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PURPOSE: Prosthetic accesses of the upper extremity have been in use for more than 25 years. Many different conduits have been employed; investigators have continually searched for a graft with superior properties. METHODS: We describe a prospective randomized study comparing the new Slider Graft (Atrium) with the Hybrid PTFE Graft (Atrium); the latter has been used for a number of years. The Slider Graft is also made of PTFE. For this study, both grafts were 6 mm in diameter and 40 cm in length. The Slider Graft has a low friction polyethylene sheath over its entire length. This sheath expedites the passage of the graft through the tunnel. At one end, the graft and the polyethylene sheath are attached to a metal tip. This tip has male threads, which may be inserted firmly into a Kelly Wyck, Atrium, or any standard non-sheath tunneling system. This alleviates graft separation, turning, and slipping during tunneling. The primary objective of this trial was to determine the safety and efficacy of the Slider Graft as compared to the Hybrid Graft in vascular access surgery. The secondary objective was to evaluate how tunneling effects graft performance. We randomized 60 subjects for this study with two equal arms. During surgery we measured various parameters including ease of tunneling, tunnel bleeding, anastomotic bleeding, graft sweating, and immediate patency. To assess arm edema we measured circumference 7.5 cm and 20 cm above the wrist, prior to surgery and in follow-up visits at 1 week, 1 month, and 3 months. Primary patency was also assessed at these visits and at 6, 9, and 12 months. RESULTS: Our results show tunneling with the Slider Graft is easier to accomplish (p = 0.0001) with reduced tunnel bleeding (p = 0.0047) and anastomotic bleeding (p = 0.042). Further, the Slider Graft virtually eliminated the complication of graft sweating and seroma development (p = 0.0005). This may be due to reduced stretching and graft wetting during insertion. At 180 days the Slider Graft demonstrated improved primary patency, which was statistically significant (p = 0.047). At 360 and 720 days the Slider Graft continued to demonstrate a trend toward improved primary patency (p = 0.160). CONCLUSIONS: This study suggests the Slider Graft has significant advantages when compared to the Hybrid Graft and highlights the importance of tunneling in creating prosthetic accesses.

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PURPOSE: The most common complication of vascular access surgery is thrombosis. This study compared the gold standard Fogarty Thrombectomy Catheter, to the new latis Catheter with an advanced monofilament matrix. METHODS: 30 patients with thrombosed access grafts were randomly assigned to undergo thrombectomy with the Fogarty or latis catheter. An angioscope measured remaining graft thrombi. RESULTS: Twenty-nine of 30 subjects were successfully thrombectomized. No statistical differences in age, gender, race, or extension graft requirements were found. Catheter use in the latis group was: 1 in 14 procedures, and 2 in 1 procedure; Fogarty group: 1 in 10 procedures, 2 in 3 procedures, and 3 in 2 procedures. The average number of catheter passes was: latis 3.06 (1-6 passes) and Fogarty 4.13 (1-9 passes). A trend in favor of the latis catheter was demonstrated; however, statistical significance was not reached (p = 0.067). The overall 6-month primary patency rates were latis (40%) and Fogarty (30%). The estimated patency at the 50th percentile for latis is 120 days and Fogarty 108 days. Statistical significance was not reached with a p-value of the Log-Rank statistic of 0.68 and a p-value of the Wilcoxon statistic of 0.78. CONCLUSIONS: The latis and Fogarty catheters are very similar. However, the latis balloon is more rugged with fewer catheters used and reduced number of passes. A difference in primary patency could not be demonstrated. The angioscope identified significant residual thrombus despite no returning thrombus from the catheter. Consequently, our protocol is modified to include the angioscope.

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Recent clinical trials aimed at attenuating complications in diabetes mellitus have generated interest in the impact of drug formulation and altered pharmacokinetics and pharmacodynamics in diabetes. Specifically, it has been proposed that the diabetic state may alter the pharmacokinetics of several cardiovascular drugs, including some calcium antagonists. The present study investigates the effects of diabetes mellitus on the pharmacokinetics and pharmacodynamics of amlodipine in hypertensive subjects with and without diabetes mellitus to determine whether the diabetic state alters these parameters. This trial consisted of a 2-week placebo washout phase, a 2-week titration phase, and a 2-week maintenance phase. Study patients included 18 hypertensive patients with type II diabetes mellitus and 10 nondiabetic hypertensive patients. Blood samples were collected after administration of amlodipine and AUC, Cmax, and tmax were determined. The acute 24-hour pharmacodynamic response to amlodipine was assessed by blood pressure and telemetric heart rate measurements. There were no significant differences for either amlodipine 5 or 10 mg in AUC (p = 0.40 for 5 mg; p = 0.59 for 10 mg), Cmax (p = 0.41 for 5 mg; p = 0.45 for 10 mg), and tmax (p = 0.79 for 5 mg; p = 0.67 for 10 mg) between diabetic and nondiabetic hypertensive subjects. Similarly, the 24-hour pharmacodynamic effects of amlodipine on systolic blood pressure, diastolic blood pressure, and heart rate did not differ between diabetic and nondiabetic subjects as assessed by repeated-measures analysis of variance. Because of the theoretical basis for anticipating that diabetes mellitus may provoke important pharmacokinetic and pharmacodynamic alterations, our study provides an important database in clearly demonstrating that the diabetic milieu did not alter the pharmacokinetics or pharmacodynamics of amlodipine.

