Search PubMed⌕ Search

Biomedical subjects

S R Ash

Publications and source records attributed to S R Ash.

At least 73 records · Page 4Linked to original sources
PubMed1978

Roux-Y intestinal bypass for administration of sorbents in uremia.

In order to minimize interaction of sorbents with food and digestive secretions, an intestinal bypass was created for sorbent administration in normal and uremic rats (N = 18) and goats (N = 5). Two separate limbs of small intestine were fashioned, one for food absorption and one for sorbent function, which joined at a Roux-Y anastomosis before the cecum. Particulate sorbent suspensions were injected into the intestine via a cutaneous stoma, and were excreted with food wastes in the feces. In animals with normal kidneys, sorbent function was calculated from changes in fecal and urinary excretion. Nitrogen clearance by the intestinal bypass was 20 to 40% of normal renal clearance in rats and goats. Potassium clearance was 40% of normal renal clearance in rats, and over 100% in goats. Sorbent treatment in anephric animals caused serum urea nitrogen concentrations to stabilize at 210 mg/dl in rats, and 110 mg/dl in goats. Serum potassium concentrations stabilized at 4.5 mEq/liter in rats, and fell to 2 mEq/liter in goats. Water balance was maintained by producing a mild osmotic diarrhea. At least three substances which accumulate in renal failure--urea, potassium, and water--were removed in therapeutically significant amounts.

Animals↗
PubMedDate not supplied

The evolution and function of central venous catheters for dialysis.

The use of central venous catheters (CVC) for acute or chronic dialysis has been a relatively recent innovation in Nephrology. The first problem addressed has been how to allow removal and return of blood at high flow rates throughout a dialysis treatment. Four solutions have emerged: place the lumens within the right atrium; place the removal lumen on the inside of the catheter; use a large catheter size; or provide independent limbs with multiple blood-entry ports to draw and return blood in all directions. Many other requirements include resistance to infection, especially the passage of organisms around the catheter. A subcutaneous Dacron cuff within a tunnel has successfully accomplished this goal for most chronic CVC dialysis catheters, but other immobilizing devices such as plugs have also been successful. Materials for CVC dialysis catheters have improved, providing strength to allow the catheters to last for several years, with flexibility to avoid vein damage (in general). However, component and material failures still occur, and some materials are incompatible with medications placed at the exit site. CVC for dialysis will remain a necessary choice for many patients beginning and continuing dialysis therapy.

Catheterization, Central Venous↗
PubMedDate not supplied

Subcutaneous capillary filtrate collector for measurement of blood glucose.

The capillary filtrate collector (CFC) is a device that creates an ultrafiltrate at 50-100 microliters/h from subcutaneous capillaries, and carries this filtrate out of the body for chemical analysis. From inside out, components include three looped hollow fiber ultrafiltration membranes, a polytetrafluoroethylene (PTFE) cuff, polyurethane tubing, a "Y" connector leading to a sampling port, a hub, and a needle placed into a 5 ml vacutainer tube. Animal studies have demonstrated that the CFC filtrate glucose level is exactly that of blood at the time the filtrate is created. The authors have performed clinical trials to determine the correlation of blood glucose and CFC glucose levels, and the time delay between contemporary samples. Seven diabetic patients wore the CFC device, tubing, and vacutainer tube for 1 month. In home monitored diabetic patients, fingerstick glucose measurements were performed at the usual daily schedule. The vacutainer was then evacuated, and this average sample analyzed and compared with the average of prior blood glucose levels. An optical device then was applied to measure the linear velocity of CFC fluid through external tubing, and predict the time for fluid to pass from fibers to the sampling port (average, 25 min). Capillary filtrate collector samples drawn at this time had glucose concentrations that generally correlated with blood levels. In diabetic patients on hemodialysis, the vacutainer was evacuated at the start of each treatment, and CFC and blood samples were drawn every 20 min during the treatment. Comparison of glucose-versus-time curves indicated a reasonable correlation between blood and CFC samples, with a delay related to flow rate (which declined 50% during dialysis).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMedDate not supplied

Push-pull sorbent based pheresis for treatment of acute hepatic failure: the BioLogic-detoxifier/plasma filter System.

