Intradialytic Morbid Events Research Articles

Ultrafiltration-induced decrease in relative blood volume is larger in hemodialysis patients with low specific blood volume: Results from a dialysate bolus administration study.

Prescribing the ultrafiltration in hemodialysis patients remains challenging and might benefit from the information on absolute blood volume, estimated by intradialytic dialysate bolus administration. Here, we aimed at determining the relationship between absolute blood volume, normalized for body mass (specific blood volume, Vs), and ultrafiltration-induced decrease in relative blood volume (∆RBV) as well as clinical parameters including body mass index (BMI). This retrospective analysis comprised 77 patients who had their dialysate bolus-based absolute blood volume extracted routinely with an automated method. Patient-specific characteristics and ∆RBV were analyzed as a function of Vs, dichotomizing the data above or below a previously proposed threshold of 65 ml/kg for Vs. Statistical methodology comprised descriptive analyses, two-group comparisons, and correlation analyses. Median Vs was 68.6 ml/kg (54.9ml/kg [Quartile 1], 83.4ml/kg [Quartile 3]). Relative blood volume decreased by 6.3% (2.6%, 12.2%) over the entire hemodialysis session. Vs correlated inversely with BMI (rs =-0.688, p < 0.001). ∆RBV was 9.8% in the group of patients with Vs <65 ml/kg versus 6.0% in the group of patients with Vs ≥65 ml/kg (p=0.024). The two groups did not differ significantly regarding their specific ultrafiltration volume, normalized for body mass, which amounted to 34.1ml/kg and 36.0ml/kg in both groups, respectively (p=0.630). ∆RBV correlated inversely with Vs (rs =-0.299, p=0.008). The present study suggests that patients with higher BMI and lower Vs experience larger blood volume changes, despite similar ultrafiltration requirements. These results underline the clinical plausibility and importance of dialysate bolus-based absolute blood volume determination in the assessment of target weight, especially in view of a previous study where intradialytic morbid events could be decreased when the target weight was adjusted, based on Vs.

Integrating Monitoring of Volume Status and Blood Volume-Controlled Ultrafiltration into Extracorporeal Kidney Replacement Therapy

PurposeVolume management in hemodialysis (HD) requires the ability to assess volume status objectively and determine treatment strategies that achieve euvolemia without compromising hemodynamic stability. The aim of this study was to compare dialysis with and without blood volume-controlled ultrafiltration (UF) in combination with body composition monitoring, and to evaluate indicators for adequate dialysis (Kt/V), ultrafiltration volume, fluid status, and the occurrence of intradialytic morbid events (IME).Patients and MethodsPatients undergoing hemodialysis or on-line hemodiafiltration with support of a blood volume monitor (BVM) – a feedback control device integrated into the 5008 and 6008 HD systems – were enrolled. Patients received treatment for four weeks using the 6008 CAREsystem and the BVM (6008+). Data on dialysis dose (Kt/V), UF volume and predialysis fluid status were documented. This data was also documented retrospectively for four weeks with (5008+) and without (5008−) the use of the BVM with the 5008 system. Comparisons were analyzed using linear mixed models.ResultsTwenty-four patients were enrolled. Kt/V was unaffected by blood volume-controlled UF (5008− vs 5008+: p=0.230) and was equally achieved with both HD systems (5008+ vs 6008+: p=0.922). The UF volume and fluid status achieved were comparable, independent of the use of UF control with BVM (5008− vs 5008+; UF volume: p=0.166; fluid overload: p=0.390) or the HD system (5008+ vs 6008+: UF volume: p=0.003; fluid overload: p=0.838), except for UF volume being higher in the 6008+ phase. IMEs occurred in less than 3% of treatments, with no difference between study phases.ConclusionThis study demonstrates that a clinical approach to kidney replacement therapy that tracks volume status and manages intradialytic fluid removal by blood volume-controlled UF delivers adequate dialysis without compromising fluid removal. It maintains volume status and ensures low incidence of IMEs.

