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Biomedical subjects

R D Swartz

Publications and source records attributed to R D Swartz.

At least 73 records · Page 4Linked to original sources
PubMed1981

Hemorrhage during high-risk hemodialysis using controlled heparinization.

The risk of worsening or commencement of bleeding in high-risk patients requiring hemodialysis has not been established. The present study of 300 dialyses in 51 patients with prospectively assessed increased risk for bleeding describes a method for limiting heparin administration by using the thrombin clotting time to assess heparin sensitivity before dialysis and to monitor heparin levels during dialysis. The procedure prevented clotting in the extracorporeal device and limited bleeding complications to 5% of cases overall. Patients with a higher risk for hemorrhage had a higher incidence of bleeding complication (26%), a larger fall in hematocrit, and more frequent requirement for blood replacement. We conclude that although hemodialysis poses a risk for actively bleeding patients, patients at risk but without active bleeding can be dialyzed with strict control of heparin administration.

Blood Coagulation Disorders↗
PubMed1979

Preventing hemorrhage in high-risk hemodialysis: regional versus low-dose heparin.

Hemodialysis in patients with increased risk for hemorrhage can be accomplished with either a regional or a low, total dose of heparin. In a prospective study of 69 series of dialyses performed on an alternating schedule of heparinization for each patient, bleeding complications during and immediately following dialysis occurred in 23 of 122 dialyses (19%) with regional heparin compared to 13 of 133 dialyses (10%) with low-dose heparin (P less than 0.05). The incidence of hemorrhage correlated with the estimated degree of bleeding risk both at expected and at occult bleeding sites, and was the same or higher with regional heparin in all categories. Hemorrhage was not correlated with preexisting coagulation abnormalities, concurrent anticoagulant drugs, level of azotemia, or ability to successfully limit systemic heparinization during dialysis. The incidence of partial clotting of the dialyzer was 3 to 5% with both heparin protocols. We conclude that regional heparinization has no clinical or practical advantage over low-total-dose heparin in preventing bleeding associated with hemodialysis.

Hemorrhage↗
PubMed1978

Renal failure following major angiography.

Acute renal failure following angiography with contrast agents is known to occur, but the circumstances and frequency of its occurrence are not well described. A retrospective review of consecutive angiographic procedures performed over a six month interval revealed a 12 per cent incidence of renal failure following angiography. The degree of failure was severe in approximately 30 per cent of these cases and was associated with a significant mortality even though renal function usually recovered. The occurrence of renal failure was associated with the presence of renal insufficiency, impaired liver function, diabetes mellitus, hypoalbuminemia and proteinuria at the time of angiography to a statistically significant level. Furthermore, combinations of these factors, particularly preexisting combined renal insufficiency and impaired liver function, were associated with an increased incidence of acute renal failure. It is concluded that angiography poses a significant hazard to patients with underlying medical problems, particularly those involving the excretory routes of the contrast agent.

Acute Kidney Injury↗
PubMed1977

Correction of postoperative metabolic alkalosis and renal failure by hemodialysis.

Three postoperative patients with oliguirc renal failure and hypochloremic metabolic alkalosis were treated with hemodialysis using a specailly prepared high-chloride, low-acetate dialysate. This mode of therapy corrected the metabolic abnormalities and was significantly more effective than treatment with commercially available high-acetate dialysate at increasing the serum chloride and hydrogen ion concentration. Furthermore, hemodialysis with high-chloride, low-acetate dialysate corrected the clinical sequelae of hypoventilation, cardiac arrhythmia, and neuromuscular irritability associated with metabolic alkalosis while treating uremia simultaneously.

Acute Kidney Injury↗
PubMedDate not supplied

Variable flow Doppler for hemodialysis access evaluation: theory and clinical feasibility.

Access thrombosis remains an enormous problem for patients on hemodialysis. Current evidence suggests that decreasing access blood flow rate is an important predictor of future access thrombosis and failure. This article describes a method for determining access volume flow and detecting access pathology. The Doppler ultrasound signal downstream from the arterial needle as a function of the variable hemodialysis blood pump flow rate, is used to determine access blood flow. By using this variable flow (VF) Doppler technique compared with duplex volume flow estimates measured in 18 accesses (16 patients with 12 polytetrafluorethylene [PTFE] grafts and 6 autogenous fistulas), the results showed a correlation of 0.83 (p < 0.0001) between these methods. In grafts with lower blood flow rates, aberrant flow patterns were observed, including stagnant or reversed flow during diastole while forward flow was maintained during systole. When reversed diastolic flow was severe, it was accompanied by access recirculation. In conclusion, we report the theory and clinical feasibility of determining access blood flow by using a VF Doppler technique. Measurements are made without the need to determine the access cross sectional area required for duplex volume flow calculations and without the need to reverse the lines required for various indicator dilution techniques. Important information is also obtained about aberrant flow patterns in patients at risk of access failure.

Blood Flow Velocity↗
PubMedDate not supplied

The relation between sodium transport and oxygen consumption in isolated perfused rat kidney.

A non-filtering isolated perfused rat kidney model was developed to determine renal oxygen consumption in the absence of tubular reabsorption. The oxygen consumption in the absence of filtration was 3.1 +/- 0.8 micron of O2/min/g. This "basal" value was substantially higher than that of 2.0 micron of O2/min/g calculated by extrapolation of a plot of sodium reabsorption vs. oxygen consumption in filtering kidneys. It was also found that ouabain 10(-4) M decreased oxygen consumption in non-filtering kidneys and acetazolamide increased it in a dose dependent fashion. Furosemide did not change "basal" oxygen consumption. In filtering kidneys, the ratio of sodium reabsorbed to oxygen consumed averaged 36.8 muEq of Na/mumole of O2. It is concluded that basal oxygen consumption is not a fixed quantity and can be changed by experimental manipulations thereby changing the relation between transport activity and oxygen consumption.

Acetazolamide↗