[Show abstract][Hide abstract] ABSTRACT: Vitamin K is involved in bone metabolism, and the clinical use of vitamin K antagonists as an anticoagulant may increase the risk of bone fracture. In our renal unit, approximately 140 uremic patients were hemodialyzed. From these patients, 11 have been under anticoagulant treatment for a long time. For the last 2 years, 5 patients presented with bone fracture, and 4 of them were undergoing oral anticoagulant treatment (acenocoumarol 1 mg daily). The dose was modified according to international normalized ratio (INR) units. The use of vitamin K antagonists as anticoagulants has been considered a cause of bleeding and is related to low bone-mineral density and a high risk of fracture. In our data, the number of patients who received oral anticoagulants (11 patients) and the number of them who presented with bone fracture (4 patients) raises the suspicion that there is an association between anticoagulant treatments and bone fractures.
[Show abstract][Hide abstract] ABSTRACT: The aim of this retrospective study was to evaluate the International Normalized Ratio (INR) in hemodialyzed uremic patients under treatment with oral anticoagulation drugs. Eleven out of one hundred and forty-two uremic hemodialyzed patients in our unit were included in the study. These 11 patients aged from 70 to 85 (mean: 76 years) were under oral anticoagulation treatment for protection from thromboembolic events. They received 1 mg acenocumarol daily with the therapeutic goal of achieving an INR between 2 and 2.5 units. During the last year, the number of total INR determinations was 129. Based on the INR levels, measurements were classified into three categories of anticoagulation, termed "under-anticoagulation", "target-anticoagulation", and "over-anticoagulation". The number, the percentage, and the mean value (+/-SD) of INR measurements for each category, respectively, were under-anticoagulation: 39, 30%, 1.78 +/- 0.14; target-anticoagulation: 48, 37.5%, 2.20 +/- 0.14; and over-anticoagulation: 42, 32.5%, 3.14 +/- 0.64. The mean value +/-SD of all INR determinations (n=129) was 2.34 +/-0.65. No thromboembolic or major bleeding events occurred in our patients with these INR. In conclusion, in elderly, hemodialyzed uremic patients with indications for oral anticoagulation treatment, adequate and safe INR levels can be achieved in a high proportion without serious deviations from the therapeutic goal by using low doses of drugs. Therefore, oral anticoagulation therapy should not be considered automatically contra-indicated in this patient group.
The International journal of artificial organs 10/2009; 32(10):752-5. · 1.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Calciphylaxis (calcific uremic arteriolopathy) is a severe complication of hemodialysis characterized by subcutaneous calcification of the small arteries and tissue necrosis. Our case report is focused on a woman receiving hemodialysis (HD) with diabetes mellitus for 20 years and severe secondary hyperparathyroidism, who presented painful subcutaneous nodules, skin necrosis and ulcerations. As the treatment of calciphylaxis is mainly empirical and controversial, we decided to administer cinacalcet with paricalcitol for the control of hyperparathyroidism and sodium thiosulfate to improve the calcification of the arterioles. Two months after the start of the therapy, parathyroid hormone (PTH) decreased significantly and the skin lesions nearly disappeared. Thus, we believe that the combination of sodium thiosulfate with cinacalcet and paracalcitol is effective for the treatment of calciphylaxis with secondary hyperparathyroidism.
The International journal of artificial organs 09/2008; 31(8):742-4. · 1.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sevelamer hydrochloride (HCl) contains multiple amines that may cause a significant dietary acid load. To evaluate the impact of sevelamer on arterial blood gases, we followed two groups of stable hemodialysis patients for 24 months. The Sevelamer Group (n = 7) did not achieve the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) goals for phosporus and Ca x P product and was switched from a calcium-based to sevelamer-based regimen. The Calcium Group (n = 7) achieved those goals and remained on calcium salts. Following sevelamer administration, a deterioration of chronic metabolic acidosis was revealed, which lasted throughout the study. Sevelamer therapy was associated with reduced cholesterol levels, improved serum phosphate, and Ca x P product, which facilitated the management of secondary hyperparathyroidism. No significant changes in acid-base status or other parameter tested were found in the Control Group. In conclusion, sevelamer intake caused small but persistent acid-base disturbances, which did not neutralize sevelamer's beneficial effects on mineral and lipid metabolism.
