Control of core temperature and blood pressure stability during hemodialysis

Do patients dialysing with higher ultrafiltration rates report more intradialytic symptoms and longer postdialysis recovery times?

BACKGROUND

Many hemodialysis (HD) patients report intradialytic symptoms, and take time to recover postdialysis. To improve quality of life, patient groups have highlighted the need to reduce postdialysis fatigue and other peridialytic symptoms. As compartmental shifts of fluid during dialysis have been proposed to cause peridialytic symptoms we investigated whether patients dialysing with higher ultrafiltration rates (UFR) reported more intradialytic symptoms and recovery times.

METHODS

We reviewed the hospital records of HD patients who completed a self-reported intradialytic symptom questionnaire, using a visual analogue scale, who had contemporaneous midweek pre- and postdialysis segmental bioimpedance measurements.

RESULTS

Six hundred and five patients returned the peridialytic symptom questionnaire with pre- and postdialysis bioimpedance measurements. The majority were male (64.8%), mean age 64.2 ± 15.6 years, duration of dialysis treatment 26.8 (10.7-59.2) months, 85% treated by hemodiafiltration and mean dialysate temperature 35.4 ± 0.4°C. We divided patients into terciles according to UFR adjusted for weight, and there was a greater fall in the ratio of extracellular water (ECW) to total body water (TBW) postdialysis in the nonfistula arm from the lower to middle to higher tercile (0.8 (0-1.54) vs. 1.28 (0.52-1.85) vs. 1.54 (0.78-2.52)), trunk (1.5 (0.74-2.27) vs. 1.53 (0.99-2.2) vs. 1.98 (1.18-2.66)), left leg (1.56 (0.49-2.25) vs. 1.77 (1.24-2.43) vs. 2.08 (1.18-2.95)), lower versus higher tercile p < 0.05. However, no differences in intradialytic symptoms or postdialysis recovery times between the UFR terciles were observed.

CONCLUSION

There were no differences in self-reported intradialytic symptoms or postdialysis recovery times with differing UFRs, despite changes in intracompartmental fluid shifts as measured by changes in ECW/TBW.

The effect of hemodialysis with cool dialysate on nausea in hemodialysis patients: A randomized clinical trial

Background and Aims

Experiencing nausea leads to decreased self-esteem and social isolation in hemodialysis patients and affects all aspects of their quality of life. Nausea and vomiting make hemodialysis unpleasant for patients leading to premature termination of hemodialysis. Therefore, based on this necessity, the present study was conducted to determine the effect of hemodialysis with cool dialysate on nausea in hemodialysis patients.

Methods

In this clinical trial, 60 eligible patients receiving hemodialysis were randomly assigned to the control (30 participants) and intervention (30 participants) groups. In the control group, the patients received standard hemodialysis (37°C) for three sessions. Simultaneously, patients in the intervention group received hemodialysis with a cold solution (of 36°C) for three sessions. The patients' nausea and shivering rates were measured using the visual analog scale and the shivering standard assessment scale, respectively. Both groups were evaluated before and after 1 week of intervention. The study did not include blinding. The trial has been registered in the Iranian Registry of Clinical Trials (IRCT) with the number IRCT20200530047597N1. The present study was financially supported by Kermanshah University of Medical Sciences, Kermanshah, Iran (no. 990220). Data were analyzed using SPSS-25 software.

Findings

The independent t test showed no statistically significant difference between the two control and experimental groups regarding the nausea rate in the three evaluation times (p < 0.05). Nevertheless, nausea severity decreased significantly after the intervention in the two groups. However, the rate of nausea in the intervention group with cold solution decreased more compared to the control group. Moreover, no patient in the intervention group experienced shivering during hemodialysis with a cool dialysate.

Conclusion

According to the results of this study, it can be stated that the use of cold hemodialysis to control nausea in patients undergoing hemodialysis requires further studies and can be recommended as a nonpharmacological treatment to manage the treatment costs in case of efficiency.

Could cooling dialysate improve inflammatory and nutritional status of hemodialysis patients?

BACKGROUND

It has been shown that dialysate cooling (lowering the dialysate temperature to 0.5 °C below central body temperature) reduces the incidence of intradialytic hypotension. Other influences on hemodialysis patients, however, have not been adequately investigated. The purpose of this study was to determine the impact of individualized dialysate cooling on nutritional and inflammatory parameters in chronic hemodialysis (HD) patients.

METHODS

Seventy HD patients were separated into two groups: group A: (control group) standard dialysate temperature was 37 °C, and group B: (intervention group) dialysate temperature was 0.5 °C below core body temperature. In addition to routine laboratory tests, blood pressure, anthropometric measurements, inflammatory markers, and the malnutrition inflammation score (MIS) were calculated.

RESULTS

After six months of dialysate cooling, intradialytic hypotension episodes were much less prevalent in the intervention group (p = 0.001). Serum ferritin, transferrin saturation (TSAT), high sensitive C-reactive protein (HS-CRP), and Interleukin-6 (IL-6) reduced following dialysate cooling, whereas serum albumin rose. In the control group, IL-6 dropped but serum ferritin, TSAT, albumin, and HS-CRP rose. In both groups, hemoglobin levels dropped, and erythrocyte sedimentation rate (ESR) rose, both groups' midarm muscle circumference and MIS worsened.

CONCLUSION

Cold dialysate decreased intradialytic hypotension with no significant improvement of the nutritional and inflammatory surrogates. However, more studies including larger number of patients with longer duration of follow up are required to adequately assess its effect on inflammation and nutrition in chronic hemodialysis patients.

