A prospective multicentre study of the role of anaemia as a risk factor in haemodialysis patients: the MAR Study.

BACKGROUND: Retrospective studies have shown hospitalization and mortality rates during haemodialysis (HD) to be associated with anaemia. METHODS: The prospective, multicentre Morbidity-and-mortality Anaemia Renal (MAR) study was designed to establish the burden of anaemia by controlling for other risk factors. Charlson index was used for comorbid adjustment. Finally, 1428 patients from 119 centres (60% men, aged 64.4 years, time on HD 15.3 months, Charlson comorbidity index 6.5 +/- 2.3) completed follow-up. They had hypertension (75.8%), diabetes mellitus (25.9%), heart failure (13.9%) and coronary disease (16.7%). Of the total patients, 94.8% were receiving erythropoietin (111.6 +/- 70.6 U/kg/week) and 76.7% i.v. iron, and haemoglobin (Hb) at inclusion was 11.7 +/- 1.5 g/dl. RESULTS: Hospitalization rate was 1.1 admissions/patient/year. Yearly mortality was 12% [35% cardiovascular (CV)]. The relative risk and confidence interval (CI) for hospitalization and death were 0.86 (0.81-0.91) and 0.82 (0.73-0.91), respectively, per 1 g/dl increase in initial Hb after adjustment for comorbidity, vintage, aetiology, access type, albumin and Kt/V. The probability of remaining free from hospitalization (CI) was 0.34 (0.27-0.41) for initial Hb <10 g/dl, 0.47 (0.41-0.53) for Hb 10-11 g/dl, 0.54 (0.49-0.59) for Hb 11-12 g/dl, and 0.63 (0.59-0.67) for Hb >12 g/dl. Same analysis for patient survival was 0.77 (0.71-0.83) for Hb <10 g/dl vs 0.82 (0.77-0.87) for Hb 10-11 vs 0.89 (0.86-0.92) for Hb 11-12 vs 0.92 (0.90-0.94) for Hb > 12 g/dl, P < 0.001. The Cox regression model for hospitalization-free survival included the risk factors initial Hb (relative risk 0.86 per 1 g/dl increase, P < 0.001) Charlson, albumin and prior CV event. CONCLUSION: Hb level predicted 1-year-survival and hospitalization. This effect persisted after adjustment for comorbidity and other prognostic factors.     

Correction of metabolic acidosis increases serum albumin concentrations and decreases kinetically evaluated protein intake in haemodialysis patients: a prospective study

Background: Metabolic acidosis in haemodialysis (HD) patients increases whole body protein degradation while the correction of acidosis reduces it. However, the effects of the correction of acidosis on nutrition have not been clearly demonstrated. Study design: In this study we have evaluated the effects of 3 months of correction of metabolic acidosis by oral sodium bicarbonate supplementation on protein catabolic rate (PCRn) and serum albumin concentrations in 12 uraemic patients on maintenance HD for at least 6 months (median 49 months; range 6-243 months). Pre-dialysis serum bicarbonate, arterial pH, serum albumin, total serum proteins, serum creatinine, plasma sodium, haemoglobin, PCRn, Kt/V, and TACurea, were evaluated before and after correction. Results: Serum bicarbonate levels and arterial pH increased respectively from 19.3±0.6 mmol/l to 24.4±1.2 mmol/l (P<0.0001) and 7.34±0.03 to 7.40±0.02 (P<0.0001). Serum albumin increased from 34.9±2.1 g/l to 37.9±2.9 g/l (P<0.01) while PCRn decreased from 1.11±0.17 g/kg/day to 1.03±0.17 g/kg/day (P<0.001). No changes in Kt/V, total serum proteins, serum creatinine, plasma sodium, haemoglobin, body weight, pre dialysis systolic and diastolic blood pressure, and intradialytic weight loss were observed. Conclusions: Our data demonstrate that correction of metabolic acidosis improves serum albumin concentration in HD patients. The correction of acidosis induced a decrease in PCRn values, as evaluated by kinetic criteria, suggesting that in the presence of moderate to severe acidosis this parameter does not reflect the real dietary protein intake of the patients probably as a result of increased catabolism of endogenous proteins. The correction of metabolic acidosis should be considered of paramount importance in HD patients.     

Tunnelled haemodialysis catheter bacteraemia: risk factors for bacteraemia recurrence, infectious complications and mortality.

