Dialysis-related Hypotension Research Articles

The efficacy and safety of ivabradine hydrochloride in hemodialysis patients with chronic heart failure.

There is little evidence for ivabradine hydrochloride in patients undergoing hemodialysis. In this open-label prospective interventional trial of hemodialysis patients with chronic heart failure, during 12 weeks of treatment, changes in Heart rate (HR), frequency of dialysis-related hypotension were examined, and we investigated health-related quality of life (HR-QOL) and adverse effects. 18 patients from 6 facilities were enrolled in the study. HR significantly decreased over time, from 87 ± 12.61/min at baseline to 75.85 ± 8.91/min (p = 0.0003), and systolic blood pressure also increased significantly (p < 0.0001). The frequency of dialysis-related hypotension was markedly reduced (p = 0.0001). The HR-QOL survey showed significant improvements in Social Functioning among others (p = 0.0178). No specific adverse events occurred. Ivabradine hydrochloride improved dialysis-related hypotension. Furthermore, the HR-QOL improvement effect were suggested. These results demonstrated the safety and effectiveness of ivabradine hydrochloride.

The effect of levocarnitine supplementation on dialysis-related hypotension: A systematic review, meta-analysis, and trial sequential analysis.

Dialysis patients have been shown to have low serum carnitine due to poor nutrition, deprivation of endogenous synthesis from kidneys, and removal by hemodialysis. Carnitine deficiency leads to impaired cardiac function and dialysis-related hypotension which are associated with increased mortality. Supplementing with levocarnitine among hemodialysis patients may diminish incidence of intradialytic hypotension. Data on this topic, however, lacks consensus. We conducted electronic searches in PubMed, Embase and Cochrane Central Register of Controlled Trials from January 1960 to 19th November 2021 to identify randomized controlled studies (RCTs), which examined the effects of oral or intravenous levocarnitine (L-carnitine) on dialysis-related hypotension among hemodialysis patients. The secondary outcome was muscle cramps. Study results were pooled and analyzed utilizing the random-effects model. Trial sequential analysis (TSA) was performed to assess the strength of current evidence. Eight trials with 224 participants were included in our meta-analysis. Compared to control group, L-carnitine reduced the incidence of dialysis-related hypotension among hemodialysis patients (pooled OR = 0.26, 95% CI [0.10-0.72], p = 0.01, I2 = 76.0%). TSA demonstrated that the evidence was sufficient to conclude the finding. Five studies with 147 participants showed a reduction in the incidence of muscle cramps with L-carnitine group (pooled OR = 0.22, 95% CI [0.06-0.81], p = 0.02, I2 = 74.7%). However, TSA suggested that further high-quality studies were required. Subgroup analysis on the route of supplementation revealed that only oral but not intravenous L-carnitine significantly reduced dialysis-related hypotension. Regarding dose and duration of L-carnitine supplementation, the dose > 4,200 mg/week and duration of at least 12 weeks appeared to prevent dialysis-related hypotension. Supplementing oral L-carnitine for at least three months above 4,200 mg/week helps prevent dialysis-related hypotension. L-carnitine supplementation may ameliorate muscle cramps. Further well-powered studies are required to conclude this benefit.

Association and predictive value of geriatric nutritional risk index, body composition, or bone mineral density in haemodialysis patients.

