Clinical and biochemical correlates of starting "daily" hemodialysis.

BACKGROUND: Daily hemodialysis has been proposed to improve outcomes for patients with end-stage renal disease. There has been increasing evidence that daily hemodialysis might have potential advantages over intermittent dialysis. However, despite these potential advantages, daily hemodialysis is infrequently used in the United States, and published accounts on the technique are few. METHODS: We describe patient outcomes after increasing their hemodialysis frequency from three to six times per week in a cohort of 72 patients treated at nine centers during 1972 to 1996. Analyses of predialysis blood pressure and laboratory parameters from 6 months before until 12 months after starting frequent hemodialysis used a repeated-measures statistical technique. RESULTS: Predialysis systolic and diastolic blood pressures fell by 7 and 4 mm Hg, respectively, after starting frequent hemodialysis (P = 0.02). Reductions were greatest among patients being treated with antihypertensive medications, despite a reduction in their dosage of medications. Postdialysis weight fell by 1.0% within one month of starting frequent hemodialysis and improved control of hypertension. After the initial drop, postdialysis weight increased at a rate of 0.85 kg per six months. Serum albumin rose by 0.29 g/dl (P < 0.001) between months 1 to 12 of treatment with daily hemodialysis. Hematocrit rose by 3.0 percentage points (P = 0.02) among patients (N = 56) not treated with erythropoietin during this period. Two years after the start of daily hemodialysis, Kaplan-Meier analyses showed a patient survival of 93%, a technique survival of 77%, and an arteriovenous fistula patency of 92%. Vascular access patency was excellent despite more frequent use of the access. CONCLUSIONS: These results suggest that in certain patients, daily hemodialysis might have advantages over three times per week hemodialysis.

Optical model for use in oceanic ecosystem models.

Modeling the plankton ecosystem requires a code for simulating the profile of irradiance from the chlorophyll profile at each time step of the integration. We have compared two existing codes with data from the Biogeochemical Ocean Flux Study: the Hydrolight radiative transfer model is accurate but too slow to use interactively in ecological models; Morel's [J. Geophys. Res. 93, 10, 749 (1988)] empirical model is much faster but produces substantial error. We have developed a streamlined version of the Hydrolight radiative transfer model that is 20 times faster than the full Hydrolight code, while limiting errors to less than 12% within the euphotic zone. This new code is both fast and accurate and is, therefore, suitable for use interactively in oceanic ecosystem models.

Prospects for a bioartificial kidney.

The developing technologies of cell therapy and tissue engineering may, in the next two decades, provide alternatives to current methods of renal replacement therapy. First, suitable organs for xenotransplantation from animals to humans may be developed, or second, as described in this report, application of tissue engineering may result in development of a range of devices to aid care of patients with renal failure. The simplest and easiest achievable devices could replace a specific aspect of renal function, such as an implantable device to produce erythropoietin. Both a bioartificial hemofilter and a renal tubule device may be developed. Ultimately this work may result in an implantable bioartificial kidney.

Vascular access survival among incident hemodialysis patients in the United States.

Vascular access failure causes substantial morbidity to hemodialysis patients. We sought to identify factors determining survival of the permanent vascular access in use at the start of end-stage renal disease during 1990 in a national sample of 784 incident hemodialysis patients insured by Medicare. Medicare claims records were used to identify access failures or revisions among patients with an arteriovenous (AV) fistula (n = 245) and an AV vascular graft (n = 539). A proportional hazards analysis of time to first failure or revision, controlled by stratification for sex, race, and cause of end-stage renal disease, was used to determine the effect of age, access type, and peripheral vascular disease on vascular access survival. Patients with an AV fistula and who were older than 65 years had a risk of access failure that was 24% lower than similar patients with an AV graft (P < 0.02). The relative risk of access failure for an AV fistula, but not an AV graft, varied significantly with age for patients younger than 65 years (P < 0.01). The relative risk of access failure for a patient with an AV fistula, compared with a patient of the same age with an AV graft, was 67% lower at the age of 40 years, 54% lower at the age of 50 years, and 24% lower at the age of 65 years. A history of peripheral vascular disease was associated with a 24% higher risk of AV graft or fistula failure (P = 0.05). Measures to decrease vascular access-related morbidity among hemodialysis patients should include reversing the current trend toward increasing use of AV grafts, particularly in patients younger than 65 years.

Predictors of type of vascular access in hemodialysis patients.