BACKGROUND: Infection is a serious complication of tunnelled cuffed catheter (TCC) use and is associated with high complication and mortality rates. Although attempts at TCC salvage after bacteraemia have been associated with high rates of recurrent bacteraemia, there have been no large studies in which multivariate analysis has been performed to control for confounding factors such as infecting organisms, diabetes, etc. METHODS: A prospective observational study was performed in chronic HD patients dialyzing with a TCC at seven outpatient HD centers. All patients diagnosed with TCC bacteraemia were observed for 3 months following initial presentation and outcomes were recorded. RESULTS: During the 2.5 year study period, 226 patients had an episode of TCC bacteraemia that met inclusion criteria, and 3 month follow-up data were available in 219 episodes. Treatment failure, defined as recurrent TCC bacteraemia with the same organism or death from sepsis, occurred in 26 patients (12%). Infectious complications (such as endocarditis, osteomyelitis, etc.) occurred in 16 patients (7%), bacteraemia with a different organism occurred in 19 patients (9%), and death from sepsis occurred in eight patients (4%). Significant predictors of treatment failure (by univariate analysis) were TCC salvage, and infection with Staphylococcus aureus, (OR = 4.2, P = 0.002; and OR = 3.3, P = 0.02, respectively). TCC salvage, when used in episodes of S. aureus bacteraemia, was associated with an 8-fold higher risk of treatment failure (P = 0.001). The presence of an abnormal TCC exit site was associated with a significantly higher rate of death from sepsis, (OR = 7, P = 0.001). Outcomes (treatment failure and infectious complications) did not differ among bacteraemic episodes where the TCC was exchanged over a guidewire compared to those in which the TCC was immediately removed followed by delayed reinsertion. In the multivariate analysis, adjusted for potential confounding covariates, the only significant predictors of treatment failure after an episode of TCC bacteraemia were TCC salvage (OR = 5.4, P = 0.003), and S. aureus (OR = 4.2, P = 0.002). In a multivariate analysis, controlling for TCC management, the only variable that was significantly associated with the development of an infectious complication was infection with S. aureus (OR = 3.5, P = 0.02). CONCLUSIONS: We have shown, using multivariate analysis and adjusting for potential confounding factors, that the use of TCC salvage and S. aureus are independent risk factors for treatment failure after an episode of TCC bacteraemia, and that S. aureus is an independent risk factor for developing an infectious complication. An infected-appearing TCC exit site is associated with a higher mortality rate. Episodes of TCC bacteraemia treated using TCC salvage are associated with the highest treatment failure rates. TCC guidewire exchange can be an acceptable practice, unless severe exit site or tunnel infection is present.     

Residual kidney function in nocturnal vs conventional haemodialysis patients: a prospective observational study

International Urology and Nephrology - Residual kidney function (RKF) provides substantial volume and solute clearance even after dialysis initiation. Preservation of RKF is associated with...     

Catheter-related bacteraemia in haemodialysis patients with HIV infection.

BACKGROUND: Tunnelled catheters are used for dialysis in over 25% of haemodialysis (HD) patients and are a major risk factor for bacteraemia. HIV-positive patients may be at particularly increased risk of catheter-related bacteraemia (CRB) due to their immunocompromised state. The present case-controlled study compared catheter-related bacteraemia with HIV-positive and HIV-negative haemodialysis patients. METHODS: Using a prospective computerized vascular access database, we identified 33 HIV-positive haemodialysis patients who had a tunneled dialysis catheter placed during a 6.5-year period. Their catheter outcomes were compared with those observed in 55 age-, sex- and access date-matched control haemodialysis patients. RESULTS: The two groups were similar in terms of age, sex, diabetes, hypertension and peripheral vascular disease, but the HIV patients were more likely to be black (94 vs 76%, P=0.03). CRB occurred in 52% of the HIV patients and 49% of the controls (P=0.83). The median infection-free catheter survival was similar in HIV-positive and negative patients (165 vs 119 days, P=0.12). Among patients with CRB, the likelihood of a Gram-negative infection was similar in both groups (18 vs 30%, P=0.37). However, polymicrobial CRB was more likely in HIV patients (41 vs 15%, P=0.049). HIV-positive patients were more likely to be hospitalized for treatment of CRB than HIV-negative patients (29 vs 7%, P=0.05). CONCLUSION: CRB is equally likely in HIV-positive and control haemodialysis patients. However, CRB is likely to be more severe in HIV-positive patients, as judged from the greater likelihood of polymicrobial infection and of hospitalization.     

