Short Time Dialysis with Continuous Blood Volume Control

Continuous measurement of haemoglobin concentration is used to control changes of blood volume during haemodialysis. Ultrafiltration is either kept constant throughout the session or after starting with a rate (1.5 to 2 l/h), is manually controlled in order to limit blood volume reduction to a preset percentage. Ultrafiltration is step-wise decreased (a) or switched on and off (b) accordingly. Blood volume decrease with constant ultrafiltration is compared with method (a) and (b) in 4 stable haemodialysis patients. Constant ultrafiltration rate and the same total amount of ultrafiltrate causes a nearly 3% (mean) greater volume reduction as compared with method (a) and (b). No difference was observed in blood pressure and heart rate. We conclude that ultrafiltration in stable haemodialysis patients can be completed in short time without consequences for cardiovascular stability.

[Diagnostic image (348). A man with peculiar calcifications on an abdominal X-ray]

An X-ray of the abdomen of a diabetic dialysis patient showed typical signs of extra-skeletal calcification with mediasclerosis and calcification of the vasa deferentia.

Sticky platelet syndrome: an underrecognized cause of graft dysfunction and thromboembolic complications in renal transplant recipients

Sticky platelet syndrome (SPS) leads to hyperaggregabilty of platelets in response to physiologic stimuli. In this report we describe three patients with clinical symptoms of SPS after renal transplantation. The first patient developed an infarction of her transplant kidney with additional, subsequent renal microinfarctions. The second patient suffered multiple strokes and deep vein thrombosis with episodes of pulmonary embolism and ischemic bowel disease due to colonic microinfarctions. The third patient experienced a long episode of unexplained respiratory and graft dysfunction immediately after transplantation until therapy for SPS was initiated, at which point symptoms resolved quickly. Kidney transplant recipients with SPS may be at increased risk of developing thrombosis, given that most immunosuppressive drugs are known to induce either endothelial cell damage or augment platelet aggregation. All patients awaiting renal transplantation should be screened for a history of thrombosis and, if appropriate, tested for SPS. Affected patients should receive dose-adjusted acetylsalicylic acid.

[Daily problems involving contact with terminally ill patients with renal failure]

Practitioners and physicians working in emergency rooms are often confronted with dialysis patients or patients who have received a kidney transplant. For dialysis patients, the mode of dialysis treatment needs to be assessed and dialysis access should be secured. Furthermore, the indications for the next dialysis treatment need to be determined. Dialysis patients often present themselves because of fluid overload, hypo- or hypertensive episodes, electrolyte disturbances, fever or cardiovascular events. Patients undergoing continuous peritoneal dialysis are at an increased risk of infection of the catheter or of peritonitis. Patients with a renal transplant require continuation of their immunosuppression and the function of the transplant should be monitored. These patients often present with infections in which case the degree of immunosuppression may need to be reduced. Vaccinations as well as an increased risk for malignancies require special attention in these patients.

[Success and failure with the Demers catheter in dialysis]

Between January 1995 and January 1999 54 Demers atrial catheters were implanted in 48 uraemic patients. Indications for implantation were: urgent need for haemodialysis with missing vascular access (39), fistula occlusion (7), low shunt flow (3) and problems with a previously implanted catheter (5). We observed 7 catheter infections, 5 catheter occlusions, 1 intraoperative air embolism, 3 haematomas and 1 dacron socket dislocation. The average period of use of an atrial catheter was 170 days, the longest period almost 2 years. The majority of catheters were explanted without any dysfunction. The long time of availability makes Demers atrial catheters an alternative to fistula for multimorbid patients on dialysis with poor long-term survival.

Adenylate cyclase of gastric mucosa in patients with chronic renal failure

It has been shown previously that antisecretory response of famotidine is altered in patients with renal failure. To evaluate the underlying mechanism(s) of this clinical observation we obtained biopsy specimens of fundic mucosa from 3 groups of patients with variable renal function (group 1 normal renal function (n = 16); group 2 chronic renal failure (n = 16), CLCR > or = 5 < 90 ml/min; group 3 hemodialysis therapy (n = 16)) (matched for age, sex, and Helicobacter pylori (Hp) status. In the homogenized samples adenylate cyclase (AC) activity was assessed and the influence of uremia on this second messenger system involved in gastric acid secretion was tested. AC activity was measured as the formation of cAMP, which was determined by RIA. The mean basal AC activity was 150 in group 1, 190 in group 2, and 120 pmol cAMP/mg protein/20 min in group 3. There was a dose-dependent stimulation by histamine (1 microM-1 mM). Emax of cAMP formation ranged between 230 and 403 pmol cAMP/mg protein/20 min and EC50 between 5.9 and 20.1 microM histamine, dependent on Hp status. Histamine-stimulated AC activation was reduced to about 50% by 0.1 mM famotidine. The sensitivity of AC to histamine seems to decrease in patients undergoing hemodialysis. Similarly, the colonization with Hp may result in decreased maximal response of the AC system towards histamine.

Influence of recombinant human erythropoietin on hematological and hemostatic parameters with special reference to microhemolysis

Twenty chronic hemodialysis patients with renal anemia (hematocrit < 25%) received recombinant human erythropoietin (40 IU/kg body weight 3 x weekly) intravenously after each dialysis. Prior to and at 4, 8 and 12 weeks after commencement of erythropoietin therapy, hematocrit together with hemostasis and microhemolysis parameters were determined. There were significant increases in hematocrit, platelet count and platelet retention, but a significant fall in the initial clearly prolonged bleeding time. Free plasma hemoglobin likewise increased. Conversely, lactate dehydrogenase, prothrombin time, fibrinogen, antithrombin III activity, protein C activity and protein S concentration were all unaltered. The positive effect on bleeding time and platelet retention is most probably caused by an increase in adenosine diphosphate due to the hematocrit-dependent rise in the blood shear stress via physiologic microhemolysis (raised free plasma hemoglobin).

