Hypertension in end-stage renal disease

Relationship between interdialytic weight gain and blood pressure among prevalent hemodialysis patients

BACKGROUND

Hypertension is common in hemodialysis patients; however, the relationship between interdialytic weight gain (IDWG) and blood pressure (BP) is incompletely characterized. This study seeks to define the relationship between IDWG and BP in prevalent hemodialysis subjects.

STUDY DESIGN, SETTING, & PARTICIPANTS

This study used data from 32,295 dialysis sessions in 442 subjects followed up for 6 months in the Crit-Line Intradialytic Monitoring Benefit (CLIMB) Study.

OUTCOMES & MEASUREMENTS

Mixed linear regression was used to analyze the relationship between percentage of IDWG (IDWG [%] = [current predialysis weight - previous postdialysis weight]/dry weight * 100) as the independent variable and systolic BP (SBP) and predialysis - postdialysis SBP (deltaSBP) as dependent variables.

RESULTS

In unadjusted analyses, every 1% increase in percentage of IDWG was associated with a 1.00 mm Hg (95% confidence interval [CI], +/-0.24) increase in predialysis SBP (P < 0.0001), 0.65 mm Hg (95% CI, +/-0.24) decrease in postdialysis SBP (P < 0.0001), and 1.66 mm Hg (95% CI, +/-0.25) increase in deltaSBP (P < 0.0001). After controlling for other significant predictors of SBP, every 1% increase in percentage of IDWG was associated with a 1.00 mm Hg (95% CI, +/-0.24) increase in predialysis SBP (P < 0.0001) and a 1.08 mm Hg (95% CI, +/-0.22) increase in deltaSBP with hemodialysis (P < 0.0001). However, in subjects with diabetes as the cause of end-stage renal disease, subjects with lower creatinine levels, and older subjects, the magnitude of the association between percentage of IDWG and predialysis SBP was less pronounced. The magnitude of percentage of IDWG on deltaSBP was less pronounced in younger subjects and subjects with lower dry weights. Results were similar with diastolic BP.

LIMITATIONS

Hemodialysis BP measurements are imprecise estimates of BP and true hemodynamic burden in dialysis subjects.

CONCLUSIONS

In prevalent hemodialysis subjects, increasing percentage of IDWG is associated with increases in predialysis BP and BP changes with hemodialysis; however, the magnitude of the relationship is modest and modified by other clinical factors. Thus, although overall volume status may impact on BP to a greater extent, day-to-day variations in weight gain have a modest role in BP increases in prevalent subjects with end-stage renal disease.

Vasopressin administration facilitates fluid removal during hemodialysis

Inadequate secretion of vasopressin during fluid removal by hemodialysis may contribute to the cardiovascular instability that complicates this therapy and administration of exogenous hormone, by supporting arterial pressure, may facilitate volume removal. To test this, we measured plasma vasopressin in patients with end-stage renal disease (ESRD) during hemodialysis and found that despite significant fluid removal, plasma vasopressin concentration did not increase. We further found that ESRD did not alter the endogenous removal rate of plasma vasopressin and that plasma hormone is not dialyzed. Finally, in a randomized, double-blinded, placebo-controlled trial in 22 hypertensive patients, we examined the effect of a constant infusion of a non-pressor dose of vasopressin on the arterial pressure response during a hemodialysis in which the target fluid loss was increased by 0.5 kg over the baseline prescription. We found that arterial pressure was more stable in the patients receiving vasopressin and that while only one patient (9%) in the vasopressin group had a symptomatic hypotensive episode, 64% of the patients receiving placebo had such an episode (P=0.024). Moreover, increased fluid removal was achieved only in the vasopressin group (520+/-90 ml vs 64+/-130 ml, P=0.01). Thus, administration of non-pressor doses of vasopressin to hypertensive subjects improves cardiovascular stability during hemodialysis and allows increased removal of excess extracellular fluid. Inadequate vasopressin secretion during hemodialysis-induced fluid removal is a likely contributor to the intradialytic hypotension that limits fluid removal.

Fluid balance, dry weight, and blood pressure in dialysis

The total amount of sodium present in the body controls the extracellular volume. In advanced renal failure, sodium balance becomes positive and the extracellular volume expands. This leads to hypertension, and vascular changes that lead to adverse cardiovascular consequences in dialysis patients. Controlling the body sodium content and the extracellular volume allows one to better control hypertension and its consequences. This can be achieved by reducing the sodium input (sodium dietary restriction and reasonably low sodium dialysate) and/or by increasing the sodium output (ultrafiltration by convection). The discontinuous nature of hemodialysis causes saw-tooth volume fluctuations. This has led to the concept of dry weight (DW), a crucial component of dialysis adequacy. Assessment and achievement of DW is feasible on pure clinical grounds. But its relative lack of accuracy (and the physicians' progressive lack of interest in bedside examination) has led to several nonclinical methods of assessing DW in an effort to improve the assessment of fluid status in dialysis patients.

Treatment time and ultrafiltration rate are more important in dialysis prescription than small molecule clearance

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Over the next three decades, dialysis duration was shorten to 4, 3, even 2 h in thrice weekly schedules. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that the time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V(urea)) equals 0.95-1.0. This number was later increased to 1.3, but the assumption that hemodialysis time is of minimal importance remained unchanged. However, Kt/V(urea) measures only the removal of low molecular weight substances and does not consider the removal of larger molecules. Nor does it correlate with the other important function of hemodialysis, namely ultrafiltration. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control leading to left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Kt/V(urea) should be abandoned as a measure of dialysis quality. The formula suggests that it is possible to decrease t as long as K is proportionately increased, but this is not true. Time of dialysis should be adjusted in such a way that patients would not suffer from symptoms related to rapid ultrafiltration, would not have other uremic symptoms and most patients would have blood pressure controlled without antihypertensive drugs.