Preventing haemodialysis catheter-related bacteraemia with an antimicrobial lock solution: a meta-analysis of prospective randomized trials.

BACKGROUND: Catheter-related bacteraemia (CRB) is a major cause of morbidity and mortality in haemodialysis patients. Interdialytic locking of catheters with antimicrobial agents has recently been investigated for the prevention of CRB. We performed a meta-analysis of randomized controlled trials (RCT) to determine the efficacy of antimicrobial lock solutions (ALS) in the prevention of CRB in haemodialysis patients. METHODS: We collected from Medline, Web of Science, the Cochrane Library and major nephrology journals, all relevant references (January 1990-March 2007). We selected RCT comparing an ALS to a standard heparin lock in CRB prevention. We extracted data concerning study quality, patient characteristics and CRB incidence. The relative risk (RR) of CRB was calculated as Ln (CRB incidence control/CRB incidence experimental) using both a fixed- and a random-effects model. RESULTS: Eight studies were included, involving 829 patients, 882 catheters and 90 191 catheter-days. The use of an ALS significantly decreased the risk of CRB (RR 0.32; 95% CI 0.10-0.42). Borderline heterogeneity was observed in the fixed-effects model (Q = 14.42; P = 0.071). Despite the under-representation of small negative studies, the high number of additional trials necessary to reverse the final effect strengthens the confidence in the overall results. Subgroup analyses stratified by the presence of diabetes, duration of follow-up, biochemical markers, proportion of tunnelled cuffed catheters, intranasal mupirocin use and citrate use in the ALS did not show significant differences, except a higher efficacy of gentamicin-containing lock solutions (P = 0.003). CONCLUSIONS: The use of ALS reduces by about a factor 3 the risk of CRB in haemodialysis patients. The achieved absolute incidence is similar to the best-published figures (presumably related to stricter hygienic measures). The limited follow-up of the studies does not exclude the onset of adverse events or bacterial resistance with longer use of ALS.     

Incidence of seroconversion for hepatitis C virus in chronic haemodialysis patients: a prospective study

We conducted a prospective study in HD patients of our unitto evaluate the incidence of seroconversion for HCV in thishigh-risk group. Two hundred and thirty-five patients were observedduring the average follow-up of 29.4 months: 183 were seronegativeand 52 seropositive for anti-HCV antibodies at the start ofthe study. During the observation period two of 183 patientsdeveloped anti-HCV antibodies late in the study, while the other181 patients remained seronegative throughout the observationperiod; anti-HCV antibodies persisted through the follow-upin the 52 HCV-positive patients at the beginning of the study.Our results showed a very low incidence of HCV seropositivity(0.44% per year) after implementation of our operative protocolincluding ‘universal precautions’ and other infectioncontrol procedures. Once infected, there is no disappearancerate of anti-HCV. The 4-RIBA results did not change during thefollow-up period. Prevalence of HCV RNA by PCR technique was41% (22 of 54) among anti-HCV-positive patients. Future investigationsare warranted to clarify the exact route of transmission ofHCV among HD patients and to reduce the rate of HCV transmissionin this clinical setting.     

Effect of acetate-free biofiltration on the anaemia of haemodialysis patients: a prospective cross-over study.