Pharmacokinetics and pharmacodynamics of roxatidine in patients with renal insufficiency

1. Roxatidine acetate, a new histamine H2-receptor antagonist, was administered in the evening (75 mg p.o.) to eight patients with renal insufficiency (CLCR 8-17 ml min-1) for 12 days and plasma drug concentrations were measured. 2. Ambulatory intragastric pH was monitored following the last dose and values were compared with those on day 1 when all patients received a placebo. 3. The terminal elimination half-life (mean +/- s.d.) of roxatidine was 10.8 +/- 2.4 h and its oral clearance was 178 +/- 43 ml min-1. 4. During roxatidine treatment gastrin levels increased slightly (median 189 vs 289 ng l-1) and the hyperparathyroid status of the patients was almost normalized (parathyroid hormone levels: median 199 vs 132 ng l-1). 5. The mean latency to a gastric pH of at least 4 was 4.3 +/- 1.4 h. The duration of action (intragastric pH > 4) was 10.6 +/- 3.9 h. 6. As in a pilot study with six patients (CLCR < or = 17 ml min-1) the recommended dosage regimen (75 mg 48 h-1) was unable to maintain gastric pH > 4 for more than 6 h, daily nocturnal intake of 75 mg roxatidine acetate appears appropriate to elevate gastric pH > 4 for a sufficient period of time.

Pharmacokinetic optimisation of the treatment of peptic ulcer in patients with renal failure

The pathogenesis of peptic ulceration is not yet clear. It could be due to an imbalance between acid secretion and mucosal defensive and/or protective mechanisms, but the association between Helicobacter pylori and peptic ulceration has questioned this hypothesis. Therefore, drugs inhibiting acid secretion and/or eradicating H. pylori are of major interest. Peptic ulcer disease is often associated with renal failure. For the selection of the proper dosage of these agents their pharmacokinetic properties and alterations in pharmacokinetics in various disease states, including renal failure, should be known. As histamine H2-receptor antagonists and pirenzepine are mainly eliminated by the renal route their elimination is dependent on creatinine clearance. Consequently, their elimination will be impaired in patients with renal insufficiency, which makes dosage reduction mandatory in these patients. No dosage supplementation is necessary after any type of dialysis because the drugs are removed in insignificant amounts by the various blood purification procedures. Misoprostol and proton pump inhibitors, such as omeprazole, lansoprazole and pantoprazole, are primarily eliminated by nonrenal routes. Therefore no dosage adjustments are necessary in patients with renal insufficiency. Bismuth salts, sucralfate and antacids should be avoided in patients with renal failure because of the accumulation of their cations and the associated risk of toxic reactions. For most agents more long term experience from comparative and double-blinded studies is needed to define better their clinical efficacy and tolerability in patients with renal failure.

Hydrodynamic thrombectomy of hemodialysis fistulas: first clinical results

PURPOSE

A hydrodynamic thrombectomy system was used for the treatment of recent dialysis shunt thrombosis.

PATIENTS AND METHODS

Sixteen shunt thromboses in 14 patients were included in the study. There were seven polytetrafluoroethylene grafts and nine native arteriovenous fistulas. Occlusion time ranged from 6 to 48 hours, and thrombus length ranged from 4 to 40 cm.

RESULTS

Thrombectomy was technically successful in 15 of 16 instances. No significant residual thrombus was found in 15 cases. In one case, half of the thrombus remained in the vessel and the procedure failed technically. One embolus to the radial artery occurred after balloon dilation following hydrodynamic thrombectomy and was removed percutaneously. Early rethrombosis within 24 hours occurred in five shunts; four more rethrombosed within 2 weeks to 3 months. Eleven shunts were available for follow-up. Cumulative patency was 41% after 6 months.

CONCLUSION

Hydrodynamic thrombectomy is a promising concept for declotting of both hemodialysis grafts and native shunts and may offer an alternative to thrombolysis and surgical thrombectomy.

Which bicarbonate concentration is adequate to lactate-buffered substitution fluids in maintenance hemofiltration?

We investigated the metabolic and hemodynamic effects of a lactate- and a bicarbonate-buffered (bicarbonate concentration 31.4 mmol/l, type I) hemofiltration substitution fluid in a prospective crossover study of 3 weeks each in 11 patients on maintenance hemofiltration. The lactate-buffered hemofiltration (lactate concentration 34-44.5 mmol/l) lead to hyperlactatemia in all patients without signs of overt lactic acidosis but showed a better control of acid-base balance (pH, base excess, standard bicarbonate) than the type I bicarbonate-buffered fluid (p < 0.01). In 6 patients a higher concentration of bicarbonate- (39.7 mmol/l, type II) buffered fluid was tested. The parameters of acid-base balance showed a better control during type II than during type I bicarbonate hemofiltration and were similar to the lactate-buffered phase. Plasma lactate levels between type I and type II bicarbonate hemofiltration were not different. Also in the steady state phase of the treatment (days 7-9 [week 3]) parameters of acid-base balance rose more to normal values during type II than during lactate-buffered hemofiltration. Hemodynamic parameters showed no differences between the three types of buffers used. Furthermore, also the type II bicarbonate fluid was well tolerated. Bicarbonate in a higher concentration (39.7 mmol/l) proved to be a safe and practical alternative to lactate-buffered hemofiltration.

Helicobacter pylori infection and serum pepsinogen A, pepsinogen C, and gastrin in gastritis and peptic ulcer: significance of inflammation and effect of bacterial eradication

OBJECTIVES

To study the relationship between Helicobacter pylori infection, gastric inflammatory scores, and fasting gastrin and pepsinogen A and C concentrations, and to evaluate the effect of treatment on these parameters.

METHODS

Gastrin and pepsinogen A and C concentrations were measured in 36 patients with gastritis, 10 gastric ulcer patients, 12 duodenal ulcer patients, and in 15 subjects with normal gastric mucosa, by standard radioimmunoassay techniques. Fifteen patients with H. pylori infection underwent triple therapy (bismuth subsalicylate, amoxicillin, metronidazole) and were reassessed 1 month later.