OBJECTIVE: Complications from vascular access account for 15% of hospital admissions among US hemodialysis patients. Complications are less frequent with arteriovenous fistulas than with synthetic grafts. We assessed clinical and nonclinical predictors of whether patients with end-stage renal disease (ESRD) starting hemodialysis receive a fistula or graft. We also investigated changes in practice between 1986-1987 and 1990. DESIGN: Cross-sectional study. SETTING: United States hemodialysis population. PATIENTS: Random, national samples of ESRD patients who started hemodialysis in 1986-1987 (n=2741) or 1990 (n=1409) from United States Renal Data System Special Studies. MAIN OUTCOME MEASURE: Type of permanent vascular access (arteriovenous fistula vs synthetic graft), analyzed using multivariate logistic regression. RESULTS: Clinical and demographic factors as well as socioeconomic status, region of residence, and year starting hemodialysis predicted the type of vascular access. Overall, 56% of patients had grafts 30 days after starting dialysis, but graft use increased from 51% in 1986-1987 to 65% in 1990 (adjusted odds ratio [AOR], 1.67 for 1990 vs 1986-1987; 95% confidence interval [CI], 1.43-1.95; P<.001). Graft use (relative to fistula) varied by region of residence (ranging from AOR, 0.20; 95% CI, 0.14-0.28; P<.001 [New England], to AOR, 2.69; 95% CI, 2.03-3.58; P<.001 [East South Central]; both relative to the national average). CONCLUSIONS: This national study documents large variations in the relative use of fistulas and grafts and a trend away from fistulas. The prevalence of comorbid conditions fails to explain these findings. Presentation and referral of patients early in the process of their ESRD, teaching surgeons to place fistulas, and training dialysis nurses to access fistulas may increase their use.

Comparison of mortality with home hemodialysis and center hemodialysis: a national study.

We sought to determine whether lower mortality rates reported with hemodialysis (HD) at home compared to hemodialysis in dialysis centers (center HD) could be explained by patient selection. Data are from the United States Renal Data System (USRDS) Special Study Of Case Mix Severity, a random national sample of 4,892 patients who started renal replacement therapy in 1986 to 1987. Intent-to-treat analyses compared mortality between home HD (N = 70) and center HD patients (N = 3,102) using the Cox proportional hazards model. Home HD patients were younger and had a lower frequency of comorbid conditions. The unadjusted relative risk (RR) of death for home HD patients compared to center HD was 0.37 (P < 0.001). The RR adjusted for age, sex, race and diabetes, was 44% lower in home HD patients (RR = 0.56, P = 0.02). When additionally adjusted for comorbid conditions, this RR increased marginally (RR = 0.58, P = 0.03). A different analysis using national USRDS data from 1986/7 and without comorbid adjustment showed patients with training for self care hemodialysis at home or in a center (N = 418) had a lower mortality risk (RR = 0.78, P = 0.001) than center HD patients (N = 43,122). Statistical adjustment for comorbid conditions in addition to age, sex, race, and diabetes explains only a small amount of the lower mortality with home HD.

Prostacyclin biosynthesis in essential hypertension before and during treatment.

Protacyclin biosynthesis was investigated in 133 untreated newly diagnosed patients with uncomplicated essential hypertension. Urinary excretion of 6-oxo-prostaglandin F1 alpha and of 2,3-dinor-6-oxo-prostaglandin F1 alpha, stable breakdown products of prostacyclin, was measured following a 1 month run-in period. To determine whether lowering blood pressure (BP) influenced prostacyclin biosynthesis, 106 consenting patients with diastolic pressure 90-120 mm Hg were allocated randomly to treatment with bendrofluazide, metoprolol, quinapril or amlodipine in an open parallel group design. Dose was increased to reduce diastolic arterial pressure to <90 mm Hg. Terazosin was added if this target BP was not achieved, and its dose increased if necessary. Urinary excretion rates of prostaglandins were measured after 1 year in patients in whom the target diastolic pressure was achieved. Mean arterial pressure varied from 106-168 mm Hg in untreated patients and excretion of both prostacyclin-derived products varied from <5 to >350 ng/g creatinine. Arterial pressure and prostaglandin excretion were not significantly correlated. In 57 patients in whom target pressure was achieved, BP before treatment was 166 +/- 2/100 +/- 1 at baseline and 144 +/- 2/86 +/- 1 mm Hg at 1 year. Excretion rates of each prostacyclin-derived product were similar before treatment and at 1 year, with no significant differences between the drugs. These findings do not support the hypothesis that deficient prostacyclin biosynthesis contributes to the pathogenesis of essential hypertension, or that increased prostacyclin biosynthesis plays a part in the response to treatment with antihypertensive medication.