BACKGROUND: The discussion about the pathogenesis of renal anaemia, whether it is primarily due to relative erythropoietin (Epo) deficiency or to uraemic inhibition of erythropoiesis, is still open. Although it has so far not been possible to identify or isolate a substance retained in uraemia with a suppressive action directed specifically against red-cell production, dialysis therapy can improve the effect of both residual endogenous Epo and exogenous rHuEpo. To what extent the mode and/or the dose of dialysis influence Epo efficacy is as yet poorly understood. METHODS: This study was performed as a single-centre trial. The protocol included a run-in period of 4 months followed by a prospective cross-over study including 6 months each of acetate-free biofiltration (AFB) with a high-flux biocompatible membrane and standard bicarbonate dialysis (BD) with a low-flux cellulosic membrane in a random sequence. AFB is a haemodiafiltration technique based on a continuous post-dilution infusion of a sterile isotonic bicarbonate solution. At the start of the run-in period (and for the entire length of the study), rHuEpo administration was withdrawn; patients whose haemoglobin (Hb) levels dropped at a level <8.0 g/dl at one single monthly check, had to be withdrawn from the study. A blood sample was collected every month for the blood gas analysis and for the determination of blood urea nitrogen, serum creatinine, sodium, potassium, calcium, phosphorus, Hb, erythrocyte, reticulocyte, leukocyte and thrombocyte cell counts, mean globular volume and haematocrit. An equilibrated single pool Kt/V(urea)>1.2 was mandatory in both treatment modalities. Serum iron, total iron-binding capacity, and ferritin were checked every 3 months. RESULTS: Twenty-three of 137 haemodialysis patients were considered eligible for the trial on the basis of the entry criteria. Of these, 15 volunteered and only 10 completed the study. No significant differences in the haematological indices, in the biochemical parameters assessing body iron stores, or in i.v. iron dosage was observed when comparing AFB with BD treatments. The equilibrated single pool Kt/V(urea) was always >1.2 and in no case was a significant difference observed when comparing AFB with BD treatments. Treatment time was significantly different between the two treatments (262+/-2 min in BD and 249+/-1 in AFB, P<0.0001). Neither pre- nor post-dialysis systolic and diastolic blood pressures, pre-dialysis serum bicarbonate and pH, pre-dialysis serum sodium, potassium, calcium, or phosphorus were significantly different when comparing the two treatment modalities. All 10 patients completed the 1-year follow-up without any major side-effects. CONCLUSIONS: Our study did not show any improvement of anaemia when treating a highly selected patient group, in the absence of any Epo therapy, with AFB compared with standard BD. Even though these conclusions cannot be extended in toto to the entire dialysis population, in which there is a large proportion of Epo-treated patients with Hb levels around 11 g/dl, we may nevertheless conclude that when patients are well selected, adequately dialysed, and not iron- and/or vitamin-depleted, the effect of a haemodiafiltration technique with a high-flux biocompatible membrane is less than might be expected from the results of uncontrolled studies.     

Iron overload in kidney transplants: prospective analysis of biochemical and genetic markers

BACKGROUND: The prevalence of iron overload and the influence of mutations in the HFE and TRF2 gene on biochemical markers of iron overload among renal transplant patients is unknown. METHODS: Serum iron, ferritin, transferrin saturation (TSAT), and liver function parameters were analyzed in a cohort of 438 renal transplants. In patients with iron overload, the time course of biochemical markers of iron status as well as the influence of iron loading mutations was investigated during a time period of 5 years. RESULTS: Of 438 renal transplant patients 41 (9.4%) presented with an iron loading phenotype (TSAT above 40% and/or ferritin above 800 ng/mL). Mutations in the HFE gene were present in 12 of 33 (36.3%) patients with iron overload. Among these one patient was homozygous for HFE C282Y, and two patients were compound heterozygous for HFE C282Y/H63D. No individual tested positive for nine other mutations in HFE as well as theTRF2 Y250X mutation. Over time we observed a decrease of mean iron and ferritin levels, and of mean TSAT in our study sample. In patients with mutations in HFE this decrease was less pronounced as compared to patients without mutations. We found an independent positive association between the presence of mutations in HFE and serum alanine-aminotransferase levels at follow-up (P= 0.003). CONCLUSION: Our study demonstrates that iron overload is frequently present in renal transplant patients and shows a continuous decrease over time. This decrease is possibly impaired by the HFE C282Y and HFE H63D mutations. Furthermore, mutations in HFE may influence liver function as reflected by increased alanine-aminotransferase concentrations.     

The prognostic impact of fluctuating levels of C-reactive protein in Brazilian haemodialysis patients: a prospective study.

