Symptomatic Intradialytic Hypotension and Mortality: An Opinionated Review

High Ultrafiltration Rate Is Associated with Increased All-Cause Mortality in Incident Hemodialysis Patients with a High Cardiothoracic Ratio

A high ultrafiltration rate (UFR) is associated with increased mortality in hemodialysis patients. However, whether a high UFR itself or heart failure with fluid overload followed by a high UFR causes mortality remains unknown. In this study, 2615 incident hemodialysis patients were categorized according to their initial cardiothoracic ratios (CTRs) to assess whether UFR was associated with mortality in patients with high or low CTRs. In total, 1317 patients (50.4%) were women and 1261 (48.2%) were diabetic. During 2246 (1087−3596) days of follow-up, 1247 (47.7%) cases of all-cause mortality were noted. UFR quintiles 4 and 5 were associated with higher risks of all-cause mortality than UFR quintile 2 in fully adjusted Cox regression analysis. As the UFR increased by 1 mL/kg/h, the risk of all-cause mortality increased 1.6%. Subgroup analysis revealed that in UFR quintile 5, hazard ratios (HRs) for all-cause mortality were 1.91, 1.48, 1.22, and 1.10 for CTRs of >55%, 50−55%, 45−50%, and <45%, respectively. HRs for all-cause mortality were higher in women and patients with high body weight. Thus, high UFRs may be associated with increased all-cause mortality in incident hemodialysis patients with a high CTR, but not in those with a low CTR.

Intérêts et limites de l’Hémodialyse Longue Nocturne

L’hémodialyse (HD) Longue Nocturne (HDLN) intermittente permet de combiner dialyse et sommeil. Ses avantages cliniques sont une vitesse d’ultrafiltration réduite, un meilleur contrôle de la volémie avec amélioration de la tolérance des séances et des performances cardiaques, une phosphatémie et des moyennes molécules mieux épurées et une meilleure survie dans les études de cohortes. La qualité de vie n’est pas altérée par la longueur des séances et elle s’améliore quand elle n’est pas optimale lors du transfert de l’HD standard vers l’HDLN. La qualité du sommeil n’est parfois perturbée mais elle n’est pas une cause importante de sortie du programme. La pérennité d’un programme d’HDLN passe par les volontés conjointes médicales et managériales, la sélection des patients stables, le respect des horaires et de la durée de séances, indispensable à la dialyse de sommeil. Les autorités de santé doivent jouer un rôle pour permettre cette modalité dans des conditions financières acceptables. L’information au patient de l’existence de l’HDLN avant le stade de la dialyse est essentielle, aidée par le témoignage des pairs. Les sociétés savantes doivent soutenir la recherche et l’information aux néphrologues. Enfin les conditions architecturales favorisant l’intimité et le sommeil sont une clé de réussite du programme.

Using the Intelligent System to Improve the Delivered Adequacy of Dialysis by Preventing Intradialytic Complications

Acute kidney failure patients while detoxificated by hemodialysis (HD) mostly or continuously faced regular problems such as low blood pressure (hypotension), muscle cramps, nausea, or vomiting. Higher intradialytic symptom leads to low-quality HD treatment. Although more known therapeutic interventions are used to relieve the HD side effects, this study was designed to investigate how intelligent systems can make highly beneficial alterations in dialysis facilities and equipment to ease intradialytic complications and help the staff deliver high-quality treatment. A search was performed among relevant research articles based on nonpharmacological intervention methods considered to prevent adverse effects of renal replacement therapy until 2020 in the PubMed databases using the terms “intradialytic complications,” “intradialytic complication interventions,” “nonpharmacological interventions,” “intradialytic exercises,” and “adequacy calculation methods.” Studies included the prevalence of intradialytic complications, different strategies with the aim of preventing complications, the outcome of intradialytic exercises on dialysis symptoms, and dialysis dose calculation methods. The results showed the incidence of hypotension varying between 5% and 30%, fatigue, muscular cramps, and vomiting as the most common complications during dialysis, which greatly affect the outcome of HD sessions. To prevent hypotension, ultrafiltration profiling, sodium modeling, low dialysate temperature, and changing the position to Trendelenburg are some strategies. Urea reduction ratio (URR), formal urea kinetic modeling (FUKM), formal single-pool urea kinetics, and online clearance monitoring (OCM) are methods for calculating the delivered dose of dialysis in which OCM is a low-cost and accessible way to monitor regularly the quality of dialysis delivered. Integration of the chair and HD machine which is in direct contact with the patient provides an intelligent system that improves the management of the dialysis session to enhance the quality of healthcare service.