Absolute blood volume variations during hemodialysis: Does dialysate temperature play a role?

Vascular refilling occurs to preserve hemodynamic stability during hemodialysis (HD). Recent studies report a feasible and noninvasive method to determine absolute blood volume (ABV), and estimate vascular refilling during HD. The objective of this study is to analyze if lowering dialysate temperature modifies variations in ABV during HD. The study was performed in 50 patients under HD. During two different sessions, relative blood volume was assessed using dialysate temperatures of 35.5°C (cool dialysate) and 36.5°C (neutral dialysate). ABV and vascular refilling were calculated using Kron et al methodology. Thirty-nine intradialytic morbid events (IMEs) were observed in 30 patients, 14 under cool dialysate and 25 during neutral dialysate. We did not found statistically differences in ABV or in refilling volume between cool and neutral temperature. When analyzing apart only those patients who presented IME, we observed lower drop in ABV in the 35.5°C dialysate treatments (0.57L) versus 36.5°C dialysate treatments (0.71L). When cool dialysate was used, the vascular refilling fraction tended to be higher, but data did not turn statistically significant. In selected groups of patients the use of cool dialysate induces lower ABV variations that could improve hemodynamic stability during HD treatments.

P1079NOVEL ULTRAFILTRATION RATE FEEDBACK CONTROLLER FOR ATTAINMENT OF RELATIVE BLOOD VOLUME TARGETS DURING HEMODIALYSIS

Abstract Background and Aims Preciado et al. have identified half-hourly relative blood volume (RBV) targets (at 30, 60…180 min) during hemodialysis (HD) that are associated with significantly improved patient survival. Attainment of these RBV targets would necessitate incessant adjustments to the ultrafiltration rate (UFR) by the dialysis nurse, which is logistically not feasible. We developed a novel proportional-integral controller that takes RBV data from the commercially available CLiC® device as an input and provides UFR suggestions to guide the RBV curve into the desired targets. The clinician specifies the desired UF goal and the maximum allowed upward/downward deviation from this goal, and the Controller then optimizes the RBV trajectory within the limits allowed by the clinician’s prescription. The present study is aimed to characterize the behavior of this novel feedback controller. Method We conducted a single-arm, prospective, interventional pilot study in subjects on chronic HD at three Avantus Renal Therapy Dialysis Centers in New York City. Subjects were treated with Fresenius 2008T HD machines. RBV was measured with the CLiC® device. CLiC® and HD machine data were fed into a research laptop running the UFR Feedback Controller software. The UFR recommendations (generated every 10 minutes) were evaluated by dialysis nurses who then either implemented or rejected them as they deemed clinically appropriate. The nurses were instructed to only override Controller recommendations if medically indicated, but not in an attempt to manage the subjects’ RBV trajectories themselves. Results Fifteen subjects (58.9 ± 15.3 years, 33% white, 53% black, dialysis vintage 4.1 ± 2.4 years, baseline interdialytic weight gain 2.6 ± 0.8 L, treatment time 222 ± 28 min) were studied (63 study visits, 4.2 ± 1.9 visits per subject). Of 300 analyzed RBV target timepoints, 63% had RBVs within the desired target range, 33% of the RBVs were above and 4% were below target. Stratified by timepoint, the on-target percentage increased from 37% at 30 min to 73% at 180 min into HD, while the proportion of RBVs above or below target decreased. In subjects with at least 4 complete study visits (N=8), looking at each of their first 4 complete visits, on average 71.8% of subjects were within the desired RBV target at 180 min into HD. The rate of intradialytic morbid events did not appear to be outside of the ordinary. There was no indication of adverse events related to the use of the UFR Feedback Controller. The Figure shows an example study visit where the UFR Feedback Controller modulates the UFR on an ongoing basis throughout the treatment to keep the RBV curve close to the ideal target trajectory (red line, defined by connecting the RBVs associated with the lowest all-cause mortality). Solid black line: RBV curve (left y-axis); dashed black line: UFR (right y-axis); green boxes: half-hourly RBV target ranges associated with improved survival. Conclusion The UFR Feedback Controller behaves as expected, steering the patients’ RBV curves toward the predefined target ranges where possible, while simultaneously guaranteeing that the prescribed fluid removal goal will be achieved. Preciado et al. had reported approx. one third of patients within the favorable RBV target range at 3h into HD. In contrast, while our pilot study was relatively small, with use of our novel UFR Feedback Controller, approx. 72% of subjects were within the desired RBV target range at 3h into HD. This novel UFR feedback control technology holds great promise for improving fluid management and clinical outcomes in HD patients without requiring additional staff time.