Dynamics of Plasma Refill Rate and Intradialytic Hypotension During Hemodialysis: Retrospective Cohort Study With Causal Methodology

Key Points

Directly studying plasma refill rate (PRR) during hemodialysis (HD) can offer insight into physiologic mechanisms that change throughout HD. PRR at the start and during HD is associated with intradialytic hypotension, independent of ultrafiltration rate. A rising PRR during HD may be an early indicator of compensatory mechanisms for impending circulatory instability.

Background

Attaining the optimal balance between achieving adequate volume removal while preserving organ perfusion is a challenge for patients receiving maintenance hemodialysis (HD). Current strategies to guide ultrafiltration are inadequate.

Methods

We developed an approach to calculate the plasma refill rate (PRR) throughout HD using hematocrit and ultrafiltration data in a retrospective cohort of patients receiving maintenance HD at 17 dialysis units from January 2017 to October 2019. We studied whether (1 ) PRR is associated with traditional risk factors for hemodynamic instability using logistic regression, (2 ) low starting PRR is associated with intradialytic hypotension (IDH) using Cox proportional hazard regression, and (3 ) time-varying PRR throughout HD is associated with hypotension using marginal structural modeling.

Results

During 180,319 HD sessions among 2554 patients, PRR had high within-patient and between-patient variability. Female sex and hypoalbuminemia were associated with low PRR at multiple time points during the first hour of HD. Low starting PRR has a higher hazard of IDH, whereas high starting PRR was protective (hazard ratio [HR], 1.26, 95% confidence interval [CI], 1.18 to 1.35 versus HR, 0.79, 95% CI, 0.73 to 0.85, respectively). However, when accounting for time-varying PRR and time-varying confounders, compared with a moderate PRR, while a consistently low PRR was associated with increased risk of hypotension (odds ratio [OR], 1.09, 95% CI, 1.02 to 1.16), a consistently high PRR had a stronger association with hypotension within the next 15 minutes (OR, 1.38, 95% CI, 1.30 to 1.45).

Conclusions

We present a straightforward technique to quantify plasma refill that could easily integrate with devices that monitor hematocrit during HD. Our study highlights how examining patterns of plasma refill may enhance our understanding of circulatory changes during HD, an important step to understand how current technology might be used to improve hemodynamic instability.

The Effects of Cool Dialysate on Vital Signs, Adequacy and Complications during Hemodialysis

BACKGROUND

Cooling the dialysate is an important factor that contributes to the hemodynamic stability in patients during hemodialysis. The aim of this study was to determine the effect of cool dialysate on vital signs, and the adequacy and common complications of hemodialysis.

MATERIALS AND METHODS

The present crossover, triple-blind, clinical trial was performed on 62 dialysis patients, who were selected through stratified block randomization. First, one group underwent hemodialysis using a cool dialysate (35°C), and the other received routine hemodialysis (36.5°C). Each patient received a total of eight hemodialysis sessions. Then, treatment methods were swapped, and each group received the other group's method. The patients' blood pressure, pulse rate, and temperature were measured before dialysis, and in the first, second, third, and fourth hours of dialysis. The frequency of common complications of hemodialysis and dialysis efficacy were measured. The marginal model and Generalized Estimating Equations (GEE) were used to analyze the data.

RESULTS

The participants' systolic (p = 0.01) and diastolic blood pressures significantly increased with a decrease in temperature (p = 0.005). The patients' pulse rate (p = 0.143), adequacy of dialysis (p = 0.922), and common complications of hemodialysis did not significantly differ between the two temperatures (p > 0.05).

CONCLUSIONS

Reducing dialysate temperature from 36.5 to 35°C led to hemodynamic stability; the blood pressure of the patients undergoing hemodialysis was more stable with the cool dialysate method and the number of drops in the blood pressure during the hemodialysis was reduced.

Blood purification with CytoSorb in critically ill COVID-19 patients: A case series of 26 patients

Severe forms of the coronavirus disease 2019 (COVID‐19) can progress to sepsis‐like complications accompanied by “cytokine storm” for which the most effective treatment has not yet been established. Our study describes the results of CytoSorb hemoadsorption in COVID‐19 patients treated on the intensive care unit (ICU). In this retrospective study, 26 patients with COVID‐19 and acute respiratory distress syndrome (ARDS) were treated with hemoadsorption therapy. Pre‐, and post‐treatment values (clinical and laboratory) were compared. Data are expressed as mean (confidence intervals, CI), or median [interquartile ranges, IQR], as appropriate. Patients received 2 hemoadsorption treatments. This resulted in a significant decrease in norepinephrine requirements, and inflammatory marker plasma concentrations (procalcitonin, C‐reactive protein, ferritin) when comparing pre versus post treatment levels. The PaO₂/FiO₂ and overall organ function (ie, Sequential Organ Failure Assessment—SOFA score) also improved significantly. Patients stayed on the ICU for 9 days and 21 of them survived. To the best of our knowledge, this is one of the largest case series to date reporting early experiences on extracorporeal hemoadsorption therapy in SARS‐CoV‐2 positive patients with hyperinflammation and moderate ARDS. Treatment proved to be effective, technically feasible and well‐tolerated.

Effect of various dialysis modalities on intradialytic hemodynamics, tissue injury and patient discomfort in chronic dialysis patients: design of a randomized cross-over study (HOLLANT)

BACKGROUND

From a recent meta-analysis it appeared that online post-dilution hemodiafiltration (HDF), especially with a high convection volume (HV-HDF), is associated with superior overall and cardiovascular survival, if compared to standard hemodialysis (HD). The mechanism(s) behind this effect, however, is (are) still unclear. In this respect, a lower incidence of intradialytic hypotension (IDH), and hence less tissue injury, may play a role. To address these items, the HOLLANT study was designed.