RESULTS

Fasting gastrin and pepsinogen A and C concentrations were significantly higher in H. pylori-positive gastritis and peptic ulcer patients than in subjects with normal mucosa and in patients with H. pylori-negative gastritis. There was a significant correlation between inflammatory scores and serum gastrin (r = 0.45, p < 0.0001), and pepsinogen A (r = 0.33, p < 0.006) and pepsinogen C (r = 0.55, p < 0.0001) concentrations. Neither sex nor age affected basal gastrin and pepsinogen concentrations. Eradication of H. pylori infection was successful in 12 patients and resulted in a significant fall in serum gastrin and in pepsinogen A and C concentrations, and in a concomitant improvement of the inflammatory scores. Serum peptide levels and gastritis scores were unchanged in those patients in whom H. pylori infection persisted.

CONCLUSIONS

These findings suggest that hypergastrinemia and hyperpepsinogenemia are secondary to H. pylori infection and are related to mucosal inflammation.

Diagnostic value of indirect pancreatic function test in serum of anuric patients with chronic renal failure

Although patients with chronic renal failure have a high incidence of chronic pancreatic disease, the condition is frequently overlooked. We have modified the pancreolauryl test--an indirect pancreatic function test--for anuric patients. The test permitted good discrimination between patients with chronic pancreatic disease and those with a normal pancreas when serum levels of fluorescein were measured 10 h after administration with a standard meal. The sensitivity at this time interval was 80% and the specificity 83%. We conclude that the pancreolauryl test with serum measurements provides a simple, noninvasive, and reliable diagnostic test for chronic pancreatic disease in anuric patients with chronic renal failure.

Influence of interdialytic weight gain on blood pressure in hemodialysis patients

The role of fluid overload in the pathogenesis of hypertension in hemodialysis patients is not clear. One problem is the lack of techniques to determine the fluid state. Recent new noninvasive techniques have become available which make it possible to accurately determine the dry weight in these patients. Therefore, we studied the influence of interdialytic weight gain on interdialytic blood pressure in 10 normotensive and 10 hypertensive hemodialysis patients without antihypertensive medication. The dry weight was determined with echography of the vena cava. The blood pressure was measured during 2-day and 3-day interdialytic periods using Spacelabs 90207 ambulatory blood pressure monitors. Mean systolic and diastolic blood pressures of the last day of the interdialytic period were compared with mean systolic and diastolic blood pressures of the 1st day of the interdialytic period. Although the interdialytic weight gain in the normotensive and hypertensive patients was greater during the 3-day than during the 2-day interdialytic period, the interdialytic systolic and diastolic blood pressure changes were not greater during the 3-day period. Also, the interdialytic blood pressure rise did not correlate significantly with weight gain, neither in the normotensive nor in hypertensive patients. No significant interdialytic blood pressure changes were found between the normotensive and the hypertensive patients. We conclude that fluid overload does not seem to play a major role in interdialytic blood pressure control in normotensive and hypertensive hemodialysis patients.

Diagnosis and treatment of a solitary infected hepatic cyst in two patients with adult polycystic kidney disease

We report on two women (one 52-year-old who underwent kidney transplantation 15 months ago and the other, 71-year-old, undergoing hemodialysis) both with adult polycystic kidney disease who had to be hospitalized because of recurrent fever attacks up to 40 degrees C without any remarkable abdominal symptoms. Staphylococcus hominis and E. coli were recovered respectively from blood cultures of both patients. Evidence for the presence of a solitary infected cyst in the liver could only be obtained by computed tomography (CT) with i.v. administration of a contrast medium. In both cases the infected liver cyst was non-operatively drained with a CT-guided percutaneous catheter and therefore the necessity of laparotomy was avoided.

Pharmacokinetics of epoetin (recombinant human erythropoietin) after long term therapy in patients undergoing haemodialysis and haemofiltration

After long term therapy with epoetin (recombinant human erythropoietin) 17 patients with end-stage renal disease (ESRD) were studied in 3 groups to assess pharmacokinetics during the intertreatment interval and during haemofiltration and dialysis treatment. Epoetin was measured by radioimmunoassay. After an intravenous bolus of epoetin 150 U/kg bodyweight, the half-life was 7.7h, steady-state volume of distribution was 0.066 L/kg and total plasma clearance was 5.4 ml/min. The mean steady-state serum concentration during multiple-dose administration was 656 U/L. The drug was not eliminated by haemofiltration or dialysis. Long term treatment of ESRD patients with epoetin does not significantly alter the pharmacokinetic profile of the drug. Epoetin dosage adjustment or substitution after haemofiltration and dialysis is not necessary.

Prevalence of antibodies to hepatitis C virus in patients on peritoneal dialysis--a multicenter study

The prevalence of antibodies to the hepatitis C virus (HCV) was determined in 333 peritoneal dialysis (PD) patients from 10 German dialysis units, using an enzyme-linked immunosorbent assay of the second generation (ELISA 2nd gen) which detects antibodies to a structural (C22) and to non-structural (C33c, C100, 5-1-1) recombinant antigens of HCV. Sera from 18/333 (5.4%) patients were anti-HCV positive versus 11/295 (3.7%) when the sera were tested by an ELISA of the first generation (ELISA 1st gen) containing only a nonstructural antigen (C100). In the 18 sera positive by ELISA 2nd gen, antibodies against at least one viral protein were found by recombinant immunoblot assay (RIBA) in 15/333 (4.5%) patients. In the sera of 11/15 (73.3%) patients HCV RNA was detected by nested PCR. Epidemiological evaluation of the patients revealed that the prevalence of anti-HCV was correlated to the female sex (p = 0.005), presence of anti-HBc (p = 0.006), duration of total dialysis (hemodialysis HD and PD) (p = 0.012), duration of HD alone (p = 0.025) and previous renal transplantation (p < 0.001). Only a weak correlation was found to blood transfusions (p = 0.041) and elevation of serum ALT concentration (p = 0.055). But no correlation was found to diagnoses of renal failure (p = 0.129), duration of PD (p = 0.963) and past surgical procedures (p = 1.0). Four of nine peritoneal dialysates of anti-HCV positive patients were found positive for HCV RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

[Treatment of stenosed or occluded hemodialysis shunts. Results of percutaneous angioplasty and combined radiologic-surgical therapy]