Diagnostic accuracy of internal jugular vein ultrasound in quantification of the central venous pressure for hemodialysis patients

Background

Assessment of the central venous pressure (CVP) is an essential hemodynamic parameter for monitoring the dialyzing patients. Our objective of the present study is to investigate the accuracy of CVP measurement by internal jugular vein US in comparison to the direct measurement by the central venous catheters for hemodialysis patients. We included 106 patients; where their CVP was assessed in two different non invasive US methods (CVPni) separately and in combination and the obtained measurements were correlated to the invasive measurements (CVPi) by catheters.

Results

By method 1, there is a highly significant positive correlation between CVPni and CVPi (ρ < 0.001) and a Pearson correlation coefficient (r = 0.913 n = 93), and by method 2, there is also a highly significant positive correlation between the CVPni and CVPi in both groups (r = 0.832, 95%, n = 106, p < 0.001), 1.935 was the cut-off point for prediction of CVP ≥ 10cmH20. For differentiation between patients with CVP < 10cmH20 and ≥ 10cmH20, the accuracy measures (sensitivity, specificity, PPV, NPV, and overall accuracy) were 100%, 79.31%, 74.47%, 100%, and 87.10% by method 1, and were 91.11%, 85.48%, 82.00%, 92.98%, and 87.85% by method 2, while the combination of both methods had gained 88.57%, 89.66%, 83.78%, 92.86%, and 89.25%, respectively.

Conclusion

The US offered a reliable and non-invasive tool for monitoring CVP. The present study has a novelty of combining more than one US method and this had reported higher accuracy measures and outperformed the use of a single method.

Machine Learning Analysis of Time-Dependent Features for Predicting Adverse Events During Hemodialysis Therapy: Model Development and Validation Study

BACKGROUND

Hemodialysis (HD) therapy is an indispensable tool used in critical care management. Patients undergoing HD are at risk for intradialytic adverse events, ranging from muscle cramps to cardiac arrest. So far, there is no effective HD device-integrated algorithm to assist medical staff in response to these adverse events a step earlier during HD.

OBJECTIVE

We aimed to develop machine learning algorithms to predict intradialytic adverse events in an unbiased manner.

METHODS

Three-month dialysis and physiological time-series data were collected from all patients who underwent maintenance HD therapy at a tertiary care referral center. Dialysis data were collected automatically by HD devices, and physiological data were recorded by medical staff. Intradialytic adverse events were documented by medical staff according to patient complaints. Features extracted from the time series data sets by linear and differential analyses were used for machine learning to predict adverse events during HD.

RESULTS

Time series dialysis data were collected during the 4-hour HD session in 108 patients who underwent maintenance HD therapy. There were a total of 4221 HD sessions, 406 of which involved at least one intradialytic adverse event. Models were built by classification algorithms and evaluated by four-fold cross-validation. The developed algorithm predicted overall intradialytic adverse events, with an area under the curve (AUC) of 0.83, sensitivity of 0.53, and specificity of 0.96. The algorithm also predicted muscle cramps, with an AUC of 0.85, and blood pressure elevation, with an AUC of 0.93. In addition, the model built based on ultrafiltration-unrelated features predicted all types of adverse events, with an AUC of 0.81, indicating that ultrafiltration-unrelated factors also contribute to the onset of adverse events.

