Biomedical subjects

M Allon

Publications and source records attributed to M Allon.

At least 19 recordsLinked to original sources

PubMed2026

Mechanisms of Hexavalent Chromium-Induced Reproductive Toxicity: A Focus on the Ovary and Placenta.

Hexavalent Chromium (Cr(VI)) is a Group A carcinogen, mutagen, and teratogen. Cr(VI) has been used by more than 50 industries, and its contamination of drinking water is widespread across the United States (U.S.). Epidemiological data of women who lived in Willits, California, U.S., indicate that environmental exposure to Cr(VI) adversely affects pregnancy outcomes and the health of their immediate offspring, resulting in a low birth rate, pregnancy loss, and spontaneous abortion, and their children (F1 offspring) experienced birth defects. However, the molecular mechanisms behind Cr(VI)-induced reproductive and developmental toxicity are poorly understood. Cr(VI) enters cells through anion transporters and is rapidly reduced to Cr(III) by endogenous antioxidants within the cell. Cr(III) forms adducts with DNA, which can block DNA replication and transcription; abnormal repair can lead to DNA double-strand breaks, mutations, micronucleus formation, chromosomal abnormalities, and increased genomic instability. Cr(VI) induces oxidative stress via the Fenton reaction, generating free radicals, and depleting antioxidants, thereby promoting apoptosis via p53-dependent and independent pathways, resulting in follicular atresia and accelerated reproductive aging. Antioxidant supplementation with resveratrol, vitamin C, and edaravone mitigates Cr(VI) toxicity in the ovary. Cr(VI) disrupts meiosis in metaphase II oocytes by causing DNA strand breaks, altering F-actin dynamics, disturbing microtubules, and leading to chromosome missegregation. Gestational exposure to Cr(VI) also disrupts placental function through multiple mechanisms by targeting trophoblast lineages. The current review focuses on genotoxicity, oxidative stress, and other mechanisms by which Cr(VI) disrupts the female reproductive and endocrine systems, with particular emphasis on the ovary and placenta.

Hexavalent chromium↗

PubMed2006

Impact of obesity on arteriovenous fistula outcomes in dialysis patients.

Fistula use for dialysis is less frequent among obese than non-obese patients. This discrepancy may be due to a lower rate of fistula placement in obese patients, a higher primary failure rate (fistulas that are never usable for dialysis), or a higher secondary failure rate (fistulas that fail after being used successfully for dialysis). Using a prospective, computerized vascular access database, we identified all patients receiving a first fistula or graft at our institution during a 2-year period. The access outcomes were compared between obese (body mass index (BMI) >or=30 kg/m2) and non-obese (BMI<30 kg/m2) patients. Fistula placement was equally likely between obese and non-obese patients (47.4 vs 47.1%). The primary failure rate of fistulas was similar in both groups (46 vs 41%, P=0.45). Among those fistulas that were usable for dialysis, the secondary survival was worse in obese patients (hazard ratio 2.74; 95% confidence interval (CI), 1.48-7.90; P=0.004). Secondary fistula survival in obese vs non-obese patients was 68 vs 92% at 1 year, 59 vs 78% at 2 years, and 47 vs 70% at 3 years. On multiple variable survival analysis with age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, fistula location, surgeon, and obesity in the model, obesity was the only significant factor predicting secondary fistula failure (hazards ratio 2.93; 95% CI, 1.44-5.93; P=0.004). In conclusion, long-term fistula survival is worse in obese than non-obese patients, owing to a higher secondary failure rate.

Adult↗

PubMed2006

Randomized comparison of ultrasound surveillance and clinical monitoring on arteriovenous graft outcomes.