Feedback control of absolute blood volume: A new technical approach in hemodialysis.

The success of automatic feedback control systems to improve hemodynamic stability by preventing relative blood volume from dropping beyond a critical value during dialysis is limited. The aim of this study was to use one of these systems for control of absolute rather than relative blood volume to prevent volume-dependent morbid events. Dialysis was delivered by a machine providing feedback control of ultrafiltration rates, relative blood volume monitoring, and accurate bolus infusion of 240 mL of dialysate to measure absolute blood volume at the beginning of dialysis. Critical relative blood volume required by the control algorithm was calculated from absolute blood volume at the beginning and a critical absolute blood volume of 67 mL/kg. In 40 stable patients, ultrafiltration was guided by blood volume using the feedback algorithm of the integrated program. Blood volume was maintained in a narrow range above the prespecified minimal value of 67 mL/kg. At the end of dialysis, absolute blood volume ranged from 67.5 to 72.5 mL/kg (69.4 ± 1.3 mL/kg). No volume-dependent intradialytic morbid event occurred. A feedback control system for relative blood volume-controlled ultrafiltration can be used for control of absolute blood volume. A prescribed target of absolute blood volume can be converted into relative blood volume, and this can subsequently be reached automatically with the integrated feedback system of the dialysis machine. Intradialytic morbid events could be considerably reduced. The whole procedure could be completely automated without altering the hardware of the dialysis device.

Adjustment of target weight based on absolute blood volume reduces the frequency of intradialytic morbid events.

Adequate volume management removing excess volume and at the same time avoiding intradialytic morbid events (IME) remains a core problem in current hemodialysis (HD) therapy. Recently, we developed a feasible method to determine absolute blood volume (Vs, in mL/kg) in patients on HD. The aim of this study was to investigate the suitability of Vs measurements for volume management. Following a 4 week baseline phase to quantify the frequency of IME, volume status was determined in a single specified HD session during which Vs was measured using dialysate dilution, volume overload (Vo, L) was measured using bioimpedance spectroscopy, and the occurrence of IME was recorded. Target weight was then adjusted and the frequency of IME was recorded during 4 weeks of follow-up. Forty-five patients participated in this study. Twenty-two (49%) patients experienced 66 IME in 12% of HD treatments during baseline. In 15 (33%) patients who experienced IME during volume assessment both Vs (60.7 ± 4.0 vs. 73.7 ± 11.3 mL/kg, P < 0.001) and Vo (1.1 ± 0.9 vs. 2.5 ± 1.8 L, P < 0.01) were significantly lower than in stable patients, respectively. The sensitivity, specificity, and accuracy of the ≤65 mL/kg Vs threshold to predict IME was 87%, 100%, and 91%, respectively. Target weight was increased (+1.5 kg) or decreased (-5 kg) in 32 patients. The frequency of IME fell to 0.9% of all HD sessions in the following 4 weeks (P < 0.001). Adjustment of target weight based on information of Vs, Vo, and IME appears as a feasible approach to reduce the frequency of IME.