Assess the association and predictive value of geriatric nutritional risk index (GNRI), body composition, and bone mineral density (BMD) in haemodialysis (HD) patients. Laboratory data, body composition parameters measured via body composition monitor, and radius, lumbar spine, femoral neck BMD measured using dual energy X-ray absorptiometry were assessed in all subjects on HD or online haemodiafiltration (HDF) at baseline. Regression analysis for GNRI, Cox proportional hazard analyses and comparison of multiple receiver operating characteristic (ROC) curves were performed. Among all 264 patients, age was 65 ± 12 years and dialysis vintage was 79 (39-144) months. GNRI tertile (T)1, T2, and T3 were 88 (85-91), 94 (93-95), and 98 (97-101), respectively. Patients in GNRI T1 had lower fat tissue index (FTI), lean tissue index, and femoral neck, lumbar spine, and distal mid-third radius BMD, but higher overhydration/extracellular fluid than patients in GNRI T2 or T3 (P < .05). GNRI was significantly associated with FTI, lean tissue index, and femoral neck, lumbar spine, and distal mid-third radius BMD (P < .01). GNRI was a significant predictor of 2-year all-cause mortality (HR 0.92, P < .05). Area under the ROC curve for all-cause mortality using traditional risk factors (age, sex, diabetes mellitus, cardiovascular disease, use of vasopressors for dialysis-related hypotension, and C-reactive protein) was 0.67 and changed by adding GNRI (0.78, P < .05), FTI (0.75), or femoral neck BMD (0.66), respectively. Associations between GNRI, body composition, and BMD were confirmed in HD patients. Combining GNRI with traditional risk factors improved mortality prediction in HD patients.

Use of vasopressor for dialysis-related hypotension is a risk factor for death in hemodialysis patients: Nationwide cohort study

Because hypotension during hemodialysis (HD) makes continuation of HD difficult and is associated with mortality, pressor approaches are necessary for patients with hypotension. However, the relationships between the pressor approaches and the risk of death have not been clarified yet. We analyzed data from a nationwide prospective cohort study of the Japanese Society for Dialysis Therapy Renal Data Registry (n = 29,309). The outcome was all-cause one-year death. The association between the use of pressor approaches and the outcome was examined using Cox proportional hazards models adjusted for baseline characteristics, propensity score matched analysis and Bayesian networks. The background features of the patients were as follows: male, 59.6%; average age, 64.5 ± 12.5 years; and patients with diabetes mellitus, 31.5%. The pressor group showed a higher risk of the outcome than the control group [adjusted hazard ratio (aHR) 1.33 (95% CI: 1.21, 1.47), p = 0.0001]. Propensity score matched analysis also showed that the matched-pressor group had a higher risk of the outcome than the matched-control group [aHR 1.30 (95% CI: 1.17, 1.45), p = 0.0001]. Moreover, the Bayesian network showed a direct causal relationship from the use of pressor approaches to the outcome. The use of oral vasopressors [aHR 1.20 (95% CI: 1.07, 1.35), p = 0.0018], intravenous injection of vasopressors [aHR 1.54 (95% CI: 1.32, 1.79), p = 0.0001] and normal saline [aHR 1.18 (95% CI: 1.05, 1.33), p = 0.0066] were associated with a high risk of the outcome. In conclusion, this study showed that the use of pressor approaches during HD may be an independent risk factor for death.

Theoretical overview of clinical and pharmacological aspects of the use of etelcalcetide in diabetic patients undergoing hemodialysis.

Etelcalcetide is the first intravenous calcimimetic agent authorized for the treatment of secondary hyperparathyroidism (sHPT) in patients undergoing hemodialysis in Europe, the US, and Japan. The relationship between sHPT and diabetes resides on complex, bidirectional effects and largely unknown homeostatic mechanisms. Although 30% or more patients with end-stage renal disease are diabetics and about the same percentage of those patients suffer from sHPT associated with hemodialysis, no data on the specificities of the use of etelcalcetide in such patients are available yet. Regarding pharmacokinetic interactions, etelcalcetide may compete with oral hypoglycemics recommended for use in patients undergoing hemodialysis and insulins detemir and degludec, causing unexpected hypocalcemia or hypoglycemia. More importantly, hypocalcemia, a common side effect of etelcalcetide, may cause decompensation of preexisting cardiac insufficiency in diabetic patients or worsen dialysis-related hypotension and lead to hypotension-related cardiac events, such as myocardial ischemia. In diabetic patients, hypocalcemia may lead to dangerous ventricular arrhythmias, as both insulin-related hypoglycemia and hemodialysis prolong QT interval. Patients with diabetes, therefore, should be strictly monitored for hypocalcemia and associated effects. Due to an altered parathormone activity in this patient group, plasma calcium should be the preferred indicator of etelcalcetide effects. Until more clinical experience with etelcalcetide is available, the clinicians should be cautious when using this calcimimetic in patients with diabetes.