Handcarried ultrasound measurement of the inferior vena cava for assessment of intravascular volume status in the outpatient hemodialysis clinic

Accurate intravascular volume assessment is critical in the treatment of patients who receive chronic hemodialysis (HD) therapy. Clinically assessed dry weight is a poor surrogate of intravascular volume; however, ultrasound assessment of the inferior vena cava (IVC) is an effective tool for volume management. This study sought to determine the feasibility of using operators with limited ultrasound experience to assess IVC dimensions using hand-carried ultrasounds (HCU) in the outpatient clinical setting. The IVC was assessed in 89 consecutive patients at two outpatient clinics before and after HD. Intradialytic IVC was recorded during episodes of hypotension, chest pain, or cramping. High-quality IVC images were obtained in 79 of 89 patients. Despite that 89% of patients presented at or above dry weight, 39% of these patients were hypovolemic by HCU. Of the 75% of patients who left HD at or below goal weight, 10% were still hypervolemic by HCU standards. Hypovolemic patients had more episodes of chest pain and cramping (33 versus 14%, P = 0.06) and more episodes of hypotension (22 versus 3%, P = 0.02). The clinic with a higher prevalence of predialysis hypovolemia had significantly more intradialytic adverse events (58 versus 27%; P = 0.01). HCU measurement of the IVC is a feasible option for rapid assessment of intravascular volume status in an outpatient dialysis setting by operators with limited formal training in echocardiography. There is a poor relationship between dry weight goals and IVC collapsibility. Practice variation in the maintenance of volume status is correlated with significant differences in intradialysis adverse events.

Hypertension and survival in chronic hemodialysis patients--past lessons and future opportunities

There is substantial controversy surrounding the benefits of control of hypertension in hemodialysis patients. Unlike the general population, some studies suggest that higher blood pressure in hemodialysis patients offers a survival advantage, what is termed as "reverse epidemiology." To critically analyze the relationship between total and cardiovascular mortality and blood pressure, peer-reviewed, published studies in hemodialysis patients were analyzed. Consideration of the world-wide experience suggests that analysis of incident cohorts reveal a clear link between elevated blood pressure and mortality. Increased pulse pressure, which is primarily due to increased systolic pressure, is also associated with cardiovascular morbidity and mortality. The counterintuitive relationship between blood pressure and mortality appears, in part, to be due to methods of data analysis. When data are analyzed with systolic or diastolic blood pressure as separate models, not conjointly, inverse relationship between blood pressure and total and cardiovascular mortality is generally seen. When both systolic and diastolic blood pressure are considered together, systolic blood pressure or increased pulse pressure assumes a major importance in predicting cardiovascular events whereas diastolic blood pressure retains the inverse relationship. Control of hypertension in hypertensive dialysis patients is associated with improved survival. Furthermore, the use of antihypertensive drug treatment is associated with improved survival regardless of blood pressure control. Low predialysis blood pressure is associated with increased cardiovascular deaths and deaths within 2 years from malignancy or withdrawal from dialysis. These data suggest that hypertension needs to be better controlled in hypertensive hemodialysis patients. Better methods of assessment of blood pressure control, consideration of cardiac structure and function, and performance of randomized controlled trials of pharmacologic and nonpharmacologic strategies are needed to establish benefits and determining goal blood pressure in hemodialysis patients.

Hypertension in dialysis

PURPOSE OF REVIEW

Hypertension is highly prevalent in dialysis patients and may be important to the high cardiovascular mortality of this population. This review shows the current direction in dialysis-associated hypertension management.

RECENT FINDINGS

Decreasing dialysate sodium concentration based on pre-hemodialysis plasma sodium concentration may have an additive effect in controlling hypertension. Sympathetic nervous system overactivity is an important feature of end-stage renal disease; a new amine oxidase, renalase, may be relevant to the pathogenesis of hypertension in this population. Similarly, drugs that block the sympathetic nervous system are uniformly protective in dialysis patients. Daily dialysis (short or long) results in better blood pressure control, and the mechanisms resulting in this effect are increasingly better understood.

SUMMARY

Long-term control of hypertension is necessary in dialysis patients. The better understanding of the dialysis-associated hypertension pathogenesis has impact on the dialysis prescription and antihypertensive drug choices.

Volume-independent mechanisms of hypertension in hemodialysis patients: clinical implications

The renin-angiotensin and sympathetic nervous systems are often activated in hemodialysis (HD) patients; the pathogenesis of this condition is discussed. Medications aimed at reducing renin and sympathetic activity may improve the cardiovascular prognosis, independent of its effect on blood pressure. This knowledge has important implications for the choice of treatment in HD patients.

HYPERTENSION IN HEMODIALYSIS PATIENTS: Dietary Sodium Restriction for Hypertension in Dialysis Patients

A close relationship between sodium and hypertension exists and this relationship is even more pronounced in renal failure and dialysis patients. Hypertension is one of the strongest predictors of poor outcome in dialysis patients. Almost all end-stage renal disease (ESRD) patients have hypertension and positive sodium balance, resulting in extracellular volume (ECV) expansion-the most important contributing factor to hypertension. Thus the effective management of hypertension requires normalization of the sodium balance and ECV. Two important methods to achieve this are limiting interdialytic weight gain (IDWG) and a dialysis process that is able to remove all IDWG and consistently attain dry weight. Since IDWG is directly dependent on sodium intake and the resulting thirst, sodium restriction is the most effective way to limit IDWG. Ultrafiltration and dialysate sodium concentration influence sodium removal, ECV control, and blood pressure (BP) control. Thus the dialysis session should be long enough to achieve dry weight and frequent enough to maintain appropriate BP.

Hypertension and cardiovascular risk assessment in dialysis patients

INTRODUCTION

Cardiovascular (CV) disease is the main cause of morbidity and mortality in dialysis patients. Hypertension in patients affected by chronic renal insufficiency (CRI) has been recognized as one of the major classical CV risk factors in CRI from the very beginning of the dialysis era. However, its treatment is still unsatisfactory.

METHODS

A discussion is employed to achieve a consensus on key points relating to the epidemiological, pathophysiological and clinical characteristics of hypertension in renal patients, in the light of global CV risk assessment.

RESULTS

CV disease is accelerated by CRI, in particular by uraemia-specific risk factors. This is reflected by the fact that general population-based equations for calculating CV risk underestimate the real CV risk in CRI and dialysis patients. Hypertension in dialysis patients is clearly a major CV risk factor. Isolated systolic hypertension with increased pulse pressure is the most prevalent blood pressure (BP) anomaly in dialysis patients, due to stiffening of the arterial tree. BP should be assessed by clinical measurements on a routine basis, leaving 24 h monitoring for selected cases. The targets of BP control should be those recommended by the present guidelines, i.e. <140/90 mmHg, or the lowest possible values that are well tolerated. The pathophysiological cornerstone of hypertension in dialysis patients is extra-cellular volume expansion, which is typically sodium-sensitive, given the loss of renal function. Therefore, the principles of hypertension treatment in dialysis are an achievement of dry body weight, proper dialysis prescription with respect to dialysis time and intra-dialytic sodium balance, and dietary sodium and water restriction. Pharmacological treatment should only be the second option, after the adequate and complete application of all other means. No comparative pharmacological trials have specifically addressed the issue of hypertension control in dialysis patients. Therefore, this workshop group had to rely largely on data obtained in the general population. Drugs interfering with the renin-angiotensin system were felt to be the first choice, as they have widely been shown to interfere significantly with CV remodelling. Despite long-standing concerns, beta-blockers are being used increasingly even in patients with congestive heart failure and ischaemic cardiomyopathy. Other drug classes may be used in association or as first-line agents according to clinical requirements.

