Non-fistula Arm Research Articles

The effect of changes in intra-compartmental bioimpedance measurements with early intra-dialytic hypotension during haemodialysis.

Intra-dialytic hypotension (IDH) remains the commonest problem associated with routine haemodialysis treatments. Fluid shifts from intracellular(ICW) and extracellular(ECW) compartments to refill plasma volume during haemodialysis with ultrafiltration. We studied the effect of relative changes in ICW and ECW indifferent body segments using multifrequency segmental bioimpedance during haemodialysis and IDH episodes. Of 42 haemodialysis patients,16 patients (38.1%) developed IDH within the first hour of dialysis. Patients with and without early IDH were well-matched for demographics and starting bioimpedance measurements. However, after 60 min, the relative change in in ECW/ICW ratio between the non-fistula arm and leg was significantly different for the early IDH group median -1.07 (-3.33 to 0.8) versus 0.61 (-0.78 to 1.8), p < 0.05, whereas there no differences in ultrafiltration rate, relative blood volume monitoring or on-line clearance. Monitoring serial changes in fluid status in different body compartments with bioimpedance may potentially prevent IDH in the future.

Arteriovenous Oscillometric Plethysmography for Fistula Functional Testing.

The aim of the presented prospective observational study was to evaluate the effect of fistula flow on peripheral wave morphology and pulse wave velocity by means of the oscillometric Vicorder®-device with the purpose of fistula surveillance. Digitized and normalized curves of 53 haemodialysis patients at the fistula and non-fistula arm were analysed. Slope parameters and the areas under the curve of characteristic sections of pulse waves as well as the power spectrum of the pulse waves and their first and second derivatives were computed. Furthermore, the amplitude of volumetric change (AMP) was assessed. Duplex sonography served as a reference method. In the comprehensive set of novel pulse wave parameters significant inter-arm differences were demonstrated and a significant delay of the systolic maximum at the fistula arm in comparison to the non-fistula arm (204 ± 3.4 vs. 162 ± 5.3 ms, p &lt; 0.001) was proven. Unexpectedly, pulse wave velocity apparently did not differ between both arms (7.85 vs. 8.05 m/s at the fistula/non-fistula side, p = 0.942). The inter-arm differences of the slope parameters were more pronounced in forearm than in upper arm fistulas. Finally, we showed that the inter-arm difference of AMP correlated with volume flow (r = 0.326 with p = 0.017). Pulse waves as assessed by oscillometric pulse wave analysis have distinct features at fistula and non-fistula arms. This is due to enhanced arteriovenous flow, i.e. in both the brachial artery and the fistula vein. The analysis of those alterations has the potential to assess fistula function.

#2464 Association of vascular access flow and volume status on fistula arm by bio-impedance analysis

Abstract Background and Aims Multi-frequency bio-impedance is a tool of body composition measure and can monitor changes in extracellular volume during dialysis. Arterio-venous fistulae (AVF) could potentially affect fluid retention in the arm. We investigated whether multi-frequency bio-impedance could defect AVF stenosis or association of AVF with fluid retention in the AVF arm. Method We measured the extracellular water (ECF) and total body water (TBW) in AVF arm following hemodialysis by multi-frequency bio-impedance (Inbody S10®) using an eight-electrode contact technique. We measured AVF or AVG flow by transonic ultrasonography using an ultrasound dilution technology (HD 03®) in hemodialysis. Results Total 82 patients (male 38 patients : female 44 patients) were enrolled. The causes of ESRD were DM : non-DM = 38 : 44. The mean age of patients was 54.89 ± 13.21 years. The ECW/TBW ration of fistula arm was a significantly higher than the ECW/TBW ration of non-fistula arm (0.389 ± 0.010 vs. 0.382 ± 0.001; p&amp;lt;0.05). The ECW/TBW ration of fistula arm was a significantly negative correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). The 5kHz reactance of fistula arm was a significantly positive correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). The 5kHz Phase Angle of fistula arm was a significantly positive correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). Conclusion Absolute and also relative extracellular fluid volumes are increased in the fistula arm of hemodialysis. We thought that extracellular fluid volumes in the fistula arm were associated with access flow level (mL/min) and/or relative fistula stenosis. We suggest that multi-frequency bio-impedance can be a useful assistant tool of vascular access flow measure.