Impaired Gut Epithelial Tight Junction Expression in Hemodialysis Patients Complicated with Intradialytic Hypotension.

Background There is accumulating evidence pointing to uremia-induced impairment of the intestinal epithelial barrier structure in advanced chronic kidney disease (CKD) and hemodialysis (HD) patients. In this study, the impact of intradialytic hypotension on intestinal barrier integrity is being explored. Methods Immunohistochemical staining was used to detect the expression of 4 types of tight junction (TJ) proteins such as occludin, zonula occludens-1 (ZO-1), claudin-1, and claudin-4, in colonic samples of a group of patients receiving segmental colectomy. Five patients with nondialysis CKD (group 2), 5 HD patients with intradialytic hypotension (group 3), and 5 non-CKD subjects (group 1) were examined. Results Both patients' groups 2 and 3 demonstrated significantly reduced expression of occludin as compared to group 1 (p < 0.05 and p < 0.01, resp.). Except for claudin-4, expression of all markers of TJ proteins was significantly reduced in patients' group 3 as compared to control (p < 0.01). In addition, decreased expressions of claudin-1 and ZO-1 were also more pronounced in group 3 when compared to group 2. Conclusions This study extends the earlier finding by demonstrating that dialysis-related hypotension caused even marked depletion of the key protein constituents of the epithelial TJ.

Atypical giant cell arteritis predominantly involving intramural coronary arteries: a case showing refractory dialysis-related hypotension

Giant cell arteritis involving intramural coronary artery branches is rare, and its clinical features remain poorly understood. We report a 56-year-old hemodialysed patient with a history of mitral valve replacement, who presented with "fever of unknown origin" and intractable hypotension. The antemortem diagnosis was very difficult and the autopsy revealed giant-cell-rich vasculitis in arteries in multiple organs. The heart was most severely involved, in which almost all of the intramural coronary artery branches were infiltrated by many multinucleated giant cells, macrophages, and lymphocytes with luminal narrowing, but the epicardial segments of the coronary arteries were spared. Superimposed on the preexisting valvular heart disease, the vasculitic lesions were thought to play a central role in severe cardiac dysfunction resulting in dialysis-related hypotension, which led to fatal non-occlusive mesenteric ischemia. This case highlights the possibility that giant cell arteritis of intramural coronary arteries could be an uncommon underlying cause of refractory dialysis-related hypotension.

The of clinical effect of Shengmai injection on dialysis-related hypotension

Objective To observe clinical effect of Shengmai injection on dialysis-related hypotension.Methods Seventy patients with dialysis-related hypotension were divided into two groups:experimental group (35 cases)and control group (35 cases). Patients in experimental group was treated with Shengmai injection,while patients in control group were given with conventional treatments. Effective rate and hemodynamics changes were measured in both groups. Results The effective rate in experimental group was significantly higher than control group (P＜ 0.05), while frequency of treatment was lower than control group (P＜ 0. 05). There were no significant difference between experimental group and control group in systolic pressure, diastolic pressure and heart rate (P ＞ 0.05). Conclusion Shengmai injection is effective and safe in dialysis-related hypotension. Key words: Shengmai injection; Hemodialysis; Hypotension

Effects of l-Carnitine on Dialysis-Related Hypotension and Muscle Cramps: A Meta-analysis