BACKGROUND: A single elevated C-reactive protein (CRP) value predicts mortality in haemodialysis (HD) patients, but the relative importance of repeated vs occasional positive systemic inflammatory response findings is not known. METHODS: To assess the influence on survival of occasional inflammation, CRP, serum albumin (S-Alb) and fibrinogen were analysed bimonthly in 180 HD patients (54% male, 49+/-14 years). Clinically significant inflammation was defined as CRP >5.1 mg/l, based on the receiver operating characteristics curve for CRP as predictor of death. Based on four consecutive measurements of CRP, patients were assigned into three groups: group 1 (n = 74; 41%), no inflammation (CRP < or = 5.1 mg/l in all measurements); group 2 (n = 65; 36%), occasional inflammation (1-3 measurements of CRP > 5.1 mg/l); and group 3 (n = 41; 23%), persistent inflammation (all measurements of CRP >5.1 mg/l). The nutritional status was evaluated by subjective global assessment (SGA) and body mass index (BMI), and the survival (21 months of follow-up) by Kaplan-Meier curve and Cox model. RESULTS: The median and range of CRP values (mg/l) for group 1, 2 and 3 were: 3.2 (3.2-5.1), 3.6 (3.2-54.9) and 13.8 (5.2-82), respectively (P<0.001), whereas the prevalence of malnutrition, assessed by SGA and BMI, did not differ significantly between the groups. The survival rate by Kaplan-Meier analysis was significantly different among the groups (chi2 = 12.34; P = 0.0004). Patients in group 3 showed the highest mortality (34%; P = 0.001), compared with group 1 (8%) and group 2 (14%; P = 0.01), respectively, whereas there was no significant difference in mortality between groups 1 and 2. Age, CRP, S-Alb level and SGA were independent predictors of mortality. CONCLUSION: The patients with a persistent elevation of CRP had a higher mortality rate than the patients with occasional CRP elevation. Thus, persistent, rather than occasional, inflammation is an important predictor of death in HD patients.     

Central venous catheter-related bacteraemia: prospective study in a Moroccan medical intensive care unit

Objective

To determine the incidence of catheter-related bacteremia (CRB) in a Moroccan medical intensive care unit, the microbiological profile of this infection and risk factors associated with its occurrence.

Study design

Prospective observational study.

Methods

Over a period of 8 months, patients who required central venous catheter (CVC) placement for a duration greater than 48 h were included in the study. The CRB has been defined by the criteria of the SRLF Consensus Conference. The proportions of colonization and CRB were expressed as incidence density (ID). Risk factors for colonization were studied in univariate analysis.

Results

One hundred and two CVC were inserted in 70 patients. The average age was 54 ± 20 years with an APACHE II of 28 ± 10. The ID of colonization and CRB were respectively 34 for 1000 days of CVC use and 8 for 1000 days of CVC use. The isolated microorganisms were Gram-negative bacilli in 73 %, Gram-positive cocci in 22 % and finally yeast in 5 %. A prolonged duration of catheterization and the absence of systemic antibiotic therapy before catheterization were the main risk factors for colonization.

Conclusion

The incidence of CRB was high. These results impose a reflection of the care team to improve protocols for prevention of such nosocomial infections.     

Iron status and cardiovascular risk factors in patients with haemodialysis versus patients with ischaemic heart disease

Aim:   The study aimed to investigate whether imbalanced iron status in patients with haemodialysis coexisted with abnormal lipid profile, higher inflammatory status and altered growth hormone–insulin-like growth factor (GH–IGF)-I axis and to compare these biochemical markers with patients with ischaemic heart disease.
Methods:   Serum samples for biochemical and immunological analyses were collected from 74 normal subjects, 138 patients with ischaemic heart disease (IHD) and 115 patients on haemodialysis (HD).
Results:   Compared with normal subjects, lower serum iron, lower total iron-binding capacity (TIBC) and higher ferritin in HD patients coexisted with decreases in high-density lipoprotein cholesterol and total bilirubin as well as increases in lactate dehydrogenase (LDH), interleukin (IL)-6, C-reactive protein (CRP) and IL-10. Decreased IGF-I and increased GH were found in HD patients whereas unchanged GH–IGF axis were found in IHD patients. Compared with IHD, much higher ferritin, lower TIBC, lower bilirubin and higher LDH levels were found in HD patients.
Conclusion:   Imbalanced iron status in patients on HD coexisted with abnormal lipid profiles, increased anaerobic activity and higher inflammatory status, which suggests that imbalanced iron status in HD patients may play a deleterious role in cardiovascular pathophysiology. Altered GH–IGF axis found in HD patients was more obvious than in IHD patients. This may imply that the GH–IGF axis system is modulated or adapted by HD.     

Pre-dilution on-line haemofiltration vs low-flux haemodialysis: a randomized prospective study.