Vascular Refilling Is Not Reduced in Dialysis Sessions with Morbid Events

Background: It is commonly believed that insufficient vascular refilling leads to hypovolemia during hemodialysis and contributes to intradialytic morbid events (IME). But data of refilling volumes at the time of IME are lacking. Methods: We compared the vascular refilling in 10 patients with IME with 14 stable patients with normal blood volume at the dialysis end (66-80 mL/kg). Results: The refilling characteristics in patients with IME did not differ from those in stable patients. The refilling fraction (refilling/ultrafiltration [UF] ratio) was 73.8 ± 9.4% in patients with IME, and 70.2 ± 6.4% in patients with normal blood volume at the end of the treatment. Refilling volume strongly correlated with UF volume in both patient groups (r² = 0.93 and r² = 0.81, respectively). Conclusion: IME are associated with a specific blood volume below 65 mL/kg. Vascular refilling is a constant fraction of UF in stable as well as in symptomatic dialysis sessions.

Determination of the critical absolute blood volume for intradialytic morbid events.

The reduction of blood volume below a critical threshold is assumed to trigger intradialytic morbid events (IME). Recently, we presented a simple method to determine the absolute blood volume during routine hemodialysis (HD) carried out without blood sampling and without injection of dyes or radiolabeled markers. Such information could be used to detect excessive volume reduction during HD and to prevent IME. Therefore, we performed a pilot study in IME-prone patients to identify the absolute blood volume at which they developed clinical symptoms. A volume of 240 mL of ultrapure dialysate was automatically infused into the extracorporeal circulation using the bolus function of a commercial online hemodiafiltration machine incorporating a blood volume monitor (BVM). The increase in relative blood volume (RBV) caused by the infusion was measured and used to determine the absolute blood volume at that time. The blood volume per kilogram body mass at the time of symptomatic IME was also determined. All IME-prone patients of a single-dialysis center were included in the study. Ten out of 12 patients became symptomatic at a specific blood volume between 65 and 56 mL/kg (mean 62 mL/kg) whereas RBV showed a wide scatter (82-97%). A specific blood volume of 65 mL/kg seems to represent the threshold for IME by this method. The technique could be completely automated without altering the hardware of the dialysis device. Present feedback systems for automated blood volume-controlled ultrafiltration could be adapted to maintain absolute blood volume above this critical volume to safely prevent volume-dependent IME.

A Simple and Feasible Method to Determine Absolute Blood Volume in Hemodialysis Patients in Clinical Practice

Background: We developed a simple method to determine the absolute blood volume (V) during hemodialysis in everyday clinical practice and examined its relationship with volume overload, clinical relevance, and accuracy. Methods: The increase in relative blood volume (RBV_post - RBV_pre) measured before and after infusion of 240 ml of ultra-pure dialysate using the bolus function of a commercial online hemodiafiltration machine incorporating a relative blood volume monitor was applied to determine absolute blood volume. The specific blood volume (V_s, blood volume per kg body mass at dry weight, in ml/kg) was compared to volume status as assessed by bioimpedance analysis and clinical criteria. Results: The blood volume measured in 30 stable hemodialysis patients was 6.51 ± 1.70 l at the beginning, corresponding to a specific blood volume of 80.1 ± 12.8 ml/kg, and dropped to 5.84 ± 1.61 l or 72.0 ± 12.1 ml/kg at the end of the dialysis session, respectively. Specific blood volume correlated with volume status assessed both clinically and by bioimpedance analysis. Intradialytic morbid events occurred only in treatments where specific blood volume fell below 65 ml/kg. The reproducibility of the technique was better than 4% and the in vitro accuracy corresponds to a resolution in V_s of better than 1 ml/kg. Conclusion: Absolute blood volume can be easily measured at the beginning of the dialysis session using the current dialysis technology. Information about V and V_s could be a promising tool to avoid intradialytic morbid events. This technique could be completely automated without altering the hardware of currently available online dialysis devices. Therefore, it is recommended that this technique be integrated into all hemodiafiltration machines.