L-Carnitine is an endogenous compound thought to be helpful in treating patients with dialysis-related hypotension and muscle cramps; however, sufficient evidence for these indications is lacking. Systematic review and meta-analysis. Adult patients with end-stage renal disease receiving long-term hemodialysis. All published English-language reports of randomized placebo-controlled trials of L-carnitine supplementation in adult long-term hemodialysis patients. Supplemental L-carnitine (or placebo) for at least 8 weeks. Random-effects pooled odds ratio for intradialytic cramping or hypotension in L-carnitine-treated participants. Of 317 potentially relevant articles, 7 (total enrollment of 193 patients) met criteria for inclusion. Four articles reported results for both hypotension and cramps, 1 had results for only hypotension, and 2 reported results for only cramps. Using data from all 6 relevant trials, the pooled odds ratio for cramping after L-carnitine supplementation was 0.30 (95% confidence interval, 0.09 to 1.00; P = 0.05). Analysis of the 5 studies examining the response of intradialytic hypotension to l-carnitine supplementation yielded a pooled odds ratio of 0.28 (95% confidence interval, 0.04 to 2.23; P = 0.2). The small number of available studies yielded limited statistical power. In addition, there was considerable interstudy heterogeneity. Although suggestive in the case of muscle cramping, the available evidence does not confirm a beneficial effect of L-carnitine supplementation on dialysis-related muscle cramping or intradialytic hypotension. Additional study in the form of large rigorous randomized trials is needed in both cases.

Falls and Fall-Related Injuries in Older Dialysis Patients

Dialysis patients are increasingly older and more disabled. In community-dwelling seniors without kidney disease, falls commonly predict hospitalization, the onset of frailty, and the need for institutional care. Effective fall prevention strategies are available. On the basis of retrospective data, it was hypothesized that the fall rates of older (> or =65 yr) chronic outpatient hemodialysis (HD) patients would be higher than published rates for community-dwelling seniors (0.6 to 0.8 falls/patient-year). It also was hypothesized that risk factors for falls in dialysis outpatients would include polypharmacy, dialysis-related hypotension, cognitive impairment, and decreased functional status. Using a prospective cohort study design, HD patients who were > or =65 yr of age at a large academic dialysis unit were recruited. All study participants underwent baseline screening for fall risk factors. Patients were followed prospectively for a minimum of 1 yr. Falls were identified through biweekly patient interviews in the HD unit. A total of 162 patients (mean age 74.7 yr) were recruited; 57% were male. A total of 305 falls occurred in 76 (47%) patients over 190.5 person-years of follow-up (fall-incidence 1.60 falls/person-year). Injuries occurred in 19% of falls; 41 patients had multiple falls. Associated risk factors included age, comorbidity, mean predialysis systolic BP, and a history of falls. In the HD population, the fall risk is higher than in the general community, and fall-related morbidity is high. Better identification of HD patients who are at risk for falls and targeted fall intervention strategies are required.

Debate Forum: Levocarnitine Therapy Is Rational and Justified in Selected Dialysis Patients