Arteriovenous graft thrombosis is a frequent event in hemodialysis patients, and usually occurs in grafts with significant underlying stenosis. Regular surveillance for graft stenosis, with pre-emptive angioplasty of significant lesions, may improve graft outcomes. This prospective, randomized, clinical trial allocated 126 hemodialysis patients with grafts to either clinical monitoring alone (control group) or to regular ultrasound surveillance for graft stenosis every 4 months in addition to clinical monitoring (ultrasound group). The two randomized groups were closely matched with respect to demographic, clinical, and graft characteristics, with the exception of a lower frequency of diabetes in the ultrasound group. The primary outcome was graft survival, and the secondary outcome was thrombosis-free graft survival. The frequency of pre-emptive graft angioplasty was 64% higher in the ultrasound group than in the control group (1.05 vs 0.64 events per patient-year, P<0.001), whereas the frequency of thrombosis was not different (0.67 vs 0.78 per patient-year, P=0.37). The median time to permanent graft failure was similar between the two groups (38 vs 37 months, P=0.93). Likewise, the median time to graft thrombosis or failure did not differ (22 vs 25 months, P=0.33). There was no significant association between diabetes and time to graft failure (P=0.93) or time to graft thrombosis or failure (P=0.88). In conclusion, the addition of regular ultrasound surveillance for graft stenosis to clinical monitoring increases the frequency of pre-emptive angioplasty, but may not decrease the likelihood of graft failure or thrombosis.

Aged↗

PubMed2006

Outcomes of thrombosed arteriovenous grafts: comparison of stents vs angioplasty.

The usual radiologic approach to thrombosed grafts is a combination of thrombectomy and angioplasty of the underlying lesion. However, the primary (unassisted) graft patency after thrombectomy is quite poor. We evaluated whether graft patency following thrombectomy is improved by placement of a stent in the stenotic lesion. Using a prospective, computerized vascular access database, we identified 14 patients with thrombosed arteriovenous (A-V) grafts treated with a stent at the venous anastomosis (stent group). The outcomes of these grafts was compared to those observed in 34 sex, age-, and date-matched control patients whose thrombosed A-V grafts were angioplastied (control group). Both groups were comparable in age, sex, race, diabetic status, graft age, and number of previous graft interventions. The immediate technical success, as indicated by the post-procedure graft to systemic pressure ratio, was similar in the stent and control groups (0.33+/-0.16 vs 0.41+/-0.17, P=0.14). The primary graft patency (time from thrombectomy to next intervention) was significantly longer for the stent group (median survival, 85 vs 27 days, P=0.02). Assisted or secondary patency (time from thrombectomy to permanent graft failure) was also longer for the stent group (median survival, 1215 vs 46 days, P=0.049). In conclusion, treatment of thrombosed grafts with a stenosis at the venous anastomosis with a stent results in longer primary and secondary graft survival, as compared to treatment with angioplasty. Stent placement may be a useful treatment modality in a subset of patients with thrombosed A-V grafts and stenosis at the venous anastomosis.

Adult↗

PubMed2005

Turbulent flow evaluation of the venous needle during hemodialysis.

Arteriovenous (AV) grafts and fistulas used for hemodialysis frequently develop intimal hyperplasia (IH) at the venous anastomosis of the graft, leading to flow-limiting stenosis, and ultimately to graft failure due to thrombosis. Although the high AV access blood flow has been implicated in the pathogenesis of graft stenosis, the potential role of needle turbulence during hemodialysis is relatively unexplored. High turbulent stresses from the needle jet that reach the venous anastomosis may contribute to endothelial denudation and vessel wall injury. This may trigger the molecular and cellular cascade involving platelet activation and IH, leading to eventual graft failure. In an in-vitro graft/needle model dye injection flow visualization was used for qualitative study of flow patterns, whereas laser Doppler velocimetry was used to compare the levels of turbulence at the venous anastomosis in the presence and absence of a venous needle jet. Considerably higher turbulence was observed downstream of the venous needle, in comparison to graft flow alone without the needle. While turbulent RMS remained around 0.1 m/s for the graft flow alone, turbulent RMS fluctuations downstream of the needle soared to 0.4-0.7 m/s at 2 cm from the tip of the needle and maintained values higher than 0.1 m/s up to 7-8 cm downstream. Turbulent intensities were 5-6 times greater in the presence of the needle, in comparison with graft flow alone. Since hemodialysis patients are exposed to needle turbulence for four hours three times a week, the role of post-venous needle turbulence may be important in the pathogenesis of AV graft complications. A better understanding of the role of needle turbulence in the mechanisms of AV graft failure may lead to improved design of AV grafts and venous needles associated with reduced turbulence, and to pharmacological interventions that attenuate IH and graft failure resulting from turbulence.

