Biomedical subjects

J Uribarri

Publications and source records attributed to J Uribarri.

At least 19 recordsLinked to original sources

PubMed2004

Efficacy of reteplase in poorly functioning hemodialysis catheters.

AIM: This is a retrospective study of reteplase efficacy for restoration of flow in occluded and poorly functioning hemodialysis catheters. PATIENTS AND METHODS: From May 1, 2001 to December 31, 2001, all hemodialysis patients seen at our university dialysis center with occluded or poorly functioning (< 200 ml/min blood flow) catheters treated with reteplase were included in the study. All catheters had been in place for more than 48 hours. Reteplase 0.4 U was instilled into each port; dwell time was 30 minutes. If aspiration had not been possible, reteplase had remained in the catheter for an additional 30 minutes. If flow was established (> 200 ml/min), the catheter was used for dialysis. If flow was not adequately established after 1 hour, the patient was referred for catheter exchange. RESULTS: Reteplase (0.4 U) was used in 50 instances to restore or improve blood flow rates in a total of 23 catheters in 19 patients. Reteplase was effective in establishing adequate blood flow rates during the current and next dialysis session in 44/50 (88%) cases; 6 cases required 1-hour dwell time. Six cases (in 5 patients) required catheter exchange; in these, an anatomic or pathologic complication was responsible for catheter malfunction. No adverse events were related to reteplase instillation during the study. CONCLUSION: Data suggest that reteplase is safe and effective in restoring flow to malfunctioning hemodialysis catheters. Results are comparable to those achieved with alteplase.

Adolescent↗

PubMed2004

Hyponatremia in peritoneal dialysis patients.

BACKGROUND: Low serum sodium is uncommon in peritoneal dialysis (PD), which is surprising in view of the important role of normal kidney function to regulate water and sodium balance. METHODS: We report 2 cases of persistent hyponatremia with balance studies in Case 1. We performed measurements of dialysate sodium and volume output over 24 hours in a group of chronic PD patients. RESULTS: The low serum sodium concentration did not vary too much with overall fluid removal via dialysis in patient 1, mainly because large quantities of sodium were removed in the dialysate. In the 24-hour studies, a significant relationship was found between net daily PD sodium removal and net daily dialysate volume removed (r = 0.65). There was no relationship between net daily PD sodium removal and serum sodium concentration. There was a linear direct correlation between serum and dialysate sodium concentration (r = 0.8) as shown by others previously. CONCLUSIONS: These results suggest that the main determinant of PD sodium loss is net dialysate ultrafiltration volume. Water loss via dialysis is necessarily associated with sodium loss. In order to maintain a normal serum sodium concentration salt intake must be proportional to the water loss induced by dialysis. The stimuli that allow dialysis patients to maintain this delicate balance between water and salt intake are of considerable interest but remain undetermined.

Aged↗

PubMed2003

Treatment of "swing point stenoses" in hemodialysis arteriovenous fistulae.

AIM: This is a retrospective study of percutaneous transluminal balloon angioplasty (PTA) efficacy for treatment of surgical vein mobilization site ("swing point") stenoses in hemodialysis arteriovenous fistulae (AVF) that fail to mature or are poorly functioning. METHOD: Between February 1, 1999, and February 28, 2001, 65 non-maturing or poorly functioning AVF were studied in 63 consecutive hemodialysis patients (30 male, 33 female, aged 26-92 years). All AVF underwent contrast angiography to study the inflow artery, AVF, outflow and central veins. PTA of stenotic sites was performed to initiate or restore AVF function. RESULTS: Seventy-eight venous and 2 arterial stenoses were found and treated with PTA in the 65 AVF. All PTA were technically successful. A total of 55 stenoses were identified in the vein at the site of surgical mobilization ("swing point"). Additionally, 19 cephalic and 4 central venous stenoses were found. During the study, 13 AVF underwent repeat PTA at the "swing point". Of the 65 AVF treated, 50 were being successfully used as an access site, 4 AVF were lost during follow-up (34-688 days; mean: 258 days) and 8 patients died within the study period. The duration of functional patency of the treated AVF was 39-660 days (mean: 280 days). CONCLUSION: Non-maturing or poorly functioning AVF frequently have stenoses in the outflow vein at the original site of surgical vein mobilization. These "swing point stenoses" are amenable to PTA, which is a safe and effective treatment for prolonging AVF patency and function.