Carnitine is a metabolic cofactor which is essential for normal fatty acid metabolism. Patients with chronic kidney disease on dialysis have been shown both to suffer from disordered fatty acid metabolism and to have a significant deficiency in plasma and tissue carnitine. Aberrant fatty acid metabolism has been associated with a number of cellular abnormalities such as increased mitochondrial permeability (a promoter of apoptosis), insulin resistance, and enhanced generation of free radicals. These cellular abnormalities have, in turn, been correlated with pathological clinical conditions common in dialysis patients including cardiomyopathy with attendant hypotension and resistance to the therapeutic effect of recombinant human erythropoietin (EPO). In 1999, the Food and Drug Administration approved levocarnitine injection for the prevention and treatment of carnitine deficiency in patients on dialysis based on documentation of free plasma carnitine levels in dialysis patients similar to other serious carnitine deficiency states for which treatment was required. Data analysis performed by expert panels convened by both the American Association of Kidney Patients and, subsequently, the National Kidney Foundation recommended a trial of levocarnitine therapy for specific subsets of dialysis patients including those with EPO resistance, dialysis-related hypotension, cardiomyopathy and muscle weakness. In 2003, the Centers for Medicare and Medicaid services convened a Medical Advisory Committee which established reimbursement on a national level for carnitine-deficient dialysis patients who had either dialysis-related hypotension or EPO resistance. Recently, a correlation between reductions in hospitalization rates of dialysis patients receiving levocarnitine therapy has been demonstrated in a large retrospective study. Despite data-based recommendations and national reimbursement, only a small minority of dialysis patients have been prescribed a therapeutic trial of levocarnitine. Whereas the reasons for the reluctance of nephrologists to prescribe this therapeutic trial are unclear, possible explanations include a lack of appreciation of the pivotal role played by carnitine in cellular metabolism and the strength of evidence for a substantial deficiency of carnitine in dialysis patients, an underestimation of the prognostic import of EPO resistance and dialysis-related hypotension, inadequate dissemination of the clinical trial data supporting the use of levocarnitine in dialysis patients, and the heterogeneous clinical response of dialysis patients to levocarnitine therapy. Difficulties in documenting both initial eligibility and evidence of improvement as a result of therapy may also be a contributing factor. This paper discusses the biological role of carnitine and its particular relevance to dialysis patients. Clinical trial data concerning an effect of therapy on EPO resistance and dialysis-related hypotension are summarized along with a discussion of the logic behind the use of levocarnitine in dialysis. Finally, the difficulties posed by a reimbursement policy based on clinical as opposed to laboratory endpoints and a heterogeneous response to therapy are addressed.

Efficacy of biventricular pacing for dialysis-related hypotension due to idiopathic dilated cardiomyopathy

A 45-year-old man who had been undergoing maintenance hemodialysis for end-stage renal failure, caused by chronic glomerulonephritis 4 years before, was admitted to our hospital for biventricular pacemaker implantation (BVP). Ten years ago, he was diagnosed with idiopathic dilated cardiomyopathy, and had been suffering from dialysis-related hypotension (DRH) due to low cardiac function over the past year. An electrocardiogram revealed complete left bundle branch block with a QRS duration of 180 ms, and echocardiography showed moderate hypokinesis of the left ventricular wall and systolic asynchronized motion of the septum and free wall. After BVP, the left ventricular ejection fraction had increased from 29% to 40%, and the transmitral rapid left ventricular filling (E wave) and atrial contraction (A wave) ratio (E/A) had improved from 1.3 to 1.0. Before and after BVP, we measured hemodynamic parameters during hemodialysis by successive echocardiography. Before BVP, systemic vascular resistance had decreased, cardiac output had not changed, and hypotension was noted. In contrast, after BVP, cardiac output had increased and systemic vascular resistance had not changed, which caused an increase in blood pressure. We conclude that BVP improved the cardiac function which resulted in an improvement in dialysis-related hypotension (DRH).

Hypotension during hemodialysis results from an impairment of arteriolar tone and left ventricular function