The results of all recanalisations of stenosed and occluded haemodialysis shunts over a period of three years are reported; there were 112 percutaneous angioplasties and 40 combined radiological-surgical procedures. In 13% of cases a metallic endoprosthesis (wall stent) and in 3% Simpson's atherectomy catheter was used. The functional results were retrospectively evaluated for all 152 interventions which involved 60 orthoptic Brescia-Cimino shunts and 19 PTFE prostheses. In addition, the primary and total functions of the treated shunts were calculated. Cumulative function rate (percentage at a given time of effective shunts) for Brescia-Cimino shunts at one year was 80% and after two years 68.5%; for the PTFE prosthesis the corresponding figures were 83.8 and 75.5% respectively. The average number of interventions per patient was 2.3 with a range of 1-7. Total functional rate of all shunts following the first percutaneous procedure after one year was 78.2%, for combined radiological-surgical procedures for the treatment of acute thromboses it was 68%. Comparison with the results of surgical treatment reported in the literature confirms the effectiveness of percutaneous or combined treatment of stenosed or acutely occluded haemodialysis shunts. The outstanding advantage of radiological intervention is its repeatability.

Pharmacokinetics and pharmacodynamics of famotidine in patients with reflux oesophagitis

The pharmacokinetics, pharmacodynamic effect and clinical efficacy of famotidine were studied in 10 patients with reflux oesophagitis Grades I and II. For the pharmacokinetic studies the patients received 20 mg famotidine i.v. The half-life of famotidine was 3.8 h, the total plasma clearance was 297 ml.min-1, and a steady state volume of distribution of 1.2 l.kg-1 was found. For pharmacodynamic assessment, intraoesophageal pH-metry was performed without and after acute treatment with famotidine 20 mg i.v. and following 3 weeks of oral famotidine 80 mg b.d. The resultant percentage total acid exposure time (pH < 4 within 24 h) were 23.9%, 19.0% and 19.2% (median), respectively (NS). At the end of 6 weeks of oral therapy, symptomatic and endoscopic improvement had occurred in 9 and 5 patients, respectively. Our study shows that the pharmacokinetics of famotidine in patients with reflux oesophagitis is comparable to that in healthy volunteers and peptic ulcer patients. The clinical response to the treatment appeared comparable to that found after other H2-receptor antagonists.

Response of vasoactive substances to reduction of blood volume during hemodialysis in hypotensive patients

Hypotension is a frequent complication in patients subjected to regular hemodialysis. Insufficient regulation of blood pressure following dialysis with ultrafiltration has been attributed to a lack in hormone activation. To determine whether altered production of vasoactive hormones is involved in the breakdown of blood pressure regulation during hemodialysis (HD), blood volume (BV), atrial natriuretic peptide (ANP), plasma renin activity (PRA), aldosterone (Aldo), norepinephrine (NE), epinephrine (Epi), intact immunoreactive parathyroid hormone (iPTH) and arginine vasopressin (AVP) were examined. The relative BV was measured by continuous hemoglobinometry during the HD period of about 240 min. The total decrease in BV at the end of treatment was 23.5 +/- 4.8% of the pretreatment value. Systolic blood pressure (SBP) was 99.6 +/- 23.0 mmHg before dialysis compared with 74.6 +/- 18.8 mmHg at the end of dialysis and heart rate (HR) increased from 76.3 +/- 5.5/min before to 92.0 +/- 10.0/min at the end of dialysis. Despite the wide range of interindividual variance, the hormonal changes indicate that hypotensive patients under HD develop reduced sensitivity of the angiotensin-renin, adrenergic and AVP systems to volumetric stimuli. A paradoxical activation in iPTH and PRA independent Aldo secretions is apparent.

Pharmacokinetics and pharmacodynamics of H2-receptor antagonists in patients with renal insufficiency

H2-receptor antagonists are frequently used in patients with renal insufficiency to treat hyperacidity and resultant peptic ulceration. All H2-antagonists are mainly eliminated by the renal route (glomerular filtration and tubular secretion). Since it is dependent on creatinine clearance (CLCR), elimination will be impaired in renal insufficiency. Protein binding and volumes of distribution (Vd) of H2-antagonists are not significantly altered in patients with renal impairment. Bioavailability (F) is similar in patients with and without renal insufficiency, except for nizatidine, which has an F that is lower in uraemic patients. When given in similar doses, mean peak concentrations (Cmax) and area under the concentration-time curve (AUC) are higher in patients with renal insufficiency than in those with normal renal function. Thus, maintenance doses of H2-antagonists should be reduced in line with reductions in CLCR. The time to reach Cmax is similar for all drugs except ranitidine, which has a delayed Cmax. Due to the decreased renal clearance (CLR), elimination half-life (t1/2) is prolonged 3- to 8-fold depending upon the degree of renal failure and the particular drug. H2-antagonists are removed by various dialysis procedures in insignificant amounts. Thus, no dosage supplementation is necessary after any type of dialysis therapy. By means of intragastric long term pH-metry it has been shown that inhibition of gastric acid secretion is prolonged in patients with renal insufficiency.

Response of vasoactive substances to intermittent ultrafiltration in normotensive hemodialysis patients

The changes in blood volume (BV), atrial natriuretic peptide (ANP), plasma renin activity (PRA), aldosterone (Aldo), norepinephrine (NE), epinephrine (Epi), parathyroid hormone (PTH), arginine vasopressin (AVP) and the cyclic nucleotides cAMP and cGMP were measured during a fluctuating BV cycle in 15 patients with end-stage renal failure maintained on chronic hemodialysis (HD). HD consisted of 4 periods of about 60 min each. The first half of each HD period consisted of ultrafiltration (UF) greater than 1,000 ml/h, and the second half consisted of no UF. Changes in relative BV were measured using continuous hemoglobinometry. Total BV at the end of treatment was 74.3 +/- 6.9% of the pretreatment volume. A significant positive correlation between BV and the levels of ANP, PTH, Epi and cGMP and an inverse correlation between BV and PRA, Aldo, AVP and NE were demonstrated. While mean values of NE and AVP levels were directly related to actual changes in BV, individual values did not homogeneously reflect this relationship. The cyclic nucleotides cGMP and cAMP did not follow immediate BV changes, but showed a significant decrease correlated with diminished BV. Based on a pre-postdialysis analysis, significant changes in PRA and Aldo were missing. It seems possible that vascular stability in dialysis patients may be maintained by the response of NE and AVP, and not by the renin-aldosterone system. The changes in ANP and cGMP values correlated most significantly (r = 0.38 and r = 0.51, p < 0.005) with the changes in BV, but no single variable could explain the blood pressure regulation during HD with intermittent rapid UF.

