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Biomedical subjects

A J Collins

Publications and source records attributed to A J Collins.

At least 37 records · Page 2Linked to original sources
PubMed2000

Impact of hematocrit on morbidity and mortality.

It has been 10 years since epoetin-alpha was approved by the federal Food and Drug Administration for use in end-stage renal disease patients. Over this period of time, clinical studies have shown a relationship between the correction of anemia and improved cardiac function, cognitive ability, sexual function, and exercise capacity. Recent large epidemiological studies have shown that mortality and morbidity are reduced when the hematocrit (Hct) level is in the range 33% to 36%, and the National Kidney Foundation's Dialysis Outcomes Quality Initiative (NKF-DOQI) guidelines recommend a target Hct of 33% to 36% to enhance patient outcomes. The most recent mortality studies show that Hcts less than 30% (or hemoglobins less than 110 gm/L) are associated with an 18% to 40% increased associated risk of death and hospitalizations. Higher Hcts in the 33% to 36% range appear to be associated with a 7% reduced risk of death and hospitalizations compared with patients with Hcts of 30% to less than 33%. Patients with sustained Hcts of 33% to 36% over 1 year appear to have the best outcome compared with patients with Hcts that fall. These studies suggest that the factors that may influence patients' ability to move into higher Hct ranges need to be determined to enhance patient outcomes. Dramatic improvement in hemodialysis patient Hct levels has occurred since 1989. Mortality and hospitalization studies support the NKF-DOQI target Hct range of 33% to 36% as providing the best associated outcomes.

Anemia, Iron-Deficiency↗
PubMed2000

Hospitalization risks between Renagel phosphate binder treated and non-Renagel treated patients.

AIM: We evaluated 152 sevelamer hydrochloride treated Medicare patients on hemodialysis in a case-controlled study matching 152 randomly selected non-sevelamer hydrochloride treated Medicare patients from the same dialysis facilities and time period. The main outcomes evaluated were the risk of all-cause hospitalization and per-member per-month (PMPM) Medicare expenditures in the follow-up period. PATIENTS AND METHODS: Medicare patients were identified from a total of 195 patients who were included in a long-term safety and efficacy clinical trial evaluating sevelamer hydrochloride [Chertow et al. 1999a]. The average serum calcium-phosphorus product as well as lipid profiles improved in the sevelamer hydrochloride treated group during the trial. Sevelamer treated patients were matched with randomly selected Medicare patients for age, gender, race, diabetic status, and geographic location. Comorbid conditions were characterized and sequential Cox regression models were applied with the outcome being risk of first hospitalization in a 17- month follow-up period. RESULTS: Across all four models, the relative risk of hospitalization was 46% to 54% less in the sevelamer hydrochloride treated group, as compared to the case control group (significant at the p-value 0.03 level). Overall, Medicare expenditures for the control patients per-member per-month were US-$4,745, compared to US-$3,368 in the sevelamer hydrochloride treated patients. CONCLUSION: Sevelamer hydrochloride treated patients had a 50% lower likelihood of hospitalization in the follow-up period after adjustments for the differences in the population. Potential bias may exist between groups because of differences in baseline characteristics that could not be adjusted for within the study design. We feel that to further advance this area, a randomized clinical trial should be performed.

Hospitalization↗
PubMed1999

Mortality risks of peritoneal dialysis and hemodialysis.

Studies of outcomes associated with dialysis therapies have yielded conflicting results. Bloembergen et al showed that prevalent patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, and Fenton et al, analyzing Canadian incident patients, found a 27% lower risk. Attempting to reconcile these differences, we evaluated incident Medicare patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplantation, death, loss to follow-up, 60 days after modality change, or end of the study period. For each 3-month survival period, we used an interval Poisson regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specific mortality, and proportionality was addressed in both regressions by separating diabetic and nondiabetic patients. The Poisson regressions showed CAPD/CCPD to have outcomes comparable with or significantly better than hemodialysis, although results varied over time. The Cox regression found a lower mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 years: risk ratio [RR] = 0. 61; Cl, 0.59 to 0.66; women age 55 years or older: RR = 0.87; Cl, 0. 84 to 0.91; men younger than 55 years: RR = 0.72; Cl, 0.67 to 0.77; men age 55 years or older: RR = 0.87; Cl, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; Cl, 0. 82 to 0.94; men: RR = 0.86; Cl, 0.81 to 0.92). The risk of all-cause death for female diabetics 55 years of age and older, in contrast, was 1.21 (Cl, 1.17 to 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be associated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over time, a nonproportionality that makes survival analyses vulnerable to the length of follow-up. Further investigation is needed to evaluate both the potential explanations for these findings and the use of more advanced statistical methods in the analysis of mortality rates associated with these dialytic therapies.