CONCLUSIONS

Hypertension in renal patients has to be given particular and continued attention, and it should be adequately treated in light of the increased CV risk of this patient population. Research into the mechanisms of uraemic cardiomyopathy and cardiovascular remodelling should provide a precious new insight and lead to more precisely targeted and more effective therapies than in the past.

Central and peripheral adaptations to physical training in patients with end-stage renal disease

Renal replacement treatment options are life-saving treatments for patients with end-stage renal disease (ESRD). However, prolonged survival in patients with ESRD is associated with various functional and morphological disorders from almost all systems. Anaemia, deconditioning, cardiac dysfunction. impairment of cardiac autonomic control and skeletal muscle weakness and fatigue, primarily because of 'uraemic' myopathy and neuropathy, are the main predisposing factors for their poor functional ability. Physical training is being recommended as a complementary therapeutic modality. There are generally 3 methods of exercise training applied in patients with ESRD: (i) the supervised outpatient programme that is held in a rehabilitation centre; (ii) a home exercise rehabilitation programme; and (iii) exercise rehabilitation programme during the first hours of the haemodialysis treatment in the renal unit. All the available training data show that the application of an exercise training programme in patients with ESRD enhances their physical fitness. This improvement is due to central and mainly peripheral adaptations. Exercise training in these patients increases aerobic capacity, causes favourable left ventricular functional adaptations, reduces blood pressure in patients with hypertension, modifies other coronary risk factors, increases the cardiac vagal activity and suppresses the incidence of cardiac arrhythmias. Moreover, exercise training has beneficial effects on muscle structural and functional abnormalities. These central and peripheral adaptations to exercise training cause an increase in their functional capacity and offer them achance of a better quality of life. Moreover, exercise training improves exercisee tolerance of renal post-transplant patients.

Sympathetic overactivity as a cause of hypertension in chronic renal failure

OBJECTIVE

To review the current literature on sympathetic mediation of hypertension in chronic renal failure.

BACKGROUND

Hypertension is present in the vast majority of patients with chronic renal failure and constitutes a major risk factor for the excessive cardiovascular morbidity and mortality in this patient population. Although, traditionally, this hypertension is thought to be largely volume-dependent, an increasing body of literature suggests that there is an important sympathetic neural component. Microneurographic studies have demonstrated sympathetic overactivity without baroreflex impairment in both hypertensive chronic hemodialysis patients as well as in those with less advanced renal insufficiency. Sympathetic nerve activity was found to be normal in hemodialysis patients with bilateral nephrectomy, leading to the hypothesis that sympathetic overactivity in uremia is caused by a neurogenic signal (carried by renal afferents) arising in the failing kidney. This hypothesis is supported by rat studies showing that renal deafferentation abrogates hypertension in the 5/6 nephrectomy model of chronic renal insufficiency. In addition, in patients with chronic renal insufficiency and renin-dependent hypertension, sympathetic overactivity was normalized by chronic angiotensin converting enzyme inhibition but not by calcium channel blockade, implicating a major central neural action of angiotensin II.

CONCLUSIONS

Sympathetic overactivity in chronic renal failure is caused by neurohormonal mechanisms arising in the failing kidney. Future clinical studies are needed to determine whether normalization of sympathetic activity should constitute an important therapeutic goal in this high-risk patient population.

Relationship between volume status and blood pressure during chronic hemodialysis

BACKGROUND

The relationship between volume status and blood pressure (BP) in chronic hemodialysis (HD) patients remains incompletely understood. Specifically, the effect of interdialytic fluid accumulation (or intradialytic fluid removal) on BP is controversial.

METHODS

We determined the association of the intradialytic decrease in body weight (as an indicator of interdialytic fluid gain) and the intradialytic decrease in plasma volume (as an indicator of postdialysis volume status) with predialysis and postdialysis BP in a cross-sectional analysis of a subset of patients (N=468) from the Hemodialysis (HEMO) Study. Fifty-five percent of patients were female, 62% were black, 43% were diabetic and 72% were prescribed antihypertensive medications. Dry weight was defined as the postdialysis body weight below which the patient developed symptomatic hypotension or muscle cramps in the absence of edema. The intradialytic decrease in plasma volume was calculated from predialysis and postdialysis total plasma protein concentrations and was expressed as a percentage of the plasma volume at the beginning of HD.

RESULTS

Predialysis systolic and diastolic BP values were 153.1 +/- 24.7 (mean +/- SD) and 81.7 +/- 14.8 mm Hg, respectively; postdialysis systolic and diastolic BP values were 136.6 +/- 22.7 and 73.9 +/- 13.6 mm Hg, respectively. As a result of HD, body weight was reduced by 3.1 +/- 1.3 kg and plasma volume was contracted by 10.1 +/- 9.5%. Multiple linear regression analyses showed that each kg reduction in body weight during HD was associated with a 2.95 mm Hg (P=0.004) and a 1.65 mm Hg (P=NS) higher predialysis and postdialysis systolic BP, respectively. In contrast, each 5% greater contraction of plasma volume during HD was associated with a 1.50 mm Hg (P=0.026) and a 2.56 mm Hg (P < 0.001) lower predialysis and postdialysis systolic BP, respectively. The effects of intradialytic decreases in body weight and plasma volume were greater on systolic BP than on diastolic BP.

CONCLUSIONS

HD treatment generally reduces BP, and these reductions in BP are associated with intradialytic decreases in both body weight and plasma volume. The absolute predialysis and postdialysis BP levels are influenced differently by acute intradialytic decreases in body weight and acute intradialytic decreases in plasma volume; these parameters provide different information regarding volume status and may be dissociated from each other. Therefore, evaluation of volume status in chronic HD patients requires, at minimum, assessments of both interdialytic fluid accumulation (or the intradialytic decrease in body weight) and postdialysis volume overload.