Hypotensive episodes are a major complication of hemodialysis. Hypotension during dialysis could be directly related to a reduction in blood volume or to a decrease in cardiovascular activation as a response to decreased cardiac filling. A decreased cardiovascular activation could be due to patient-related or to dialysis-related factors. In order to study the isolated effect of a reduction in filling pressure, lower body negative pressure (LBNP) causes activation of the cardiovascular reactivity with a decrease in cardiac filling, but without the influence of the dialysis procedure that could affect cardiovascular reactivity. We studied the relationship between relative blood volume (RBV), central venous pressure (CVP), systolic arterial pressure, heart rate, stroke volume index (SI), and total peripheral resistance index (TPRI) during a combined dialysis/ultrafiltration and during LBNP to -40 mmHg in 21 hemodialysis patients with a high incidence of hypotension. Systolic arterial pressure, heart rate, SI and TPRI were measured by Finapres. CVP was measured after cannulation of the jugular vein. During dialysis RBV was measured by a blood volume monitor (BVM). In order to study the conditions in which hypotension occurred after dialysis, we divided the patients into 2 groups: hypotensive (H) and non-hypotensive (NH) during dialysis. Baseline levels did not show any significant differences. During dialysis systolic arterial pressure declined gradually in the H group from 30 minutes before the onset of hypotension. There was a similar decrease of RBV and increase of heart rate in both groups with a large interindividual variation. At hypotension, H patients showed a significantly smaller increase in TPRI as compared to NH patients. The reduction in SI tended to be greater at hypotension, while CVP decreased to a similar extent in both groups. Moreover, during LBNP, a similar reduction in CVP resulted in a much smaller decrease in SI. Systolic arterial pressure was only slightly lowered due to a much greater increase in TPRI. We conclude that dialysis-related hypotension in our patient group did not result from an inability to maintain blood volume or from decreased cardiac filling. Hypotension appeared to result from the inability to adequately increase arteriolar tone and a reduction in left ventricular function. Both vascular tone and left ventricular function appeared to be impaired by the dialysis procedure.

Levocarnitine and Dialysis: A Review

Among the various metabolic abnormalities documented in dialysis patients are abnormalities related to the metabolism of fatty acids. Aberrant fatty-acid metabolism has been associated with the promotion of free-radical production, insulin resistance, and cellular apoptosis. These processes have been identified as important contributors to the morbidity experienced by dialysis patients. There is evidence that levocarnitine supplementation can modify the deleterious effects of defective fatty-acid metabolism. Patients receiving hemodialysis and, to a lesser degree, peritoneal dialysis have been shown to be carnitine deficient, as manifested by reduced levels of plasma free carnitine and an increase in the acyl:free carnitine ratio. Cardiac and skeletal muscles are particularly dependent on fatty-acid metabolism for the generation of energy. A number of clinical abnormalities have been correlated with a low plasma carnitine status in dialysis patients. Clinical trials have examined the efficacy of levocarnitine therapy in a number of conditions common in dialysis patients, including skeletal-muscle weakness and fatigue, cardiomyopathy, dialysis-related hypotension, hyperlipidemia, and anemia poorly responsive to recombinant human erythropoietin therapy (rHuEPO). This review examines the evidence for carnitine deficiency in patients requiring dialysis, and documents the results of relevant clinical trials of levocarnitine therapy in this population. Consensus recommendations by expert panels are summarized and contrasted with present guidelines for access to levocarnitine therapy by dialysis patients.

Dialysis-Related Hypotension as a Cause of Progressive Frontal Lobe Atrophy in Chronic Hemodialysis Patients: A 3-Year Prospective Study

Background/Aim: Brain atrophy is known to develop more rapidly in hemodialysis (HD) patients than other individuals. The present study was designed to examine the role of HD-related hypotension in brain atrophy in patients on chronic HD. Methods: By using magnetic resonance imaging, whole brain atrophy was assessed by the ventricular-brain ratio (VBR; ventricular area/whole brain area). Frontal brain atrophy was assessed by the frontal atrophy index (FAI; frontal brain area/intracranial frontal space). The number of lacunae was also counted. We studied 32 HD patients without symptomatic neurological abnormalities or diabetes mellitus: male/female ratio 19/13; mean age ± SD 53 ± 10 (range 28–77) years; mean HD duration ± SD 11 ± 6 (range 1–22) years. Magnetic resonance imagings were taken in 1995 and 1998. All dialysis-related hypotension episodes during the same period were identified from the medical records and counted. Results: The VBR ranged from 8.8 to 18.7% in 1995 (12.8 ± 2.2%) and was not different in 1998 (13.1 ± 2.7%). However, the VBR increased by more than 5% in 14 patients, and their HD duration of 13 ± 6 years was significantly longer than that of 18 patients with stable VBR (p < 0.05). The FAI in 1995 was 62.2 ± 4.2% (range 55.8–71.3%) and decreased significantly to 59.7 ± 4.7% (range 50.2–70.9%) in 1998 (p < 0.05). The change in FAI correlated significantly with both the total number of dialysis-related hypotension episodes (r = 0.45, p < 0.05) and the increase in number of lacunae (r = 0.42, p < 0.05). Conclusion: Our results suggest that dialysis-related hypotension plays a role in progressive frontal lobe atrophy in HD patients.