[Show abstract][Hide abstract] ABSTRACT: Urea kinetic modeling (Kt/V) is used to assess adequacy of hemodialysis (HD). However, serial Kt/V measurements may vary with time in the same patient, making the interpretation of the results difficult. The aim of the present study was to find the frequency and the causes that account for these fluctuations of Kt/V. Fifty-nine patients undergoing chronic HD were included in this prospective study. The results of monthly single pool Kt/V values were analyzed during a 6-month period. Duration of maintenance HD prior to the study was 4.49 +/- 3.6 (+/-SD) years. Any change of >0.2 from the previous 2-month average values was defined as abnormal. A total of 354 urea kinetic modeling sessions were recorded during 6 months in 59 patients. Of these, 38 (10.7%) met the criteria for abnormal value. Twenty-four measurements (6.7%) revealed lower while 14 (3.9%) demonstrated higher Kt/V values. Supervised sampling and conforming to the prescribed dialysis dose were applied for all abnormal measurements a week later. Among the group with lower Kt/V value, nine were due to noncompliance (shorter dialysis), four lower blood flow (Qb), four reversed needles, and one fistula thrombosis. Finally, in six cases no problem could be identified and a repeat measurement failed to document lower values. In the high-value group, nine cases were expected as there was an effort to increase dialysis dose prescription while five cases were due to false postdialysis sampling ("venous samples"). Overall, 29/354 (8.1%) measurements were in real disagreement with dialysis prescription. Lower-than-expected values are quite often due to reduced blood processing (shorter dialysis, lower Qb, and recirculation) and higher values due to inaccurate postdialysis sampling. Any possible pitfall in Kt/V measurements should be investigated before changing dialysis prescription in a stable HD patient.
[Show abstract][Hide abstract] ABSTRACT: Background
Lipoprotein(a), Lp(a), has been recognized as an atherogenic and thrombogenic lipoprotein in the general population and in hemodialysis (HD) patients. In addition, fibrinogen and fibronectin may promote atherothrombosis. The aim of this study was to investigate any possible relationship between Lp(a) and thrombogenic coagulation proteins in non-diabetic HD patients.Patients and Methods
Serum Lp(a) and plasma fibrinogen, plasminogen, and fibronectin levels were measured pre-HD in 60 uremic patients (30 male, 30 female) aged 58.6±8.0 years who had been receiving HD treatment for 61.3±50.7 months. The control group comprised 20 age- and sex-matched healthy subjects. All patients were receiving erythropoietin treatment.ResultsThe mean serum Lp(a) (33.88±34.12 mg/dL) and plasma fibrinogen (329.45±80.62 mg/dL) levels were significantly higher in the HD patients compared with those in the controls (16.70±10.36 and 254.00±43.34 mg/dL, respectively; p<.05 and p<.001, respectively). Plasminogen levels did not differ between the HD patients (11.64±3.22 mg/dL) and the control group (10.67±1.41 mg/dL, p>.05). Fibronectin levels were slightly increased in the HD patients (33.96±5.49 mg/dL) versus in the control group (30.9±5.80 mg/dL, p<.05). There was a significant positive correlation between Lp(a) and fibrinogen levels (r=0.305, p<.02), as well as between Lp(a) and fibronectin levels (r=0.360, p<.01). Moreover, there was a significant positive correlation between fibrinogen and fibronectin levels (r=0.587, p<.0001).Conclusions
According to our results, in non-diabetic HD patients, abnormal serum Lp(a) levels significantly correlated with abnormal levels of fibrinogen and fibronectin. There is a concern that the relationship between these atherogenic and thrombogenic acute-phase proteins may contribute to the increased incidence of atherosclerotic cardiovascular disease in this patient population.