CONCLUSIONS

Our results demonstrated that algorithms combining linear and differential analyses with two-class classification machine learning can predict intradialytic adverse events in quasi-real time with high AUCs. Such a methodology implemented with local cloud computation and real-time optimization by personalized HD data could warn clinicians to take timely actions in advance.

Effect of acute intradialytic aerobic and resistance exercise on one-day blood pressure in patients undergoing hemodialysis: a pilot study

BACKGROUND

Hypertension and intradialytic hypotension are independent risk factors for mortality in hemodialysis patients. We hypothesized that intradialytic exercise would increase blood pressure (BP) during dialysis and decrease it during the postdialytic period. The present study aimed to investigate the effect of acute intradialytic exercise on BP both during dialysis and for 20 hours postdialysis, and to detect any differences in effects of aerobic exercise (AE), resistance exercise (RE), and usual care (UC-the control condition).

METHODS

Eleven patients undergoing maintenance hemodialysis performed two complete sets of AE or RE, with a 1-hour rest between the sets. The patients performed AE, RE and UC over three consecutive weeks at 7-day intervals. Intradialytic BP was measured using an oscillometric BP monitor (N.=11), and ambulatory BP was measured for 20 hours after each dialysis session using an ambulatory BP monitor (N.=8).

RESULTS

The mean BP of the patients in the AE and RE interventions increased during exercise (P<0.05), with the exception of the first set of AE. However, only RE increased BP significantly compared with UC (P<0.05). Following dialysis, daytime ambulatory BP was significantly lower after AE and RE than after UC (P<0.05).

CONCLUSIONS

Acute intradialytic exercise interventions are effective in increasing BP during dialysis and decreasing daytime ambulatory BP after dialysis. Longer observation periods and larger sample sizes will be needed to confirm our findings. Also further studies should be performed on patients prone to intradialytic hypotension.

Effect of Mealtime During Hemodialysis on Patients' Complications

Introduction: Food intake during hemodialysis increases the risk of problems such as hypotension, nausea, and vomiting in patients undergoing hemodialysis. This study aimed to determine the effect of mealtime during dialysis on the patients' complications. Methods: This is a quasi-experimental study consisted of all eligible hemodialysis patients in Hamadan teaching hospitals. All of 48 patients were selected through census method. The research was conducted in two sessions. At both sessions, patients were kept fasting prior to hemodialysis. In the first session, after one hour and in the second session after two hours of hemodialysis, a meal containing 350 kcal of energy was given to the patients. Blood pressure and intensity of nausea and vomiting was measured and recorded immediately before the start of hemodialysis, and then every half an hour before the termination of the hemodialysis. Results: The results showed that in both sessions, food intake caused a drop in the systolic and diastolic blood pressure, but changes in the mealtime had no effect on the systolic and diastolic blood pressure. Also, statistical test showed that changes in the mealtime had no significant impact on the intensity of nausea and vomiting. Conclusion: Food intake during hemodialysis had no effect on the nausea and vomiting, but caused a drop in the systolic and diastolic blood pressure, the drop continued for one hour and one and a half hour after the meal. It is suggested, mealtime in the early hours of hemodialysis could be better managed during the hemodialysis process.

Feasibility of intermittent back-filtrate infusion hemodiafiltration to reduce intradialytic hypotension in patients with cardiovascular instability: a pilot study

Background

Intradialytic hypotension (IDH) is one of the major problems in performing safe hemodialysis (HD). As blood volume depletion by fluid removal is a major cause of hypotension, careful regulation of blood volume change is fundamental. This study examined the effect of intermittent back-filtrate infusion hemodiafiltration (I-HDF), which modifies infusion and ultrafiltration pattern.

Methods

Purified on-line quality dialysate was intermittently infused by back filtration through the dialysis membrane with a programmed dialysis machine. A bolus of 200 ml of dialysate was infused at 30 min intervals. The volume infused was offset by increasing the fluid removal over the next 30 min by an equivalent amount. Seventy-seven hypotension-prone patients with over 20-mmHg reduction of systolic blood pressure during dialysis or intervention-requirement of more than once a week were included in the crossover study of 4 weeks duration for each modality. In a total of 1632 sessions, the frequency of interventions, the blood pressure, and the pulse rate were documented.