Aged↗
PubMed1999

Modelling molecular mechanisms controlling sequential gene expression in differentiating mammalian enterocytes.

The gut epithelium represents a continuous developmental system in which cell proliferation in intestinal crypts is followed by the sequential expression of digestive and absorptive functions as enterocytes migrate out of crypts to the tips of intestinal villi. We have developed a mathematical model in the present work to mimic these sequential aspects of enterocyte differentiation. Using this model allows the characteristics of lactase expression to be ascribed to transcriptional control. In the case of a glucose transporter, however, it became necessary to assume an additional translational control that decreased exponentially as enterocytes migrated along villi. The suggestion that this type of modelling is useful in predicting which set of enterocytes is likely to use translation or transcription to control gene expression is also discussed.

Animals↗
PubMed1999

Long-term outcome of dialysis patients in the United States with coronary revascularization procedures.

BACKGROUND: The optimal method of coronary revascularization in dialysis patients is controversial, as previous small retrospective studies have reported increased cardiac events after percutaneous transluminal coronary angioplasty (PTCA) compared with coronary artery bypass (CAB) surgery. The purpose of this study was to compare the long-term survival of chronic dialysis patients in the United States following PTCA or CAB surgery. METHODS: Dialysis patients hospitalized from 1978 to 1995 for first coronary revascularization procedure after initiation of renal replacement therapy were retrospectively identified from the United States Renal Data System database. Survival for the endpoints of all-cause death, cardiac death, myocardial infarction, and cardiac death or myocardial infarction was estimated by the life-table method and was compared by the log-rank test. The impact of independent predictors on survival was examined in a Cox regression model with comorbidity adjustment. RESULTS: The in-hospital mortality was 5.4% for 6887 PTCA patients and 12.5% for 7419 CAB patients. The two-year event-free survival (+/-SE) of PTCA patients was 52.9 +/- 0.7% for all-cause death, 72.5 +/- 0.7% for cardiac death, and 62.0 +/- 0.7% for cardiac death or myocardial infarction. In CAB patients, the comparable survivals were 56.9 +/- 0.6, 75.8 +/- 0.6, and 71.3 +/- 0. 6%, respectively (P < 0.02 for PTCA vs. CAB surgery for all endpoints). After comorbidity adjustment, the relative risk of CAB surgery (vs. PTCA) performed 1990 to 1995 for all-cause death was 0. 91 (95% CI, 0.86 to 0.97); cardiac death, 0.85 (95% CI, 0.78 to 0. 92); myocardial infarction, 0.37 (95% CI, 0.32 to 0.43); and cardiac death or myocardial infarction 0.69 (95% CI, 0.64 to 0.74). CONCLUSIONS: In this retrospective study, dialysis patients in the United States had better survival after CAB surgery compared with PTCA, but our study does not exclude the possibility of more unfavorable coronary anatomy in the PTCA patients at baseline. Our data support the need for prospective trials of newer percutaneous coronary revascularization procedures in dialysis patients.

Adult↗
PubMed1999

An unusual helical micro-organism found in the gut lumen of human subjects.

An earlier report described the discovery of a micro-organism in the form of a double helix in human small bowel biopsies. Mucosal biopsies of the stomach and small bowel obtained from patients with rheumatic diseases and dyspepsia by enteroscopy and gastroscopy were fixed for scanning electron microscopy to investigate the organism further. In 62% of biopsies, an organism in the form of a double helix with bifid ends, 5-30 microm long, was found lying free on the surface of the mucosa. The organism has been demonstrated in the stomach, duodenum and small bowel. Flagella were never seen to be associated with the organism. In spite of its helical form, the organism lacks many of the factors associated with spirochaete morphology. It is suggested that this, as yet unnamed organism, may be found throughout the length of the digestive tract. Its pathological significance is not known.

Aged↗
PubMed1999

Hematocrit level and associated mortality in hemodialysis patients.