[Show abstract][Hide abstract] ABSTRACT: Renovascular hypertension is the most common curable form of secondary hypertension. Renin angiotensin system activation depends on the balance between renin production by the kidney and renin degradation by the liver. Thus, we aimed to examine whether deviation of renin-rich blood from the affected kidney into the portal circulation (portalization) can ameliorate renovascular hypertension.
We selected a porcine model of unilateral renal artery stenosis because the pig's anatomy and physiology are comparable to those of humans and because pigs have already been found capable of developing chronic renovascular hypertension. Angiography and ultrasonography were deliberately used to evaluate renal artery stenosis and the renal-portal shunt. Histology was used to examine the effects of portalization on the kidney and liver after a period of two months.
As expected, following the creation of a left renal artery stenosis both renin activity and mean blood pressure measurements increased from 1.23 +/- 0.06 ng/mL/h and 85.6 +/- 0.5 mm Hg at baseline to 4.59 +/- 0.02 ng/mL/h and 126 +/- 1.76 mm Hg, respectively. After portalization renin activity returned to the normal range (1.59 +/- 0.07 ng/mL/h) followed by a concomitant reduction of mean blood pressure to 91 +/- 2 mm Hg. Moreover, a significant correlation was observed between changes in renin activity and blood pressure measurements during the two stages of the experiment. Both the kidney and liver remained macroscopically and microscopically intact at the end of the experiment.
Portalization of the affected kidney can ameliorate renovascular hypertension and therefore, it might be of benefit in those individuals with fibromascular or atheromatous lesions in the renal artery or its branches not amenable to balloon angioplasty or surgical revascularization.
[Show abstract][Hide abstract] ABSTRACT: This study determines the relationship between interdialytic water retention (IWR) and acid-base homeostasis in uremic patients under regular hemodialysis (HD). To this aim, in 33 regular bicarbonate HD sessions of 11 uremic patients (three HD sessions of 1 week for each patient), blood samples were received from arterial line immediately pre- and post-HD anaerobically in heparinized syringes and the HCO3-, pH, and pco2 were determined. Also in the studied HD sessions, the IWR was estimated and the apparent bicarbonate space percentage (ABS%) pre- and post-HD was calculated by Fernandez et al. (Eq. 1). The mean +/- SD values pre-HD (ABS% = 54.15 +/- 1.49, HCO3- = 18.54 +/- 2.0 mmol/L, pH = 7.32 +/- 0.02, pco2 = 35.44 +/- 3.10 mmHg) and post-HD (ABS% = 49.88 +/- 0.6, HCO3- = 26.33 +/- 1.6 mmol/L, pH = 7.44 +/- 0.02, pco2 = 37.69 +/- 3.00 mmHg) show metabolic acidosis pre-HD and slight alkalosis post-HD. There was a significant positive correlation between IWR and ABS% pre-HD (r = 0.650, p < .0001) and post-HD (r = 0.655, p < .0001), but a significant negative correlation between IWR and HCO3- pre-HD (r = -0.502, p < .003) and post-HD (r = -0.700, p < .001), as well as between IWR and pH pre-HD (r = -0.516, p < .002) and post-HD (r = -0.377, p < .03). In addition, there was a significantly negative correlation between IWR and pco2 post-HD (r = -0.656, p < .001), but not pre-HD (r = 0.0136, PNS). The significantly positive relationship between IWR and ABS% pre- and post-HD, in combination with the significantly negative correlation between HCO3- and pH pre- and post-HD, indicates that the IWR negatively influences the acid-base homeostasis in hemodialysis patients without residual renal function, and may worsen the cardiovascular physiology and tissue oxygenation of these patients.