The BioLogic-DT (detoxifier) System is an extracorporeal blood treatment device that uses the membranes of a cellulosic plate dialyzer to propel blood in and out through a single lumen access (on a 12 sec cycle) and circulates a suspension of powdered charcoal and cation exchanger through the dialysate spaces to absorb many soluble toxins in the treatment of hepatic failure. The BioLogic-DTPF (detoxifier/plasma filter) System adds two Gambro plasma filters downstream from the plate dialyzer, which allows most of the blood plasma to pass out of the blood, contact powdered charcoal in a suspension, and then return to the blood during each 12 sec cycle (creating push-pull sorbent based pheresis). A roller pump exchanges charcoal suspension between the plasma filter case and a 700 ml bag of powdered charcoal suspension. At a blood flow rate of 150-200 ml/min, 100 ml/min of plasma moves bidirectionally through the plasma filter membranes. Direct contact of plasma with charcoal outside the plasma filter membranes removes creatinine with a clearance rate equal to plasma flow (100 ml/min); clearance of strongly protein bound toxins, such as unconjugated bilirubin, is lower (10-40 ml/min). In this article, the authors explain the mechanisms of operation of this system and present in vitro tests that define its chemical efficiency. Also described are potential problems, tests that indicate the severity of these problems, and monitors and algorithms to detect or avoid these problems in clinical use of the system. The results of the treatment of two patients with acute hepatic failure and coma using the BioLogic-DTPF System are reviewed.

Aged↗
PubMedDate not supplied

Comparison of blood flow rates and hydraulic resistance between the Mahurkar catheter, the Tesio twin catheter, and the Ash Split Cath.

The Ash Split Cath (Medcomp, Harleysville, PA) is a recently introduced dual lumen permanent catheter designed to be placed through the internal jugular vein into the superior vena cava by single venipuncture technique. The transcutaneous portion is a 14 French cylindrically shaped catheter with D-shaped lumens and a Dacron (DuPont, Wilmington, DE) cuff. At the entrance to the jugular vein, the catheter splits into two separate D-shaped limbs that then merge into multiholed cylindrical tips in the vena cava. Split Caths (n = 10) have been placed in patients with end-stage renal disease and used for outpatient dialysis for approximately 2 months. Flow rates and hydraulic resistance have been compared with Mahurkar (Bard, Salt Lake City, UT) (n = 22) and Tesio (Medcomp) (n = 17) catheters in the same unit. Average blood flow rates (Qb) were 295 +/- 42 (SD) for Ash Split Caths vs 279 +/- 38 and 300 +/- 39 ml3/min for Mahurkar and Tesio catheters, respectively, and hydraulic resistances were 0.44 +/- 0.17, 0.52 +/- 0.15, and 0.56 +/- 0.11 mmHg/ml/min, respectively (not significant). No Split Caths have been removed for bleeding or flow complications. The Split Cath provides the simplicity of placement and removal of a single-bodied catheter with flow advantages of independent, cylindrical, multiholed tips.

Biophysical Phenomena↗
PubMedDate not supplied

Systemic inflammatory response syndrome treatment by powdered sorbent pheresis: the BioLogic-Detoxification Plasma Filtration System.

Systemic inflammatory response syndrome (SIRS) is one of the most common causes of death in intensive care unit patients. The detoxification plasma filtration (DTPF) system (HemoCleanse, Inc., West Lafayette, IN) combines the DT hemodiabsorption system in series with a push-pull pheresis PF system (a suspension of powdered sorbents surrounding 0.5 microm plasma filter membranes). Bidirectional plasma flow (at 80-100 ml/min) across the PF membranes provides direct contact between plasma proteins and powdered sorbents, as well as clearance of cytokines (tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6) at a rate of 15-25 ml/min, without evidence of saturation for 90 minutes. In a U.S. Food and Drug Administration approved study we treated eight patients with SIRS and organ failure with a single DTPF treatment, using powdered charcoal as sorbent in four patients and powdered charcoal and silica in four patients. Treatments proceeded for 6 hours with proper heparin anticoagulation (activated clotting time 250-300 sec) and appeared safe. All patients improved during the treatments and each had increased blood pressure and decreased need for pressor agents. Plasma cytokine levels stabilized or decreased during treatment and were significantly lower the morning after treatment. Multiple organ dysfunction (MOD) and Acute Physiology Chronic Health Evaluation II scores and organ function gradually improved in most patients, and two patients survived for more than 28 days and two for more than 14 days. The DTPF System may prove beneficial in treatment of patients with sepsis.

Adult↗
PubMedDate not supplied

The computerized notation system: a portable, self-contained system for entry of physicians' and nurses' notes.