Arteriovenous Anastomosis↗

PubMed2001

Predictors of arteriovenous graft patency after radiologic intervention in hemodialysis patients.

Arteriovenous grafts in hemodialysis patients are prone to recurrent stenosis and thrombosis, requiring frequent radiologic and surgical interventions to optimize their long-term patency. Little is known about the factors that determine graft outcome after a radiologic intervention. The present study examined the clinical and radiologic predictors of intervention-free graft survival after elective angioplasty or thrombectomy. A prospective computerized database was used to determine the outcomes subsequent to all graft angioplasties (n = 330) and thrombectomies (n = 326) performed at the University of Alabama at Birmingham between April 1, 1996, and June 30, 1999. Primary graft survival rates after angioplasty and thrombectomy were 86% versus 43% at 1 month, 71% versus 30% at 3 months, 51% versus 19% at 6 months, and 28% versus 8% at 12 months, respectively. The median intervention-free graft survival time was substantially longer after angioplasty than thrombectomy (6.7 versus 0.6 months; P < 0.001). The superior outcome of angioplasty over thrombectomy was observed even for the subset of procedures with no residual stenosis (median survival, 6.9 versus 2.5 months; P < 0.001). The median graft survival was inversely related to the magnitude of residual stenosis for both elective angioplasty and thrombectomy. Median intervention-free graft survival after angioplasty was inversely related to the postangioplasty intragraft to systemic systolic pressure ratio (7.6, 6.9, and 5.6 months for ratios <0.4, 0.4 to 0.6, and >0.6, respectively; P < 0.001). Intervention-free graft survival after angioplasty or thrombectomy was not affected by graft location (forearm versus upper arm), number of stenotic sites, or presence of diabetes. In conclusion, graft survival is substantially longer after elective angioplasty than thrombectomy, even when the radiologic appearance after the procedure suggests complete resolution of the stenotic lesion. Moreover, the risk for requiring a subsequent graft intervention can be predicted from two simple radiologic measurements: grade of stenosis and intragraft to systemic systolic blood pressure ratio. These parameters may help determine the frequency of monitoring for recurrent stenosis in a given graft.

Aged↗

PubMed2001

Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients.

BACKGROUND: Current DOQI guidelines encourage placing arteriovenous (AV) fistulas in more hemodialysis patients. However, many new fistulas fail to mature sufficiently to be usable for hemodialysis. Preoperative vascular mapping to identify suitable vessels may improve vascular access outcomes. The present study prospectively evaluated the effect of routine preoperative vascular mapping on the type of vascular accesses placed and their outcomes. METHODS: During a 17-month period, preoperative sonographic evaluation of the upper extremity arteries and veins was obtained routinely. The surgeons used the information obtained to plan the vascular access procedure. The types of access placed, their initial adequacy for dialysis, and their long-term outcomes were compared to institutional historical controls placed on the basis of physical examination alone. RESULTS: The proportion of fistulas placed increased from 34% during the historical control period to 64% with preoperative vascular mapping (P < 0.001). When all fistulas were assessed, the initial adequacy rate for dialysis increased mildly from 46 to 54% (P = 0.34). For the subset of forearm fistulas, the initial adequacy increased substantially from 34 to 54% (P = 0.06); the greatest improvement occurred among women (from 7 to 36%, P = 0.06) and diabetic patients (from 21 to 50%, P = 0.055). In contrast, the initial adequacy rate of upper arm fistulas was not improved by preoperative vascular mapping (59 vs. 56%, P = 0.75). Primary access failure was higher for fistulas than grafts (46.4 vs. 20.6%, P = 0.001), but the subsequent long-term failure rate was higher for grafts than fistulas (P < 0.05). Moreover, grafts required a threefold higher intervention rate (1.67 vs. 0.57 per year, P < 0.001) to maintain their patency. The overall effect of this strategy was to double the proportion of patients dialyzing with a fistula in our population from 16 to 34% (P < 0.001). CONCLUSIONS: Routine preoperative vascular mapping results in a marked increase in placement of AV fistulas, as well as an improvement in the adequacy of forearm fistulas for dialysis. This approach resulted in a substantial increase in the proportion of patients dialyzing with a fistula in our patient population. Fistulas have a higher primary failure rate than grafts, but have a lower subsequent failure rate and require fewer procedures to maintain their long-term patency.