METHODS

HOLLANT is a Dutch multicentre randomized controlled cross-over trial. In total, 40 prevalent dialysis patients will be included and, after a run-in phase, exposed to standard HD, HD with cooled dialysate, low-volume HDF and high-volume HDF (Dialog iQ® machine) in a randomized fashion. The primary endpoint is an intradialytic nadir in systolic blood pressure (SBP) of < 90 and < 100 mmHg for patients with predialysis SBP < 159 and ≥ 160 mmHg, respectively. The main secondary outcomes are 1) intradialytic left ventricle (LV) chamber quantification and deformation, 2) intradialytic hemodynamic profile of SBP, diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP), 3) organ and tissue damage, such as the release of specific cellular components, and 4) patient reported symptoms and thermal perceptions during each modality.

DISCUSSION

The current trial is primarily designed to test the hypothesis that a lower incidence of intradialytic hypotension contributes to the superior survival of (HV)-HDF. A secondary objective of this investigation is the question whether changes in the intradialytic blood pressure profile correlate with organ dysfunction and tissue damage, and/or patient discomfort.

TRIAL REGISTRATION

Registered Report Identifier: NCT03249532 # ( ClinicalTrials.gov ). Date of registration: 2017/08/15.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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 (0.57 L) versus 36.5°C dialysate treatments (0.71 L). When cool dialysate was used, the vascular refilling fraction tended to be higher, but data did not turn statistically significant.

CONCLUSIONS

In selected groups of patients the use of cool dialysate induces lower ABV variations that could improve hemodynamic stability during HD treatments.

Evaluation of the effect of Cooled HaEmodialysis on Cognitive function in patients suffering with end-stage KidnEy Disease (E-CHECKED): feasibility randomised control trial protocol

BACKGROUND

Cognitive impairment is common in haemodialysis (HD) patients and is associated independently with depression and mortality. This association is poorly understood, and no intervention is proven to slow cognitive decline. There is evidence that cooler dialysis fluid (dialysate) may slow white matter changes in the brain, but no study has investigated the effect of cooler dialysate on cognition. This study addresses whether cooler dialysate can prevent the decline in cognition and improve quality of life (QOL) in HD patients.

METHODS

This is a multi-site prospective randomised, double-blinded feasibility trial.

SETTING

Four HD units in the UK.

PARTICIPANTS AND INTERVENTIONS

Ninety HD patients randomised (1:1) to standard care (dialysate temperature 36.5 °C) or intervention (dialysate temperature 35 °C) for 12 months.

PRIMARY OUTCOME MEASURE

Change in cognition using the Montreal Cognitive Assessment (MoCA).

SECONDARY OUTCOME MEASURES

Recruitment and attrition rates, reasons for non-recruitment, frequency of intradialytic hypotension, depressive symptom scores, patient and carers burden, a detailed computerised cognitive test and QOL assessments.

ANALYSIS

mixed method approach, utilising measurement of cognition, questionnaires, physiological measurements and semi-structured interviews.

DISCUSSION

The results of this feasibility trial will inform the design of a future adequately powered substantive trial investigating the effect of dialysate cooling on prevention and/or slowing in cognitive decline in patients undergoing haemodialysis using a computerised battery of neuro-cognitive tests. The main hypothesis that would be tested in this future trial is that patients treated with regular conventional haemodialysis will have a lesser decline in cognitive function and a better quality of life over 1 year by using cooler dialysis fluid at 35 °C, versus a standard dialysis fluid temperature of 36.5 °C. This also should reflect in improvements in their abilities for activities of daily living and therefore reduce carers' burden. If successful, the treatment could be universally applied at no extra cost.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03645733 . Registered retrospectively on 24 August 2018.

Intradialytic Hypotension: Mechanisms and Outcome

Intradialytic hypotension (IDH) occurs in approximately 10-12% of treatments. Whereas several definitions for IDH are available, a nadir systolic blood pressure carries the strongest relation with outcome. Whereas the relation between IDH may partly be based on patient characteristics, it is likely that also impaired organ perfusion leading to permanent damage, plays a role in this relationship. The pathogenesis of IDH is multifactorial and is based on a combination of a decline in blood volume (BV) and impaired vascular resistance at a background of a reduced cardiovascular reserve. Measurements of absolute BV based on an on-line dilution method appear more promising than relative BV measurements in the prediction of IDH. Also, feedback treatments in which ultrafiltration rate is automatically adjusted based on changes in relative BV have not yet resulted in improvement. Frequent assessment of dry weight, attempting to reduce interdialytic weight gain and prescribing more frequent or longer dialysis treatments may aid in preventing IDH. The impaired vascular response can be improved using isothermic or cool dialysis treatment which has also been associated with a reduction in end organ damage, although their effect on mortality has not yet been assessed. For the future, identification of vulnerable patients based on artificial intelligence and on-line assessment of markers of organ perfusion may aid in individualizing treatment prescription, which will always remain dependent on the clinical context of the patient.

Dialysate temperature reduction for intradialytic hypotension for people with chronic kidney disease requiring haemodialysis

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of haemodialysis (HD), and a risk factor of cardiovascular morbidity and death. Several clinical studies suggested that reduction of dialysate temperature, such as fixed reduction of dialysate temperature or isothermal dialysate using a biofeedback system, might improve the IDH rate.