Adult↗

PubMed2002

Obese and non-obese hemodialysis patients have a similar prevalence of functioning arteriovenous fistula using pre-operative vein mapping.

AIMS: The arteriovenous fistula (AVF) is the preferred hemodialysis access. Subset analyses of both the HEMO and DOPPS studies have shown that obese hemodialysis patients have a lower prevalence of functioning AVF. Doppler ultrasound may increase the prevalence of functioning AVF in obese subjects. PATIENTS AND METHODS: The effect of pre-operative vein mapping employed between 10/01/98 and 12/08/00 on the prevalence of functioning AVF in a single university hemodialysis program was studied. Preoperative ultrasound was performed to study venous and arterial systems on both arms. RESULTS: There were 50 obese patients, defined as bodymass index (BMI) > or = 27 kg/m2, and 130 patients with a lower BMI. The groups were similar in mean age and diabetes prevalence. The obese group had statistically significantly more females 34/50 versus 61/130 with p = 0.01. There was no statistically significant difference between the vein mapping parameters studied in the two BMI groups, including mean mid-forearm cephalic vein diameter, distal radial artery peak systolic velocity and subclavian vein patency. No obese patient required venography. There was no significant difference between the number of functioning AVF in both groups (22/50 obese, 48/130 lower BMI, p = 0.24). CONCLUSIONS: Pre-operative vein mapping is associated with a similar prevalence of functioning AVF in obese and lower BMI patients. Pre-operative ultrasound screening is a useful tool to promote AVF placement in obese patients.

Adult↗

PubMed2001

Reteplase in the treatment of thrombosed hemodialysis grafts.

PURPOSE: To prospectively evaluate the efficacy and safety of reteplase with percutaneous transluminal angioplasty (PTA) in the treatment of thrombosed polytetrafluoroethylene hemodialysis arteriovenous grafts (AVGs). MATERIALS AND METHODS: Forty-two patients were entered into the study. Sixty-two procedures in 43 grafts were performed. One unit of reteplase and 4,000 units of heparin were administered into the AVGs. Routine venography and percutaneous transluminal angioplasty (PTA) was then performed. Patients were transferred for hemodialysis immediately after the procedure. RESULTS: Technical success was achieved in 92% of the cases. Four cases involved intentional repeat thrombosis because of poor outflow and/or need for a new graft site. Minor complications occurred in 6.5% of the cases. No major complications occurred. The mean procedure time for experienced versus less-experienced interventionalists was significantly shorter (P <.001). Primary patency rates were 50%, 34%, and 34% at 30, 90, and 180 days, respectively. CONCLUSION: Reteplase in conjunction with heparin and PTA is a safe and effective means of thrombolysis of AVGs. Its efficacy is comparable to that of other available thrombolytic drugs.

Adult↗

PubMed2001

Thrombolysis of clotted hemodialysis grafts with tissue-type plasminogen activator.