Inhibition by nitroprusside of platelet calcium mobilization: evidence for reduced sensitivity to nitric oxide in essential hypertension.

OBJECTIVE: Although platelets from patients with moderate hypertension are abnormally sensitive to agonist-induced aggregation, their sensitivity to antagonists is not known. Nitric oxide (NO) is an endogenous antagonist of platelet function. The objective of this study was to determine whether platelet sensitivity to the inhibitory activity of sodium nitroprusside, a donor of NO, is abnormal in hypertension. DESIGN AND METHODS: Untreated patients with uncomplicated essential hypertension (mean arterial pressure > 120 mmHg) were studied. The rise in cytosolic calcium in response to 9,11-deoxy-11 alpha, 9 alpha-epoxymethanoprostaglandin F2 alpha (U46619, a thromboxane mimetic) was measured in fura-2-loaded platelets from 20 patients and 15 normotensive healthy subjects. Inhibition by sodium nitroprusside was measured in a further group of 14 patients and 20 normotensive subjects. RESULTS: Basal cytosolic calcium concentration and the rise in this parameter induced by U46619 were significantly greater in platelets from hypertensive patients than in those from normotensive controls. The mean half-maximal inhibitory concentration of nitroprusside to calcium mobilization induced by 3 mumol/l U46619 was 3.1-fold greater in platelets from hypertensive patients than in those from controls (95% confidence interval 1.6-6.0). CONCLUSION: The sensitivity of platelets to nitroprusside is reduced in essential hypertension. This reduced sensitivity to NO might influence the risk of arterial thrombosis in hypertensives.

Is this the right time to come out? Case study.

In this fictional case study, Adam Lawson is a promising young associate at Kirkham McDowell Securities, a St. Louis underwriting and financial advisory firm. Recently, Adam helped to bring in an extremely lucrative deal, and soon he and a few other associates will be honored for their efforts at the firm's silver anniversary dinner. George Campbell, vice president in mergers and acquisitions, is caught unprepared when Adam tells him that, after serious reflection, he has decided to bring his partner, Robert Collins, to the banquet. George is one of Adam's biggest supporters at the firm, and he personally has no problem with Adam being gay. But it is one thing for Adam to come out of the closet at the office. It is quite another to do so at a public company-client event. After all, Kirkham McDowell's client roster includes some very conservative companies--one of the country's largest defense contractors, for example. George is concerned with how Adam's openness about his sexual orientation will play with their clients and, as a result, how senior management will react. Adam has not come to George for permission to bring Robert to the dinner. But clearly Adam wants some sort of response. George has never faced sexual diversity issues in the workplace before, and there is no company policy to guide him. Just how negative an effect could Robert have on Adam's career with the firm and the firm's relationship with its clients? Isn't it possible that even the firm's most conservative clients will simply decide that Adam's choice of guest is a personal matter--not a business one?(ABSTRACT TRUNCATED AT 250 WORDS)

Disopyramide kinetics in patients with acute myocardial infarction.

The kinetic behavior of disopyramide was studied in 20 patients with suspected myocardial infarction: in 13 of these, the diagnosis was subsequently confirmed. All received a 400-mg oral loading dose of disopyramide base followed by an oral maintenance regimen of either 100 or 200 mg 4 times daily. The elimination half-life (t1/2beta) was longer (p less than 0.05) in patients with confirmed infarction than in patients with unconfirmed infarction [38.0 +/- 3.7 hr (mean +/- SEM) compared to 24.3 +/- 0.8 hr, and 21.2 +/- 2.1 hr compared to 7.2 +/- 2.4 hr for the 100- and 200-mg maintenance dose regimens, respectively]. The t1/2beta was dose dependent for infarct and noninfarct patients. Two of the patients with confirmed infarction failed to reach trough plasma levels equal to or exceeding the lower end of the manufacturer's recommended therapeutic range (3.3 mug/ml) during the study. For the remaining 11 patients the time taken to achieve trough plasma levels of 3.3 mug/ml varied from 18 to 170 hr; hence plasma disopyramide concentration in these patients was suboptimal at a time when the risk of arrhythmias is high. Modification of existing oral loading dose regimens is therefore required for optimization of oral disopyramide therapy.

Acute transmural myocardial infarction associated with active Coxsackie virus B infection.

Out of a total of 233 patients suffering from transmural myocardial infarction, 20 patients were found to have serologic evidence of a concurrent active Coxsackie virus B infection. While the infection may have been coincidental, it is also possible that the virus may have played some part in the illness. Conceivably, myocarditis could be mistaken for infarction or, by some mechanism as yet unknown, the virus might precipitate infarction in susceptible subjects.