Decreasing intra-dialytic morbid events and assessment of dry weight in children on chronic hemodialysis using non-invasive changes in hematocrit.

Achieving dry weight after hemodialysis (HD) is critical as chronic fluid over-load can result in left ventricular hypertrophy, while small fluid shifts may result in intra-dialytic morbid events (IME). In the pediatric population, estimating dry weight can be difficult due to growth while on dialysis. Continuous non-invasive monitoring of the hematocrit (NIVM) has been proposed as a more accurate method of estimating dry weight. Fifteen pediatric patients on chronic HD (6 males and 9 females; mean age 11.4 ± 2.28 years) were included in an uncontrolled prospective study involving three phases. In phase 1, patients were observed for one month for their dry weight and frequency of IME. Phase 2 consisted of using NIVM-guided ultrafiltration algorithm for rate of blood volume (BV) reduction and post-dialysis refill, recommending an intra-dialytic reduction in BV of 8% in the first hour and <4% per hour thereafter and without significant post-dialytic vascular refill. Phase 3 comprised a one month period for comparing the results. IME decreased from 33 episodes per 180 sessions in phase 1 to 4 per 180 sessions during phase 3 (P = 0.04), without a significant difference in pre-systolic or post-systolic or mean BP before and after the intervention (all P >0.1). In phase 1, 40% of patients experienced no IME, 33% experienced one or two IME while 27% experienced more than two IME; during phase 3, 80% experienced no IME, 20% experienced one or two IME while no one experienced more than two IME. NIVM can serve as an objective method for determining dry weight as well as predicting and preventing IME in the pediatric population on maintenance HD.

Pneumatic compression devices to avoid intradialytic morbid events

Pneumatic compression devices to avoid intradialytic morbid events

Simultaneous Blood Temperature Control and Blood Volume Control Reduces Intradialytic Symptoms

Intra-dialytic morbid events (IME; e.g. hypotension, cramps, headaches) are frequent complications during hemodialysis (HD), known to be associated with ultrafiltration-induced hypovolemia and body temperature changes. Feedback control of blood volume adjusts the ultrafiltration rate in order to keep the blood volume above the patient's individual limit; feedback control of blood temperature maintains the mean arterial blood temperature at the individual pre-dialytic level. Each of these methods reduces the frequency of IME. In a randomized clinical trial the simultaneous application of both feedback controls was investigated for the first time. In 15 weeks, each patient went through 3 study phases: an observational screening phase, a standard phase (STD), and a blood temperature- and blood volume-control phase (CTL). Patients with at least 5 sessions with IME out of 15 sessions in the screening phase were eligible for the study and randomized either into sequence STD-CTL or CTL-STD. 26 patients completed the study according to protocol, and 778 HD treatments were analyzed. The general treatment parameters were similar in both study phases: treatment duration (STD: 244 min, CTL: 243 min, NS), pre-dialytic weight (STD: 72.3 kg, CTL: 72.2 kg, NS), and weight loss due to ultrafiltration (STD: 3.26 kg, CTL: 3.15 kg, NS). The proportion of HD treatments with IME was 32.8% during STD and 18.0% during CTL (p=0.024). The frequency of HD sessions with IME was significantly reduced by 45% compared to standard HD in this randomized clinical trial by use of individualized HD treatments with simultaneous feedback control of blood volume and blood temperature.