Hypertension in hemodialysis patients

Hypertension is very common and often poorly controlled in patients undergoing chronic hemodialysis. While high blood pressure has been documented to adversely impact several intermediate outcomes of cardiovascular disease, whether hypertension is an independent risk factor for mortality in this population is not clear. Expansion of extracellular fluid volume is the major pathophysiologic mechanism for the development of hypertension in these patients; however, alterations in other humoral mechanisms also play a significant role. Optimization of volume status is, therefore, the cornerstone of therapy with additional use of antihypertensive medications as needed. Good quality prospective studies are urgently needed to define the measurement techniques and blood pressure goals, and to develop therapeutic strategies for more effective management of hypertension in this high-risk population.

Utility of the inferior vena cava diameter as a marker of dry weight in nonoliguric hemodialyzed patients

We have previously reported that the maximal inferior vena cava (IVC) diameter during quiet expiration (IVCe) measured by ultrasonography correlates well with the amount of body fluid, especially the circulating blood volume(2) and proposed using the criteria of IVC diameter to determine dry weight (DW) in anuric hemodialyzed (HD) patients: standard IVCe of pre- and post-HD are 14.9 +/- 0.4 and 8.2 +/- 0.3 mm, respectively (1). However, the same post-HD IVC criterion should not be applied to nonoliguric HD patients because it could result in rapid deterioration of residual renal function due to forced dehydration. Although the biochemical DW marker plasma atrial natriuretic peptide (ANP) is useful to evaluate hypervolemia but not hypovolemia, both hyper- and hypovolemia can be detected by IVC measurement. In the present study, we investigated whether the IVC diameter serves as an optimal evaluation of DW in nonoliguric HD (NO-HD) patients, avoiding not only overhydration but also dehydration. The IVCe and plasma ANP levels were measured in 14 euvolemic patients with chronic renal failure at conservative period (CP-CRF) and 11 NO-HD patients, in whom the average daily urine volume was more than 500 ml/day. In NO-HD patients, DW was adjusted to attain the euvolemic state with normotensive blood pressure, lack of edema, and lack of temporal oliguria after HD. The ANP in CP-CRF patients was 109.3 +/- 15.3 pg/ml, and pre- and post-HD ANP levels in NO-HD patients were 145.3 +/- 23.5 and 97.5 +/- 13.5 pg/ml, respectively. IVCe in CP-CRF was 13.4 +/- 0.9 mm, and pre- and post-HD IVCe in NO-HD patients were 14.2 +/- 1.0 mm and 11.9 +/- 0.9 mm, respectively. Although the post-HD IVCe was greater (i.e., less hypovolemic) than that in anuric HD patients, and close to the IVCe in CP-CRF, pre-HD IVCe was comparable with that in anuric HD patients. In addition, the pre-HD ANP level was no higher than that in CP-CRF. Thus, in NO-HD patients, the post-IVCe of 11.9 +/- 0.9 mm would be a marker for an appropriate DW setting avoiding severe post-HD dehydration as well as excessive hypervolemia during the interdialytic period.

Effects of haemodialysis on diabetic macular leakage

AIM

To evaluate the effects of haemodialysis on macular oedema by fluorescein angiography in patients with diabetic retinopathy and end stage renal disease.

METHODS

In this prospective study, fluorescein angiography was performed on 40 eyes of 22 non-insulin dependent diabetic patients with end stage renal disease just before (baseline) and 4 weeks after the beginning of haemodialysis. The change of macular leakage was determined by evaluating the same phase of the angiograms.

RESULTS

Fluorescein angiograms obtained at 4 weeks showed that macular leakage was unchanged in 28/40 eyes (70%), decreased in 4/40 eyes (10%), and increased in 8/40 eyes (20%) when compared with the baseline appearance.

CONCLUSIONS

These results indicate that haemodialysis does not benefit macular leakage in diabetic patients receiving haemodialysis for end stage renal disease.

Long-term prognosis and incidence of acute myocardial infarction in patients on chronic hemodialysis. The Okinawa Dialysis Study Group

Mortality from cardiovascular disease is high in chronic dialysis patients. We observed the occurrence of acute myocardial infarction (AMI) in the chronic dialysis population in Okinawa, Japan. A total of 3,741 chronic dialysis patients (2,073 men, 1,668 women) were followed up for 10 years from April 1, 1988, to March 31, 1998. Only definite cases of AMI were registered. Data were compared with AMI registry data obtained from the general population of the same district. The total duration of observation was 15,748.8 patient-years. During the study period, 61 patients (40 men, 21 women) had AMI. The incidence of AMI was 3.9/1,000 patient-years (men, 4.4/1,000 patient-years; women, 3.1/1,000 patient-years). Twenty-four percent of the AMI cases occurred at 12 months after starting dialysis therapy. Mean age at onset of AMI was 60.9 +/- 11. 4 (SD) years; 58.9 +/- 11.4 years in men and 64.7 +/- 10.7 years in women. Survival rates after AMI were 50.8% at 1 month, 45.0% at 6 months, 36.5% at 12 months, and 13.0% at 44 months. Patients with diabetes mellitus (DM) had a greater incidence of AMI and a worse prognosis than patients without DM. The long-term prognosis of AMI was poor in chronic dialysis patients.

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Seasonal variations of blood pressure and overhydration in patients on chronic hemodialysis

Blood pressure (BP) has a seasonal cycle in the general population and in patients undergoing maintenance dialysis, but the causes remain unclear. We studied the BP measurements recorded at fixed hours three times weekly from 1994 to 1997 in 102 hemodialysis patients. We obtained monthly averages of the following variables: predialysis mean BP, greatest overhydration (OH) estimated by predialysis body weight excess over dry weight, chronic OH estimated by the remaining postdialysis weight excess over dry weight, urea reduction ratio (URR) in dialysis, and monthly means for daylight span and outdoor temperature over the study period. Average BP in the population diminished over the 48-month period, associated with a decrease in chronic OH (r = 0.66; P < 0.0005) but independent of greatest OH. BP and chronic OH presented synchronous seasonal variations, with peaks in late autumn and early winter and troughs in summer. These biological rhythms were inversely related to the seasonal daylight span and outdoor temperature. Both BP and chronic OH periods were synchronous with the daylight annual cycle and preceded the seasonal variations of temperature by 1 month. Multiple regression analysis showed that chronic OH and daylight, but not URR or temperature, had a significant independent association with BP changes. These results show the existence of seasonal variations of BP in dialysis patients that are associated and synchronous with seasonal changes in chronic OH status. Both cycles depend on conditions influenced by the annual daylight span more than by external temperature.