[Show abstract][Hide abstract] ABSTRACT: Several clinical and experimental observations suggest that an intact and activated renin-angiotensin system (RAS) may be an important determinant of erythropoiesis in a variety of clinical conditions, including hypertension, chronic renal insufficiency or failure, chronic obstructive pulmonary disease, and congestive heart failure. Accordingly, RAS inactivation may confer susceptibility to the hematocrit-lowering effects of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Indeed, a dose-dependent decrease in hematocrit is observed within the first month of such therapy. In the majority of patients with hypertension decreases in hematocrit values after RAS inactivation are small and not clinically important. In extreme conditions, however, such as erythrocytosis after successful renal transplantation, secondary polycythemia of chronically hypoxemic COPD patients, erythrocytosis associated with renovascular hypertension, severe cardiac or renal failure, the hematocrit-lowering effect of angiotensin-converting enzyme inhibitors and angiotensin receptor blocker may be profound and even lead to or worsen anemia. Hematocrit reaches its nadir value within three months, and then it remains stable during long-term observations. After discontinuation of RAS blockade, hematocrit values rise gradually over the next three to four months towards the pretreatment levels. The mechanism(s) related to this phenomenon is not yet fully understood, but angiotensin II seems to be responsible for inappropriately sustaining secretion of erythropoietin despite hematocrit elevation and capable to directly stimulate the erythroid progenitors in bone marrow to produce erythrocytes.
Current Topics in Medicinal Chemistry 02/2004; 4(4):483-6. DOI:10.2174/1568026043451311 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Posttransplant erythrocytosis (PTE) is defined as a persistently elevated hematocrit to a level greater than 51% after renal transplantation. It occurs in 10% to 15% of graft recipients and usually develops 8 to 24 months after engraftment. Spontaneous remission of established PTE is observed in one fourth of the patients within 2 years from onset, whereas in the remaining three fourths it persists for several years, only to remit after loss of renal function from rejection. Predisposing factors include male gender, retention of native kidneys, smoking, transplant renal artery stenosis, adequate erythropoiesis prior to transplantation, and rejection-free course with well-functioning renal graft. Just as in other forms of erythrocytosis, a substantial number (approximately 60%) of patients with PTE experience malaise, headache, plethora, lethargy, and dizziness. Thromboembolic events occur in 10% to 30% of the cases; 1% to 2% eventually die of associated complications. Posttransplant erythrocytosis results from the combined trophic effect of multiple and interrelated erythropoietic factors. Among them, endogenous erythropoietin appears to play the central role. Persistent erythropoietin secretion from the diseased and chronically ischemic native kidneys does not conform to the normal feedback regulation, thereby establishing a form of "tertiary hypererythropoietinemia." However, erythropoietin levels in most PTE patients still remain within the "normal range," indicating that erythrocytosis finally ensues by the contributory action of additional growth factors on erythroid progenitors, such as angiotensin II, androgens, and insulin-like growth factor 1 (IGF-1). Inactivation of the renin-angiotensin system (RAS) by an angiotensin-converting enzyme (ACE) inhibitor, or an angiotensin II type 1 AT1 receptor blocker represents the most effective, safe, and well-tolerated therapeutic modality.
Kidney International 05/2003; 63(4):1187-94. DOI:10.1046/j.1523-1755.2003.00850.x · 8.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Off-pump coronary artery bypass grafting (CABG) has been recently revived, because cardiopulmonary bypass (CPB) appears to worsen the multiple organ dysfunction after conventional CABG. To evaluate the safety and efficacy of the off-pump CABG in chronic dialysis patients, we compared the perioperative morbidity and mortality between 15 dialysis patients who underwent off-pump CABG at our center over the past 8 years with that of a concurrent group of 19 patients who underwent conventional CABG. Patients were selected for off-pump CABG only when complete revascularization was technically feasible. We found that off-pump CABG is as safe and effective as conventional CABG in selected dialysis patients. It might even be beneficial, because it is associated with less hematocrit drop and blood product use, a lower catabolic rate, and fewer dialysis requirements after surgery. However, the impact of off-pump technique on the long-term clinical outcome and resource utilization in renal patients requires further investigation.