BACKGROUND: Accumulation of larger molecular weight uraemic toxins molecules may have a negative effect on the cardiovascular and nutritional state of dialysis patients and influence uraemic symptomatology. Their clearance can be enhanced by the use of haemofiltration (HF). METHODS: The effects of low-flux haemodialysis (HD) (ultrapure dialysate; polyamide membranes) and pre-dilution on-line HF (1:1 blood/substitution ratio; target filtration volume: 1.2 times body weight) on cardiovascular and nutritional parameters, interdialytic levels of uraemic toxins and quality of life (QOL; Laupacis questionnaire) were assessed during 1 year follow-up. Forty patients were randomized. RESULTS: After 1 year, 27 patients were eligible for analysis (HF: 13 patients; HD: 14 patients). Left ventricular mass index did not change in the HF patients (127+/-33 --> 131+/-36 g/m(2) after 12 months) or in the HD group (135+/-34 --> 138+/-32 g/m(2)). Also, there were no changes in pulse wave velocity, and 48 h systolic and diastolic blood pressures. Lean body mass, assessed by dual-energy X-ray absorptiometry, increased in the HF group (44.8+/-8.9 --> 46.2+/-9.6 kg; P<0.05), but not in the HD group (49.4+/-9.2 --> 50.6+/-8.8 kg), although differences between groups were not significant. Insulin-like growth factor-1 levels remained stable in the HF patients, but decreased in the HD group (P<0.05 between groups). QOL for physical symptoms improved in the HF group (4.2+/-1.2 --> 5.0+/-1.1; P<0.05 within the HF group and P = 0.06 between groups), but not in the HD group (4.0+/-1.0 --> 4.4+/-1.4). beta2-microglobulin, complement factor D and homocysteine decreased significantly in the HF but not in the HD group, whereas l-ADMA, leptin and advanced glycation end-products-related fluorescence did not change. CONCLUSIONS: No changes in cardiovascular parameters were observed during pre-dilution on-line HF compared with low-flux HD. Treatment with on-line HF resulted in marked changes in the uraemic toxicity profile, an improvement in physical well-being and a small improvement in nutritional state.     

The tolerance and efficacy of interferon-alpha in haemodialysis patients with HCV infection: a multicentre, prospective study.

BACKGROUND: A prospective multicentre study was initiated in HCV-infected haemodialysis patients to assess the tolerance and efficacy of alpha-2b interferon. METHODS: We had planned to include 120 patients with HCV RNA detectable by polymerase chain reaction (PCR) (Amplicor Roche) and histologically documented chronic hepatitis. The dose of alpha-interferon was 3 million units (MU) three times weekly (TTW), to be reduced to 1.5 MU TTW in case of side-effects. Tolerance was evaluated monthly; virological efficacy was evaluated by PCR. A liver biopsy was performed at month 18 (M18). RESULTS: (a) TOLERANCE: After 37 patients had been included, the study was discontinued by the promoting institution because of severe side-effects requiring that treatment be stopped in 19 patients. The side-effects were: cardiac (4) neuropsychiatric (2), digestive (3), acute necrosis of the graft (1), severe asthenia (9), minor side-effects were observed in 22 patients. A complete 12-month course was completed in 12 patients for the 3 MU TTW dose and in six patients for the 1.5 MU TTW reduced dose. Normal ALT level (OR, 0.16; CI 95%, 0.03-0.89) at inclusion was associated with interruption of treatment (univariate analysis). (b) EFFICACY: Sustained virological response was observed in only seven (18.9%), of the 18 patients who completed the treatment (38%). Increased ALT at inclusion (OR, 1.04; CI 95%, 1.01-1.09) and cumulated doses of interferon (OR, 1.01; CI 95%, 1.004-1.026) were jointly associated with a sustained response, while positive PCR at M2 was strongly predictive of treatment failure. CONCLUSION: Tolerance of interferon is poor in haemodialysis patients. Sustained response is fairly high in patients who have 12 months of treatment and seems to be based on the immune status of the patients (ALT) and the cumulative doses of interferon.     

The natural history of autogenous radio-cephalic wrist arteriovenous fistulas of haemodialysis patients: a prospective observational study.