Proto-dialytic cardiac function relates to intra-dialytic morbid events

Intra-dialytic morbid events (IDME) such as intra-dialytic hypotension (IDH) and muscle cramps frequently complicate haemodialysis (HD). Cardiac dysfunction is highly prevalent in HD patients. We investigated the relationship between proto-dialytic (i.e. early intra-dialytic) cardiac function and IDME in HD patients. Heart rate, beat-to-beat blood pressure (BP) and cardiac output were continuously measured during the first 30 min of dialysis treatment using the Task Force™ Monitor. Total peripheral resistance index (TPRI) was calculated from cardiac index (CI) and BP. Univariate, multivariate and logistic regression analyses were employed to relate IDME to haemodynamic predictors; Kaplan-Meier method was employed for time-to-event analysis. Fourteen HD patients (age 67 ± 15 years; 7 females) were studied. Dialysis treatment was complicated by IDH and muscle cramps in 4 and 8 out of 30 sessions, respectively. CI was higher in patients without IDME (2.6 ± 0.5 L/min/m(2)) as compared to those with muscle cramps (2.0 ± 0.3 L/min/m(2)) or IDH (1.8 ± 0.2 L/min/m(2); all P < 0.05). CI and TPRI at baseline independently predicted IDME in a multivariate regression analysis (odds ratio: 0.043 per unit of CI, 95% confidence interval: 0.003-0.611; odds ratio: 1.124 per unit of TPRI, 95% confidence interval: 1.25-1.01). Patients were stratified by tertiles of CI. IDME occurred in the two lower tertiles, whereas patients in the upper tertile were event free (log-rank test, P < 0.002). Low CI and high TPRI in the first 30 min of HD are associated with an increased risk of IDME.

Reduced Complications during Hemodialysis by Automatic Blood Volume Controlled Ultrafiltration

Intradialytic morbid events (IMEs, mostly hypotension) are frequent complications during hemodialysis (HD). This study investigated whether automatic feedback control via adjustment of the ultrafiltration rate reduces IME frequency. In this multi-center cross-over study, 56 hypotension-prone patients were treated both with standard HD (sHD, applying a constant ultrafiltration rate) and HD applying a blood volume controlled ultrafiltration rate (cHD). The relative blood volume (RBV) was continuously monitored. The individual relative blood volume limit (RBVcrit ) was determined from the measured RBV during initial sHD. During cHD, the ultrafiltration rate was automatically adjusted to keep the actual RBV above RBVcrit. In 3,081 HD treatments, slightly fewer IMEs were observed during cHD than during sHD (0.785+/-0.613 versus 0.695+/-0.547 per treatment, P=0.144). Less symptomatic events were seen during cHD: -13% for symptomatic hypotension (0.594 versus 0.685 per treatment, P=0.120), and -32% for cramps (0.049 versus 0.072 per treatment, P=0.009). Thirty-one patients with the highest IME rate (IME in at least every second treatment) especially benefited from cHD: 1.185+/-0.554 versus 0.979+/-0.543 IME per treatment (P=0.004). The reduction in blood pressure (BP) and the increase in heart rate were lower during the treatments with cHD than with sHD: systolic BP: -18.8+/-26.7 versus -22.2+/-28.9 mmHg (P=0.007), diastolic BP: -7.8+/-14.8 versus -9.1+/-15.3 mmHg (P=0.064), heart rate: 1.8+/-10.4 versus 2.3+/-11.6 per minute (P=0.014). Neither treatment duration nor ultrafiltration volume was significantly different between cHD and sHD. For cHD, less intradialytic morbid events were observed than for sHD, and pre- to post-dialytic changes in blood pressure and heart rate were less pronounced.

On-Line Haemodiafiltration versus Haemodialysis: Stable Haematocrit with Less Erythropoietin and Improvement of Other Relevant Blood Parameters