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to verify if the degree of pre-HD acidosis and its correction post-HD is related to body fluid expansion during the interdialytic period. Twelve uremic patients without major problems, with stable hematocrit, with regular and similar HD-session characteristics, but widely varying amounts of body fluid expansion in the interdialytic period were included. Blood samples were collected from arterial line pre- and post-HD, anaerobically in heparinized syringes, for determination of HCO3-, pH and PaCO2 (radiometer Copenhagen ABL 300 Acid-Base Laboratory), in two similar HD-sessions for each patient (12 patients, 24 HD-sessions). The percentage (%) of body weight gain in the interdialytic period was also estimated. For each patient, the mean value of parameters studied in the two HD-sessions was used for the evaluation of findings. According to mean values (+/-SD) of HCO3-, pH and PaCO2 Pre-HD (18.26+/-1.99 mmol/L, 7.31+/-0.03, 36.27+/-2.5 mmHg respectively) and post-HD (26.37+/-1.7, 7.43+/-0.03, 38.43+/-2.10 respectively) patients are acidotic pre-HD and slightly alkalemic post-HD. Correlation between the percentage (%) of interdialytic body weight gain (IBWG) and the values of HCO3-, pH and PaCO2, Pre-HD (r=-0.814, p<0.001; r=-0.931, p<0.001; r=0, 100 NS; respectively) and post-HD (r=-0.958, p<0.001; r=-0.937, p<0.001; r=-0.504 NS; respectively) indicates a significant and negative relationship of IBWG% with HCO3- and pH pre- and post-HD, but not with PCO2. In conclusion, the negative relationship of IBWG% with HCO3- and pH pre- and post-HD indicates that the body fluid expansion during the interdialytic period contributes to a dilutional acidosis pre-HD, but not to a contraction alkalosis post-HD, by the elimination of fluid during the HD-session.
The International journal of artificial organs 02/2003; 26(2):135-8. · 1.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Endovascular repair of abdominal aortic aneurysms (AAA) is an alternative to conventional surgical aortic reconstruction. However the presence of renal artery stenosis (RAS) and/or accessory renal arteries may alter the endovascular approach in these cases.We present two cases with infrarenal aneurysms and a coexisting unilateral renal artery stenosis (first case) and accessory renal artery (second case).In both patients endovascular treatment was undertaken. In the first patient a stent was placed for the RAS and an aortic endograft with suprarenal fixation for the aneurysm. In the second patient the placement of an aortic endograft with suprarenal fixation occluded the accessory renal artery.In the first patient renal function was normal pre- and post-intervention. In the second patient, renal function was normal pre-intervention but showed a slight deterioration postoperatively, returning to normal after 10 days. Both patients were normotensive pre- and post-intervention.In conclusion, RAS and AAA may be treated by the placement of a stent and a stent-graft simultaneously. During endovascular repair of AAA, a significant accessory renal artery (around 3mm in diameter) may safely be excluded in patients with otherwise normal renal function.
EJVES Extra 10/2002; 4(4):61-64. DOI:10.1053/ejvx.2002.0174
[Show abstract][Hide abstract] ABSTRACT: We describe three patients with abdominal aortic aneurysm (AAA) and renal artery stenosis (RAS). These patients were treated by placement of an aortic endograft and angioplasty or stenting of the renal artery. After the procedure renal function improved or remained stable in two patients and deteriorated slightly in one. Blood pressure was reduced in one hypertensive patient and remained normal in the other two normotensive patients. In conclusion, simultaneous treatment of AAA and RAS with aortic endograft placement and renal artery angioplasty with or without stent, is a safe and effective technique for selected high-risk patients.