Adult↗

PubMed2001

Simplified citrate anticoagulation for continuous renal replacement therapy.

BACKGROUND: Regional anticoagulation with trisodium citrate is an effective form of anticoagulation for continuous renal replacement therapy (CRRT) for patients with contraindications to heparin. However, because of the metabolic complications of trisodium citrate, it is a complicated technique requiring specialized dialysis solutions. We have designed a simplified protocol for citrate regional anticoagulation for CRRT. METHODS: Two percent trisodium citrate was delivered at 250 mL/h via the prefilter port of a COBE PRISMA device, with the rate adjusted to maintain a postfilter ionized calcium (iCa++) <0.5 mmol/L. A central calcium gluconate infusion was used to maintain a systemic iCa++ at 1.1 mmol/L. A standard dialysate solution consisting of 0.9% saline, KCl 3 mmol/L, and MgSO4 1 mmol/L was delivered at 1000 mL/h. We retrospectively reviewed the outcomes and complications associated with this protoco1 in 29 patients treated from July 1999 to October 1999, evaluating the frequency of clotting of the dialyzer, bleeding complications, citrate toxicity, and patient mortality. RESULTS: The Kaplan-Meier curve for dialyzer survival demonstrated a 61% survival rate at 48 hours. There were no episodes of significant bleeding or citrate toxicity. Seventy-two percent of patients died for reasons unrelated to CRRT. CONCLUSIONS: A CRRT protocol using regional 2% trisodium citrate anticoagulation is not associated with significant bleeding complications or citrate toxicity, and represents a simplified approach compared with previous applications using 4% trisodium citrate.

Animals↗

PubMed2001

Clinical consequences of infected arteriovenous grafts in hemodialysis patients.

Arteriovenous (AV) graft infection is a serious adverse event in hemodialysis patients; however, there is little published literature describing its consequences. We identified prospectively all AV graft infections occurring at our institution during a 4.5-year period. We analyzed immediate complications, as well as long-term consequences, including the need for subsequent vascular-access procedures and duration of catheter-dependent dialysis therapy. Ninety graft infections were identified in 78 patients, yielding a rate of 8.2 infections/100 graft-years. Patients with graft infection were much more likely to have a low serum albumin level (<3.5 g/dL) in the month preceding the infection compared with noninfected controls (73% versus 18%; P < 0.001). Infections occurred within 1 month of graft placement in 15%, at 1 to 12 months in 44%, and longer than 1 year from surgery in 41%. The pathogen was a gram-positive coccus in 97% of cases, particularly Staphylococcus aureus (60%) and Staphylococcus epidermidis (22%). The initial graft infection entailed hospitalization for a mean of 7.5 days. Eleven patients (12%) developed a total of 17 major complications, including death (5 patients), clinical sepsis requiring vasopressors (4 patients), septic arthritis (3 patients), epidural abscess (1 patient), endocarditis (1 patient), osteomyelitis (1 patient), myocardial infarction (1 patient), and cerebrovascular accident (1 patient). After removal of an infected graft, patients were catheter dependent for a median of 3.8 months. The duration of catheter dependence was less than 3 months in 36%, 3 to 6 months in 38%, 6 to 12 months in 14%, and greater than 1 year in 12%. During the period of catheter dependence, patients required a mean of 9.7 access procedures, including graft removal (1.0 procedure), nontunneled dialysis catheters (4.4 procedures), tunneled dialysis catheters (3.0 procedures), and new permanent accesses (1.4 procedures). In addition, patients averaged 0.85 episodes of bacteremia while they were catheter dependent. In conclusion, graft infection results in substantial morbidity, prolonged dependence on dialysis catheters, and multiple vascular-access procedures.