PURPOSE: To evaluate prospectively the efficacy of treating thrombosed hemodialysis arteriovenous polytetrafluoroethylene (PTFE) grafts using tissue-type plasminogen activator (tPA) and percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: Forty-two sequential thrombosed PTFE dialysis grafts in 33 patients presented for declotting. All 42 grafts were treated with a modified lysis and PTA technique with use of 2 mg tPA and 3,000-5,000 U heparin in a total volume of 5 mL, administered into the graft via an angiocatheter. The elapsed time from tPA injection until completion was recorded. Prospective data collection included demographic information, technical details of the procedure, immediate outcomes, complications, and patency rates. RESULTS: Technical success, defined as complete graft recanalization with a palpable thrill after treatment plus successful hemodialysis, was achieved in all cases, except five. These five cases were deliberate graft closures due to inadequacy of the outflow veins to support an arteriovenous graft after successful lysis. Mean lysis time was 40.8 minutes and mean room procedure time after the lysis period was 65.4 minutes. Eight procedure-related complications occurred (two major and six minor). The follow-up period was 4-241 days, with an estimated mean of 157 days. The 30-day and 90-day primary patency rates were 57% and 50%, respectively. CONCLUSIONS: Treatment of thrombosed PTFE dialysis grafts with use of 2 mg tPA and 3,000 U of heparin is safe and effective. Use of this modified lysis and PTA technique allows an expeditious procedure in the angiography suite. However, this technique precludes imaging of the outflow veins before treatment, so that grafts entering diffusely diseased veins may need to be closed after successful lysis.

Angioplasty, Balloon↗

PubMed2001

Doqi guidelines for nutrition in long-term peritoneal dialysis patients: a dissenting view.

The DOQI guidelines recommend a dietary protein intake of 1.2 to 1.3 g/kg/d in long-term peritoneal dialysis patients. A quantitative analysis of the relationship between this high protein intake and phosphorus intake shows that this daily load of protein is likely to lead to hyperphosphatemia in anuric patients with borderline dialysate clearance. Currently available phosphorus binders are not efficient enough to offset completely the adverse effects of a phosphorus-rich diet. An inverse correlation has been shown between serum phosphorus and outcome among dialysis patients, probably mediated by an increase in the Ca x P product. Evidence, theoretic or experimental, that such a high protein intake is by itself beneficial to dialysis patients is lacking. Because high protein intake may increase the daily load of phosphorus and predispose to hyperphosphatemia, it may lead to harmful consequences, and it should be modified. Using the general recommendation for normal subjects plus the usual excessive nitrogen loss during peritoneal dialysis, between 0.9 and 1 g/kg/d most likely would be an appropriate protein intake without exposing the patient to excessive phosphorus load.

Humans↗

PubMed2001

Gender modulates responsiveness to recombinant erythropoietin.

Several investigators reported that individuals with diabetes and women on hemodialysis treated with recombinant erythropoietin (EPO) attained lower hematocrits than individuals without diabetes and men. It is unclear whether these observed differences in achieved hematocrits are caused by inherent biological differences in responsiveness to EPO or undetected differences in modifiable factors that affect response to EPO. Also potentially modulating response to EPO is diurnal variation in the bioavailability of serum iron. To address these issues, we studied 309 patients undergoing hemodialysis in two large facilities in New York City. Retrospective data collected monthly for 3 months included patients' hematocrit, dose of EPO, urea reduction ratio (URR), total amount of intravenous iron administered, serum albumin concentration, transferrin saturation, and time of day patient underwent dialysis. The 309 study subjects (165 women, 144 men) included 207 blacks (67%), 74 Hispanics (24%), 23 whites (7%), and 5 Asians (2%) with a mean age of 55.4 +/- 15.6 (SD) years. Despite a greater mean URR (74% +/- 6.4% versus 71% +/- 6%; P = 0.001) and a 39% greater dose of EPO (97 +/- 65 versus 59 +/- 53 U/kg; P = 0.001), women (36% +/- 3.5%) had hematocrits equivalent with men (36.5% +/- 3.7%; P = not significant [NS]). There was no difference in the amount of intravenous iron administered to men (375 +/- 389 mg) and women (377 +/- 413 mg; P = NS). Diabetes mellitus (P = 0.48) did not significantly affect the odds of attaining a hematocrit greater than 33% after adjustment for URR, EPO dose, and amount of intravenous iron administered. The time of day a patient underwent dialysis (P = 0.93) had no effect on their response to EPO. We conclude that gender, but not diabetes status or time of dialysis, modulates response to EPO in hemodialysis patients.