Although a number of clinical studies have shown that increased hematocrits are associated with improved outcomes in terms of cognitive function, reduced left ventricular hypertrophy, increased exercise tolerance, and improved quality of life, the optimal hematocrit level associated with survival has yet to be determined. The association between hematocrit levels and patient mortality was retrospectively studied in a prevalent Medicare hemodialysis cohort on a national scale. All patients survived a 6-mo entry period during which their hematocrit levels were assessed, from July 1 through December 31, 1993, with follow-up from January 1 through December 31, 1994. Patient comorbid conditions relative to clinical events and severity of disease were determined from Medicare claims data and correlated with the entry period hematocrit level. After adjusting for medical diseases, our results showed that patients with hematocrit levels less than 30% had significantly higher risk of all-cause (12 to 33%) and cause-specific death, compared to patients with hematocrits in the 30% to less than 33% range. Without severity of disease adjustment, patients with hematocrit levels of 33% to less than 36% appear to have the lowest risk for all-cause and cardiac mortality. After adjusting for severity of disease, the impact of hematocrit levels of 33% to less than 36% is vulnerable to the patient sample size but also demonstrates a further 4% reduced risk of death. Overall, these findings suggest that sustained increases in hematocrit levels are associated with improved patient survival.

Adult↗
PubMed1999

Hematocrit levels and hospitalization risks in hemodialysis patients.

The association between hematocrit level and future hospitalization risks in hemodialysis patients has not been fully investigated on a national level. A total of 71,717 prevalent Medicare hemodialysis patients who survived a 6-mo entry period from July 1 through December 31, 1993 were studied, and their risk of hospitalizations was evaluated the next year. Five hematocrit groups were defined from Medicare recombinant human erythropoietin-treated patients: <27%, 27 to <30%, 30 to <33%, 33 to <36%, and > or =36%. A Cox regression model was used to investigate the association between hematocrit level and the risk of first hospitalization, and the Andersen-Gill regression model evaluated multiple hospitalizations during the next year, adjusting for patient comorbidity and severity of disease. Compared with the baseline group of 30 to <33%, patients with hematocrit levels <30% had a 14 to 30% increased risk of hospitalization without disease severity adjustment (p = 0.0001) and a 7 to 18% increased risk with disease severity adjustment (p = 0.0001). Patients in the 33 to <36% group had the lowest risk at 0.93 and 0.88 (p = 0.0001), with and without adjustment for disease severity. It is concluded that patients with hematocrits of <30% have an increased risk of future hospitalization, with hematocrit levels between 33 and 36% having the lowest associated risks.

Adult↗
PubMed1999

Biochemical markers of bone metabolism in mild ankylosing spondylitis and their relationship with bone mineral density and vertebral fractures.

OBJECTIVE: To determine the relationship of biochemical markers of bone metabolism in patients with mild ankylosing spondylitis (AS) with disease activity, bone mineral density (BMD), and vertebral fractures. METHODS: A total of 56 male patients with mild AS were studied. All patients had BMD measured by dual x-ray absorptiometry of the lumbar spine and hip and radiographs of the thoracic and lumbar spines. Radiographs of patients with AS were evaluated morphometrically and vertebral fractures were defined using established criteria. Serum osteocalcin, total and bone alkaline phosphatase (ALP, BALP, respectively), 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), urinary deoxypyridinoline (Dpyr), and pyridinoline (Pyr) were measured in the patients with AS and compared with 52 age and sex matched controls. Thirty-nine healthy male subjects aged 50-60 years, recruited from primary care registers, had spinal radiographs and served as controls for vertebral fractures. RESULTS: Patients with AS had reduced BMD of the lumbar spine, 0.98 (0.1) g/cm2 [T score = -1.14 (1.2) and Z score = -1.01 (1.2)], and femoral neck, 0.83 (0.1) g/cm2 [T score = -1.44 (1.2) and Z score = -0.73 (1.1)]. Of the 56 patients with AS, 11 (19.6%) had a vertebral fracture, whereas only one of 39 control subjects did (2.6%). Patients with AS had significantly lower mean serum osteocalcin compared with controls [9.03 (2.7) microg/l vs 11.05 (2.33) microg/l; p < 0.001], and significantly higher mean serum ALP [73.09 (19.5) U/l vs 53.02 (16.7) U/l; p < 0.001] and BALP [38.54 (9.9) U/l vs 30.35 (8.28) U/l; p < 0.001]. There was no significant difference in the excretion of Dpyr and Pyr between patients with AS and controls [4.90 (3.9) nmol/mmol vs 4.00 (3.6) nmol/mmol, and 15.66 (10.8) nmol/mmol vs 12.24 (10.3) nmol/mmol, respectively]. There were no significant differences in the mean 25-OHD and PTH levels in patients with AS compared to controls [20.03 (1.6) micromol/l vs 18.9 (2.9) micromol/l and 3.31 (1.5) pmol/l vs 2.63 (0.4) pmol/l, respectively]. The biochemical markers of bone formation and resorption correlated well with inflammatory indices of disease activity (acute phase reactants), but not with BMD of the lumbar spine or femoral neck. No significant difference was seen in any marker of bone turnover when AS patients with vertebral fractures were compared with those without. CONCLUSION: Bone turnover in patients with mild AS is characterized by low serum osteocalcin and ALP in the presence of normal calciotropic hormones. Biochemical markers of bone metabolism do not correlate with BMD or vertebral fractures. The disparity between osteocalcin and alkaline phosphatase in patients with AS needs further evaluation.