Anti-Bacterial Agents↗

PubMed2000

Bacteremia associated with tunneled dialysis catheters: comparison of two treatment strategies.

BACKGROUND: Tunneled dialysis catheters are often used for temporary vascular access in hemodialysis patients, but are complicated by frequent systemic infections. The treatment of bacteremia associated with infected tunneled catheters requires both antibiotic therapy and catheter replacement. We compared the outcomes of two treatment strategies for catheter-associated bacteremia: exchange of the existing catheter with a new one over a guidewire versus catheter removal with delayed replacement. METHODS: We retrospectively analyzed the outcomes of all cases of tunneled dialysis catheter-associated bacteremia during a two-year period. The infection-free survival time of the subsequent catheter was evaluated in two groups of patients: group A (31 catheters), exchange of the existing infected catheter with a new catheter over a guidewire, and group B (38 catheters), removal of the infected catheter followed by delayed catheter replacement 3 to 10 days later. Patients in both groups received three weeks of systemic antibiotic therapy. Cox proportional hazard models were used to evaluate the factors predictive of infection-free survival time of the replacement catheter. RESULTS: On univariate proportional hazard regression analysis, the infection-free survival time of the replacement catheter was similar for groups A and B (P = 0.72), whereas the hazard of infection was significantly greater for patients with hypoalbuminemia (serum albumin < 3.5 g/dL), as compared with patients with a normal serum albumin (hazard ratio 2.81, 95% CI, 1. 21, 6.53, P = 0.016). The infection-free survival time was not affected by patient age, sex, diabetic status, or type of organism (gram-positive coccus vs. gram-negative rod). CONCLUSIONS: The infection-free survival time associated with the subsequent catheter is similar for the two treatment strategies. However, exchanging the catheter for a new one over a guidewire minimizes the number of separate procedures required by the patient. Hypoalbuminemia is the major risk factor for recurrent bacteremia in the replacement catheter.

Adult↗

PubMed2000

Natural history of arteriovenous grafts in hemodialysis patients.

Most hemodialysis patients in the United States have an arteriovenous graft as their vascular access. Grafts have a relatively short life span and are prone to recurrent stenosis and thrombosis, requiring multiple salvage procedures to maintain their patency. There is little information in the literature regarding the clinical factors that determine graft survival and complications. We evaluated prospectively the outcomes of 256 grafts placed at a single institution during a 2-year period. A salvage procedure to maintain graft patency (thrombectomy, angioplasty, or surgical revision) was required in 29% of the grafts at 3 months, 52% at 6 months, 77% at 12 months, and 96% at 24 months. Thus, primary graft survival (time from graft placement to the first intervention) was only 23% at 1 year and 4% at 2 years. Primary graft survival was significantly less among patients with hypoalbuminemia compared with patients with a normal serum albumin level (P = 0.003). Secondary graft survival (time from graft placement to permanent graft failure) was 65% at 1 year and 51% at 2 years. Neither primary nor secondary graft survival was significantly correlated with patient age, sex, diabetic status, body mass index, or graft site. A mean of 1.22 interventions per graft-year were required to maintain access patency, including 0.51 thrombectomies, 0.54 angioplasties, and 0.17 surgical revisions. In conclusion, hypoalbuminemia is a strong predictor of the requirement for an early graft intervention. Patients with hypoalbuminemia may require a heightened index of suspicion in monitoring their grafts for evidence of stenosis.

Aged↗

PubMed2000

Factors associated with the prevalence of arteriovenous fistulas in hemodialysis patients in the HEMO study. Hemodialysis (HEMO) Study Group.