Adult↗

PubMed2001

Hemodialysis access placement with preoperative noninvasive vascular mapping: comparison between patients with and without diabetes.

We retrospectively analyzed data on preoperative vascular mapping in 195 consecutive patients to investigate the common belief that patients with diabetes are poor candidates to have an arteriovenous fistula placed as dialysis access because they lack suitable blood vessels. There was no difference in venous diameter, arterial diameter, and arterial peak systolic velocity measurements between patients with and without diabetes. Patients with diabetes had a greater prevalence of vascular calcifications and greater cuff measurements of systolic segmental arterial pressure. In 140 of 195 patients, subsequent vascular access surgery had been performed in our institution, and 127 of these patients were on hemodialysis therapy at the end of the study period. There was no difference in the prevalence of fistula placement (66% versus 60%; chi-square = 2.6; df = 2; P = 0.28, not significant [NS]) and percentage of functioning fistulae between patients with and without diabetes (67% versus 62%; chi-square = 0.27; df = 1; P = 0.61, NS). The percentage of patients dialyzed through a temporary catheter was equal in patients with and without diabetes (18%). In summary, patients with diabetes seem to be as good candidates for arteriovenous fistula placement as patients without diabetes. Additional studies are required to determine the long-term outcome of fistulae in patients with diabetes.

Arteries↗

PubMed2001

Dialysis patient characteristics and outcomes: the complexity of social work practice with the end stage renal disease population.

This article describes a demonstration project designed to explore psychosocial risk and resiliency factors, social work interventions and health-related outcomes with dialysis patients. The study is unique in including an interdisciplinary research team to guide the process, using available data contained within the medical record and focusing on interventions and outcomes over time rather than at one or two points in patients' treatment histories. It demonstrates the complexity of practice with dialysis patients and the crucial role for social workers in enhancing patient outcomes. Secondary benefits of this methodology and implications for social work practice and research are discussed.

Academic Medical Centers↗

PubMed2000

Relationship between phosphorus and creatinine clearance in peritoneal dialysis: clinical implications.

Elevated serum phosphorus levels are associated with increased morbidity and mortality in dialysis patients. To study the determinants of serum phosphorus levels and phosphorus clearance, we measured phosphorus concentrations in 24-hour collections of dialysate and residual urine output during routine urea kinetics in 56 peritoneal dialysis patients. Dietary records were used to estimate oral phosphorus intake, and the net gastrointestinal absorption of phosphorus was determined measuring the amount of phosphorus excreted in 24 hours. Dialysate to plasma ratios of phosphorus and creatinine were very similar, and the peritoneal clearances of phosphorus and creatinine correlated well and were of the same magnitude. High transporters in the peritoneal equilibration test had greater phosphorus and creatinine clearances than low transporters. In patients with residual urine output, the renal clearances of phosphorus and creatinine also correlated well. Comparing two groups of patients with a similar Kt/V of 2 and greater but different levels of creatinine clearance, either greater or less than 60 L/wk, the patients with the greater creatinine clearance also had a greater phosphorus clearance (7.0 +/- 2.2 versus 4.3 +/- 0.7 mL/min/1.73 m(2)) and significantly lower serum phosphorus levels (4.8 +/- 0.9 versus 5.9 +/- 1.4 mg/dL) despite a greater daily amount of phosphorus absorption (490 +/- 190 versus 336 +/- 100 mg/d). In summary, creatinine clearance measurements provide a good estimate of phosphorus clearance and how much dietary phosphorus and therefore protein can be tolerated.

Creatinine↗

PubMed2000

Adequacy of dialysis and differences in hematocrit among dialysis facilities.