Adult↗
PubMed1999

Testosterone and testosterone free index in mild ankylosing spondylitis: relationship with bone mineral density and vertebral fractures.

OBJECTIVE: To determine the androgen status of men with mild ankylosing spondylitis (AS) and to evaluate the relationship of sex hormones with bone mineral density (BMD) and vertebral fractures. METHODS: Fifty-six male patients with mild AS were studied. All patients had BMD measured by dual x-ray absorptiometry (DXA) of the lumbar spine and hip, and had radiographs of the thoracic and lumbar spines. Radiographs were evaluated morphometrically, and vertebral fractures were defined using established criteria. Serum total testosterone, sex hormone binding globulin (SHBG), follicle stimulating hormone (FSH), and luteininzing hormone (LH) were measured in the patients with AS and 52 age matched controls. Testosterone free index (TFI) was calculated. RESULTS: There was a small, not significant reduction in serum total testosterone in patients with AS compared to controls [16.02 (5.0) vs 21.0 (6.2) nmol/l]. Serum SHBG was significantly lower in patients with AS [27.29 (10.6) vs 35.0 (13.0) nmol/l; p < 0.001] compared to controls. There was no significant difference in the mean TFI between patients and controls [58.7 (21.2) vs 60 (22.2) nmol/l; p > 0.05] or in the levels of LH and FSH. No significant correlation was found between sex hormones, BMD, and vertebral fractures in patients with AS. CONCLUSION: Sex hormones are not altered significantly in patients with mild AS and do not appear to be related to BMD or vertebral fractures. Osteopenia in men with mild AS is therefore unlikely to be secondary to hypogonadism.

Adult↗
PubMed1998

Poor long-term survival after acute myocardial infarction among patients on long-term dialysis.

BACKGROUND: Cardiovascular disease is common in patients on long-term dialysis, and it accounts for 44 percent of overall mortality in this group. We undertook a study to assess long-term survival after acute myocardial infarction among patients in the United States who were receiving long-term dialysis. METHODS: Patients on dialysis who were hospitalized during the period from 1977 to 1995 for a first myocardial infarction after the initiation of renal-replacement therapy were retrospectively identified from the U.S. Renal Data System data base. Overall mortality and mortality from cardiac causes (including all in-hospital deaths) were estimated by the life-table method. The effect of independent predictors on survival was examined in a Cox regression model with adjustment for existing illnesses. RESULTS: The overall mortality (+/-SE) after acute myocardial infarction among 34,189 patients on long-term dialysis was 59.3+/-0.3 percent at one year, 73.0+/-0.3 percent at two years, and 89.9+/-0.2 percent at five years. The mortality from cardiac causes was 40.8+/-0.3 percent at one year, 51.8+/-0.3 percent at two years, and 70.2+/-0.4 percent at five years. Patients who were older or had diabetes had higher mortality than patients without these characteristics. Adverse outcomes occurred even in patients who had acute myocardial infarction in 1990 through 1995. Also, the mortality rate after myocardial infarction was considerably higher for patients on long-term dialysis than for renal-transplant recipients. CONCLUSIONS: Patients on dialysis who have acute myocardial infarction have high mortality from cardiac causes and poor long-term survival.

Adult↗
PubMed1998

Isolation, characterisation and mapping of simple sequence repeat loci in potato.