BACKGROUND: Arteriovenous (AV) fistulas are the vascular access of choice for hemodialysis patients, but only about 20% of hemodialysis patients in the United States dialyze with fistulas. There is little information known about the factors associated with this low prevalence of fistulas. METHODS: Multiple logistic regression analysis was used to evaluate the independent contribution of factors associated with AV fistula use among patients enrolled in the HEMO Study. The analysis was conducted in 1824 patients with fistulas or grafts at 45 dialysis units (15 clinical centers). RESULTS: Thirty-four percent of the patients had fistulas. The prevalence of fistulas varied markedly from 4 to 77% among the individual dialysis units (P < 0.001). Multiple regression analysis revealed five demographic and clinical factors that were each independently associated with a lower likelihood of having a fistula, even after adjustment for dialysis unit. Specifically, the prevalence of fistulas was lower in females than males [adjusted odds ratio (AOR) 0.37, 95% CI, 0.28 to 0.48], lower in patients with peripheral vascular disease than in those without (AOR 0.55, 95% CI, 0.38 to 0.79), lower in blacks than in non-blacks (AOR 0.64, 95% CI, 0.46 to 0.89), lower in obese patients (AOR per 5 kg/m(2) body mass index, 0.76, 95% CI, 0.65 to 0.87), and lower in older patients (AOR per 10 years, 0.85, 95% CI, 0.78 to 0.94). The differences in the prevalence of fistulas among the dialysis units remained statistically significant (P < 0.001) after adjustment for these demographic and clinical factors. Finally, there were substantial variations in the prevalence of fistulas even among dialysis units in a single metropolitan area. CONCLUSIONS: Future efforts to increase the prevalence of fistulas in hemodialysis patients should be directed at both hemodialysis units and patient subpopulations with a low fistula prevalence.

Age Distribution↗

PubMed2000

US vascular mapping before hemodialysis access placement.

PURPOSE: To prospectively assess the effect of preoperative ultrasonographic (US) mapping on surgical selection, placement of arteriovenous fistulas (AVFs) and grafts, and negative surgical exploration rates. MATERIALS AND METHODS: US assessment of the upper extremity arterial and venous anatomy was performed in 70 patients with chronic renal failure before surgical evaluation. The surgeon documented the planned access procedure, which was based on physical examination results, and then reviewed the US preoperative mapping report. The surgical procedure and outcome were recorded. RESULTS: Fifty-two of the 70 patients who underwent mapping had vascular access placement. Preoperative US mapping resulted in a change in the planned surgical procedure in 16 (31%) of the 52 patients. An AVF rather than the planned graft was placed in eight (15%) patients. The AVF placement rate increased from 32% (126 of 395 patients) to 58% (30 of 52 patients). Unsuccessful surgical explorations decreased from 11% (28 of 256) to 0%. CONCLUSION: Preoperative US mapping before hemodialysis access placement can result in a change in surgical management, with an increased number of AVFs placed and an improved likelihood of selecting the most functional vessels preoperatively. Further study is needed to determine longer term outcomes.

Adolescent↗

PubMed1999

Predictors of adequacy of arteriovenous fistulas in hemodialysis patients.

BACKGROUND: Dialysis access procedures and complications represent a major cause of morbidity, hospitalization, and cost for chronic dialysis patients. To improve the outcomes of hemodialysis access procedures, recent clinical guidelines have encouraged attempts to place an arteriovenous (A-V) fistula, rather than an A-V graft, whenever possible in hemodialysis patients. There is little information, however, about the success rate of following such an aggressive strategy in the prevalent dialysis population. METHODS: We evaluated the adequacy of all A-V fistulas placed in University of Alabama at Birmingham dialysis patients during a two-year period. A fistula was considered adequate if it supported a blood flow of >/=350 ml/min on at least six dialysis sessions in one month. Fistula adequacy was correlated with clinical and demographic factors. RESULTS: The adequacy could be determined for 101 fistulas; only 47 fistulas (46.5%) developed sufficiently to be used for dialysis. The adequacy rate was lower in older (age >/= 65) versus younger (age < 65) patients (30.0 vs. 53.5%, P = 0.03). It was also marginally lower in diabetics versus nondiabetics (35.0 vs. 54.1%, P = 0.061) and in overweight (BMI >/= 27 kg/m2) versus nonoverweight patients (34.5 vs. 55.2%, P = 0.07). The adequacy rate was not affected by patient race, smoking status, surgeon, serum albumin, or serum parathyroid hormone. The adequacy rate was substantially lower for forearm versus upper arm fistulas (34.0 vs. 58.9%, P = 0.012). The adequacy of forearm fistulas was particularly poor in women (7%), patients age 65 or older (12%), and diabetics (21%). In contrast, upper arm fistulas were adequate in 56% of women, 54% of older patients, and 48% of diabetics. CONCLUSIONS: An aggressive approach to the placement of fistulas in dialysis patients results in a less than 50% early adequacy rate, which is considerably lower than that reported in the past. Moreover, the success rate of fistulas is even lower for certain patient subsets. To achieve an optimal outcome with A-V fistulas, we recommend that they be constructed preferentially in the upper arm in female, diabetic, and older hemodialysis patients.