Compliance and reactivity of the peripheral venous system in chronic intermittent hemodialysis

A reduced venous compliance and/or inadequate venoconstriction could impair hemodynamics during hemodialysis. Therefore, compliance and reactivity of the peripheral venous system were assessed in hemodialysis patients and controls using strain gauge plethysmography. Reactivity of the venous system towards an efferent sympathetic stimulus was assessed using a cold pressor test. Results showed that venous compliance was reduced in hypertensive hemodialysis patients compared to normotensive dialysis patients (P = 0.013) and normotensive controls (P = 0.004). After one dosage with a directly acting venodilator (nitroglycerin 5 mg s.l.) and 3 days of treatment with an alpha 1-sympathicolytic agent (Doxazosin 2 mg), venous compliance remained unaltered in hypertensive dialysis patients. During the cold pressor test, the blood pressure response, rise in noradrenaline levels and decline in venous compliance were normal in hemodialysis patients. However, their response to the Valsalva manoeuver was significantly impaired (P = 0.011) compared to healthy controls. We conclude that hypertension, not renal failure, causes the reduction of peripheral venous compliance in hemodialysis patients, for which structural factors might be responsible. Despite the existence of autonomous neuropathy, the reaction of the peripheral venous system towards an efferent sympathetic stimulus is intact in hemodialysis patients.

Role of the venous system in hemodynamics during ultrafiltration and bicarbonate dialysis

A reduced venous compliance (VC) and inadequate venoconstriction may impair hemodynamics during hemodialysis, the first by impairing plasma volume preservation and by inducing a steep fall in central venous pressure (CVP) during minor plasma volume loss, the second by inadequate mobilization of hemodynamically inactive blood volume. For the protocol A, the relation between VC, the fall in plasma volume and the decline in central venous pressure (CVP) was assessed in 12 hemodialysis (HD) patients, aged 40 to 74 years, during isolated ultrafiltration (UF). The patients were ultrafiltrated for one hour at an UF rate of 1 to 1.5 liter/hr. VC was measured by strain gauge plethysmography with direct i.v. pressure measurements. CVP was assessed directly via a subclavian catheter. PVP was measured using the serial hematocrit method. VC correlated inversely with the fall in plasma volume (r = -0.66; P less than 0.025) and with the fall in CVP (corrected for UF volume) (r = -0.62; P less than 0.025). In the protocol B, the constriction of veins and resistance vessels was assessed sequentially during isolated UF and during UF combined with bicarbonate HD (UF + HD) by measuring the change in venous tone (VT) and vascular resistance (FVR) of the forearm. Twelve HD patients were studied (age 30 to 64 years). VT and FVR were measured using strain gauge plethysmography. The UF rate was equal during isolated UF and UF + HD (1 liter/hr). In six patients, the measurements were started with isolated UF and in six patients with UF + HD.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary hyperparathyroidism and sonographic evaluation of parathyroid gland hyperplasia in dialysis patients

Ninety-six hemodialysis patients were examined by ultrasonography of the parathyroid glands to study the prevalence of parathyroid gland hyperplasia and to assess the relevance of sonography in the evaluation of secondary hyperparathyroidism. The results were compared with clinical, biochemical and radiological parameters. Thirty-two (33.3%) patients had sonographically enlarged glands. Of them 19 had 1 and 13 had 2 and more enlarged glands. Patients with enlarged glands, compared to those with undetected glands, had a significantly higher frequency of bone and joint pains (65.5% vs 40.6%), radiological features of hyperparathyroid bone disease (in hands 28.1% vs 6.9%, in acromioclavicular joints 37.5% vs 13.6%) and higher levels of intact serum parathyroid hormone (1-84) concentration (52.8 +/- 47.9 pmol/l vs 18.1 +/- 18.0 pmol/l) and serum alkaline phosphatase concentration (260.2 +/- 201.1 U/l vs 129.8 +/- 127.3 U/l). Those with enlarged glands had been on dialysis for a longer period (87.7 +/- 51.0 months vs 62.5 +/- 47.4 months). The severity of secondary hyperparathyroidism increased with the number of enlarged glands. Our study shows that ultrasonography is a useful noninvasive screening method for the evaluation of secondary hyperparathyroidism in patients on hemodialysis and that sonographically enlarged glands may be a measure of the severity of secondary hyperparathyroidism.

Effect of Helicobacter pylori infection on 24 hour intragastric acidity in patients with gastritis and duodenal ulcer

Helicobacter pylori status, gastric histology, and 24 hour acidity were studied in 35 gastritis patients, 21 duodenal ulcer patients, and 14 subjects with normal gastric mucosa. H pylori was identified in 21 of 35 patients with chronic active gastritis and in 19 of 21 duodenal ulcer patients, but in none of those with normal gastric mucosa. Mean scores of activity of gastritis were similar in H pylori positive gastritis and duodenal ulcer patients, but were significantly lower in H pylori negative gastritis patients (2.1 (0.8) and 2.3 (0.9) v 1.4 (0.7); p < 0.01, respectively). Median 24 hour hydrogen ion activity (interquartile range) was 21 (8.9-38.0) mmol/l in normal subjects and 23 (11.2-49.0) mmol/l, 19 (7.1-33.1) mmol/l, 44 (25.1-63.1) mmol/l, and 36 (31.6-39.8) mmol/l respectively in gastritis and duodenal ulcer patients with and without H pylori infection. During all predefined time periods, intragastric acidity was significantly higher in patients with H pylori positive duodenal ulcers compared with gastritis patients and normal subjects. However, there was no significant difference in intragastric acidity between the H pylori positive and negative gastritis patients. These results suggest that most of the subjects with chronic H pylori infection have normal gastric acidity.