OBJECTIVES

This review aimed to evaluate the benefits and harms of dialysate temperature reduction for IDH among patients with chronic kidney disease requiring HD, compared with standard dialysate temperature.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register up to 14 May 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs), cross-over RCTs, cluster RCTs and quasi-RCTs were included in the review.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted information including participants, interventions, outcomes, methods of the study, and risks of bias. We used a random-effects model to perform quantitative synthesis of the evidence. We assessed the risks of bias for each study using the Cochrane 'Risk of bias' tool. We assessed the certainty of evidence using Grades of Recommendation, Assessment, Development and Evaluation (GRADE).

MAIN RESULTS

We included 25 studies (712 participants). Three studies were parallel RCTs and the others were cross-over RCTs. Nineteen studies compared fixed reduction of dialysate temperature (below 36°C) and standard dialysate temperature (37°C to 37.5°C). Most studies were of unclear or high risk of bias. Compared with standard dialysate, it is uncertain whether fixed reduction of dialysate temperature improves IDH rate (8 studies, 153 participants: rate ratio 0.52, 95% CI 0.34 to 0.80; very low certainty evidence); however, it might increase the discomfort rate compared with standard dialysate (4 studies, 161 participants: rate ratio 8.31, 95% CI 1.86 to 37.12; very low certainty evidence). There were no reported dropouts due to adverse events. No study reported death, acute coronary syndrome or stroke.Three studies compared isothermal dialysate and thermoneutral dialysate. Isothermal dialysate might improve the IDH rate compared with thermoneutral dialysate (2 studies, 133 participants: rate ratio 0.68, 95% CI 0.60 to 0.76; I² = 0%; very low certainty evidence). There were no reports of discomfort rate (1 study) or dropouts due to adverse events (2 studies). No study reported death, acute coronary syndrome or stroke.

AUTHORS' CONCLUSIONS

Reduction of dialysate temperature may prevent IDH, but the conclusion is uncertain. Larger studies that measure important outcomes for HD patients are required to assess the effect of reduction of dialysate temperature. Six ongoing studies may provide much-needed high quality evidence in the future.

Individualized Cool Dialysate as an Effective Therapy for Intradialytic Hypotension and Hemodialysis Patients' Perception

Intradialytic hypotension (IDH) is the most common dialytic complication. Recurrent episodes of ischemia secondary to hemodynamic instability are associated with cardiomyopathy, increased risk of thrombosis of arteriovenous fistula, decreased quality of life, and increased mortality. Cool dialysate may be an effective approach to reducing intradialytic hypotension by promoting peripheral vasoconstriction. Most studies to date are small and do not employ individualized cool dialysates (ICD). The study consisted of standard and cool phases, with patients as their own controls. During the standard phase, participants underwent hemodialysis (HD) at their usual dialysate temperature at 37°C for six consecutive hemodialysis sessions. In the cool phase, the dialysate temperature was set at the core baseline temperature -0.5°C for six more sessions. We compared hemodynamic parameters during the standard and cool phases. A total of 93 participants were included. The number of IDH episodes during the standard and cool phases were 3.3 ± 2.8 and 2.0 ± 2.2 per patient respectively (P < 0.001). Other hemodynamic parameters including lowest intradialytic mean arterial pressure were significantly increased with ICD. We found that there was a high baseline rate of feeling cold among all participants and it increased after the implementation of ICD; however, the dropout rate was approximately 5%. ICD is an effective tool to decrease the frequency of IDH in the HD population and we provide a pragmatic, real-world approach to implement this technique.

Influence of ultrasound on the clearance of toxic substances from Polysulfone hollow fiber membrane used in a dialyzer filter

The aim of this work was to investigate the potential of high frequency ultrasound for the cleaning of a Polysulfone (PSU) ultrafiltration membrane used in hemodialysis. The blood substitute solution flowing through the hollow fiber membrane used in the High Flux F60 dialyzers has been sonicated by ultrasonic (US) waves with 1 MHz frequency and 2 W/cm2 in situ intensity. The solution was comprised of toxic compounds such as Urea, Creatinine, Vitamin B12 and Inulin. The effect of US was represented by comparison of the clearance in both OFF and ON ultrasound conditions. The results of these studies have been demonstrated that US can enhance the permeability of the PSU dialyzer membrane. Results revealed that US had significant effect (p-value ˂ 0.05) on the clearance of Inulin as a large molecule (5200 D) and accelerated its filtration by 28%. The proposed dialysis method can be used alongside the existing dialysis machine.

Novel Insights into the Pathogenesis and Prevention of Intradialytic Hypotension

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of haemodialysis (HD) and associated with adverse outcomes, especially when a nadir definition (systolic blood pressure <90 mm Hg) is used. The pathogenesis of IDH is directly linked to the discontinuous nature of the HD treatment, in combination with patient-related factors such as age, diabetes mellitus and cardiac failure.

SUMMARY

Although the decline in blood volume due to removal of fluid by ultrafiltration is the prime mover, thermally induced reflex vasodilation compromises the haemodynamic response to hypovolemia. Recent studies have stressed the relevance of changes in tissue perfusion during HD, which may translate in long-term organ damage. Monitoring changes in tissue perfusion, for which emerging evidence becomes available, appears to have great promise in the fine-tuning of the dialysis procedure. Key Messages: While it is unlikely that IDH can be completely prevented, reduction in inter-dialytic weight gain, prevention of an increase in core temperature by adjusting the dialysate temperature and more frequent or prolonged dialysis treatment remain cornerstones in providing a more comfortable and safe treatment.