Oscillometric pulse wave analysis for detecting low flow arteriovenous fistula

BackgroundPulse wave analysis may be useful to assess fistula function. We aimed to prospectively evaluate if convenient oscillometric devices are applicable to detect flow below 500 ml/min in a real life clinical setting.MethodsPulse waves were recorded ambilaterally with the vicorder® device at the brachial artery in 53 patients on haemodialysis with native fistula. Primary variables consisted of the mean slope between the systolic maximum and the diacrotic notch (Slope2), the sum of the mean slopes in the four characteristic sections of pulse waves (Slope∑) and the amplitude of relative volumetric change in the measuring cuff at the upper arm (AMP). Fistula flow was measured with the use of duplex sonography using a standardized approach.ResultsParameter values above or below the median indicated measurement at the non-fistula side, with sensitivities/specificities of 0.79/0.79 (p < 0.001) for Slope 2, 0.64/0.64 (p = 0.003) for Slope∑ and 0.81/0.81 (p < 0.001) for AMP if measurements at the fistula and non-fistula arm were considered. ROC-analyses of parameter values measured at the fistula to detect low flow demonstrated AUCs (with CI) of 0.652 (0.437–0.866, p = 0.167) for Slope2, 0.732 (0.566–0.899, p = 0.006) for Slope∑ and 0.775 (0.56–0.991, p = 0.012) for AMP. The point with maximal youden’s index was regarded as optimal cut-off, which corresponded to sensitivities and specificities of 0.8/0.56 for slope2, 0.86/ 0.56 for Slope∑ and 0.93/0.78 for AMP.ConclusionFunctional surveillance with oscillometry is a promising clinical application to detect a low fistula flow. Among all investigated pulse wave parameters AMP revealed the highest diagnostic accuracy.Graphical

Accumulation of Advanced Glycation End Products Independently Increases the Risk of Hospitalization Among Hemodialysis Patients

Objective: To determine the association between AGE accumulation detected by skin-autofluorescence (SAF) and hospitalization among ESKD patients.Materials and Methods: 196 ESKD patients from two hemodialysis (HD) units in Bangkok were enrolled in this retrospective study from November 2015 to March 2016. Before HD treatment, AGEs were measured with the SAF device on the area with intact skin on the volar surface of the non-fistula arm. The study concluded in December 2020, and the number of and causes of hospitalization were reviewed. A logistic regression model was used to determine the association between SAF level and patient hospitalization.Results: Of the 196 patients enrolled in the study, SAF was measured in 165 patients with a mean (SD) age of 69.2 (13.0) years. Most of the participants were non-smokers who had hypertension and diabetes and were on high-flux dialyzers. The average weekly spKt/V was 2.1, and the mean (SD) SAF was 3.05 (0.81) AU. The group with high SAF consisted of older patients and had a higher proportion of diabetics and smokers, but this was not statistically significant when compared to the low SAF group. In the multivariable analysis model, SAF greater or equal to 3.05 AU (OR = 2.28; 95% CI, 1.05–4.94; P &lt; 0.05) and increased age (OR = 1.05; 95% CI, 1.01–1.09; P &lt; 0.05) were associated with an increased risk of hospitalization.Conclusion: Higher values of age and SAF were independently associated with increased risk of hospitalization among ESKD patients.

The Case | Connecting the “dots”

A 52-year-old male was admitted with concerns of malaise, nonspecific back pain, and 14-kg unintentional weight loss over 3 months. He has end-stage kidney failure secondary to IgA nephropathy with dialysis vintage of 13 years and has been anuric. His background includes parathyroidectomy with a one-gland implantation to the nonfistula arm, hemicolectomy for ischemic colitis, large incisional hernia, obesity, and anxiety. There was no smoking history or family history of malignancy.