Journal of Human Hypertension 06/2002; 16(5):367-9. DOI:10.1038/sj.jhh.1001367 · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine the relationship between interdialytic weight gain and acid-base balance pre- and posthemodialysis in uremic patients undergoing hemodialysis with a high bicarbonate dialysate (39 mmol/L). To this end we studied 8 stable uremic patients on regular hemodialysis thrice weekly who had stable hematocrit values for at least 3 months, similar clinical characteristics including dry weight but widely varying interdialytic weight gain. Arterial line blood samples were collected anaerobically in heparinized syringes pre- and posthemodialysis in 4 consecutive hemodialysis sessions for the determination of pH, Paco2, and HCO3. Prehemodialysis values (mean +/- SD) were pH = 7.34 +/- 0.03, Paco2 = 36.43 +/- 1.4, and Hco3 = 20.1 +/- 1.55. Posthemodialysis values were pH= 7.47 +/- 0.02, Paco2 = 38.72 +/- 2.0, and HCO3 = 27.73 +/- 1.72. In other words, patients were moderately acidemic prior to and moderately alkalemic after the hemodialysis session. Of note, a significant negative correlation was revealed between the interdialytic weight gain and the values of prehemodialysis blood pH (r = -0.721, p < 0.001) and HCO3 (r = -0.836, p < 0.001) and posthemodialysis pH (r = -0.533, p < 0.001), Paco2 (r = -0.623, p < 0.001) and HCO3 (r = -0.815, p < 0.001), suggesting an important role of the interdialytic weight gain on acid-base equilibrium of uremic patients undergoing hemodialysis. Thus, patients with high interdialytic weight gains may require higher bicarbonate concentrations to achieve normal acid-base status whereas patients with low interdialyic weight gains may require lower bicarbonate concentrations to prevent alkalemia at the end of dialysis.
[Show abstract][Hide abstract] ABSTRACT: to present our experience with stent placement in renal arteries in solitary kidneys for treating renal insufficiency.
in 26 patients with solitary kidney (17 men, 9 women, mean age: 63 years), presented with renal insufficiency (se-creat >0.144 mmol/l), stent was placed in a stenosed renal artery. We analysed the clinical outcome, based on the level of creatinine at 3 months following the procedure. Clinical benefit was considered when there was a decrease compared to the baseline creatinine by >20% or a stabilisation of the creatinine value (+/-20% of the baseline).
in 16 of the 26 patients (62%), clinical benefit was achieved. However, 38% of the study population, renal function continued to deteriorate. Baseline creatinine value was the single best predictor for clinical benefit achievement (odds ratio: 13; 95% confidence intervals: 1.6-107, p=0.01).
renal stenting results in improvement or stabilisation of renal function in the majority of the patients with solitary kidneys and renal artery stenosis, presenting with renal insufficiency. Because best outcome was observed mainly in those patients with not progressed renal insufficiency, intervention should be focused on that group.
European Journal of Vascular and Endovascular Surgery 01/2002; 23(1):49-54. DOI:10.1053/ejvs.2001.1535 · 3.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It has been reported recently that a number of cytokines, mainly tumor necrosis factor (TNF), interleukin (IL)-1β, and IL-6, can alter lipid metabolism and produce hyperlipidemia. Studies in hemodialysis (HD) patients have demonstrated increased production of these cytokines during HD. In order to investigate any possible relationship between changes of cytokines and lipid concentrations during HD in the serum of 25 uremic patients on chronic HD using modified cellulose membranes, TNF, IL-1β, IL-6, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), lipoprotein a (Lp[a]), and total proteins were measured immediately before (pre-HD) and after HD (post-HD), in one session. The post-HD values were corrected according to the hemoconcentration based on the changes in serum total proteins. Serum TNF and IL-1β levels were significantly increased from 38.24 ± 17.85 pg/ml and 2.60 ± 3.64 pg/ml pre-HD to 48.86 ± 25.21 and 3.49 ± 4.08 pg/ml post-HD, p < 0.001 and p < 0.05 respectively. Also Lp(a) levels presented a statistically significant increase post-HD and were almost doubled (pre-HD: 15.41 mg/dl, to post-HD: 27.39 mg/dl, p < 0.05). Serum IL-6 as well as serum TC, TG, HDL-C, and LDL-C did not show any statistically significant alterations during HD. A significant positive correlation was detected between TNF and Lp(a) values post-HD (r: 0.413, p: 0.04), but not between pre-HD values. No further relationship between serum cytokines and the other estimated lipid parameters was observed, either between pre- or post-HD values. Our results indicate that release of TNF and IL-1β during HD have no effect on serum lipids concentration, except on Lp(a). It seems that the acute rise of this lipoprotein during hemodialysis may be related with the TNF overproduction.