Prevalence of hepatitis C virus infections in dialysis patients and their contacts using a second generation enzymed-linked immunosorbent assay

The prevalence of antibodies to the hepatitis C virus (HCV) was determined in 498 hemodialysis patients from three german dialysis units, 121 staff members and 42 family members using an enzyme-linked immunosorbent assay (ELISA) of the second generation which detects antibodies to a structural (C22) and to non-structural (C33c, C100, 5-1-1) recombinant antigens to HCV. Using the second generation ELISA 115 patients (23.1%) were anti-HCV positive versus 77 (15.5%) when sera were tested by an ELISA of the first generation containing only a non-structural antigen (C100). In 34 of these 40 discordant sera antibodies against at least one viral protein was found by a recombinant immunoblot assay. Of 5 sera containing antibodies to only one viral protein (C22) 3 were HCV RNA positive by polymerase chain reaction. Epidemiological evaluation of the patients revealed that the prevalence of anti-HCV was correlated to the duration of dialysis but not to the number of blood transfusions. Of 121 staff members 2 (1.6%) and 2 of 42 family members (4.7%) were positive indicating a low risk of the patients' contacts of acquiring HCV infection.

Immunoreactive parathyroid hormone after volume change in normo- and hypotensive hemodialysis patients

The effects of reduced blood volume during hemodialysis on circulating immunoreactive parathyroid hormone (PTH) were determined in relation to changes in blood pressure and heart rate in normo- and hypotensive patients with end stage renal failure. During dialysis the plasma concentration of PTH did not change in normotensives, while PTH increased significantly in patients with a fall in blood pressure during a 25% reduction in effective intravascular volume. The blood volume was measured continuously during hemodialysis using the authors' hemoglobin measurement system. The decrease in blood volume in both groups was comparable. The results suggest that secretion of PTH during hemodialysis may play a role in hemodynamic instability during hemodialysis.

[The signal behavior of parathyroid adenomas in MRT--the contrast ratio of the thyroid and fatty tissue]

A quantitative analysis of signal relationships using T1, proton and T2 weighted spin echo sequences was carried out using 20 parathyroid adenomas demonstrated by MRI. T1 weighted sequences from 15 adenomas were also examined following intravenous injection of Gd-DTPA. No typical signal relationship could be defined. In 4 cases the administration of contrast medium markedly increased the contrast between the adenoma and the thyroid gland. In 12 cases the tumour could be examined histologically following removal. In 2 cases there was oedema of the tumour and corresponding increased intensity of the T2 weighted sequences; in none of the other cases was there any clear correlation between the signals and the histology.

Bismuth subsalicylate in the treatment of H2 blocker resistant duodenal ulcers: role of Helicobacter pylori

Fifty nine patients with Helicobacter pylori positive duodenal ulcers that failed to heal after a six week course of treatment with H2 blockers were randomly assigned to one of the following three regimens: (i) bismuth subsalicylate, 600 mg three times daily (n = 19), (ii) ranitidine, 300 mg at night (n = 20), (iii) bismuth subsalicylate plus ranitidine (n = 20). Cumulative ulcer healing rates after four and eight weeks respectively were as follows: bismuth subsalicylate 74% (14/19) and 95% (18/19), ranitidine 40% (8/20) and 65% (13/20), bismuth subsalicylate plus ranitidine 80% (16/20) and 95% (19/20). Bismuth subsalicylate treatment was better than ranitidine at both four and at eight weeks (p less than 0.05). The clearance rates for H pylori after four weeks were: bismuth subsubsalicylate 58%, ranitidine 0%, bismuth subsalicylate plus ranitidine 55%. After stopping bismuth therapy bacterial recrudescence frequently occurred. After bismuth treatment 86% (19/22) of ulcers had healed if H pylori had been cleared, whereas only 65% (11/17) had healed if H pylori persisted (NS). This study shows that bismuth subsalicylate is more effective in the treatment of resistant duodenal ulcers than standard dose ranitidine. It may be that suppression of H pylori by bismuth subsalicylate promotes ulcer healing.

Blood pressure during the interdialytic period in haemodialysis patients: estimation of representative blood pressure values

The estimation of representative blood pressure (BP) levels is difficult in haemodialysis (HD) patients as it is not known whether pre- or postdialytic blood pressure are predictive for the average interdialytic BP. Furthermore, the day-night BP rhythm can be disturbed in HD patients. Therefore, in this study, BP was measured during the interdialytic period using non-invasive ambulatory BP measurements in four hypotensive, six normotensive, and 12 hypertensive HD patients. It was assessed whether pre- or postdialytic BP was representative for the average interdialytic BP. Furthermore, the nocturnal BP reduction was compared between HD patients, seven normotensive controls and eight treated subjects with essential hypertension. Postdialytic BP was superior to predialytic BP in predicting the average BP during the interdialytic period. BP did not differ significantly between day 1 and day 2 of the interdialytic period but increased rapidly in the hours before dialysis. Weight gain (corrected for actual body-weight) did not correlate significantly with the increment in systolic BP (r = 0.21; P = 0.2) or diastolic BP (r = -0.02; P = 0.5) during the interdialytic period. The nocturnal decline in systolic BP was significantly attenuated (P less than 0.001) in hypertensive HD patients compared with normotensive controls. The nocturnal reduction in diastolic BP was significantly less in hypotensive (P less than 0.001) and normotensive (P less than 0.001) HD patients compared with normotensive controls and in hypertensive HD patients compared with normotensive (P less than 0.001) and hypertensive (P less than 0.001) controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and pharmacodynamics of cisapride in patients undergoing hemodialysis

Twenty-two patients who were receiving hemodialysis were studied in three groups of eight subjects each to assess the pharmacokinetics during the dialysis-free interval and during hemodialysis treatment and to assess the pharmacodynamics of cisapride. Cisapride and its metabolite norcisapride were measured by use of HPLC and gas chromatography, respectively. The pharmacodynamic effect of cisapride was measured by means of radionuclide gastric emptying. After a single oral dose of 20 mg the terminal half-life of cisapride was 9.6 +/- 3.3 hours, the volume of distribution was 4.8 +/- 3.3 L/kg, the total oral plasma clearance was 380 +/- 161 ml/min, the area under the curve was 1024 +/- 447 ng.hr/ml (mean +/- SD). Norcisapride only could be detected in the dialysate (0.36 +/- 0.067 mg) and was eliminated by a hemodialysis clearance of 34.7 +/- 7.9 ml/min. Cisapride reduced gastric retention from 77.6% +/- 21.1% to 43.7% +/- 18.2% of maximum filling (40 minutes after meals) and normalized the abnormal gastric emptying time in patients receiving dialysis. Cisapride dosage adjustment or substitution after hemodialysis is not necessary.