Results

During I-HDF, interventions for symptomatic hypotension were reduced significantly from 4.5 to 3.0 (per person-month, median) and intradialytic systolic blood pressure was 4 mmHg higher on average. The heart rate was lower during I-HDF than HD in the later session. Older patients and those with greater interdialytic weight gain responded to I-HDF.

Conclusions

I-HDF could reduce interventions for IDH. It is accompanied with the increased intradialytic blood pressure and the less tachycardia, suggesting less sympathetic stimulation occurs. Thus, I-HDF could be beneficial for some hypotension-prone patients.

UMIN registration number

000013816.

Acute effect of citrate bath on postdialysis alkalaemia

INTRODUCTION

The correction of metabolic acidosis caused by renal failure is achieved by adding bicarbonate during dialysis. In order to avoid the precipitation of calcium carbonate and magnesium carbonate that takes place in the dialysis fluid (DF) when adding bicarbonate, it is necessary to add an acid, usually acetate, which is not free of side effects. Thus, citrate appears as an advantageous alternative to acetate, despite the fact that its acute effects are not accurately known.

OBJECTIVE

To assess the acute effect of a dialysis fluid containing citrate instead of acetate on acid-base balance and calcium-phosphorus metabolism parameters.

MATERIAL AND METHODS

A prospective crossover study was conducted with twenty-four patients (15 male subjects and 9 female subjects). All patients underwent dialysis with AK-200-Ultra-S monitor with SoftPac® dialysis fluid, made with 3 mmol/L of acetate and SelectBag Citrate®, with 1 mmol/L of citrate and free of acetate. The following were measured before and after dialysis: venous blood gas monitoring, calcium (Ca), ionic calcium (Cai), phosphorus (P) and parathyroid hormone (PTH).

RESULTS

Differences (p<0.05) were found when using the citrate bath (C) compared to acetate (A) in the postdialysis values of: pH, C: 7.43 (0.04) vs. A: 7.47 (0.05); bicarbonate, C: 24.7 (2.7) vs. A: 27.3 (2.1) mmol/L; base excess (BEecf), C: 0.4 (3.1) vs. A: 3.7 (2.4) mmol/L; corrected calcium (Cac), C: 9.8 (0.8) vs. A: 10.1 (0.7) mg/dL; and Cai, C: 1.16 (0.05) vs. A: 1.27 (0.06) mmol/L. No differences were found in either of the parameters measured before dialysis.

CONCLUSION

Dialysis with citrate provides better control of postdialysis acid-base balance, decreases/avoids postdialysis alkalaemia, and lowers the increase in Cac and Cai. This finding is of special interest in patients with predisposing factors for arrhythmia and patients with respiratory failure, carbon dioxide retention, calcifications and advanced liver disease.

Short and Long-Term Effects of the Angiotensin II Receptor Blocker Irbesartan on Intradialytic Central Hemodynamics: A Randomized Double-Blind Placebo-Controlled One-Year Intervention Trial (the SAFIR Study)

Background and Aim

Little is known about the tolerability of antihypertensive drugs during hemodialysis treatment. The present study evaluated the use of the angiotensin II receptor blocker (ARB) irbesartan.

Design

Randomized, double-blind, placebo-controlled, one-year intervention trial.

Setting and Participants

Eighty-two hemodialysis patients with urine output >300 mL/day and dialysis vintage <1 year.

Intervention

Irbesartan/placebo 300 mg/day for 12 months administered as add-on to antihypertensive treatment using a predialytic systolic blood pressure target of 140 mmHg in all patients.

Outcomes and Measurements

Cardiac output, stroke volume, central blood volume, total peripheral resistance, mean arterial blood pressure, and frequency of intradialytic hypotension.