Hemodynamic response to lower body negative pressure in hemodialysis patients

Background: Hypovolemia is thought to have an important role in the pathogenesis of dialysis-related hypotension. Methods: We studied the effect of hypovolemia simulated by lower body negative pressure (LBNP) in 11 hypotension-prone (HP) and 11 hypotension-resistant (HR) hemodialysis patients. LBNP was applied stepwise from 0 to −20 to −40 mm Hg. Systolic arterial pressure, heart rate, and central venous pressure (CVP) were recorded continuously after cannulation of the right jugular vein. Stroke volume index was measured at each step echocardiographically. At the end of each level of LBNP, blood samples were obtained to measure norepinephrine (NE), epinephrine (E), and atrial natriuretic peptide (ANP) levels. Results: At baseline, CVP (12 ± 5 and 16 ± 7 mm Hg), heart rate (72 ± 9 and 70 ± 13 beats/min), cardiac index (2.3 ± 0.6 and 2.5 ± 0.9 L/min), NE (median, 341 pg/mL [range,198 to 789 pg/mL] and 365 pg/mL [range, 177 to 675 pg/mL] or 2.02 nmol/L [range, 1.17 to 4.66 nmol/L] and 2.16 nmol/L [range, 1.05 to 4.00 nmol/L]), E (median, 46 pg/mL [range, 18 to 339 pg/mL] and 58 pg/mL [range, 21 to 122 pg/mL] or 251 pmol/L [range, 98 to 1,951 pmol/L] and 317 pmol/L [range, 115 to 666 pmol/L]) were similar, whereas systolic arterial pressure (141 ± 26 versus 164 ± 22 mm Hg) and ANP (median, 441 pg/mL [range, 152 to 1,330 pg/mL] versus 804 pg/mL [range, 517 to 3,560 pg/mL] ng/L) were lower (P < 0.05) in HP patients. In response to LBNP (−40 mm Hg), CVP decreased by 6.5 ± 4.0 mm Hg in the HP group and 4.9 ± 4.9 mm Hg in the HR group. In HP patients, this decrease was associated with a greater decrease in SI (37% ± 16% versus 27% ± 16%) and systolic arterial pressure (19% ± 21% versus 4% ± 14%) than in HR patients. Plasma ANP levels did not change, whereas increases in NE and E levels were similar in HP and HR patients. Conclusion: Patients who frequently experience episodes of hypotension during dialysis also are prone to develop hypotension during LBNP, which results from reduced myocardial contractile reserve and/or inadequate sympathetic tone.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers. Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy. Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.

Dry weight in hemodialysis: Volemic control

In dialysis patients the chronic fluid overload may represent a nonphysiologic condition which brings both arterial hypertension and hemodynamic instability. Volume expansion is significantly correlated to casual predialysis blood pressure and 24-hour arterial pressure. The normalization of the patient hydration status is not only followed by a reduction in pressure values but also by an improvement of the circadian blood pressure rhythm. On the other hand, hypovolemia and underhydration combined with an impaired cardiovascular regulatory response may generate the dialysis-related hypotension. Many techniques have been introduced to obtain an objective measurement of the hydration status: postdialysis radiological chest examination, plasma atrial natriuretic peptide (ANP), and plasma cyclic guanidine monophosphate (cGMP) levels, multifrequency electrical bioimpedance and the continuous plasma volume measurement. The latter, alone or in combination with provocative tests (stop and go of the ultrafiltration), may help in optimizing plasma volume contraction. The plasma volume monitoring avoids the risk of hypovolemic hypotension and facilitates the achievement of a correct dry body weight. The biofeedback system, exploiting the automatic control of the intradialytic variations, may represent an additional advantage in the formulation of an ideal postdialysis blood volume that overlaps the patient's dry weight.

