percutaneous recanalization results aren't magnificent but there is only kind treatment for many patients with fistula failure.

[Measurement of fluid compartments using electrical bioimpedance for assessment of target weight in hemodialysis patients]

The prescription of optimal hydration status in hemodialysis patients remains a much disputed topic in dialysis treatment. In particular, assessment of the patients optimal weight ("target weight") poses considerable difficulties. Multifrequency bioimpedance spectroscopy analysis (BIS) has been recommended as a non invasive, practical, and relatively non expensive method to determine hydration and nutritional status in patients on maintenance hemodialysis (HD). In the current study we used whole body BIS analysis for determination of body water (BW) compartments; total body water (TBW), extracellular water (ECW), and intracellular water (ICW) in 133 healthy adults, and in 227 hemodialysis patients with end-stage renal disease. BIS results were compared to anthropometric measurements. Our results showed strong correlation between TBW measured by BIS in control group in comparison to anthropometric calculation (p = 0.001). In HD patients we observed higher range of TBW, and TBW/ECW ratio (from 15.6 to 56.1 L and from 0.33 to 0.78), as measured by BIS at pre-HD, and also post-HD period (TBW ranged from 13.1 to 56.2 L, ECW/TBW ratio ranged from 0.33 to 1.27). The TBW BIS results did not correlate with anthropometric calculation. We postulate using of multi-frequency bioimpedance technique in precise determination of fluid compartments and in consequence in the assessment of "target weight" in hemodialysis population.

[Basic terminology for describing hemodialysis fistula]

Many specialists: nephrologists, surgeons, radiologists and nurses pay much attention to dialyzed patient using different terminology. The presented work establishes the principal rules of describing hemodialysis fistula to find convergence in terminology.

[Use of bioimpedance spectroscopy techniques for monitoring fluid balance in patients with end stage renal failure]

Adequate body hydration is considered the key element of fluid management in critically ill patients including group with end stage renal failure. Bioimpedance technique is widely used as a non-invasive, simple and accurate method to measure body composition. The purpose of the paper was to prescribe the using of single, and multifrequency bioimpedance spectroscopy technique for estimation of fluid balance in end-stage renal patients. We also discussed some measurements and data modelling problems, including postural change effect, and intercompartmental fluid shift during dynamic monitoring of fluid balance.

[Effect of arterio-venous fistula blood flow dynamics on ECG abnormalities in chronic hemodialysis patients]

The dialysis doses is mostly dependent on well functional permanent vascular access. From the other hand high vascular access blood flow (Qva) may induce cardiac problems in HD patients. The purpose of this study was to investigate the effect of vascular access dynamics on electrocardiographic abnormalities in hemodialysis patients. Therefore, forty non-diabetic, HD patients, with native vascular access (VA) were divided into two equal groups; with Qva > 1500 ml/min (group A), and also Qva < 1500 ml/min (group B). The average of VA survival period was 28 +/- 18 (mean +/- SE) (group A), and 29 +/- 15 (months) (group B). The Qva measurements monitoring by color Doppler sonography included also: maximal velocity (Vmax), time average of maximal velocity (TAMX), pulsate index (PI), and resistive index (RI). Kt/V index was calculated, as classical parameter of adequacy, and also shunt recirculation using 3 urea samples was measured. For estimation of cardiac function we used M-mode echocardiography, and 24-hours ECG (Holter) monitoring. The occurrence of ventricular (VE), and supraventricular extrasystoles (SVE), ST-T, and ST characteristic as well were monitored by 24-hours Holter.

CONCLUSIONS

1. In the group with high Qva (A) we observed significantly higher number of VE, and also of SVE recorded by Holter monitoring compared with the low Qva group (B). 2. The mean number of patients with ST-T changes was higher in group A (12 vs. 7), but number of patients with recorded by Holter ST depression, and ST elevation between investigated groups were similar. 3. The mean number of ventricular arrhythmias of Lown classified as 4A, and 4B of Lown grading was significantly higher in the group with high Qva (A).

Effects of serotonin-active drugs on prolactin secretion in male rats

The effects of several serotonin acting drugs on serum prolactin levels were studied in male rats. Administration of the serotonin precursor, 5-hydroxytryptophan (5-HTP; 250 mg/kg ip) or pargyline (5 mg/kg ip) with 5-HTP (100 mg/kg ip) significantly increased serum prolactin concentration. Pretreatment of rats with the serotonin agonist, quipazine (10 mg/kg ip) caused increase in serum prolactin levels. Depletion of serotonin stores by pretreatment with p-chloro-phenylalanine methyl-ester (PCPA; 3 x 300 mg/kg ip) significantly prevent the effect of quipazine on prolactin levels. Serotonin uptake blocker, fluoxetine (10 mg/kg ip) produces an increase in the prolactin concentrations of the serum. Administration of the reserpine (2.5 mg/kg sc) did not affect serum prolactin levels. Both serotonin receptor blockers, cyproheptadine (0.5 mg/kg ip) and pizotifen (1 mg/kg ip) caused a week decrease in the serum prolactin levels. Significant changes in concentrations of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in brain of rats pretreated with above serotonin-active drugs were found. These results indicate that serotonergic system can modify secretion of prolactin.