Adult↗

PubMed1998

Prospective evaluation of an anemia treatment algorithm in hemodialysis patients.

Current guidelines recommend maintaining the hematocrits of chronic hemodialysis patients in the low to mid-30s. Maintaining patients' hematocrits within a narrow range requires frequent monitoring of their hematocrits and iron studies and periodic adjustment of erythropoietin doses and administration of intravenous iron. We designed a simple anemia treatment algorithm to streamline the management of anemia in hemodialysis patients. The protocol required formal monthly decisions about the administration of intravenous iron or changes in erythropoietin dose. This algorithm was implemented by dialysis nurses and evaluated prospectively for 6 months in a single dialysis unit (30 patients). The proportion of patients whose hematocrits were within the desired target (31% to 35%) increased from 27% at baseline to 61% during months 4 through 6 of the algorithm. Conversely, the proportion of patients whose hematocrit values were below the target decreased from 46% at baseline to 18% during months 4 through 6 of the algorithm (P=0.004). The percentage of patients whose hematocrit values were above the target did not increase. The proportion of patients whose transferrin saturation was less than 18% decreased from 47% at baseline to 20% during months 4 through 6 of the algorithm (P=0.04). The weekly erythropoietin dose administered decreased from 11,200+/-1,400 units at baseline to 9,400+/-1,200 units in month 6 of the algorithm (P=0.06). We conclude that a simple anemia treatment algorithm implemented by dialysis nurses is feasible and efficacious and may increase the proportion of hemodialysis patients whose hematocrit values are within the target range, without increasing erythropoietin requirements.

Adult↗

PubMed1998

The effect of a self-monitoring tool on self-efficacy, health beliefs, and adherence in patients receiving hemodialysis.

OBJECTIVE: Assess the effectiveness of a self-monitoring tool on perceptions of self-efficacy, health beliefs, and adherence in patients receiving hemodialysis. DESIGN: A monthly intervention using a pretest, posttest design over a 6-month period. Both the treatment and control groups were randomly selected and received surveys to assess health beliefs, perceptions of self-efficacy for performing specific healthful behaviors, and renal diet knowledge at baseline, before intervention, and 6 months later. The treatment group also received monthly feedback of monthly phosphorus levels and interdialytic weight gains. SETTING: A university hospital-based 43-chair ambulatory dialysis center. SUBJECTS: Forty patients with end-stage renal disease (25 men and 15 women, age 26 to 78 years), on chronic hemodialysis for at least 2 months and with a history of noncompliance with phosphorus and/or fluid restrictions for 1 or more months. MAIN OUTCOME MEASURES: Self-efficacy, health beliefs, knowledge, biochemical, and demographic variables were analyzed. Analysis of variance tests of repeated measures were used to examine relationships between adherence with phosphorus and fluid restrictions to health beliefs and perceptions of self-efficacy after training in self-monitoring. RESULTS: Overall, there were no significant improvements in adherence with phosphorus and fluid restrictions between the two groups, although a comparison within the groups revealed the treatment group had a statistically significant decrease in mean phosphorus levels of 7.14 to 6.22 mg/dL (P = .005) from baseline to month 3. However, because this value was not maintained, it was not statistically significant. No significant differences existed between the two groups for health beliefs and perceptions of self-efficacy. Knowledge scores in the treatment group, however, improved significantly as compared to the control group (P = .008) and was a significant increase from baseline (P = . 002). In the control group, all scores fell slightly but this difference was not significant. CONCLUSIONS: The benefits of patient self-monitoring and behavioral contracting upon adherence in patients on hemodialysis are inconclusive, as serum phosphorus and interdialytic weight gains did not differ between the two groups. The interventional tools also appeared to have little effect on perceptions of self-efficacy and health beliefs. Trends of improvement, however, did exist for phosphorus within the treatment group and subjects in this group had a statistically significant increase in knowledge scores over time. Additional research using repeated measures design is needed to explore the effects of increased frequency and duration of an intervention on the attainment of patient clinical outcome measures.