P1333PULSE WAVE ANALYSIS UNDER THE CONDITIONS OF HIGH ARTERIAL FLOW: ASSESSMENT OF SHUNT FUNCTION AND REACTIVE HYPEREMIA

Abstract Background and Aims Fistula-creation as well as reactive hyperaemia increase local arterial blood flow. We wanted to analyse the impact of these haemodynamic changes on pulse wave (PW) morphology to assess fistula- and endothelial function. Method We conducted a clinical pilot study including 56 patients with functioning forearm fistula. PW morphology in the A. brachialis was assessed tonometrically at the non-fistula and fistula arm using the SpygmoCor® device. We also performed a PW analysis on the non-fistula arm under the condition of reactive hyperaemia (possible in 43 patients). Duplex-sonography was used as a complementary and reference method. Results In comparison to measurements under physiologic conditions, both the fistula arm (a) and the non-fistula arm with reactive hyperemia (b) showed marked differences in the pulse wave morphology (figure). The changes in PW morphology were most prominent in the area of the diacrotic notch and could be assessed as the differences of the sum of the mean slope (Δλ in mmHg/ms) between the diacrotic notch and the main preceding and subsequent inflexion point. Measurement with duplex-sonography confirmed increased peak blood flow velocity in the arteria brachialis (ΔVmax in cm/s) under both conditions. Statistical significance could be proved for Δλ and for ΔVmax (table). Finally, bivariate regression analysis revealed a correlation of Δλ with ΔVmax (figure; c: p=0.001 and r=-0,483 for interarm-differences of the fistula and non-fistula arm; d: p= 0.030 and r=-0.343 for the differences between the physiologic state and reactive hyperaemia at the non-fistula arm). Conclusion PW analysis under high flow conditions has the potential to be a new useful clinical tool in nephrology to monitor fistula- as well as endothelial function assessed by reactive hyperaemia. The findings should be verified in a trial with clinical endpoints.

The effect of an arteriovenous fistula and haemodialysis on anthropometric measurements of the upper arm.

Haemodialysis (HD) patients are at increased risk of sarcopenia. Measurements of triceps skinfold thickness (TSFT) and mid-upper arm circumference (MUAC) are used to estimate muscle mass. An arteriovenous fistula is the preferred vascular access for HD patients, and we wished to determine whether anthropometric measurements were affected by the fistula and HD treatment. One hundred and forty-four HD patients, 90 (62.5%) males, mean age 63.1 ± 15.4 years, had measurements pre- and post-HD. TSFT was similar in the arms, whereas MUAC and corrected mid-upper arm muscle circumference (CMUAMC) were greater in the fistula compared with the non-fistula arm (MUAC pre-HD 30.0 ± 5.2 vs 29.2 ± 4.7 and post-HD 29.6 ± 5.1 vs 28.5 ± 4.7, p < 0.001; MUAMC 23.5 ± 4.0 vs 22.5 ± 4.1, and post-HD 22.9 ± 4.0, and 22.0 ± 3.7 cm p < 0.01). Following HD; TSFT did not change, but MUAC and CMUAMC fell significantly in both arms (p < 0.01). When screening for sarcopenia in HD patients, anthropometric measurements should be taken post-HD in the non-fistula arm.

Measurement of Muscle Strength in Haemodialysis Patients by Pinch and Hand Grip Strength and Comparison to Lean Body Mass Measured by Multifrequency Bio-Electrical Impedance

Background: Muscle weakness is a risk factor for mortality in haemodialysis (HD) patients; we wished to determine whether measuring the composition of the arm with bioimpedance was associated with arm muscle strength. Methods: We measured pinch strength (PS) and hand grip strength (HGS) in 250 adult HD patients with corresponding post-dialysis multifrequency bioelectrical assessments with segmental body analysis. Results: Mean age 64.0 ± 15.6, 66% male and 45.6% diabetic. The maximum HGS in the dominant or non-fistula arm was 18.9 ± 9.2 kg and PS 4.09 ± 1.96 kg respectively, with a correlation of r = 0.80, p < 0.001. HGS was associated with body cell mass (β 0.37, p < 0.001) and PS with appendicular muscle mass (β 0.06, p < 0.001). Both HGS and PS were independently associated with the ratio of extracellular water (ECW) to total body water (TBW); β -139.5, p = 0.024, β -44.8, p < 0.001 in the arm. The presence of an arterio-venous fistula increased the ECW/TBW ratio in the arm from 0.383 ± 0.009 to 0.390 ± 0.012, p < 0.05. Conclusion: Muscle strength measured by HGS and PS was associated with both markers of whole body and segmental body composition within the arm, particularly ECW/TBW. Bioimpedance measurements and assessment of muscle strength should be measured in the non-fistula arm.

Skin autofluorescence advanced glycosylation end products as an independent predictor of mortality in high flux haemodialysis and haemodialysis patients.