Solanum tuberosum L. DNA sequences containing simple sequence repeat (SSR) motifs were extracted from the EMBL database, cDNA and selectively enriched small-insert DNA libraries. Enrichment was achieved using either triplex affinity capture or single-strand hybridisation selection. One hundred and twelve primer pairs which successfully amplified products of the correct size from potato DNA were ultimately designed and synthesised. Ninety-eight of these revealed length polymorphisms in a panel of four diploid and two tetraploid clones, in agreement with the high information content of this class of markers which has been found in other species. All of the markers were assigned a quality score of 1-5 based on their potential usefulness. Eighty-nine loci from 65 of the primer pairs were located on two genetic linkage maps of potato by segregation analysis of the amplified alleles. Fifty-two of the SSRs were clearly single locus. The maps were aligned using 23 SSR primer pairs and 13 RFLP loci mapped in both populations. The markers described constitute a class which should replace Restriction Fragment Length Polymorphisms (RFLP) as the markers of choice for future genetic studies in potato. The sequences of the primers, together with other information on these markers are provided.

Base Sequence↗
PubMed1998

Trends in anemia treatment with erythropoietin usage and patient outcomes.

Recombinant erythropoietin, first approved for Medicare reimbursement in June 1989, was prescribed at initial doses for dialysis patients of 2,500 to 2,700 U per administration independent of hematocrit level. By 1997, however, patients with hematocrits less than 30% were administered 6,000 U/dose, compared with 4,500 U administered to patients with hematocrits of 33% to 36%. Since 1990, the percentage of patients with hematocrits less than 30% decreased from 60% to 22% in 1997, whereas the percentage of patients with hematocrits of 33% to 36% increased from 10% to 30%. In 1997, Medicare initiated the Hematocrit Measurement Audit (HMA) policy, which was directed at reducing the percentage of claims for hematocrits greater than 36% and increasing the stability of the hematocrit levels. The policy change achieved the initial effect but resulted in a reduction of the mean hematocrit as well. The policy was changed in 1998 in response to patient and provider concerns. Mortality studies show that hematocrits less than 30% (or hemoglobin levels < 110 g/L) are associated with an 18% to 40% increased associated risk for death. Higher hematocrits of 33% to 36% appear to be associated with a 7% reduced risk for death. The risk for hospitalization parallels that of mortality. Patients with sustained hematocrits of 33% to 36% over 1 year appear to have the best outcome compared with patients with hematocrits that decrease. The latter are at greater risk than those patients in whom the hematocrits increase. In conclusion, dramatic improvements in hemodialysis patient hematocrits have occurred since 1989. Mortality and hospitalization studies support the National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF DOQI) target hematocrit range of 33% to 36% as providing the best associated outcomes.

Anemia↗
PubMed1998

Dialysis unit and patient characteristics associated with reuse practices and mortality: 1989-1993.

The diverse patient and dialysis unit characteristics in the United States pose challenges for assessing the safety and efficacy of reuse practices. A 10% random sample of period-prevalent hemodialysis patients from units practicing conventional dialysis (<25% of patients with high-efficiency/high-flux dialysis) were analyzed. The data included 13,926 patient observations in 1989-1990 and 20,422 in 1991-1993. Centers for Disease Control and Prevention and Health Care Financing Administration facility survey Medicare data were analyzed with a Cox regression model, evaluating the risk of reuse compared with no reuse and adjusting for comorbidity, unit characteristics, and profit status. In 1989-1990, freestanding and hospital-based units that did not reuse dialyzers were not significantly different from each other in mortality rates. In 1991-1993, however, no-reuse, freestanding, for-profit units had higher risks (relative risk [RR] = 1.23, P = 0.003) compared with no-reuse, hospital-based, nonprofit units. No-reuse, hospital-based, for-profit units, in contrast, were associated with a lower mortality risk (RR = 0.70, P = 0.0001). An isolated higher risk associated with peracetic acid manual reuse in freestanding units (1989-1990) was identified in for-profit units only. In the 1991-1993 period, an increased mortality risk was noted in hospital-based, nonprofit units practicing formaldehyde automatic reuse, and in freestanding, for-profit units using glutaraldehyde, which accounted for <5% of all units. All other interactions of reuse germicide and technique were not different from no-reuse. The varying mortality rates identified in both no-reuse and reuse units using conventional dialysis suggest that other factors, such as dialysis therapy and anemia correction (both known predictors of patient survival), have a greater influence on U.S. mortality than reuse germicides and techniques.

Adult↗
PubMed1997

Quantification of hemodialysis: analysis of methods and the relevance to patient outcome.