Tripotassium dicitrato bismuthate: absorption and urinary excretion of bismuth in patients with normal and impaired renal function

We have investigated the absorption and urinary excretion of tripotassium dicitrato bismuthate during a treatment course of 4 weeks in 7 patients with normal renal function (creatinine clearance 115 +/- 29 ml/min; mean +/- S.D.), in 7 patients with impaired renal function (creatinine clearance = 34 +/- 19 ml/min) and in 4 dialysed patients. Following the first dose of tripotassium dicitrato bismuthate (216 mg bismuth b.d.), and after 2 and 4 weeks of treatment (dialysed patients received only 108 mg/b.d.), plasma and urine concentrations of bismuth were monitored for 2 and 24 h, respectively. After stopping therapy plasma and urine concentrations of bismuth were followed for 4 and 6 weeks, respectively. In all three groups of patients small amounts of bismuth (mean values 0.26 to 0.28% of dose) were rapidly (transient mean peak concentrations between 40 and 134 micrograms/L) reached within about 30 to 40 min, absorbed and plasma levels demonstrated a wide intra- and inter-individual variability. Absorption profiles were not altered during the treatment course; however, the trough plasma concentration of bismuth demonstrated an about 3- to 5-fold accumulation (correlated to creatinine clearance) from about 5 micrograms/L to 15 micrograms/L (normal renal function) or to 20-25 micrograms/L (impaired renal function). Pre-study bismuth levels could be detected within 2 to 4 weeks after stopping therapy in all subjects whereas urinary concentrations were still elevated 6 weeks after the course of treatment. Our results indicate that tripotassium dicitrato bismuthate is absorbed in very low amounts during standard therapy. However, dependent on renal function, accumulation to non-toxic levels does occur during a course of treatment. It appears prudent to halve tripotassium dicitrato bismuthate dosage in patients with severe renal insufficiency (creatinine clearance less than or equal to 20 ml/min) to avoid any possible toxic risks. In such patients monitoring of the plasma bismuth concentration might be helpful, especially if longer or repeated treatment is anticipated.

Circadian pattern of intragastric acidity in duodenal ulcer patients: a study of variations in relation to ulcer activity

The relation between intragastric acidity and duodenal ulcer activity was studied prospectively in 21 patients with endoscopically proved duodenal ulcers. The 24 hour intragastric acidity was measured on four separate occasions by continuous recording using combined glass electrodes: (a) in the presence of an ulcer crater without treatment; (b) during active ulceration being treated with ranitidine; (c) during early healing after a six week course of ranitidine; (d) during late healing six months after acute ulceration. Intragastric acidity was also monitored in 20 healthy subjects. At all stages of ulcer activity and during all predefined time periods, duodenal ulcer patients had significantly higher gastric acidity than healthy control subjects. Duodenal ulcer patients showed a similar circadian pattern of intragastric acidity during exacerbation of ulcer disease and in remission during the early and late ulcer healing periods. These results argue against a direct relation between the activity of duodenal ulcer disease and gastric acidity. It is concluded that the chronic recurrent course of duodenal ulcer disease does not result from a fluctuation in intragastric acidity.

Follow-up results after stent placement in failing arteriovenous shunts: a three-year experience

Self-expandable endoprostheses were used in 18 failing arteriovenous shunts after unsuccessful balloon dilatation. Technical success was satisfactory with an early patency in 17 of 18 shunts. Thrombosis right after stenting occurred in three shunts but was successfully treated in two. Follow-up history revealed recurrent events of reobstruction due either to stent or shunt stenoses or thrombosis. Restenosis within the stented segment was responsible for reobstruction in about half the cases. Although patency was low with 27% at 18-month follow-up, repeated intervention established a shunt survival rate of 77% at 18-month follow-up. Stent placement in AV shunts is useful for overcoming acute problems of balloon dilatation but does not prevent restenosis.

Intragastric long-term pH-metry in hemodialysis patients. A study with famotidine

The onset and duration of famotidine action were studied in 14 hemodialysis (HD) patients and 16 healthy controls (control group: CG) who were examined by ambulatory intragastric 24-hour pH-metry. 20 mg famotidine was administered i.v. 90 min after HD in the afternoon (AN; 2 p.m.; n = 8) or evening (E; 8 p.m.; n = 6), followed by a standard meal. Mean onset of action in the AN and E groups of the HD patients was 90.3 +/- 28.2 min and 98.8 +/- 29.8 min, and in CG patients 36.3 +/- 11.9 min and 53.6 +/- 22.3 min, respectively (p less than 0.05). Duration of action in the AN and E groups of the HD patients was 22.7 +/- 2.1 h and 21.6 +/- 2.6 h, and in CG patients 6.0 +/- 1.1 h and 11.4 +/- 1.6 h, respectively (p less than 0.05). Our study showed a retarded and prolonged action of famotidine in HD patients. The time of administration of famotidine had no effect on its action in HD patients. This is in contrast to normal subjects in whom evening administration delays the onset and prolongs the duration of famotidine action in comparison to afternoon administration.