Despite the clearly established relationship between adequacy of dialysis and response to erythropoietin, recent guidelines on anemia management in end-stage renal disease (ESRD) omit mention of dialysis adequacy while advocating the use of large amounts of intravenous iron. To determine the relative effects of adequacy of dialysis and intravenous iron on hematocrit, we studied 309 hemodialysis patients and analyzed data from 141 hemodialysis facilities in New York State (ESRD Network 2), as well as data from all 18 ESRD Networks in the United States, for the last quarter of 1997. Among the 309 subjects, mean hematocrit differed between quartiles of urea reduction ratio (URR; F statistic = 4; P: = 0.008). Patients with URRs greater than 70% were 2.6 times more likely to have hematocrits greater than 33% (odds ratio, 2.6; 95% confidence interval [CI], 1.3 to 5.3; P: = 0.009) after adjustment for other factors. Mean dialysis facility (n = 141) hematocrits correlated directly with mean URRs (r = 0.32; P: = 0.001). Facilities with a mean URR greater than 70% were three times more likely to have a mean hematocrit greater than 33% (odds ratio, 3; 95% CI, 1.2 to 7.5; P: = 0.02). The percentage of patients in each of the 18 ESRD Networks with hematocrits of 33% or greater correlated inversely with the percentage of patients administered intravenous iron (r = -0.53; P: = 0.03) after adjustment for dose of erythropoietin. We conclude that adequacy of dialysis predicts the response to erythropoietin at both patient and dialysis facility levels. Patients with low hematocrits primarily because of inadequate dialysis may inappropriately be administered excess intravenous iron intended as a corrective measure.

Hematocrit↗

PubMed2000

Marked hyperlactatemia associated with severe alkalemia in a patient with thrombotic thrombocytopenic purpura.

This report describes a case of severe alkalemia associated with a blood lactate level greater than 13 mEq/L in a patient without evidence of hypotension or hypoxemia. The patient, who had the clinical manifestations of thrombotic thrombocytopenic purpura (TTP), developed the alkalemia from an acute respiratory alkalosis superimposed on an existing metabolic alkalosis. Profound alkalemia may impair oxygen delivery because of stronger hemoglobin-oxygen affinity, vasoconstriction, and alterations in the redox potential of cytochrome c. We suggest that the synergistic effects of a sudden, extreme alkalemia and the localized tissue hypoxia that resulted from extensive microvascular thrombi secondary to TTP caused the patient's hyperlactatemia.

Adult↗

PubMed2000

The obsession with high dietary protein intake in ESRD patients on dialysis: is it justified?

BACKGROUND: The belief that dialysis patients require a much higher intake of protein than the average person is widely held among nephrologists and a recent editorial review on the care of patients undergoing hemodialysis advised a protein intake of at least 1.5 g/kg/day in this population. In theory, the requirements for daily protein intake of dialysis patients should be the same as normals plus whatever extra obligatory nitrogen losses are imposed by the dialytic process. Since the average loss of protein and/or amino acids is about 8 g/day in peritoneal dialysis and 8 g per session in hemodialysis patients, the daily intake of protein in dialysis patients needs to be increased only by this small magnitude. METHODS: All the literature reporting on nitrogen balance data on different protein intakes in chronic maintenance dialysis patients was reviewed and analyzed. RESULTS: There were 3 balance studies addressing this issue in hemodialysis patients and 6 in peritoneal dialysis patients. These data show that dialysis patients are in nitrogen balance even with a protein intake as low as 0.7 g/kg/day. CONCLUSIONS: The nitrogen balance data confirm that in stable dialysis patients a safe requirement of protein intake is about 1 g/kg/day and attempts at increasing protein intake beyond this value are not warranted. The persistent recommendation of a high dietary intake of protein for dialysis patients may reflect the influence of two other issues: the belief that dialysis is a catabolic event, and the data showing an inverse correlation between protein intake and outcome.

Dietary Proteins↗

PubMed1999

Association of acidosis and nutritional parameters in hemodialysis patients.

