Tesio catheter: radiologically guided placement, mechanical performance, and adequacy of delivered dialysis.

PURPOSE: Tunneled catheters are an alternative means of vascular access for patients in need of hemodialysis who cannot undergo dialysis through a surgical shunt. This study was undertaken to evaluate the performance of the Tesio dialysis catheter. MATERIALS AND METHODS: A prospective study of the Tesio catheter was performed. Follow-up data regarding catheter function and adequacy of dialysis were obtained from nine hemodialysis facilities. RESULTS: Seventy-nine Tesio catheters were placed in 71 patients. Immediate technical success was 99% (78 of 79 catheters). The procedure complication rate was 9% (seven catheters). Only two complications required intervention: one fatal air embolism and one chest wall hematoma. Sixty-seven catheters in 60 patients were followed up for a total of 4,367 catheter days. Overall, catheter-related infection occurred in 9% (six of 67 catheters). Primary catheter patency was 87% at 1 week, 82% at 1 month, 72% at 3 months, and 66% at 6 months. Mean blood flow was 286 mL/min immediately after insertion, 301 mL/min at 3 months, and 306 mL/min at 6 months. Adequate dialysis dose as reflected by a urea reduction ratio of 60 or more or a urea kinetic modeling, or Kt/V, value of 1.2 or more was observed on at least one occasion for 74% and 76% of catheters, respectively. CONCLUSION: The Tesio catheter is a reasonable means of vascular access for patients who undergo dialysis but are not candidates for surgical shunt placement.

Effect of renal disease and hemodialysis on foscarnet pharmacokinetics and dosing recommendations.

BACKGROUND: Foscarnet is an antiviral agent commonly used for managing patients with cytomegalovirus infection. Despite its clinical usefulness, foscarnet is associated with substantial adverse effects including nephrotoxicity. Moreover, foscarnet is primarily eliminated unchanged through the kidneys, thus requiring aggressive dose adjustment during kidney failure. To develop specific dosage guidelines, information on the disposition of this compound in patients with varying degrees of renal function and those requiring dialysis is essential. DESIGN: Twenty-six subjects were enrolled in this study and divided into five groups depending on their degree of renal dysfunction. Group 1 included subjects with normal renal function; group 5 included subjects requiring maintenance hemodialysis. Nondialysis study subjects received a single 60-mg/kg intravenous dose of foscarnet whereas hemodialysis subjects received two intravenous doses, separated by 1 week, to compare the effects of conventional and high-flux dialysis methods. RESULTS: Mean plasma clearance in control subjects averaged 2.1+/-0.7 ml/minute/kg and declined proportionally with changing renal function as indicated by the regression equation: Clp (ml/minute/kg) = 1.48 [CrCl (ml/minute/kg)]-0.08 (r2 = 0.82). Mean half-life averaged 1.9+/-0.1 hours in normal subjects and increased to a mean of 25+/-19 hours in study subjects with severe impairment not on dialysis. Foscarnet dialysis clearance (based on dialysate recovery) averaged 183 ml/minute with conventional dialysis methods and 253 ml/minute during high-flux procedures, which resulted in removal of 37% and 38% of a dose for the two methods, respectively. CONCLUSIONS: These data indicate that substantial dosage adjustments must be made in renal failure patients. Therefore, a patient-specific dosage nomogram has been developed.

Subcutaneous tissue oxygen tension falls during hemodialysis.

The effect of hemodialysis on subcutaneous tissue oxygen tension was studied in nine patients. During hemodialysis, blood pressure decreased, pulse increased, and all patients lost weight. Arterial blood oxygen tension fell insignificantly, from 79 to 73 mm Hg. Subcutaneous oxygen tension decreased from 52 to 28 mm Hg (p less than 0.001). Because adequate tissue oxygenation is necessary for wound healing and resistance to infection, we postulate that hemodialysis may contribute to the wound morbidity frequently seen in dialyzed patients.

Independence of hydrogen ion secretion and transport of other electrolytes in turtle bladder.

The relationship between hydrogen ion secretion and the transport of other electrloytes was examined in the isolated urinary bladder of the water turtle. Symmetrical solutions which were free from exogenous carbon dioxide and bicarbonate bathed the two surfaces of the preparation, and the spontaneous electrical potential of the bladder was nullified by a voltage clamp. Active transport of sodium from mucosal to serosal medium was confirmed by simultaneous bidirectional flux measurements and found to be slightly, but not significantly, greater than the short-circuit current. In the absence of sodium in the bathing solutions, the normal potential difference across the bladder reversed and the current required to nullify this reversed potential difference had the same magnitude as the simultaneously measured rate of hydrogen ion secretion. The results indicate that, under these experimental conditions, the bladder transports sodium and hydrogen ion actively, but that chloride movement does not contribute to the short-circuit current. The rate of secretion of hydrogen ion was not affected by replacement of the sodium in the bathing media by cesium, or by inhibition of sodium transport by dinitrophenol. Acidification continued when chloride in the solutions was replaced by sulfate, or when potassium or calcium was removed from the solution bathing the mucosal surface. Secretion of hydrogen ion by the turtle bladder is not dependent on the simultaneous transport of other electrolytes across the bladder.