Quantification of small solute removal in patients treated with chronic hemodialysis (HD) is widely used to assessed the adequacy of both prescribed and delivered treatment. Four recent American studies have demonstrated a clear relationship between delivered dialysis dose and outcome in chronic HD patients. Although a number of HD quantification methods have been proposed, no specific technique is accepted as the gold standard at present. The primary goal of this review is to provide a critical assessment of the four recently published studies relating to HD outcome to dialysis dose. As these studies involved a variety of therapy quantification methods, a review of the most common techniques used to measure dialysis dose is also presented. In addition, two unresolved issues that have recently come to the forefront of HD quantification are presented. These issues are the role of dialysate-side measurement of HD dose and the potential limit of the beneficial effect of increasing HD dose on clinical outcome. Finally, the overall design of the NIH HD adequacy trial is discussed, with particular attention paid to the kinetic methods used in the study.

Humans↗
PubMed1996

Determination of residual renal function with iohexol clearance in hemodialysis patients.

Residual renal function (RRF) may contribute significantly to the total dialysis prescription. Conventional quantitation of RRF in hemodialysis (HD) patients is measured by urea clearance and requires a 24-hour urine collection which is often difficult to perform and inaccurate. The renal clearance of iohexol was evaluated as an alternative method for RRF assessment (iohexol-derived RRF) in hemodialysis patients. An intravenous bolus of iohexol (12 ml; 300 mg iodine/ml) was administered to 42 hemodialysis patients following routine HD. A single blood sample was obtained approximately 44 hours later (pre-HD) to determine the plasma clearance of iohexol using x-ray fluorescence methods. Total body clearance of iohexol (CTBio) and non-renal clearance of iohexol (CNRio) 2.87 +/- 0.3 ml/min (mean +/SEM) were used to calculate iohexol-derived RRF (CTBio-CNRio). Iohexol-derived RRF determinations were then compared to urea clearance-derived RRF measurements. The RRF contribution to the dialysis prescription was also calculated utilizing iohexol-derived RRF compared to urea-derived RRF. Iohexol-derived RRF did not differ from urea-derived RRF (2.48 +/- 0.3 vs. 2.64 +/- 0.4 ml/min, P = 0.21). The RRF contribution to the weekly dialysis prescription (Kt/V) did not differ when iohexol-derived RRF was compared to urea-derived RRF (0.94 +/- 0.1 vs. 0.93 +/- 0.1, P = 0.9). Additionally, the effect of iohexol on RRF was assessed in 17 HD patients. Urea-derived RRF determinations one week after iohexol exposure did not differ from those measured one week prior to iohexol exposure (3.17 +/- 0.6 vs. 2.91 +/- 0.5 ml/min, respectively). Thus, renal clearance of iohexol can be an accurate and safe measure of RRF in HD patients and potentially simplify delivery of the dialysis prescription.

Adult↗
PubMed1996

Multicenter clinical validation of an on-line monitor of dialysis adequacy.

Quantitation of hemodialysis by measuring changes in blood solute concentration requires careful timing when taking the postdialysis blood sample to avoid errors from postdialysis rebound and from recirculation of blood through the access device. It also requires complex mathematical interpretation to account for solute disequilibrium in the patient. To circumvent these problems, hemodialysis can be quantified and its adequacy assessed by direct measurement of the urea removed in the dialysate. Because total dialysate collection is impractical, an automated method was developed for measuring dialysate urea-nitrogen concentrations at frequent intervals during treatment. A multicenter clinical trial of the dialysate monitoring device, the Biostat 1000 (Baxter Healthcare Corporation, McGaw Park, IL) was conducted to validate the measurements of urea removed, the delivered dialysis dose (Kt/V), and net protein catabolism (PCR). The results were compared with a total dialysate collection in each patient. During 29 dialyses in 29 patients from three centers, the paired analysis of urea removed, as estimated by the dialysate monitor compared with the total dialysate collection, showed no significant difference (14.7 +/- 4.7 g versus 14.8 +/- 5.1 g). Similarly, measurements of Kt/V and PCR showed no significant difference (1.30 +/- 0.18 versus 1.28 +/- 0.19, respectively, for Kt/V and 42.3 +/- 15.7 g/day versus 52.2 +/- 17.4 g/day for PCR). When blood-side measurements during the same dialyses were analyzed with a single-compartment, variable-volume model of urea kinetics, Kt/V was consistently overestimated (1.49 +/- 0.29/dialysis, P < 0.001), most likely because of failure to consider urea disequilibrium. Because urea disequilibrium is difficult to quantitate during each treatment, dialysate measurements have obvious advantages. The dialysate monitor eliminated errors from dialysate bacterial contamination, simplified dialysate measurements, and proved to be a reliable method for quantifying and assuring dialysis adequacy.

Cross-Sectional Studies↗