Haemodialysis (HD) patients have an increased risk of cardiovascular death. In addition to the standard cardiovascular disease (CVD) risk factors, HD patients have additional risk factors including bone mineral disorders, anaemia and uraemic toxins, including advance glycosylation end product (AGEs). AGEs increase in HD patients due to reduced renal clearance and increased production. Tissue AGEs measured by skin autofluorescence (SAF) have been shown to be more reliable and reproducible to asses AGE accumulation in HD patients compared with serum levels. We wished to determine whether increasing SAF due to AGEs was associated with reduced survival in HD patients. We measured SAF in the non-fistula arm in a cross-sectional study of 332 thrice weekly HD outpatients who were then followed prospectively for 30 months. Mean patient age was 65.7 ± 15.1 years, 64.2% male, 41.9% diabetic, mean dialysis vintage 65.1 (range 1-413) months, with an average sessional Kt/Vurea of 1.43 ± 0.34. A percentage of 61.1 had a history of hypertension, 32.2% had CVD, 16% had peripheral vascular disease (PVD) and 37% was current smokers. The mean SAF was 3.27 ± 0.96 IU, and patients with SAF above the mean (>3.27 IU) had a higher risk of death, and higher SAF was independently associated with increased mortality: hazard ratio 12.95 (1.60-104.8), P = 0.016. Accumulation of AGEs, measured by SAF, was independently associated with higher risk of death in HD patients. Additional studies are required to determine whether a reduction in tissue AGEs in dialysis patients may reduce mortality in this high-risk population.

Creation of an Arteriovenous Fistula Is Associated with Significant Acute Local and Systemic Changes in Microvascular Function

Background: Native arteriovenous fistulae (AVF) are the vascular access of choice for haemodialysis. The consequences of AVF formation on microvascular function, locally or systemically, are unknown. Methods: We recruited 43 predialysis patients undergoing AVF formation. Patients were studied 2 weeks prior to the planned AVF operation and 2 weeks postoperatively. Thirteen patients with failed AVF were subsequently utilised as sham controls. Laser Doppler perfusion imaging was used to measure subcutaneous microvascular blood flow. Microvascular function was assessed as an increase in perfusion in response to iontophoretic administration of vasodilatory stimuli assessing endothelial-dependent (ED) and non-endothelial-dependent (NED) vasodilatation. Results: Patients with successful AVF formation had a significantly reduced ED vasodilatation in the fistula arm (-36 ± 46%, p < 0.001). Only NED vasodilatation was significantly reduced in the non-fistula arm (23 ± 40%, p = 0.01). Patients who had an unsuccessful AVF operation exhibited no recordable changes. Conclusions: Formation of an AVF was associated with local and remote changes in microcirculation. Further assessments are underway to examine the contributions of local shear stress, vasoreactive substances and the autonomic responses. Although the clinical significance of these findings is not yet clear, it is intriguing that AVF formation is associated with such widespread and profound changes in microperfusion.

Changes in Upper Limb Extracellular Water Content during Hemodialysis Measured by Multi-Frequency Bioimpedance

Hemodialysis patients are at risk of chronic volume overload, with consequent increased cardiovascular morbidity and mortality. Multifrequency bioimpedance allows assessment of body fluid volumes. Devices vary from two paired electrodes which measure bioimpedance down one side of the body to four paired electrodes which measure both sides of the body. As arteriovenous fistulae may cause arm swelling, we investigated whether the presence of a fistula affected bioimpedance limb measurements. We audited the change in extracellular water (ECW) and total body water (TBW) in the arms following hemodialysis in 414 adult patients attending for routine mid-week hemodialysis session by multifrequency bioimpedance using a four-paired electrode bioimpedance device (InBody 720; Biospace, Seoul, South Korea). Patients with right-sided brachial fistulae had a greater percentage ECW/TBW in the fistula arm both prior to and post dialysis compared to those dialyzing with catheters (pre 39.6 ± 3.5 vs. 38.4.3 ± 1.6 and post 38.5 ± 1.3 vs. 37.8 ± 1.1, p<0.01), but there was no difference in the ECW/TBW in the non-fistula arm, pre dialysis between those dialyzing with fistulae compared to catheters, but the ECW/TBW was greater post dialysis with both brachial (38.4 ± 1.1) and radial fistulae (38.1 ± 1.3) compared to those with catheters (37.7 ± 0.9, p<0.05 respectively). Although absolute and also relative extracellular fluid volumes are increased in the fistula arm of hemodialysis patients, particularly right-sided and with brachial fistulae, the amount of fluid is unlikely to be of clinical significance when making bioimpedance measurements in the non-fistula side of the body to determine volume status.