Background: Controlled randomised studies to prove improved cardiovascular stability and improved anaemia management during on-line haemodiafiltration (oHDF) are scarce. Methods: 70 patients were treated with both haemodialysis (HD) and oHDF in a cross-over design during 2 × 24 weeks at a dialysis dose of eKt/V≧1.2. Patients randomised into group A started on HD and switched over to oHDF, whereas patients in group B began with oHDF and were treated with HD afterwards. Intradialytic morbid events (IME), such as symptomatic hypotension or muscle cramps, were noted in case of appearance. Blood parameters reflecting anaemic status, phosphate status, lipid metabolism, oxidative stress, and accumulation of advanced glycation end products were recorded either monthly or at the end of each study phase. Results: The mean incidence of IME was 0.15 IME per treatment, and there was no statistical difference between oHDF and HD. A higher haematocrit (oHDF 31.5% vs. HD 30.5%, p < 0.01) at a lower erythropoietin dose (oHDF 4,913 vs. HD 5,492 IU/week, p = 0.02) was found during oHDF, when the sequence of HD and oHDF had not been taken into account. For the study groups, the results were less distinct: in group A, a higher haematocrit (HD 30.4% vs. oHDF 32.0%, p < 0.01) at a comparable erythropoietin dose (HD 5,421 vs. oHDF 5,187 IU/week, ns) was observed during oHDF, whereas in group B an identical haematocrit (oHDF 30.8% vs. HD 30.7%, ns) was achieved at a reduced erythropoietin dose (oHDF 4,622 vs. HD 5,568 IU/week, p < 0.01). During oHDF, lower levels of free and protein-bound pentosidine and of serum phosphate were found. Conclusion: In contrast to other studies, no benefit regarding cardiovascular stability for oHDF was found, but oHDF could well offer a potential benefit regarding anaemia correction, inflammation, oxidative stress, lipid profiles, and calcium-phosphate product.

The (wind) chill factor controlled

The (wind) chill factor controlled

ULTRAFILTRATION (UF) PULSE TECHNIQUE TO MEASURE ABSOLUTE BLOOD VOLUME (V) DURING HEMODIALYSIS (HD) REVISITED

The measurement of relative blood volume (RBV) by on-line techniques during HD has been of limited value in preventing intradialytic morbid events because of variable RBV thresholds (RBV*) where patients become symptomatic. Additional information on V could he helpful in detecting more reliable RBV*. V was measured early (V1, 25 min) and late (V2, 120 min) into HD analyzing the rate of RBV changes before and after a step-change in UF-rates based on a model presented previously (Schallenherg et al., Life Support Systems, 1987). Contrary to previous assumptions the technique provides initial V(0), independently of the timing of the UF-pulse when unmodified RBV curves are used. This value is theoretically correct for a stable distribution of red blood cells between different parts of the circulation measured as the ratio of whole body hematocrit to macro hematocrit (Fcells). However, the assumption of a constant Fcells is violated with increased degrees of hemodynamic compensation. Rescaling the RBV curves to the time (t) of the UF-pulse yields V(t). RBV(t) and V(t) were measured in 3 patients during HD. Comparison of RBV(2,1) (a) obtained by on-line monitoring to V2/V1 (b) obtained from V(t) revealed significant differences (dRBV=a-b) between volume changes which can be explained by changes Fcells, d positive (negative) difference indicating an increase (decrease) in Fcells (Tab. 1).The differences between real and apparent blood volume changes (dRBV) may account for the variability in observed RBV*.

Computational analysis of blood volume curves and risk of intradialytic morbid events in hemodialysis

Blood volume (BV) curves have been used to prevent intradialytic morbid events (IMEs) caused by hypotensive episodes in hemodialysis treatment. However, no standardized parameter is available to describe BV dynamics and to enable online interference with ultrafiltration rates in unselected patients. Moreover, only time-dependent BV reduction and absolute hematocrit threshold, but not BV variability, have been suggested as markers of pending hypotension. The present study therefore deals with a computer-aided analysis of indices characterizing both BV reduction per time and BV variability in treatments of nonselected maintenance hemodialysis patients. The methodology uses indices obtained by mathematical analysis of BV curves and was designed to potentially enable automatic interference with ultrafiltration. In 46 out of 380 treatments (12.1%), IMEs occurred. In these treatments, the indices for long- and short-term variability and slope of the curves were significantly lower than in treatments without IMEs. Moreover, the last 10 minutes before an IME were characterized by additionally decreased variability and slope. In a risk analysis of long-term variability and IMEs, we established an index below 16 to be associated with the highest risk of IMEs. Using these kind of index thresholds and online analysis of BV curves, automatic management of ultrafiltration by BV dynamics could be a promising concept to avoid intradialytic morbidity.