BACKGROUND: Clinical practice guidelines have supported vascular access surveillance programmes on the premise that the natural history of the vascular access will be altered by radiological or surgical interventions after vascular access dysfunction is detected. The primary objective of this study was to assess the actual risk of thrombosis of autogenous radio-cephalic (RC) wrist arteriovenous fistulas (AVFs) without any pre-emptive interventions. METHODS: We enrolled 52 randomly selected adult Caucasian prevalent haemodialysis (HD) patients, all with autogenous RC wrist AVFs, into this prospective, observational study aimed to follow the natural history of their AVFs for 4 years. The protocol prescribed avoiding any surgical or interventional radiological procedures until access failure (AVF thrombosis or a vascular access not assuring a single-pool Kt/V > or =1.2). The subjects underwent yearly assessments of vascular access blood flow rate by means of a saline ultrasound dilution method. RESULTS: All failures of vascular access were due to AVF thrombosis; none were attributed to an inadequacy of the dialysis dose. AVF thrombosis occurred in nine cases; a rate of 0.043 AVF thrombosis per patient-year at risk. A receiver operating characteristic curve, evaluating the diagnostic accuracy of baseline vascular access blood flow rate values in predicting AVF failure, showed an under-the-curve area of 0.82+/-0.05 SD (P = 0.01). The value of vascular access blood flow rate, identified as a predictor of AVF failure, was <700 ml/min with an 88.9% sensitivity and 68.6% specificity. When subdividing the population of AVFs into two groups according to the baseline vascular access blood flow rates, two out of the nine thromboses occurred among the AVFs that had baseline blood flow rates >700 ml/min (n = 31), whereas seven occurred among the AVFs that had baseline blood flow rates <700 ml/min (n = 21). The 4 year cumulative actuarial survival was 74.36 and 20.80%, respectively (log-rank test, P = 0.04). The 24 AVFs that remained patent at the end of the 4 years maintained a median blood flow rate > or =900 ml/min at all time points studied. Worth noting is that, five of them (20.8%) remained patent throughout the study with a blood flow rate consistently < or =500 ml/min. CONCLUSIONS: This study shows a very low rate of AVF thrombosis per patient-year at risk and a high actuarial survival of autogenous RC wrist AVFs, particularly of those having a blood flow rate >700 ml/min. Thus, a vascular access blood flow rate <700 ml/min appears to be a reliable cut-off point at which to start a closer monitoring of this parameter-which may lead to further investigations and possibly interventions relevant to the function of the AVFs.     

持续性血液透析患者铁代谢与贫血状况的研究

目的 观察维持性血液透析(maintenance hemodialysis,MHD)患者铁过载的相关情况及其与贫血的相关性.方法 采用单中心、回顾性临床研究.选择2014年6月至2014年12月本院维持血液透析患者120例,按SF水平分为三组.A组(SF≤500 mg/L,n=60),B组(500 mg/L＜ SF≤1000 mg/L,n =35)和C组(SF＞ 1000 mg/L,n =25).调查患者的促红细胞生成素的用量、静脉补铁剂量、血红蛋白的变化、尿素氮、肌酐、全段甲状旁腺激素以及铁调素的水平.结果 C组患者的静脉铁补充剂量、输血量均大于A、B两组(P＜0.05),A组血红蛋白变化量大于B、C两组(P＜0.05),C组铁调素高于A、B两组(P＜0.05).结论 慢性肾衰竭维持血液透析的患者在SF≤500 mg/L,静脉补铁能有效地改善贫血,如补铁过量;SF＞ 1000 mg/L并不能显著的改善贫血及表现出铁代谢紊乱.     

Iron overload and mobilization in long-term hemodialysis patients

Iron overload from repeated transfusions of RBCs in long-term hemodialysis patients is a problem of increasing clinical significance. We report on the prevalence of and diagnostic criteria for identification of hemodialysis patients with iron overload. In 150 unselected hemodialysis patients, 62 (41%) had ferritin levels greater than 2,000 ng/mL (normal = 10 to 360 ng/mL). In 16 of these patients, accurate transfusion histories were obtained and ferritin levels correlated with calculated transfusional iron burden (r = 0.553, P less than .05). These patients could be divided into two distinct groups on the basis of their response to a single dose (2 g, IV) of deferoxamine: "high" responders had twice the level of feroxamine (the chelated product of deferoxamine and iron) of the "low" responders (P less than .001). High responders also had significantly higher prevalence of the "hemochromatosis" alleles A3, B7, and B14 than a large group of dialysis patients awaiting transplantation (71% v 37%, P less than .001). In two patients with iron overload and clinically significant bone disease, bone histology revealed prominent iron staining at the calcification front. We conclude that transfusional iron overload is a significant clinical problem in long-term hemodialysis patients, that may also be associated with bone pathology.