Results

At baseline, the groups were similar regarding age, comorbidity, blood pressure, antihypertensive medication, ultrafiltration volume, and dialysis parameters. Over the one-year period, predialytic systolic blood pressure decreased significantly, but similarly in both groups. Mean start and mean end cardiac output, stroke volume, total peripheral resistance, heart rate, and mean arterial pressure were stable and similar in the two groups, whereas central blood volume increased slightly but similarly over time. The mean hemodynamic response observed during a dialysis session was a drop in cardiac output, in stroke volume, in mean arterial pressure, and in central blood volume, whereas heart rate increased. Total peripheral resistance did not change significantly. Overall, this pattern remained stable over time in both groups and was uninfluenced by ARB treatment. The total number of intradialytic hypotensive episodes was (placebo/ARB) 50/63 (P = 0.4). Ultrafiltration volume, left ventricular mass index, plasma albumin, and change in intradialytic total peripheral resistance were significantly associated with intradialytic hypotension in a multivariate logistic regression analysis based on baseline parameters.

Conclusion

Use of the ARB irbesartan as an add-on to other antihypertensive therapy did not significantly affect intradialytic hemodynamics, neither in short nor long-term, and no significant increase in hypotensive episodes was seen.

Trial registration

Clinicaltrials.gov NCT00791830

Hemodialysis immediately after cardiac catheterization is a risk factor for intradialytic hypotension

Many hemodialysis clinicians have noticed that patients frequently develop intradialytic hypotension (IDH) immediately after cardiac catheterization (CC). However, precise data about the incidence of IDH immediately after CC are scarce. This study involved a single-center, retrospective, cross-sectional design. We reviewed the medical records of all HD patients who underwent CC between January 2009 and March 2012 at Hiroshima Prefectural Hospital. IDH was defined as a fall of systolic blood pressure of more than 20 mm Hg or a fall of mean blood pressure of more than 10 mm Hg, with symptoms according to the K/DOQI criteria. Data on a total of 112 patients were obtained: 64 patients commenced HD immediately after CC (IA group) and 48 patients underwent HD on the day after CC (ND group). The overall incidence of IDH was 34% (38/112). The incidence of IDH was significantly higher in the IA group than in the ND group (27/64, 42% vs. 11/48, 23%; P < 0.05). Multivariate logistic regression analysis showed that IA (odds ratio, 5.39; 95% confidence interval, 1.76 to 16.49; P < 0.01), coronary stenosis (odds ratio, 4.16; 95% confidence interval, 1.49 to 11.64; P < 0.05) were independently associated with IDH. This study revealed that HD immediately after CC is associated with a higher incidence of IDH. Clinicians should consider that HD following CC be scheduled for the next day, especially in patients with coronary stenosis.

The choice of dialysate sodium is influenced by hemodialysis frequency and duration: what should it be and for what modality?

Cardiovascular disease is the leading cause of mortality in hemodialysis patients. A chronic state of volume and pressure overload contributes, and central to this is the net sodium balance over the course of a hemodialysis. Of recent interest is the contribution of the dialysate sodium concentration (Dial-Na+) to clinical outcomes. Abundant evidence confirms that in thrice-weekly conventional hemodialysis, higher Dial-Na+ associates with increased intradialytic weight gain, blood pressure, and cardiovascular morbidity and mortality. On the other hand, low Dial-Na+ associates with intradialytic hypotension in the same patient population. However, the effect of Dial-Na+ in short hours daily hemodialysis (SHD; often referred to as "quotidian" dialysis), or nocturnal dialysis (FHND) is less well studied. Increased frequency and duration of exposure to a diffusive sodium gradient modulate the way in which DPNa+ alters interdialytic weight gain, predialysis blood pressure, and intradialytic change in blood pressure. Furthermore, increased dialysis frequency appears to decrease the predialysis plasma sodium setpoint (SP), which is considered stable in conventional thrice-weekly patients. This review discusses criteria to determine optimal Dial-Na+ in conventional, SHD and FHND patients, and identifies areas for future research.