Electrocautery induced artifactual ST segment depression in leads II, III and aVF on intra operative 5-lead electrocardiogram

To the Editor, We describe a case of electrocautery-induced artifactual inferior wall ischemic changes in a 31 year old male patient with chronic kidney disease (CKD) undergoing repeat live donor kidney transplantation. He was a known case of CKD since last 7 years and undergone live donor kidney transplantation 6 years back. He was on maintenance hemodialysis twice a week again since a year. He was continued to be hypertensive since last 10 years even after kidney transplantation and was on three anti hypertensive medications. He had dyspnea on exertion class II and New York Heart Association status II. His preoperative 12-lead electrocardiogram (ECG) showed normal sinus rhythm with left ventricular hypertrophy (LVH). Echocardiogram reported concentric LVH, mild mitral regurgitation, mild pulmonary artery hypertension, minimal pericardial effusion and left ventricular ejection fraction of 40 %. All anti hypertensive medications were continued till morning on day of surgery. In the operating room, 5-lead ECG, pulse oximetry and non-invasive blood pressure monitoring was applied on non-fistula arm. Anesthesia was induced with fentanyl, propofol and atracurium. Right internal jugular central venous catheter was placed under ultrasound guidance and surgery was allowed to start. Immediately after skin incision, ST segment depression was noted in lead II (Fig. 1a). He was hemodynamically stable with blood pressure of 147/89 mm Hg and pulse rate of 88 per minute. ST segment depressions were temporary and intermittent with the use of unipolar electrocautery by surgeon. Correct placement of ECG electrodes was confirmed and all lead ECG view was seen on monitor to look at other leads for similar changes. It was noticed that ST segment depressions were present in lead II, III and aVF with slight ST elevation in aVR (Fig. 1b). These intermittent and temporary ECG changes were present and reproducible throughout the surgery. Electrocautery (anode) plate was applied on posterior aspect of upper part of right thigh, quite away from the ECG electrodes. Monitor used was one attached to Datex-Ohmeda S/5 Avance anesthesia workstation and was in routine use without similar occurrence in other cases. Post operative his 12-lead ECG was same as preoperative and enzyme marker (troponin T, troponin I and CK-MB) were negative for ischemia or infarction. Electrocautery induced artifact in intraoperative ECG showing ST changes have been reported previously. Jain et al. [1, 2] reported electrocautery induced ST segment depression in two different patients with coronary artery disease undergoing non cardiac surgeries. In an another case reported by Jain et al. [3] showed ST segment elevation in lead V5 with concurrent ST depression in lead II, in a CKD patient undergoing cadaveric kidney transplantation. Similar ST segment depression was also reported by Ketchey et al. [4]. In present case ST segment depressions were noted in lead II, III and aVF, and this point toward diagnosis of inferior wall ischemia or it can be a mirror image of ischemia in another area (e.g. anterior ischemia) or other non-ischemic diseases. Being an American society of anesthesiologist physical status grade III patient, kidney transplant recipient patient is always at great suspicion for perioperative cardiac arrhythmias, myocardial ischemia and infarction. The five S. L. Solanki (&) K. Kishore V. K. Goyal Department of Anesthesiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Rae-Bareilly Road, Lucknow 226014, India e-mail: me_sohans@yahoo.co.in

Hand grip strength as a nutritional marker in pd and hemodialysis patients

This is a prospective study evaluating hand grip strength as a nutritional marker in maintenance dialysis patients. Thirty CAPD and 50 MHD patients were assessed for hand grip strength (in the non-fistula arm) and demographic variables. In the MHD, 60% diabetic and in PD 66.7% were diabetic. In the MHD patients, Mean Age - 53.62±12.45, 78% Males and 22% Females, Hb-9.7±1.1 g/dL and 3.86±2.83 years on dialysis and in PD patients, mean age - 58.6±11.52 , 63.3% males and 26.7% females, Hb – 10.5±1.4 g/dL and 3.33±2.6 mean years on dialysis. Hand Grip Strength was 11.58 + 3.7 kg pre-dialysis and 9.2 + 3.6 kg post dialysis in MHD and 10.8 + 2.9 kg in PD patients. We found that malnutrition was present in 90% of MHD (10% severe, 24% moderate, 56% mild) and 100% (6.7% severe, 40% moderate, 53.3% mild) of PD patients via hand grip comparison. In conclusion, hand grip strength is a simple tool to measure the muscle mass as a measure of malnutrition in dialysis patients.