Hypertension in end-stage renal disease patients

The prevalence of hypertension is extremely high in end-stage renal disease, and is a probable contributor to the epidemic of cardiovascular disease in end-stage renal disease. However, the paucity of prospective, randomized clinical trials makes it difficult to precisely define treatment strategies. Therefore, at present time the guidelines developed by the National Kidney Foundation's Cardiovascular Disease Task Force should be followed.

Does Blood Pressure Control by Gentle Ultrafiltration Improve Survival in Hemodialysis Patients?

Agentle ultrafiltration can be achieved using a long and slow hemodialysis. It is easier to achieve gentle ultrafiltration if the interdialytic weight intake is moderate ( i.e., if the patient maintains a low sodium diet) and if diffusion allows for a negative or nil sodium balance during the session ( i.e., dialysate sodium < 140 mmol/L). A gentle ultrafiltration allows control of blood pressure by reducing the extracellular volume to its ideal level, the "dry weight," at the end of the session. Controlling blood pressure reduces cardiovascular mortality, which is by far the foremost cause of death in hemodialysis. Controlling blood pressure means reducing the occurrence of both hypertension and hypotension. Hypotension has been reported to correlate with mortality in hemodialysis as much as or more than hypertension itself. This "U-curve" phenomenon is not paradoxical. It displays two distinct facts on the same figure: an increased early mortality in hypotensive patients (hypotension is a marker of frailty or congestive heart failure, both of which cause increased mortality) and, on the other hand, the well-established, long-term increased mortality in hypertensive patients. Hypotension is not a mandate to undertreat hypertension.

Cardiac effects of exercise rehabilitation in hemodialysis patients

Exercise training has well documented beneficial effects in a variety of cardiac disorders. End stage renal disease patients present many cardiovascular complications and suffer from impaired exercise capacity. No study to date has adequately examined the cardiac responses to exercise training in renal patients on hemodialysis (HD). To determine the effects of an exercise rehabilitation program on the left ventricular function at rest and during submaximal effort, 38 end-stage renal disease patients on maintenance HD were randomised into three groups. Sixteen of them (group A--mean age 46.4+/-13.9 years), without clinical features of heart failure, participated in a 6-month supervised exercise renal rehabilitation program consisting of three weekly sessions of aerobic training, 10 (group B--mean age 51.4+/-12.5 years) followed a moderate exercise program at home, and the other 12 (group C--mean age 50.2+/-7.9 years) were not trained and remained as controls. The level of anemia and the HD prescription remained constant during the study. Fifteen sex- and age-matched sedentary individuals (group D--mean age 46.9+/-6.4 years) were the healthy controls. All subjects at the start and end of the program underwent physical examination, laboratory tests, treadmill exercise testing, M-mode and 2-D echocardiograms performed at rest and at peak of supine bicycle exercise. Left ventricular volumes (EDV, ESV) and mass (LVM) were measured and ejection fraction (EF), stroke volume index (SVI) and cardiac output index (COI) were calculated by standard formulae. The maximal oxygen consumption increased by 43% (P<0.001) and the exercise time by 33% (P<0.001) after training in group A, by 17% (P<0.001) and 14% (P<0.01), respectively, in B, and both remained unchanged in group C. Training in group A was also associated with an increase in LVIDd (from 52.1+/-6.4 to 54.0+/-6.1 mm, P<0.001) and LVM (226+/-67 to 240+/-84 g, P<0.05) at rest with no change noted in groups B and C. Following a 6-month exercise training in group A an increase was also found in the resting EF by 5% (P<0.01) and SVI by 14% (P<0.001). There was no change found in groups B and C. Supine bicycle exercise after training in group A was associated with an improvement in EF by 14% compared to the pre-training change (P<0.001), SVI by 14% (P<0.001) and COI by 73% (P<0.001). These changes from rest to submaximal exercise were less pronounced in group B following training at home. The untrained patients demonstrated no changes in LV systolic function over the 6-month period. These results demonstrate that intense exercise training improves LV systolic function at rest in HD patients; both intense and moderate physical training leads to enhanced cardiac performance during supine submaximal exercise.

Treatment of hypertension in dialysis patients by ultrafiltration: role of cardiac dilatation and time factor

We retrospectively analyzed the blood pressure (BP) and cardiothoracic index (CTi) of 67 hemodialysis patients with hypertension who could be followed up for at least 8 months. A new treatment policy was adopted, aimed at strict volume control. Dietary salt restriction was strongly emphasized. Ultrafiltration (UF) was applied during regular dialysis sessions and sometimes in additional sessions, as long as BP and CTi remained at greater than normal values. All antihypertensive drugs were discontinued at the beginning of treatment. Average BP decreased from 173 +/- 17/102 +/- 9 to 139 +/- 18/86 +/- 11 mm Hg after 6 months and to 118 +/- 12/73 +/- 6 mm Hg after 36 months. Corresponding values for CTi were 52% +/- 4%, 47% +/- 3%, and 42% +/- 4%, respectively. Conventional relatively short dialysis (three times weekly for at least 4 hours) can achieve normal BPs with prolonged effort in most patients, whereas improvement in heart condition facilitates this.

Blood pressure variability as an adverse prognostic risk factor in end-stage renal disease

BACKGROUND

Prospective and case-control studies show that blood-pressure variability is an independent risk factor for severe organ damage and cardiovascular events in hypertensives. We prospectively studied the association between systolic blood pressure variability and cardiovascular mortality and mortality from all causes in end-stage renal disease patients.

METHODS AND RESULTS

The subjects were 144 patients (86 men, 58 women; mean age+/-SD, 52+/-13 years) who underwent dialysis in the same dialysis centre and were examined for blood-pressure variability. The study period was 38 months beginning in January 1995, during which six cardiovascular and seven noncardiovascular fatalities occurred. Coefficient of variation in systolic blood pressure in 1994, as an indicator of systolic blood pressure variability, ranged from 7.8 to 14.6%. Cumulative incidence of death from all causes was related to coefficient of variation in systolic blood pressure. The difference between the maximum and minimum systolic blood pressure (deltaSBP) in 1994 ranged from 44 to 146 mmHg (mean+/-SD, 78+/-13 mmHg) and correlated significantly with coefficient of variation in systolic blood pressure (r = 0.65, P<0.0001). Cox regression analysis was used to identify the independent predictors for mortality. The hazard ratio for death from all causes increased 1.63 times per 1% increase in coefficient of variation in systolic blood pressure (hazard ratio; 95% confidence interval: 1.63; 1.05-2.53) and 1.03 times per 1 mmHg increase in deltaSBP (1.08; 1.03-1.14).