Definitions of intradialytic hypotension

Intradialytic hypotension (IDH) is a common and often distressful complication of hemodialysis. However, despite its clinical significance, there is no consensus, evidence-based medical definition for the condition. Over the years, numerous definitions have been implemented in both the clinical and research settings. Definition inconsistencies have hindered data synthesis and the development of evidence-based guidelines for the prevention and treatment of IDH, as well as prevented accurate estimation of the population burden of IDH and patient risk assessment. Most existing IDH definitions are comprised of one or more of the following components: (1) intradialytic BP criteria (requisite BP declines or minimum BP thresholds), (2) the provision of interventions aimed at restoring effective arterial volume, and/or (3) patient-reported symptoms. Remarkably, there are insufficient data to inform IDH definition construction, and it remains unknown if a single, universal definition can adequately capture the condition across patient subgroups, and in clinical and research settings.

Measurement of Cardiac Output and Blood Volume During Hemodialysis with Fluorescent Dye Dilution Technique

Intradialytic hypotensive events (IDH) accompanied by deleterious decreases of the cardiac output complicate up to 25% of hemodialysis treatments. Monitoring options available to track hemodynamic changes during hemodialysis have been found ineffective to anticipate the occurrence of IDH. We have assembled opto-electronic instrumentation that uses the fluorescence of a small bolus of indocyanine green dye injected in the hemodialysis circuit to estimate cardiac output and blood volume based on indicator dilution principles in patients receiving hemodialysis. The instrument and technique were tested in 24 adult end-stage renal failure subjects during 64 hemodialysis sessions. A single calibration factor could be used across subjects and across time. Intra-subject variability of the measurements over time was <10%. Stroke volume index (SVI) (mean ± SEM = 34 ± 1 vs. 39 ± 2 mL m^-2) and central blood volume (CBV) index (783 ± 36 vs. 881 ± 33 mL m^-2) were lower at the beginning of the sessions in which IDH eventually occurred. Cardiac index, SVI, and CBV index decreased with hemodialysis in all treatment sessions but the decrease was more intense in the IDH sessions. We conclude that hemodynamic monitoring can be implemented in patients receiving hemodialysis with minimal disruption of the treatment and could help understand intradialytic hypotension.

Haemodialysis and haemodiafiltration lead to similar changes in vascular stiffness during treatment

BACKGROUND

Haemodiafiltration (HDF) has been reported to cause less hypotension than haemodialysis (HD). We hypothesized that HDF causes less change in vascular tone, thereby reducing hypotension.

METHODS

Aortic pulse wave velocity (PWVao) was measured in 284 patients, during a single dialysis session using cooled dialysate (117 HD, 177 HDF). Patient groups were matched for age, sex and cardiovascular comorbidity.

RESULTS

Systolic blood pressure (SBP) declined from 144 ± 26 to 133 ± 26 after 20 minutes, and to 131 ± 26 mmHg post HD, and for HDF from 152 ± 26 to 143 ± 27 after 20 minutes, then to 138 ± 27 mmHg post HDF. Net Ultrafiltration rates to achieve weight loss were similar; HD 0.13 ± 0.06 vs HDF 0.12 ± 0.05 mL/kg/min. PWVao did not change after 20 minutes HD 0.42(-0.7 to 1.3), HDF 0.5 (-0.6 to 1.8) or at the end of the session: HD -0.39 (1.5 to 1.2), HDF -0.41(-2.0 to 1.3) m/s. Aortic augmentation index (AiAxo), assessment of vascular tone fell significantly with both HD; 20 minutes by 6.2 (-2.5 to 14), end 5.6 (-6.7 to 13.9), and HDF 20 min by 4.2 (-2.5 to 10), end 7.8 (-0.8 to 19.3), with no difference between HD and HDF. The ultrafiltration rate correlated with % change in aortic SBP (r = 0.28 p = 0.004), but not with changes in PWVao or augmentation indices.

CONCLUSIONS

Blood pressure declined during both HD and HDF treatments, as did augmentation indices, unrelated to weight loss, suggesting a reduction in vascular stiffness occurs independently of treatment modality. We did not observe an advantage for HDF.

Effect of Lowering the Dialysate Temperature in Chronic Hemodialysis: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Lowering the dialysate temperature may improve outcomes for patients undergoing chronic hemodialysis. We reviewed the reported benefits and harms of lower temperature dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched the Cochrane Central Register, OVID MEDLINE, EMBASE, and Pubmed until April 15, 2015. We reviewed the reference lists of relevant reviews, registered trials, and relevant conference proceedings. We included all randomized, controlled trials that evaluated the effect of reduced temperature dialysis versus standard temperature dialysis in adult patients receiving chronic hemodialysis. We followed the Grading of Recommendations Assessment, Development and Evaluation approach to assess confidence in the estimates of effect (i.e., the quality of evidence). We conducted meta-analyses using random effects models.

RESULTS

Twenty-six trials were included, consisting of a total of 484 patients. Compared with standard temperature dialysis, reduced temperature dialysis significantly reduced the rate of intradialytic hypotension by 70% (95% confidence interval, 49% to 89%) and significantly increased intradialytic mean arterial pressure by 12 mmHg (95% confidence interval, 8 to 16 mmHg). Symptoms of discomfort occurred 2.95 (95% confidence interval, 0.88 to 9.82) times more often with reduced temperature compared with standard temperature dialysis. The effect on dialysis adequacy was not significantly different, with a Kt/V mean difference of -0.05 (95% confidence interval, -0.09 to 0.01). Small sample sizes, loss to follow-up, and a lack of appropriate blinding in some trials reduced confidence in the estimates of effect. None of the trials reported long-term outcomes.