Range for Normal Body Temperature in Hemodialysis Patients and Its Comparison with That of Healthy Individuals

Background/Aims: Patients with chronic kidney disease undergoing hemodialysis have an altered homeostasis leading to altered body temperatures. We aimed to determine the range for normal body temperature in hemodialysis patients and compared it to healthy individuals. Also, we determined how much axillary temperatures differed from oral temperatures in both groups and whether axillary temperature is affected by the presence of an arteriovenous fistula (AVF) in hemodialysis patients. Methods: Oral and axillary (left & right) temperatures were recorded using an ordinary mercury-in-glass thermometer in 400 subjects (200 hemodialysis patients, 200 healthy individuals) at the Sindh Institute of Urology and Transplantation from mid-May to mid-June 2006. Comparisons were made between the temperatures of both groups. Results: Mean oral temperature in hemodialysis patients was higher than in healthy individuals [98.7°F (37°C) vs. 98.4°F (36.8°C); p < 0.001], as was the mean average axillary temperature [97.7°F (36.5°C) vs. 97.5°F (36.3°C); p = 0.02] and mean left axillary temperature [97.9°F (36.6°C) vs. 97.6°F (36.4°C); p < 0.001]. The fistula arm had higher axillary temperature in 77 (44%) hemodialysis patients. The difference between oral and axillary temperatures varied widely, making it impossible to obtain an accurate correction factor in both groups. Conclusion: Hemodialysis patients have higher normal body temperatures than healthy individuals. Axillary temperatures require cautious interpretation. In hemodialysis patients, the non-fistula arm should be preferred for recording axillary temperatures, as the presence of AVF may cause discrepancies in temperature measurements.

A Continuous and Non-Invasive Arterial Pressure Monitoring System in Dialysis Patients

Background: As symptomatic intradialytic hypotension in the hemodialysis (HD) patient is often a sudden event whose onset cannot be predicted by means of extemporary measures, continuous blood pressure (BP) measurement would be far more useful. We tested a new continuous noninvasive BP monitoring system, Harmonized Alert Sensing Technology (HASTE), which, by means of the analysis of the finger pulse wave, obtained from an O₂ sensor, estimates a beat-to-beat systolic pressure value (Esys) and supplies a continuous read-out. The study aim sought to verify the reliability of this non-invasive instrument in continuously providing systolic pressure values during HD. Methods: We studied 18 patients during HD treatment, initially comparing the Esys with the invasive blood pressure measurement (SYS). Subsequently, the Esys derived from the O₂ sensor in the arm with the shunt (S) and the arm without (N), respectively, were both compared with the cuff measurement. Results: The mean difference between SYS and Esys was 0.7 ± 13.3 mm Hg (p < 0.01; r = 0.80). There was a mean difference of 0.2 ± 21.9 mm Hg (p = NS; r = 0.67) between Esys(N) and Esys(S). The correlation was not statistically significant even between Esys(N) or Esys(S) versus the cuff measurement, respectively. Patient movement compromised the accuracy of the estimations made using the O₂ sensor in the non-fistula arm. Conclusions: A good correlation between the data estimated by HASTE compared with invasive BP suggests that the instrument may prove useful for continuously monitoring the blood pressure trends during the dynamic hemodialysis situation. However, its sensibility needs to be improved in order to be used indifferently in both arms with a view to achieving real intradialytic hypotension prevention.