CONCLUSION

These results suggest that systolic blood pressure variability may be a significant prognostic factor in end-stage renal disease.

Dialysis modality and the risk of allograft thrombosis in adult renal transplant recipients

BACKGROUND

Renal vascular thrombosis (RVT) is a rare but catastrophic complication of renal transplantation. Although a plethora of risk factors has been identified, a large proportion of cases of RVT is unexplained. Uremic coagulopathy and dialysis modality may predispose to RVT. We investigated the impact of the pretransplant dialysis modality on the risk of RVT in adult renal transplant recipients.

METHODS

Renal transplant recipients (age 18 years or more) who were enrolled in the national registry between 1990 and 1996 (N = 84,513) were evaluated for RVT occurring within 30 days of transplantation. Each case was matched with two controls from the same transplant center and with the year of transplantation. The association between RVT and 18 factors was studied with multivariate conditional logistic regression.

RESULTS

Forty-nine percent of all cases of RVT (365 out of 743) occurred in repeat transplant recipients with an adjusted odds ratio (OR) of 5.72 compared with first transplants (P < 0.001). There were a significantly higher odds of RVT in peritoneal dialysis (PD)-compared with hemodialysis (HD)-treated patients (OR = 1.87, P = 0.001). Change in dialysis modality was an independent predictor of RVT: switching from HD to PD (OR = 3.59, P < 0.001) and from PD to HD (OR = 1.62, P = 0.047). Compared with primary transplant recipients on HD (OR = 1.00), the highest odds of RVT were in repeat transplant recipients treated with PD (OR = 12.95, P < 0.001) and HD (OR = 4.50, P < 0.001). Other independent predictors of RVT were preemptive transplantation, relatively young and old donor age, diabetes mellitus and systemic lupus erythematosus as causes of end-stage renal disease, recipient gender, and lower panel reactive antibody levels (PRAs).

CONCLUSIONS

The strongest risk factors for RVT were retransplantation and prior PD treatment. Prevention of RVT with perioperative anticoagulation should be studied in patients who have a constellation of the identified risk factors.

Assessment of dry weight in hemodialysis: an overview

Fluid balance is an integral component of hemodialysis treatments to prevent under- or overhydration, both of which have been demonstrated to have significant effects on intradialytic morbidity and long-term cardiovascular complications. Fluid removal is usually achieved by ultrafiltration to achieve a clinically derived value for "dry weight." Unfortunately, there is no standard measure of dry weight and as a consequence it is difficult to ascertain adequacy of fluid removal for an individual patient. Additionally, there is a lack of information on the effect of ultrafiltration on fluid shifts in the extracellular and intracellular fluid spaces. It is evident that a better understanding of both interdialytic fluid status and fluid changes during hemodialysis is required to develop a precise measure of fluid balance. This article describes the current status of dry weight estimation and reviews emerging techniques for evaluation of fluid shifts. Additionally, it explores the need for a marker of adequacy for fluid removal.

"U" curve association of blood pressure and mortality in hemodialysis patients. Medical Directors of Dialysis Clinic, Inc

BACKGROUND

Hypertension may play an important role in the pathogenesis of the excess cardiovascular and cerebrovascular (CV) morbidity observed in hemodialysis patients (HD). However, the optimal blood pressure (BP) range for HD patients has not been defined. We postulated that there is a "U" curve relationship between BP and CV mortality. To explore this hypothesis we studied 5,433 HD patients in Dialysis Clinic Inc., a large not-for-profit chain, over a five year period.

METHODS

Cox regression, with fixed and time-varying covariates, was used to assess the effect of systolic blood pressure (SBP) and diastolic blood pressure (DBP), pre- and post-dialysis, on CV mortality, while adjusting for age, gender, ethnicity, primary cause of end-stage renal disease, Kt/V, serum albumin, and antihypertensive medications.

RESULTS

The overall impact of BP on CV mortality was modest. Pre-dialysis, neither systolic nor diastolic hypertension were associated with an increase in CV mortality. Post-dialysis, SBP > or = 180 mm Hg (RR = 1.96, P < 0.015) and DBP > or = 90 mm Hg (RR = 1.73, P < 0.05) were associated with increased CV mortality. Low SBP (SBP < 110 mm Hg) was associated with increased CV mortality, pre- and post-dialysis.

CONCLUSIONS

The results suggest the presence of a "U" curve relationship between SBP post-dialysis and CV mortality in HD patients.

Seasonal variation of blood pressure in maintenance hemodialysis

CONTEXT

Seasonal variation in arterial blood pressure has been reported in studies with hypertensive and normotensive subjects. However, the influence of seasonal change on blood pressure of hemodialysis patients has not been reported.

OBJECTIVE

To investigate the seasonal variation of blood pressure in Brazil, a tropical country, in patients on hemodialysis.

DESIGN

Prospective, cohort study.

SETTING

Dialysis unit of a tertiary medical center (a teaching hospital of the University of São Paulo School of Medicine, São Paulo).

PATIENTS

Sixteen patients with chronic renal failure undergoing hemodialysis.

OUTCOMES

Blood pressure, body weight, and ambient temperature were evaluated during 6 hemodialysis sessions carried out on 13 days during the four seasons.

RESULTS

The diastolic blood pressure was lower in summer than in fall and winter (95 +/- 8 vs 107 +/- 10 and 101 +/- 10 mmHg, respectively; p < 0.05). The same was observed with mean blood pressure (116 +/- 8 vs 130 +/- 11 and 124 +/- 9 mmHg, respectively; p < 0.01). On the other hand, the ambient temperature was higher in summer than in fall and winter (23.0 +/- 1.6 vs 19.5 +/- 3.0 and 15.8 +/- 1.9 degrees C, respectively; p < 0.01).

CONCLUSIONS

We concluded that for patients with chronic renal failure the blood pressure has a seasonal variation with higher pressures in fall and winter than in summer. Thus, further studies are needed to elucidate the impact of this observation on the adjustment of antihypertensive treatment and on morbidity and mortality in maintenance dialysis patients.

The natriuretic effect of nifedipine gastrointestinal therapeutic system remains despite the presence of mild-to-moderate renal failure

BACKGROUND

Calcium channel blockers facilitate the renal excretion of sodium and this effect is maintained during chronic administration of these drugs. However, it is unknown whether this natriuretic effect remains despite the presence of a decreased renal function.

OBJECTIVE

To compare the natriuretic capacity of nifedipine gastrointestinal therapeutic system (GITS) and lisinopril in patients with mild-to-moderate chronic renal failure.