CONCLUSIONS

In patients receiving chronic hemodialysis, reduced temperature dialysis may reduce the rate of intradialytic hypotension and increase intradialytic mean arterial pressure. High-quality, large, multicenter, randomized trials are needed to determine whether reduced temperature dialysis affects patient mortality and major adverse cardiovascular events.

Peri-dialytic hypertension and hypotension: another U-shaped BP-outcome association

Park et al. performed a retrospective analysis of a large hemodialysis cohort to describe the relationship between pre- to postdialysis changes in BP and mortality. Their study demonstrated adverse outcomes associated both with large decreases and with any increase in blood pressure pre- to postdialysis. Although limitations exist in this analysis, which lacked intradialytic blood pressure measurements, the results support the ongoing concern about the potential adverse hemodynamic stress associated with conventional three-times-weekly hemodialysis.

Efficacy of hemocontrol biofeedback system in intradialytic hypotension-prone hemodialysis patients

We conducted a study to determine whether the hemocontrol biofeedback system (HBS) can improve intradialytic hypotension (IDH) in hypotension-prone hemodialysis (HD) patients compared with conventional HD. In this multicenter prospective crossover study, 60 hypotension-prone patients were serially treated by conventional HD for 8 weeks (period A), by HD with hemoscan blood volume monitoring for 2 weeks (period B0), and by HBS HD for 8 weeks (period B1). The number of sessions complicated by symptomatic IDH during 24 HD sessions (14.9 ± 5.8 sessions, 62.1% in period A vs 9.2 ± 7.2 sessions, 38.4% in period B1, P<0.001) and the number of IDH-related nursing interventions in a session (0.96 ± 0.66 in period A vs 0.56 ± 0.54 in period B1, P<0.001) significantly decreased in period B1 than in period A. Recovery time from fatigue after dialysis was significantly shorter in period B1 than in period A. The patients with higher post-dialysis blood pressure, lower difference between pre- and post-dialysis blood pressure, less frequent IDH, and higher pre- and post-dialysis body weight in period A responded better to HBS in period B1 in regard to the reduction of IDH. In conclusion, HBS may improve the patient tolerability to HD by reducing the IDH frequency and promoting faster recovery from fatigue after dialysis.

Assessment of subjective and hemodynamic tolerance of different high- and low-flux dialysis membranes in patients undergoing chronic intermittent hemodialysis: a randomized controlled trial

Clinical experience and experimental data suggest that intradialytic hemodynamic profiles could be influenced by the characteristics of the dialysis membranes. Even within the worldwide used polysulfone family, intolerance to specific membranes was occasionally evoked. The aim of this study was to compare hemodynamically some of the commonly used polysulfone dialyzers in Switzerland. We performed an open-label, randomized, cross-over trial, including 25 hemodialysis patients. Four polysulfone dialyzers, A (Revaclear high-flux, Gambro, Stockholm, Sweden), B (Helixone high-flux, Fresenius), C (Xevonta high-flux, BBraun, Melsungen, Germany), and D (Helixone low-flux, Fresenius, Bad Homburg vor der Höhe, Germany), were compared. The hemodynamic profile was assessed and patients were asked to provide tolerance feedback. The mean score (±SD) subjectively assigned to dialysis quality on a 1-10 scale was A 8.4 ± 1.3, B 8.6 ± 1.3, C 8.5 ± 1.6, D 8.5 ± 1.5. Kt/V was A 1.58 ± 0.30, B 1.67 ± 0.33, C 1.62 ± 0.32, D 1.45 ± 0.31. The low- compared with the high-flux membranes, correlated to higher systolic (128.1 ± 13.1 vs. 125.6 ± 12.1 mmHg, P < 0.01) and diastolic (76.8 ± 8.7 vs. 75.3 ± 9.0 mmHg; P < 0.05) pressures, higher peripheral resistance (1.44 ± 0.19 vs. 1.40 ± 0.18 s × mmHg/mL; P < 0.05) and lower cardiac output (3.76 ± 0.62 vs. 3.82 ± 0.59 L/min; P < 0.05). Hypotension events (decrease in systolic blood pressure by >20 mmHg) were 70 with A, 87 with B, 73 with C, and 75 with D (P < 0.01 B vs. A, 0.05 B vs. C and 0.07 B vs. D). The low-flux membrane correlated to higher blood pressure levels compared with the high-flux ones. The Helixone high-flux membrane ensured the best efficiency. Unfortunately, the very same dialyzer correlated to a higher incidence of hypotensive episodes.

Attending rounds: A patient with intradialytic hypotension

Intradialytic hypotension is the most common adverse event that occurs during the hemodialysis procedure. Despite advances in machine technology, it remains a difficult management issue. The pathophysiology of intradialytic hypotension and measures to reduce its frequency are discussed. An accurate assessment of dry weight is crucial in all patients on dialysis and especially those patients prone to intradialytic hypotension. The presence of edema and hypertension has recently been shown to be a poor predictor of volume overload. Noninvasive methods to assess volume status, such as whole body and segmental bioimpedance, hold promise to more accurately assess fluid status. Reducing salt intake is key to limiting interdialytic weight gain. A common problem is that patients are often told to restrict fluid but not salt intake. Lowering the dialysate temperature, prohibiting food ingestion during hemodialysis, and midodrine administration are beneficial. Sodium modeling in the absence of ultrafiltration modeling should be abandoned. There is not enough data on the efficacy of l-carnitine to warrant its routine use.