There is extensive literature supporting an important role for acidosis in inducing net protein breakdown, both in experimental animals and humans. However, the clinical importance of the moderate intermittent metabolic acidosis frequently observed in hemodialysis patients has not been determined. We performed a cross-sectional analysis of the baseline laboratory data in the first 1,000 patients recruited to the Hemodialysis Study, looking for correlations between predialysis serum total carbon dioxide levels and parameters related to dietary intake and nutritional status. We found the mean predialysis serum total carbon dioxide level was moderately low (21.6 +/- 3.4 mmol/L; mean +/- SD) despite the use of bicarbonate dialysate and an average single-pool Kt/V of 1.54. Predialysis serum total carbon dioxide level correlated negatively with normalized protein catabolic rate (P < 0.001), suggesting patients with lower serum total carbon dioxide levels have a greater protein intake. The degree of acidosis observed in our patients does not seem to have a deleterious effect on the nutritional status of these patients because correlation of serum total carbon dioxide level with nutritional parameters, such as serum creatinine and serum albumin levels, was either negative or not statistically significant. Further investigation of the effect of modifying serum bicarbonate concentration on nutritional markers is needed to test these hypotheses.

Acidosis↗

PubMed1999

Recurrence of scleroderma in a renal allograft from an identical twin sister.

A patient with scleroderma developed renal failure secondary to recurrence of scleroderma in a renal allograft from an identical twin. This report reviews the previous reports of scleroderma recurrence in renal allografts; the differential diagnosis of scleroderma renal crisis, including cyclosporine toxicity, malignant hypertension, and allograft rejection; and the pathophysiology of this disease.

Diagnosis, Differential↗

PubMed1999

Carboxyhemoglobin and lactate levels do not correlate in critically ill patients.

Endogenous carbon monoxide (CO) is produced in the degradation of heme by heme oxygenase. Studies have shown that hypoxia induces heme oxygenase production of CO in vascular tissue. Because elevated plasma lactate levels are associated with tissue hypoxia, we determined if there was any correlation between lactate and carboxyhemoglobin (COHb) levels in a group of critically ill patients with a high likelihood of hypoxia. In a 7.5-month period, 5322 simultaneous arterial COHb and lactate measurements were performed routinely on 183 patients with a blood gas analyzer in the Department of Veterans Affairs Medical Center, Bronx, New York, Surgical Intensive Care Unit. Sixty-one percent of the patients had elevated lactate levels (> 2.5mmol/L), and 46% had elevated COHb levels (> 1.5%). Lactate levels ranged from 0.12 to 22.7 mmol/L and COHb levels from 0% to 4.8%. There was no correlation between lactate and COHb levels (r = .07 with P < .0001). Levels of endogenous CO do not increase in situations in which lactate production is increased. It is possible that changes in endogenous production of CO may not significantly affect the circulating level of COHb. Although readily available, COHb levels do not seem to be clinically useful as markers of critical illness.

Animals↗

PubMed1999

Protein intake seems to respond to increases in Kt/V despite baseline Kt/V greater than 1.2.

The nutritional status is a strong predictor of outcome in hemodialysis patients. Adequate delivery of dialysis is necessary for hemodialysis patients to maintain their protein nutrition. In general, a single-pool Kt/V of 1.2 has been considered adequate dialysis. We recently decided to maximize the blood flow during hemodialysis in all of our patients; this enabled us to increase the dose of delivered dialysis in those patients who were not initially utilizing their maximum blood flow. There were 18 patients who already received a Kt/V greater than 1.2. We were able to increase Kt/V even further in 10 of them, resulting in a significant increase in nPCR and a trend to increase serum albumin over the next 6 months of follow-up. The mean normalized protein catabolic rate (nPCR) and serum albumin remained unchanged in the remaining 8 patients whose Kt/V could not be increased. Our data provide evidence that protein intake in hemodialysis patients will increase with an increase in delivered dialysis above the level generally considered to be adequate.

Dietary Proteins↗