METHODS

An open-label, randomized, comparative study was conducted to compare the natriuretic capacity of nifedipine GITS and lisinopril in the presence of mild-to-moderate renal failure (creatinine clearance 30-80 ml/min). After a wash-out period of 4 weeks an intravenous saline infusion (30 ml/kg of body weight of isotonic saline in 4 h) was performed and repeated after 4 weeks of active therapy. Two sex- and age-matched groups of hypertensive patients (n = 25) were included in the study. Renal failure was diagnosed as secondary to nephrosclerosis in all the patients.

RESULTS

A significant increase in the renal capacity to excrete the sodium load was observed in patients receiving nifedipine GITS (n = 11) but not in those taking lisinopril (n = 13). Both drugs controlled blood pressure to a similar extent. No changes were observed in body weight, glomerular filtration rate and renal plasma flow (measured as inulin and paraaminohippurate clearances). A significant drop was observed in urinary albumin excretion after lisinopril, but not after nifedipine. Heart rate was higher in nifedipine group.

CONCLUSION

The natriuretic capacity of nifedipine GITS remains despite the presence of mild-to-moderate chronic renal failure. Such an effect takes place in the absence of changes in renal hemodynamics, suggesting that it is caused by a direct tubular effect.

Effects of hypervolemia on interdialytic hemodynamics and blood pressure control in hemodialysis patients

The influence of hypervolemia on hemodynamics and interdialytic blood pressure, as well as in relation to vascular compliance, was investigated in 10 hemodialysis patients who were not receiving vasoactive medication. All subjects were studied during a relative normovolemic interdialytic period (from 1 kg below dry weight postdialytic until dry weight predialytic) and a hypervolemic interdialytic period (from 1 kg above dry weight postdialytic until 3 kg above dry weight predialytic). Interdialytic blood pressure was measured with an ambulatory blood pressure monitor. Cardiac output was echographically measured and total peripheral resistance calculated postdialytic, mid-interdialytic, and predialytic. At the same time, a blood sample was drawn for analyzing vasoactive hormones, sodium, and hematocrit. In all patients, ideal dry weight was estimated by echography of the caval vein. Arterial and venous compliance were measured with an ultrasound vessel wall movement detector system and a strain-gauge plethysmograph. After fluid load, an increase in intravascular volume, an increase in caval vein diameter and cardiac output, and a decrease in peripheral resistance was observed. No significant influence of a 3-L fluid load was found on interdialytic blood pressure course (153+/-24 mm Hg/90+/-19 mm Hg in the hypervolemic period and 146+/-27 mm Hg/89+/-22 mm Hg in the normovolemic period). Sodium and osmolality were similar in the hypervolemic and normovolemic interdialytic periods. After fluid load, a decrease in arginine vasopressin and angiotensin II was observed, which probably contributed to the decreased systemic vascular resistance. Catecholamines were not influenced by fluid load, but increased during the interdialytic period, suggesting accumulation after dialysis. Three of the 10 patients had higher systolic but not diastolic blood pressures after fluid load (159+/-13 mm Hg/81+/-22 mm Hg in the hypervolemic period and 135+/-16 mm Hg/81+/-22 mm Hg in the normovolemic period). No correlation could be found between arterial or venous compliance and blood pressure changes. We concluded that a 3-L interdialytic fluid load does not result in higher blood pressure in most hemodialysis patients.

Cardiac disease in chronic uremia: clinical outcome and risk factors

Cardiac disease is common and is the major killer in end-stage renal disease (ESRD). Cardiac failure is a highly malignant condition in ESRD patients. Cardiac failure mediates most of the adverse prognostic impact of ischemic heart disease. Left ventricular (LV) abnormalities are already present at initiation of dialysis therapy in approximately 80% of patients. These abnormalities (ie, systolic dysfunction in approximately 15%, LV dilatation with preserved systolic function in 30%, concentric LV hypertrophy [LVH] in 40%) independently predict ischemic heart disease and cardiac failure, and are the largest baseline predictor of mortality after 2 years on dialysis therapy. The associations between classical risk factors (eg, hyperlipidemia, smoking, hypertension) and cardiac outcomes in ESRD are inconsistent. "Uremic" risk factors represent a nascent, but potentially important field. In our prospective 10-year study of 433 patients starting renal replacement therapy, we identified the following as major independent risk factors for cardiac disease: (1) hypertension (concentric LVH, LV dilatation, ischemic heart disease, cardiac failure, inverse relationship with mortality); (2) anemia (LV dilatation, cardiac failure, death); and (3) hypoalbuminemia (ischemic heart disease, cardiac failure, death). Transplantation dramatically improved LV abnormalities, suggesting that a uremic environment is cardiotoxic. Multiple risk factors act in concert to produce cardiac disease in ESRD; many of these are avoidable, suggesting that the enormous burden of disease can be reduced considerably.

Low diastolic blood pressure, hypoalbuminemia, and risk of death in a cohort of chronic hemodialysis patients

In a previous report, we showed that nutritional status and especially serum albumin had great predictive value for death in chronic hemodialysis patients, whereas blood pressure did not. In the present study, we analyzed the causes of death in consideration of the relationship between serum albumin and blood pressure. A total of 1,243 Okinawan patients (719 males, 524 females) undergoing hemodialysis in January 1991 were followed up through the end of 1995. Three hundred forty-two of the patients died, 45 received transplants, and 12 were transferred by the end of the follow-up period. The total duration of observation was 5,110.3 patient-years. Blood pressure as well as clinical and laboratory variables were determined immediately prior to the first dialysis session in January 1991. The crude death rate was 40.0% when the diastolic blood pressure (DBP) <70 mm Hg, 35.0% at 70 to 79 mm Hg, 25.0% at 80 to 89 mm Hg, 25.0% at 90 to 99 mm Hg, and 13.0% at >100 mm Hg. The death rate showed an inverse correlation with DBP. DBP showed a significant positive correlation with serum albumin (r = 0.137, P < 0.001) and age (r = -0.325, P < 0.0001). The adjusted odds ratio (95% confidence interval) of death was 0.84 (0.71 to 0.99) with 10 mm Hg increments in DBP when the reference DBP was less than 69 mm Hg. Low DBP may be a manifestation of malnutrition and/or cardiovascular disease in chronic hemodialysis patients. Target DBP levels may be higher levels in chronic hemodialysis patients than the general population.