Noninvasive techniques for prevention of intradialytic hypotension

Episodes of hypotension during hemodialysis treatment constitutes an important clinical problem which has received considerable attention in recent years. Despite the fact that numerous approaches to reducing the frequency of intradialytic hypotension (IDH) have been proposed and evaluated, the problem has not yet found a definitive solution--an observation which, in particular, applies to episodes of acute, symptomatic hypotension. This overview covers recent advances in methodology for predicting and preventing IDH. Following a brief overview of well-established hypotension-related variables, including blood pressure, blood temperature, relative blood volume, and bioimpedance, special attention is given to electrocardiographic and photoplethysmographic (PPG) variables and their significance for IDH prediction. It is concluded that cardiovascular variables which reflect heart rate variability, heart rate turbulence, and baroreflex sensitivity are important to explore in feedback control hemodialysis systems so as to improve their performance. The analysis of hemodialysis-related changes in PPG pulse wave properties hold considerable promise for improving prediction.

Shengmai injection, a traditional chinese patent medicine, for intradialytic hypotension: a systematic review and meta-analysis

Intradialytic hypotension (IDH) is a global public health problem. A rising number of IDH sufferers resort to Chinese patent medicine, Shengmai Injection (SMI) in China. The objectives of present study are to assess the effectiveness and safety of SMI as an adjunct therapy for IDH. A systematic search of 6 medical databases was performed up to December 2011. Randomized trials involving SMI adjuvant therapy versus conventional therapy were identified. RevMan 5.0 was used for data analysis. Ten randomized clinical trials with 437 participants were identified. Methodological quality was considered inadequate in all trials. Compared with conventional therapy, SMI adjunct therapy showed significant effects in improving the clinic effective rate (P < 0.01), decreasing the incidence of IDH episode (P < 0.01), decreasing the frequency of nursing interventions (P < 0.01), and increasing diastolic blood pressure (P < 0.01). There was no statistical significance in the improvement of mean arterial pressure (P = 0.22) and systolic blood pressure (P = 0.08) between two groups. Four studies had mentioned adverse events, but no serious adverse effects were reported in any of the included trials. In conclusion, SMI adjunct therapy appears to be potentially effective in treatment of IDH and is generally safe. However, further rigorous designed trials are needed.

Mathematical modeling of thermal and circulatory effects during hemodialysis

Intradialytic hypotension (IDH) is one of the most common complications of hemodialysis (HD) treatment. The initiating factor of IDH is a decrease in blood volume, which is related to an imbalance between ultrafiltration (UF) and refilling rate. Impaired reactivity of resistance and capacitance vessels in reaction to hypovolemia plays possibly a major role in the occurrence of IDH. These vessels also fulfill an important function in body temperature regulation. UF-induced cutaneous vasoconstriction would result in a reduced surface heat loss and an increase in core temperature. To release body heat, skin blood flow is increased at a later stage of the HD treatment, whereby possibly IDH can occur. The aim of the study is to develop a mathematical model that can provide insight into the impact of thermoregulatory processes on the cardiovascular (CV) system during HD treatment. The mathematical procedure has been created by coupling a thermo-physiological model with a CV model to study regulation mechanisms in the human body during HD + UF. Model simulations for isothermal versus thermoneutral HD + UF were compared with measurement data of patients on chronic intermittent HD (n = 13). Core temperature during simulated HD + UF sessions increased within the range of measurement data (0.23°C vs. 0.32 ± 0.41°C). The model showed a decline in mean arterial pressure of -7% for thermoneutral HD + UF versus -4% for isothermal HD + UF after 200 min during which relative blood volume changed by -13%. In conclusion, simulation results of the combined model show possibilities for predicting circulatory and thermal responses during HD + UF.

Rationale and design of a multi-centre randomised controlled trial of individualised cooled dialysate to prevent left ventricular systolic dysfunction in haemodialysis patients

Background

The main hypothesis of this study is that patients having regular conventional haemodialysis (HD) will have a smaller decline in cardiac systolic function by using cooler dialysate. Cooler dialysate may also be beneficial for brain function.

Methods/Design

The trial is a multicentre, prospective, randomised, un-blinded, controlled trial. Patients will be randomised 1:1 to use a dialysate temperature of 37°C for 12 months or an individualised cooled dialysate. The latter will be set at 0.5°C less than the patient’s own temperature, determined from the mean of 6 prior treatment sessions with a tympanic thermometer, up to a maximum of 36°C. Protocol adherence will be regularly checked. Inclusion criteria are incident adult HD patients within 180 days of commencing in-centre treatment 3 times per week with capacity to consent for the trial and without contra-indications for magnetic resonance imaging. Exclusion criteria include not meeting inclusion criteria, inability to tolerate magnetic resonance imaging and New York Heart Association Grade IV heart failure. During the study period, resting cardiac and cerebral magnetic resonance imaging will be performed at baseline and 12 months on an inter-dialytic day. Cardiovascular performance during HD will also be assessed by continuous cardiac output monitors, intra-dialytic echocardiography and biomarkers at baseline and 12 months. The primary outcome measure is a 5% between-group difference in left ventricular ejection fraction measured by cardiac magnetic resonance imaging at 12 months compared to baseline. Analysis will be by intention-to-treat. Secondary outcome measures will include changes in cerebral microstructure and changes in cardiovascular performance during HD. A total of 73 patients have been recruited into the trial from four UK centres. The trial is funded by a Research for Patient Benefit Grant from the National Institute of Healthcare Research. AO is funded by a British Heart Foundation Clinical Research Training Fellowship Grant. The funders had no role in the design of the study.

Discussion

This investigator-initiated study has been designed to provide evidence to help nephrologists determine the optimal dialysate temperature for preserving cardiac and cerebral function in HD patients.