Acute effects of haemodialysis on biochemical modulators of endothelial function

To assess the acute effects of haemodialysis (HD) on biochemical factors modulating endothelial function. Academic medical centre. Forty patients (age 63.5 +/- 2.2 years, mean +/- SEM) undergoing HD. Folic acid (F), homocysteine (tHcy), asymmetric dimethylarginine (ADMA), high-sensitivity C-reactive protein (CRP) and malondialdehyde (MDA) were measured pre-HD, 1 h after commencing HD and within the last hour of HD (end-HD). Endothelium-dependent and -independent vasodilatation were measured by applanation tonometry (changes in augmentation index, AIx, postinhaled salbutamol and postsublingual nitroglycerin) in conjunction with biochemical measurements. Marked reductions in serum F (616 +/- 73 vs. 273 +/- 30 nmol L(-1), P < 0.001), tHcy (16.3 +/- 0.7 vs. 11.2 +/- 0.5 micromol L(-1), P < 0.001) and ADMA (0.64 +/- 0.02 vs. 0.47 +/- 0.02 micromol L(-1), P < 0.001) occurred end-HD, whereas CRP and MDA levels did not significantly change. There was no significant change in endothelium-dependent vasodilatation, whereas endothelium-independent vasodilatation improved end-HD (-23.1 +/- 1.9 vs. -17.3 +/- 1.3%, P = 0.018). Regression analysis showed that both higher ADMA (P = 0.029) and lower F levels (P = 0.040) end-HD were determinants of reduced endothelium-dependent vasodilatation end-HD (R(2) = 0.23). HD is associated with significant reductions in F, tHcy and ADMA serum concentrations. The lack of significant effects of HD on endothelium-dependent vasodilatation could be secondary to the concomitant loss of factors either enhancing (F) or impairing (ADMA) endothelial function.

Arterial Stiffness Assessed by Digital Volume Pulse Correlates With Comorbidity in Patients With ESRD

Digital volume pulse (DVP), a noninvasive method for indirect assessment of arterial stiffness, was not tested previously in patients with end-stage renal disease (ESRD). Therefore, we compared the DVP-derived stiffness index (SI(DVP)) with aortic pulse wave velocity (PWV) determined by means of Doppler ultrasonography in 2 groups of patients with ESRD and analyzed the correlation between SI(DVP) and comorbidity. Photoplethysmography was performed on the index finger of the dominant hand or the hand from the nonfistula arm in 49 renal transplant (TX) recipients and 48 hemodialysis (HD) patients. Pulse curves were analyzed with computer assistance. Comorbidity was assessed by using an established index. The intrasubject variability of SI(DVP) was 5.7%. SI(DVP) and aortic PWV values correlated significantly (r = 0.66; P = 0.001) in patients with ESRD. SI(DVP) could not be assessed reliably in 25% and 6% of HD patients and TX recipients, respectively. Multivariate regression analyses showed that SI(DVP) increased with age in both HD patients and TX recipients (r = 0.61; P < 0.001) and with systolic blood pressure (r = 0.53; P < 0.025), mean arterial pressure (r = 0.47; P < 0.05), and pulse pressure (r = 0.52; P = 0.02) in TX recipients. Severity of comorbid status was associated highly with individual residuals of age-adjusted SI(DVP) in HD patients and TX recipients (P < 0.001). DVP allows the measurement of arterial stiffness in most, but not all, patients with ESRD. SI(DVP) values correlate with comorbidity in HD patients and TX recipients.

Effects of arteriovenous fistulas on cardiac oxygen supply and demand

Arteriovenous (AV) fistulas used for hemodialysis access may affect cardiac load by increasing the preload while decreasing the afterload. In dogs, AV fistulas have also been shown to affect coronary perfusion negatively. We investigated the net effect of AV fistulas on cardiac oxygen supply and demand. Aortic pressure waves were reconstructed from finger pressure recordings obtained on the nonfistula arm using a wave-form filter. Changes in systolic, mean, and diastolic aortic pressure were calculated, together with changes in heart rate (HR), stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR) during a 60-second compression of AV fistulas in 10 patients. Changes in cardiac supply and demand were estimated by calculating the area under the aortic pressure curve during diastole [diastolic pressure time index (DPTI)] and systole [systolic pressure time index (SPTI)], respectively. During fistula compression, systolic, mean and diastolic pressure increased by 4.2 +/- 4.3, 2.6 +/- 3.0, and 2.8 +/- 2.9 mm Hg (mean +/- SD, all P < 0.05). The HR decreased by 3.8 +/- 2.5 beats per minute (P < 0.01), and SV decreased 3.7 +/- 6.1% (NS). CO decreased 9.4 +/- 8.6%, and SVR increased 14.3 +/- 11.7% (both P < 0.05). The SPTI increased by 1.5 +/- 1.5 mm Hg.sec (P < 0.01), and the DPTI increased by 7.6 +/- 8.1 mm Hg.sec (14.8% increase, P < 0.05) during compression. The ratio of supply and demand (DPTI/SPTI) improved by 13.5 +/- 13.0% (P < 0.01) when the fistula was compressed. AV fistulas have a small effect on left ventricular oxygen demand, but decrease cardiac oxygen supply considerably.