Less symptomatic hypotension using blood volume controlled ultrafiltration

Symptomatic hypotension due to ultrafiltration (UF) is one of the most frequent unwanted side effects of dialysis therapy. Using hemoglobinometry for continuous monitoring of blood volume (BV), ultrafiltration rate (UFR) can be adapted to actual changes in BV. A control system is shown in which UFR is set according to a predefined profile of BV. The conditions of control are: relative BV shall decrease steadily; BV shall decrease rapidly during the first 60 min of dialysis, thereafter decrease in BV should be less; UFR shall be as high as possible; and dry weight should be obtained within a given time. Application of this controlled UF method in 10 dialysis patients shows significantly fewer hypotensive periods and muscle cramps compared to conventionally constant UFR. It is concluded that BV controlled UF is an important step toward optimizing dialysis therapy.

Hyperaluminaemia in critically ill patients: role of antacid therapy and impaired renal function

A significant rise in serum concentrations of aluminum was demonstrated in 23 patients prophylactically treated with the antacid magaldrate, whereas no increase in serum aluminium was observed in another 26 critically ill patients, in whom the use of antacids was avoided. In parallel, urinary excretion rates of aluminum rose to values close to maximum 72 h after antacid therapy had been started. Hyperaluminaemia was most marked in patients with acute renal failure undergoing continuous haemofiltration, but a significant increment in serum aluminium was also noted in patients with impaired renal function in the predialytic state. In the latter group and in patients with normal renal function there was a significant negative correlation between urinary excretion rates of aluminium and creatinine clearance after 48 h of treatment suggesting an enhancement of gastrointestinal absorption of aluminium in the presence of chronic renal failure. Maximum serum concentrations of aluminium did attain critical values in some patients with acute renal failure, but no overt signs of aluminium toxicity were noted. However, in light of both, possible subtle toxicity and enhanced absorption of aluminium in critically ill patients with renal failure, the prophylactic use of antacids in this setting should be re-evaluated cautiously.

Calcium carbonate as a phosphate binder in dialysis patients: evaluation of an enteric-coated preparation and effect of additional aluminium hydroxide on hyperaluminaemia

Calcium carbonate has been successfully used as a phosphate binder in patients with chronic renal failure; however, a high frequency of hypercalcaemia has been reported. To study the effects of calcium carbonate preparations with different dissolution characteristics on the incidence of this side effect, we conducted a double-blind, crossover trial in 21 patients undergoing chronic haemodialysis. Aluminum hydroxide therapy was replaced with calcium carbonate. The subjects then randomly received either an enteric-coated or a gastric-coated preparation. Calcium carbonate (3.1-3.6 g/d) controlled serum phosphate concentrations as effectively as aluminium hydroxide (2.9 g/d). Concurrently, there was a significant rise in mean serum calcium and a fall in serum concentrations of both parathyroid hormone and osteocalcin, the latter suggesting a decrease in bone turnover. Overall, hypercalcaemic episodes developed in 9 patients (43%) and occurred at a considerable frequency (33 episodes per 100 patient-months) during treatment with the gastric-coated formulation. Following conversion to enteric-coated calcium carbonate (3.6 g/d) patients had fewer occurrences of hypercalcaemia (12 episodes per 100 patient-months, P less than 0.05) and, as compared to the gastric-coated preparation, increases in serum calcium greater than 3.00 mmol/l were not observed at all. Hyperaluminaemia was regressive during therapy with calcium carbonate, but addition of small doses of aluminium hydroxide caused a large rise in serum aluminium concentrations after infusion of desferrioxamine, indicating an enhanced rate of absorption or aberrant compartmentalization of aluminium. We conclude that calcium carbonate can control hyperphosphataemia in dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Technical aspects and results of percutaneous transluminal angioplasty in Brescia-Cimino dialysis fistulas

Our experience with percutaneous transluminal angioplasty for treatment of stenoses and occlusions in surgically created arteriovenous fistulas (Brescia-Cimino) is reported. Methodological aspects are emphasized. Forty-nine PTAs were performed in 36 patients, in 3 combined with the use of a vascular metallic endoprosthesis (Wallstent). The initial success rates for stenoses and occlusions were 91% and 77%, respectively. Long stenoses and occlusions (greater than 4 cm) showed significantly worse initial results (55%) as compared to short ones (95%). Of the primarily successfully treated shunts, 90% are still functioning after a mean follow-up time of 8 months. The results indicate that PTA may replace surgical intervention as the primary method for treatment of insufficient flow for internal arteriovenous shunts, provided fresh thrombi are not the cause of the occlusion. Metallic endoprostheses and the use of atherectomy catheters were shown to be a valuable adjunct to classical PTA in selected cases.

Vasoactive hormones during hemodialysis with intermittent ultrafiltration

The correlations between actual blood volume (BV), blood pressure (BP), heart rate, and plasma levels of renin activity (PRA), serum aldosterone (ALD), antidiuretic hormone (ADH), epinephrine (E), norepinephrine (NE), atrial natriuretic factor (ANF), cGMP, and cAMP were investigated in 10 stable patients during HD. HD consisted of four periods of about 60 min each. One half with an UF rate greater than 1,000 ml/h, followed by a time interval of 30 min without UF resulting in a "saw tooth" profile of BV. Decrease in BV was measured by continuous hemoglobinometry. Average total decrease in BV was 25%, while BP and HR did not change significantly. E, NE, ANF and ADH levels were directly related to actual changes in BV, suggesting that BP regulation in this special mode of HD is mainly supported by endogenous catecholamine and ADH secretion. The second messenger cGMP did not follow actual BV changes, but showed a significant decrease correlated with diminished BV. A significant change in PRA and ALD was missing. It is concluded that vascular stability in these patients is maintained by the response of catecholamins and ADH to decrease in blood volume, and not by the renin-aldosterone system.

Kinetic modelling and continuous on-line blood volume measurement during dialysis therapy

Changes of relative blood volume during haemodialysis therapy have been investigated using kinetic modelling and on-line blood volume registration by continuous haemoglobinometry. An exponential relation has been found between blood volume reduction per litre of ultrafiltrate and the amount of fluid overload. Between the amount of refilling and ultrafiltration rate there was also an exponential dependence. There was a linear relation between the change in plasma sodium concentration and blood volume. An acceptable correspondence was found between calculated and measured data.