Adult↗

PubMed1998

A multidisciplinary approach to hemodialysis access: prospective evaluation.

Dialysis access procedures and complications represent a major cause of morbidity, hospitalization and cost for chronic dialysis patients. To improve outcomes and reduce the cost of hemodialysis access procedures we developed a multidisciplinary approach, involving nephrologists, access surgeons, and radiologists. A full-time dialysis access coordinator scheduled all access procedures with the surgeons and radiologists, and tracked outcomes. A computerized database was developed for prospective documentation of procedures and complications. Confidential, detailed analyses and recommendations for improvements were provided periodically to the surgeons and radiologists. The major changes arising from the multidisciplinary approach were as follows: (1) The approach to clotted grafts evolved from an inpatient surgical procedure to an outpatient radiologic procedure. The immediate technical success rate of graft declots increased from 48% to 69%. (2) Elective placement of arteriovenous (A-V) grafts evolved from a three-day inpatient hospitalization to a largely outpatient procedure. The proportion of A-V grafts placed as same day surgery or outpatient surgery increased from 16% to 81%. (3) Surgical complications of new A-V graft surgery decreased from 25% to 11%. (4) Aggressive detection and correction of graft stenosis decreased the incidence of graft thrombosis by 60%, from 0.70 to 0.28 events per patient-year. (5) The proportion of native A-V fistula construction in new dialysis patients increased from 33% to 69%. In conclusion, an integrated multidisciplinary approach markedly reduced surgical complications of access surgery and decreased access failures. These improvements occurred despite a marked decrease in hospitalization for access procedures, with a substantial cost saving.

Aged↗

PubMed1998

Hemodialysis access graft stenosis: US detection.

PURPOSE: To prospectively evaluate the sensitivity of ultrasonography (US) in diagnosing stenosis of hemodialysis access grafts and their drainage veins in patients clinically suspected of having graft dysfunction. MATERIALS AND METHODS: Thirty-eight patients in whom dysfunction of their hemodialysis access grafts was suspected underwent both Doppler US and angiography. Gray-scale and color US were combined with spectral analysis of the graft, anastomoses, and venous outflow. Flow velocity at anastomoses and suspected stenotic areas was measured. The volume of flow in the graft was also measured. The prospective US criterion for diagnosis of stenosis was a focal twofold or higher elevation of peak systolic velocity (PSV) compared with the PSV immediately upstream. A blinded angiographic evaluation of the graft and drainage veins followed US. Angiographic diagnosis of stenosis required at least 50% narrowing in luminal diameter. US and angiographic results were then compared. RESULTS: Angiography allowed diagnosis of 43 stenoses in 34 patients. US depicted 92% (37 of 40) of these stenoses, with a 94% positive predictive value for any individual patient. Focal 2- to 2.9-times PSV elevation was associated with 75% or greater stenosis. Graft flow volume and resistive index change did not correlate with stenosis. CONCLUSION: US reliably depicts stenoses of hemodialysis access grafts and drainage veins in a clinically selected population when PSV criteria are used.

Adult↗