Trial registration

ISRCTN00206012 and UKCRN ID 7422

Korean red ginseng improves blood pressure stability in patients with intradialytic hypotension

Introduction. Intradialytic hypotension (IDH) is a common complication during hemodialysis which may increase mortality risks. Low dose of Korean red ginseng (KRG) has been reported to increase blood pressure. Whether KRG can improve hemodynamic stability during hemodialysis has not been examined. Methods. The 8-week study consisted of two phases: observation phase and active treatment phase. According to prehemodialysis blood pressure (BP), 38 patients with IDH were divided into group A (BP ≥ 140/90 mmHg, n = 18) and group B (BP < 140/90 mmHg, n = 20). Patients were instructed to chew 3.5 gm KRG slices at each hemodialysis session during the 4-week treatment phase. Blood pressure changes, number of sessions disturbed by symptomatic IDH, plasma levels of vasoconstrictors, blood biochemistry, and adverse effects were recorded. Results. KRG significantly reduced the degree of blood pressure drop during hemodialysis (P < 0.05) and the frequency of symptomatic IDH (P < 0.05). More activation of vasoconstrictors (endothelin-1 and angiotensin II) during hemodialysis was found. The postdialytic levels of endothelin-1 and angiotensin II increased significantly (P < 0.01). Conclusion. Chewing KRG renders IDH patients better resistance to acute BP reduction during hemodialysis via activation of vasoconstrictors. Our results suggest that KRG could be an adjuvant treatment for IDH.

Intra-dialytic hypotension and blood volume and blood temperature monitoring

Intra-dialytic hypotension (IDH) is a common problem affecting haemodialysis patients. Its aetiology is complex and influenced by multiple patient and dialysis factors. IDH occurs when the normal cardiovascular response cannot compensate for volume loss associated with ultrafiltration, and is exacerbated by a myriad of factors including intra-dialytic fluid gains, cardiovascular disease, antihypertensive medications and the physiological demands placed on patients by conventional haemodialysis. The use of blood volume monitoring and blood temperature monitoring technologies is advocated as a tool to predict and therefore prevent episodes of IDH. We review the clinical utility of these technologies and summarize the current evidence of their effect on reducing the incidence of IDH in haemodialysis population.

Dialysate and blood temperature during hemodialysis: comparing isothermic dialysis with a single-pass batch system

The Genius is a convenient single-pass batch hemodialysis system. Dialysate is heated during the preparation phase. Once the container is filled at one of the three available starting temperatures, dialysate cools spontaneously. As dialysate temperature plays an important role in hemodynamic stability, knowledge of the instantaneous dialysate temperature is important. We documented the evolution of dialysate temperature during Genius dialysis with dialysate prepared at two different temperatures (low and medium) as well as its effect on blood temperature and hemodynamic stability. Genius dialysis was compared to isothermic dialysis obtained by a module programmed to obtain a constant blood temperature. With Genius, dialysate temperature progressively decreased from 36.3 (low) and 37.6°C (medium) in the beginning to 34.4 and 35.3°C at the end of the session, both following first-order kinetics. During isothermic dialysis, dialysate cooled from 37.3 to 35.4°C, being warmer than with Genius low. Blood temperature decreased during dialysis with Genius low, from 36.4 to 36.2°C, whereas with medium temperature, blood temperature initially rose from 36.4°C at 15 min to 36.5 and 36.6°C at 30 and 60 min, respectively, followed by a decrease from 180 min onward, to 36.4°C at the end. During isothermic dialysis, blood temperature remained stable, as expected. Blood pressure decreased during all three schedules, with the highest value at 15 min during isothermic dialysis, and at the end of the session, the lowest value with isothermic dialysis.

Urea kinetics and intermittent dialysis prescription in small animals

Hemodialysis improves survival for animals with acute kidney injury beyond what would be expected with conventional management of the same animals. Clinical evidence and experience in human patients suggest a role for earlier intervention with renal replacement to avoid the morbidity of uremia and to promote better metabolic stability and recovery. For a large population of animal patients, it is the advanced standard for the management of acute and chronic uremia, life-threatening poisoning, and fluid overload for which there is no alternative therapy.

Hemofiltration and hemodiafiltration reduce intradialytic hypotension in ESRD

Symptomatic intradialytic hypotension is a common complication of hemodialysis (HD). The application of convective therapies to the outpatient setting may improve outcomes, including intradialytic hypotension. In this multicenter, open-label, randomized controlled study, we randomly assigned 146 long-term dialysis patients to HD (n = 70), online predilution hemofiltration (HF; n = 36), or online predilution hemodiafiltration (HDF; n = 40). The primary end point was the frequency of intradialytic symptomatic hypotension (ISH). Compared with the run-in period, the frequency of sessions with ISH during the evaluation period increased for HD (7.1 to 7.9%) and decreased for both HF (9.8 to 8.0%) and HDF (10.6 to 5.2%) (P < 0.001). Mean predialysis systolic BP increased by 4.2 mmHg among those who were assigned to HDF compared with decreases of 0.6 and 1.8 mmHg among those who were assigned to HD and HF, respectively (P = 0.038). Multivariate logistic regression demonstrated significant risk reductions in ISH for both HF (odds ratio 0.69; 95% confidence interval 0.51 to 0.92) and HDF (odds ratio 0.46, 95% confidence interval 0.33 to 0.63). There was a trend toward higher dropout for those who were assigned to HF (P = 0.107). In conclusion, compared with conventional HD, convective therapies (HDF and HF) reduce ISH in long-term dialysis patients.