The Computerized Notation System (CNS) is a portable microprocessor system designed for use in outpatient clinics, hospital wards, and intensive care units. It can produce essentially all written communications required of both physicians and nurses, with printout at the bedside or in the clinic examining room. It is designed to ameliorate several problems which have limited direct computer entry by physicians and nurses (keyboard and processor access, marginal typing skills, lack of immediate printout, and logical restriction of menu choices). The system encourages and simplifies use of the problem-oriented approach to the patient, by producing organized, legible daily notes and patient summaries. Printouts of the system are compatible with the present hospital and clinic "paper charts." Clinical trials have confirmed the applicability, variability, and acceptability of the CNS in both hospital and outpatient practice.

Computers↗
PubMedDate not supplied

The pocket medical record--do we need a centralized medical data base?

A microprocessor-generated portable medical record has been developed as an alternative to a centralized digital medical data base. The medical information in this data base is processed and selected by physicians or nurses, with direct entry to the computer. Speed and accuracy of input are aided by this software program. Implementation of the program in several medical institutions has shown that the portable medical data base is useful in transfer of medical information among such institutions, and that the data base is adaptable to a variety of practice settings.

Computers↗
PubMedDate not supplied

The training and use of an artificial neural network to monitor use of medication in treatment of complex patients.

An artificial-neural-network-based drug interaction warning system was developed for use with a computerized real-time entry medical records system. The goal of the study was to provide physicians and nurses with timely warnings of potential drug interactions as therapies were prescribed. In a dialysis unit, physicians and clinical pharmacists defined rules of proper drug therapy, then trained a neural network with those rules. When the network was used to review the therapies of this patient population, a number of inconsistencies were discovered, and medication orders were changed on several patients. Real-time implementation of this monitoring system could provide messages to assure that drug therapy is consistent and proper, according to rules created by the providers of healthcare, thus preventing occasional mistakes in drug therapy.

Drug Interactions↗
PubMedDate not supplied

Evolution of the medical record format during two years' use of an open-format microcomputer charting system.

In 1988, the authors implemented a microcomputer charting system (SmartChart) within a busy dialysis unit and an outpatient dialysis practice, to be used as the primary recording instrument for physicians and nurses. The program defined the organization of the medical record as three types of titles: problems, therapies, and numerics. Each title had a variety of associated data, such as comments, dosages, values and normals. Predefined care plans were created, and keyboard entry was in a completely open format. Over the next two years, the overall format of this medical record proved to be highly effective, and strict problem orientation allowed both nurses and physicians to use the same problem list. A more specific organization of the title lists in the medical record was needed, however. Separate symbols were placed in front of: problem titles related to prior therapies; problems recorded during current therapies; History and Physical (H&P) data; Plans/Orders; and inactive problems. PRN therapies, those therapies related to patient treatments, vital signs, and numeric data recorded during treatments were identified. The basic format of the medical record that evolved has proven suitable for outpatient, inpatient, and specialized treatment centers.

Attitude to Computers↗
PubMedDate not supplied

Innovative peritoneal dialysis: flow-thru and dialysate regeneration.

As the peritoneal dialysis (PD) patient's residual renal function declines, the dialysis dose must be increased. However, the options for increasing the dose are limited to increasing the number of exchanges and/or the volume of each exchange. A review of the literature indicates that the dialysis dose can be significantly increased by flow-through PD, wherein the dialysate flows continuously into the peritoneal cavity through one catheter and out another and/or by regenerating the spent dialysate, thereby, significantly increasing the dialysate flow rate. Flow-thru PD has been used with and without dialysate regeneration. Regeneration has been used with standard inflow/outflow PD. In nearly all cases, substantially increased clearances over standard PD were obtained with reported urea and creatinine clearances as high as 58 and 48 ml/min, respectively. Applying flow-thru to the PD patient would require two catheters or a dual lumen catheter, and to obtain optimum clearances, the dialysate should be pumped through the peritoneal cavity at a high flow rate. Regenerating the dialysate allows high dialysate flow rates while reducing the total amount of dialysate required. For the continuous ambulatory peritoneal dialysis (CAPD) patient, the unit would have to be wearable; whereas for the patient on automated PD, flow-thru and/or regeneration PD could be incorporated into the equipment. With sorbent regeneration, the protein in the spent PD could be purified and returned to the patient thereby minimizing protein loss, increasing ultrafiltration, and enhancing the removal of protein-bound metabolic toxins.

Humans↗