Use of the medical differential diagnosis to achieve optimal end-stage renal disease outcomes

Compared with the general population, end-stage renal disease (ESRD) patients continue to have a higher than expected morbidity and mortality. Hypoalbuminemia, anemia, hypertension, and inadequate dialysis are all thought to contribute to the high morbidity and mortality among ESRD patients. Anemia algorithms should help to standardize the approach to anemia and the use of recombinant human erythropoietin (rHuEPO), but clinicians still must review each patient individually, searching for and treating the multitude of interrelated factors that affect rHuEPO responsiveness. Hypoalbuminemia is a very strong predictor of increased morbidity and mortality in dialysis and nondialysis patients. The causes of hypoalbuminemia are multifactorial, and diagnosis of the cause of hypoalbuminemia is usually elusive. The basis of the poorer survival in US dialysis patients remains controversial, but inadequate dialysis has been implicated. To assure adequate dialysis, the dialysis prescription must be individualized for each patient, and delivered dialysis must be routinely monitored. Hypertension is associated with left ventricular hypertrophy, which is also an important determinant of survival in ESRD patients. Hypertension should be treated in ESRD patients in conjunction with other interventions that are known to reverse left ventricular hypertrophy. Special efforts must be made in the medical management of hypoalbuminemia, anemia, hypertension, and dialysis treatment adequacy to improve survival in patients with ESRD.

Predictors of stroke in patients receiving chronic hemodialysis

To identify the risk factors of stroke in patients receiving maintenance hemodialysis, we conducted a prospective study on patients in Okinawa, Japan. Patients with end-stage renal disease who were treated with maintenance hemodialysis before the end of 1990 and were alive on January 1, 1991 (N = 1,243) were studied. Medical records and pertinent data as of January 1, 1991 were compiled. All occurrences of stroke were recorded throughout the follow-up period, and until the end of 1995. The duration of observation was 5,110.3 patient-years. A total of 90 cases of stroke were observed, including 63 (70.0%) cerebral hemorrhage, 20 (22.2%) cerebral infarction, and 7 (7.8%) subarachnoid hemorrhage. Multiple logistic analysis identified hypertension as an independent predictor of stroke, with an odds ratio of 2.38 and a 95% confidence interval from 1.26 to 4.50. The present study demonstrates that the high incidence of stroke is at least partially explained by insufficient control of hypertension. Every effort to control hypertension is warranted in chronic dialysis patients.

Secondary hypertension: evaluation and treatment

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.

The inferior vena cava diameter as a marker of dry weight in chronic hemodialyzed patients

We have previously reported that the diameter of the inferior vena cava (IVC) reflects the amount of body fluid in hemodialyzed (HD) patients. The present study was undertaken to depict the criteria of IVC diameters for determining dry weight (DW) in anuric HD patients. In healthy subjects, the maximal diameters during quiet expiration (IVCe) and the minimal diameters during quiet inspiration (IVCi) were 16.7 +/- 3.2 and 5.7 +/- 5.4 mm, respectively (mean +/- SD). The collapsibility index (CI, 1 - IVCi/IVCe), which inversely correlates with the central venous pressure, was 0.68 +/- 0.29. In anuric HD patients, the IVCe/CI values before and after HD were 14.9 +/- 3.2/0.68 +/- 0.24 and 8.2 +/- 2.3/0.94 +/- 0.09, respectively. IVCe decreased proportionally to the amount of ultrafiltration. In HD patients with hypervolemic pulmonary edema, the IVCe and CI values were 22.4 +/- 2.9 and 0.22 +/- 0.11, respectively. We proposed that IVCe/CI after HD is 8 +/- 3 mm/0.9 +/- 0.1 as the markers of DW in anuric HD patients and that an IVCe value > or = 22 mm together with a CI < or = 0.22 implies the warning level of body fluid retention.

Plasma renin activity in hemodialyzed patients during long-term follow-up

Plasma renin activity (PRA) and mean arterial pressure (MAP) were determined in 11 patients after the initiation of maintenance hemodialysis for 8 to 10 years. PRA increased significantly from 2.3 +/- 0.5 to 6.5 +/- 1.3 ng/mL/h, whereas MAP was lowered during follow-up, and there was a strong correlation between these two (r = 0.88, P < 0.001). Immediately before initiating hemodialysis, PRA was negatively correlated with the increase in PRA (r = 0.62, P < 0.05) and positively correlated with the reduction in MAP (r = 0.65, P < 0.05). PRA was elevated and MAP was markedly reduced in patients whose PRA was relatively low immediately before initiating hemodialysis, whereas PRA tended to be reduced and MAP was unchanged in patients with higher levels of PRA. These data suggest that renin secretion continues even after disuse atrophy of the kidneys with almost complete deterioration of its excretory function.

Neural control of renal function in health and disease

The renal sympathetic innervation of the kidney exerts significant effects on multiple aspects of renal function, including renal haemodynamics, tubular sodium and water reabsorption and renin secretion. These effects constitute an important control system which is important in the physiological regulation of arterial pressure and total body fluid and sodium homeostasis. Abnormalities in this regulatory mechanism have pathophysiological consequences and are manifest in clinically relevant human disease states. Decreased renal sympathetic nerve activity results in impaired renin secretion, the inability to conserve sodium normally and an attenuated ability to dispose of both acute and chronic sodium loads. Increased renal sympathetic nerve activity contributes significantly to the excess renal sodium retention and related renal abnormalities observed in both hypertension and oedema forming conditions, such as cardiac failure, cirrhosis and nephrotic syndrome.

Long-term control of hypertension and the predictive value of peripheral plasma renin activity after ablation of end stage kidneys with a new embolic agent

Embolization of end-stage kidneys using our own embolizing agent Vilanol (partially hydrolyzed polyvinyl acetate) was performed in 10 patients with hypertension refractory to conservative therapy. Native kidneys were embolized in 7 patients with chronic renal failure, nonfunctioning renal transplants in 2 patients, and a shrunken kidney in 1 patient. Five of the 10 patients had high (9.96-18.2 ng/ml/h) peripheral renin (PR) levels. The embolization was technically successful in 4 of these 5 patients and was immediately followed by a marked decrease in PR, and simultaneous improvement in blood pressure (BP). The other 5 patients had very low PR levels (0.07-0.65 ng/ml/h), and a reduction in BP was observed in 4 after embolization. One patient died following embolization from cardiac arrest due to hyperkalemia. Six patients (3 in each group) have been on follow-up for 2-5 years with sustained decrease in BP. We conclude that the new agent is effective for renal ablation and control of refractory hypertension.