Hemodialysis Immediately after Acute Myocardial Infarction

Acute myocardial infarction (AMI) is common in patients who have end-stage renal disease. However, the prudent interval after AMI until resuming hemodialysis is unknown. Also incidence and severity of intradialytic morbid events during the initial dialysis treatment after AMI have not been determined. We conducted a retrospective analysis of the course of hemodialyses performed immediately after AMI in 13 maintenance hemodialysis patients (group 1) hospitalized with AMI over the 5-year period 1988-1992. For comparison, the incidence of intradialytic morbid events (hypotension--systolic blood pressure < 90 or diastolic blood pressure < 60 mm Hg or a fall in systolic or diastolic blood pressure of > 30 mm Hg--with and without symptoms, arrhythmias, and unplanned termination of hemodialysis was extracted from the charts of 9 maintenance hemodialysis patients (group 2) admitted during the same period with angina but no AMI, and in 13 stable ambulatory hemodialysis patients (group 3) dialyzed during the same period who had no evidence of heart disease. Patients in groups 1 and 2 were sorted by time interval from onset of chest pain to initiation of hemodialysis (< 12, 12-24, and > 24 h). In group 1, we examined the relationship of anatomic location of AMI, number of antihypertensive medications, predialysis left ventricular systolic ejection fraction, and various other clinical and laboratory parameters to the incidence intradialytic morbid events. The mean (+/- SD) age of the study subjects was 67 +/- 7.5 years in group 1, 57 +/- 3.7 in group 2, and 60 +/- 11 years in group 3 (p = 0.6). Arrhythmias and early termination of dialysis did not occur in any patient. Intradialytic hypotension (IDH) was recorded in 5 (38%) of 13 patients in group 1, in 3 (33%) of 9 in group 2, and in 2 (15%) of 13 patients in group 3 (p = 0.47). 4 (80%) of 5 patients in group 1 had multiple episodes of IDH. There were 0.92 +/- 1.4 episodes of IDH per patient in group 1 as compared with a rate of 0.44 +/- 0.68 per patient in group 2, and of 0.15 +/- 0.36 per patient in group 3 (p = 0.2). IDH responded to 0.9% normal saline replacement in all cases. Group 1 patients who had IDH (n = 5) were older (68 +/- 3 vs. 58 +/- 7 years, p = 0.01), had a lower diastolic blood pressure at the start of hemodialysis (59 +/- 13 vs. 83 +/- 13 mm Hg; p = 0.01), had a lower post-AMI left ventricular systolic ejection fraction (42 +/- 19 vs. 62 +/- 10%; p = 0.04), and also had a lower predialysis serum albumin level (3.6 +/- 0.4 vs. 4.1 +/- 0.4 g/dl; p = 0.09) than those who did not have IDH (n = 8). All 5 group 1 patients who had IDH (100%) had had prior AMI as compared with 2 (25%) of 8 of those who did not have IDH (p = 0.02). AMI involved the inferior myocardial wall in more (4 of 5; 80%) of the group 1 patients who had IDH as compared with those who did not have IDH (2 of 8; 25%; odds ratio = 9.5; p = 0.08; 95% confidence interval = 0.7-341.0). In group 1 patients, the time from onset of chest pain to hemodialysis did not affect the risk of IDH (p = 0.4). We conclude that a low diastolic blood pressure at onset of hemodialysis prior myocardial infarction, inferior myocardial wall involvement, advanced age, and a low predialysis serum albumin level are risk factors for the development of hypotension during the first hemodialysis session after AMI.

Chronic hepatitis B virus infection and interferon-α

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