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CONTEXT: There is relatively little data available on the management of patients with severe, uncomplicated hypertension and severe hypertension with stable hypertensive complications. OBJECTIVE: To determine the incidence, clinical features, acute management, and clinical course of severe, uncomplicated hypertension and severe hypertension with stable hypertensive complications presenting for emergency department care in a large public teaching hospital. DESIGN: Chart survey of consecutive emergency department visits. PATIENTS: Ninety-one of 2898 consecutive visits to a public teaching hospital emergency department were specifically for severe, uncomplicated hypertension. RESULTS: Of 2898 consecutive medical emergency department visits, there were 142 (4.9%) patient visits specifically for systolic blood pressure (SBP) > or =220 mm Hg or diastolic blood pressure (DBP) > or =120 mm Hg. Ninety-one of the 142 patient visits were for severe hypertension in the absence of acute target organ impact or neuroretinopathy. Eighty-nine patients received acute drug therapy. Twenty-nine patients received two drugs, and 15 received three drugs. Sixty-eight patients (75%) received clonidine, and 15 (16.5%) received short-acting nifedipine despite widely published concerns about the safety of this practice. We found a wide variability of blood pressure response to treatment. The average decline in SBP was 50+/-31 mm Hg and the average decline of DBP was 34+/-20 mm Hg over 4.2+/-2.9 h. Forty-two patients (46%) had the SBP reduced to less than 160 mm Hg, and 46 patients (50%) the DBP to less than 100 mm Hg. Long-term management and follow-up were suboptimal. Of 74 patients discharged from the emergency room, 22 patients (30%) returned because of uncontrolled hypertension within an average of 33+/-28 days, 10 patients with hypertensive complications. CONCLUSIONS: Severe hypertension continues to present an important and common problem. Physicians appear to place a strong emphasis on acute lowering of the blood pressure to near-normal levels. Patients are frequently lost to follow-up and have a very high rate of recurrent emergency department visits and hypertensive complications. This study points to a need for detailed, specific practice guidelines and comprehensive disease management protocols for severe, uncomplicated hypertension.

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In an open-labeled trial with eight elderly patients (aged 62 to 87 years) suffering from nocturnal leg cramps refractory to treatment with quinine sulfate, we ruled out other active disease processes and substituted verapamil hydrochloride therapy (120 mg at bedtime). Response to treatment was assessed by biweekly observations by the primary care physician and nightly by the research registered nurse for the entire duration of the trial, lasting eight weeks. Observations made and clinical conditions reported were indicative of improvement and disappearance of cramping when therapy was changed from quinine to verapamil. This noteworthy improvement in patients with recumbent nocturnal leg cramps is an important finding and merits further investigation.

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The pharmacokinetics of ranitidine were studied in ten patients with renal failure (creatinine clearance, 6-54 mL/min) after intravenous (IV) (50 mg) and oral doses (150 mg). After oral administration, peak plasma concentrations of 378-808 ng/mL were obtained in two to six hours. Plasma concentrations declined very slowly and concentrations greater than 100 ng/mL were obtained for 16 to 20 hours after the dose. The elimination half-life following oral administration was 8.5 +/- 2.8 hours (standard deviation [SD]), and the bioavailability of ranitidine was 43.3% +/- 10.5%. After IV administration, the elimination half-life, plasma clearance, renal clearance, and volume of distribution were 7.0 +/- 1.0 hours, 170 +/- 38 mL/min, 36.0 +/- 25.0 mL/min, and 1.3 +/- 0.4 L/kg, respectively. About 20% of the IV dose and 9% of the oral dose were recovered unchanged in urine. There was a significant correlation between the renal clearance of ranitidine and creatinine clearance (r = .74, P less than .05) after IV administration. The elimination half-life in patients with renal insufficiency is about three times greater than that reported in the literature for healthy subjects. Similarly, the plasma clearance in these patients is about 20% of that reported in healthy subjects. The results indicate that ranitidine elimination is appreciably reduced in renal failure and that an adjustment of dose in patients with renal failure is warranted. A dose of 75 mg bid may be adequate in maintaining the therapeutic plasma concentrations that are required for adequate H2-blocking activity.

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The pharmacokinetics of ranitidine and its removal by hemodialysis were determined in 9 patients with chronic renal failure requiring hemodialysis. Ranitidine (50 mg) was administered as an intravenous bolus at the beginning of the dialysis procedure, which lasted for 4 h. The elimination half-life, plasma clearance and volume of distribution (VD area) of ranitidine in these patients were 9.0 +/- 2.6 h (mean +/- SD), 305 +/- 152 ml/min and 3.5 +/- 1.9 liters/kg, respectively. About 8% of the administered dose was removed during a single dialysis procedure. The elimination of ranitidine is appreciably reduced in these patients. These results suggest that the dose of ranitidine should be adjusted in patients with severe renal failure who are undergoing hemodialysis, and a suitable schedule for dosing such patients is suggested.

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