Acute effects of haemodialysis on central venous and arterial pressure characteristics

AIM

Haemodynamic stability of patients during haemodialysis (HD) sessions is of pivotal importance and accurate determination of dry weight remains a challenge. Little information is available about central venous and aortic pressure during dialysis. In this pilot study we used a non-invasive technique to describe the changes in central venous pressure (CVP) during dialysis.

METHODS

An ultrasound-assisted pressure-manometer was used at the cephalic vein during haemodialysis to quantify CVP. Central aortic pressure changes were assessed as aortic augmentation index and subendocardial viability ratio. Bioimpedance was applied to measure total body water, as well as extracellular and intracellular water before and after HD. Measurements were performed prior during and after 1 and 2 h on HD.

RESULTS

Ten patients were included with a median age of 72 years (23-82). Haemodialysis reduced the weight by 2.0 kg, corresponding to a measured decrease in total body water of 1.9 L. The mean CVP showed a significant decrease (9.0-0.8 cmH₂O; P = 0.0005) during dialysis. The significant drop in CVP was found during the first hour (9-2.8 cmH₂O). Starting and stopping dialysis was reflected by a reduction of 2.6 cmH₂O and a rise of 2.8 cmH₂O (n.s.). Aortic augmentation index decreased from 26.1% to 21.0% (n.s.). Subendocardial viability ratio increased from 126% to 156% (P < 0.05) during HD, and decreased to 139% direct after HD (n.s.).

CONCLUSION

This is the first study that illustrates a prominent reduction of CVP during the first hour of haemodialysis. Non-invasive CVP measurement is feasible during haemodialysis and adds another piece in the puzzle of factors involved in haemodynamic stability.

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.

Hypertension in hemodialysis patients: an opinion-based update

Hypertension is highly prevalent in hemodialysis patients but its management remains a matter of debate. In this review, we discuss the observational studies on the association of blood pressure with outcomes, measurement of blood pressure in hemodialysis patients and present an opinion-based approach to treating hypertension.

Hydration measurement by bioimpedance spectroscopy and blood pressure management in children on hemodialysis

BACKGROUND

Hypertension is frequent in chronic hemodialyzed patients and usually treated by reducing extracellular fluid. Probing dry weight only based on a clinical evaluation may be hazardous, especially in case of volume independent hypertension.

METHODS

We performed a 1-year retrospective study in three pediatric centers to define the relation between blood pressure (BP) and hydration status, assessed by whole-body bioimpedance spectroscopy (BIS). We analyzed 463 concomitant measurements of BP, relative overhydration (rel.OH), and plasma sodium (Napl) in 23 children (mean age 13.9 ± 5.1 years).

RESULTS

Pre-dialytic under-hydration (rel.OH < -7%) was present in 5.4% of the sessions, out of which 24% showed hypertension. Normohydration (rel.OH -7 - +7%) was observed in 62.4% of the sessions, 45.3% of them revealed hypertension. Moderate OH (rel.OH +7 - +15%) was present in 21% of the sessions, 47.4% of them showed normal BP. In 11.2% of the sessions, severe overhydration (rel.OH > +15%) was assessed, however, the majority (73%) showed normal BP. Patient-specific Napl setpoint could not be described. Mean dialysate sodium concentration was higher than mean Napl.

CONCLUSIONS

Hypertension is not always related to overhydration. Therefore, BIS should restrict the practice of "probing dry weight" in hypertensive children. Moreover, sodium dialytic balance needs to be considered to improve BP management.

The dynamics of prognostic indicators: toward earlier identification of dialysis patients with a high risk of dying

Mortality remains stubbornly high in patients receiving chronic dialysis treatment. Identifying at-risk patients is essential for implementation of supportive therapies. The Monitoring Dialysis Outcomes (MONDO) database shows that in 40,000 dialysis patients worldwide who died, systolic blood pressure, interdialytic weight gain, and serum albumin declined progressively, and C-reactive protein increased more than 12 months before death, indicating that predictive models may be developed to enable nephrologists to improve the clinical outcome of dialysis patients.