Variability of relative blood volume during haemodialysis.

A decrease in blood volume is thought to play a role in dialysis-related hypotension. Changes in relative blood volume (RBV) can be assessed by means of continuous haematocrit measurement. We studied the variability of RBV changes, and the relation between RBV and ultrafiltration volume (UV), blood pressure, heart rate, and inferior caval vein (ICV) diameter. In 10 patients on chronic haemodialysis, RBV measurement was performed during a total of one hundred 4-h haemodialysis sessions. Blood pressure and heart rate were measured at 5-min intervals. ICV diameter was assessed at the start and at the end of dialysis using ultrasonography. The changes in RBV showed considerable inter-individual variability. The average change in RBV ranged from -0.5 to -8.2% at 60 min and from -3.7 to -14.5% at 240 min (coefficient of variation (CV) 0.66 and 0.35 respectively). Intra-individual variability was also high (CV at 60 min 0.93; CV at 240 min 0.33). Inter-individual as well as intra-individual variability showed only minor improvement when RBV was corrected for UV. We found a significant correlation between RBV and UV at 60 (r= -0.69; P<0.001) and at 240 min (r= -0.63; P<0.001). There was a significant correlation between RBV and heart rate (r= -0.39; P<0.001), but not between RBV or UV and blood pressure. The level of RBV reduction at which hypotension occurred was also highly variable. ICV diameter decreased from 10.3+/-1.7 mm/m(2) to 7.3+/-1. 5 mm/m(2). There was only a slight, although significant, correlation between ICV diameter and RBV (r= -0.23; P<0.05). The change in ICV-diameter showed a wide variation. RBV changes during haemodialysis showed a considerable intra- and inter-individual variability that could not be explained by differences in UV. No correlation was observed between UV or changes in RBV and either blood pressure or the incidence of hypotension. Heart rate, however, was significantly correlated with RBV. Moreover, IVC diameter was only poorly correlated with RBV, suggesting a redistribution of blood towards the central venous compartment. These data indicate that RBV monitoring is of limited use in the prevention of dialysis-related hypotension, and that the critical level of reduction in RBV at which hypotension occurs depends on cardiovascular defence mechanisms such as sympathetic drive.

Regulation of blood pressure in chronic renal failure: determinants of hypertension and dialysis-related hypotension

Regulation of blood pressure is of crucial importance in the management of patients with chronic renal failure. in the predialysis phase, hypertension is common. Apart from volume overload and an inappropriately activated renin-angiotensin system, overactivity of the sympathetic nervous system appears to play a role as well. Sympathetic outflow may be enhanced by elevated Angiotensin II levels. Maintenance treatment with angiotensin converting enzyme inhibition normalizes sympathetic overactivity in hypertensive patients with chronic renal failure. In view of the unfavourable role of increased sympathetic activity in cardiovascular disease and prognosis, normalization of sympathetic outflow may be a new treatment goal.Hemodialysis is often complicated by sudden hypotension, causing considerable distress and morbidity. Reduction of blood volume causes sympatho-excitation, vasoconstriction and tachycardia. Sudden hypotension, however, is accompanied by acute withdrawal of sympathetic activity, vasodilation and relative bradycardia, also known as the Bezold-Jarisch reflex. Subtle fluctuations in vasomotor tone in hypovolemic conditions can elicit this reflex. In a series of experiments we showed that reduction of blood volume plays a pivotal role in the pathogenesis of hypovolemic hypotension. Autonomic neuropathy and dysfunction of the central opioid system have been proposed as causative mechanisms in dialysis-related hypotension. We, however, could not confirm a pathogenetic role for either mechanism.