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Biomedical subjects

S R Ash

Publications and source records attributed to S R Ash.

At least 19 recordsLinked to original sources
PubMed1995

Peritoneal dialysis for acute renal failure: the safe, effective, and low-cost modality.

With the emphasis on acute renal failure and the popularity of continuous renal replacement therapy, peritoneal dialysis is a frequently overlooked and undervalued method of dialytic support. This review is purposefully set in a "continuous" format and addresses the frequently encountered problems that arise with these systems. Continuous peritoneal dialysis delivery in the intensive care unit and other forms of continuous therapies are compared using the following criteria: access, efficiency, biocompatibility, and hemodynamic stability. Specific study results are reviewed comparing the outcome of patients supported with peritoneal dialysis versus hemodialysis in the intensive care setting, and extrapolations from the chronic support areas are also drawn. Specific advantages and shortcomings are listed for each therapy.

Acute Kidney Injury↗
PubMed1994

Hemodiabsorption in treatment of acute hepatic failure and chronic cirrhosis with ascites.

Hemodiabsorption is a selective chemical removal process during which blood passes through dialysis membrane packages surrounded by a suspension of fine sorbent particles. The BioLogic-DT system contains charcoal and cation exchangers in a suspension that passes through dialysate spaces of a cellulosic membrane plate dialyzer. The system has proven effective in treatment of patients with serious drug overdose and has demonstrated positive effects in treatment of stage 4 coma due to hepatic failure. Recently, the charcoal in this system has been preloaded with branch chain amino acids to return these acids to patients while aromatic amino acids are removed. Further improvements include addition of osmotically active agents to the priming fluid and sorbent to increase blood oncotic pressure and transfer of ascitic fluid to blood while ultrafiltration transfers fluid out of the blood. Clinical testing of these improvements is now beginning in patients with ascites and encephalopathy due to chronic hepatic insufficiency and cirrhosis. Future improvements will include protein permeable membranes to increase removal of protein-bound toxins and addition of hepatic cells downstream from the hemodiabsorption unit.

Ascites↗
PubMed1993

T-fluted peritoneal dialysis catheter.

While the current Tenckhoff catheter is generally successful, outflow failure due to omental obstruction, pericatheter hernias, pericatheter leaks, and exit infections remains a major cause for dropout from peritoneal dialysis therapy. Further, the irregular outflow characteristics of the catheter make highflow automated dialysis problematic. We have developed a catheter with a thin transabdominal tube connecting in a T-shape to a transverse cylinder resting against the parietal peritoneum, with flutes (grooves) as ports. The catheter can be inserted through the 3-mm diameter Quill guide of the Y-TEC peritoneoscopic system. Studies in normal dogs indicated that the T-fluted catheter allowed daily exchanges with 2 L of peritoneal dialysate without outflow obstruction, and peritoneoscopic inspection 2-4 weeks later showed no omental attachment to the grooved ports. By comparison, curled Tenckhoff catheters uniformly developed omental obstruction within 2-4 days, and all such catheters had firm omental attachment to the side holes. Five T-fluted catheters have been placed in continuous ambulatory peritoneal dialysis (CAPD) patients who had prior complications with Tenckhoff catheters (infections, leaks, and outflow failure). One patient with multiple intraperitoneal adhesions developed outflow failure of the T-fluted catheter, similar to a prior Tenckhoff catheter. All other T-fluted catheters had consistent outflow rates and no complications. In long-term use the T-fluted catheter should prevent omental attachment, deep cuff extrusion, pericatheter hernias, subcutaneous cuff erosion, and exit-site infection, although this is not yet proven.

Animals↗
PubMed1993

Peritoneal catheters and exit-site practices: toward optimum peritoneal access.

The peritoneal catheter is the CAPD patient's lifeline. Advances in catheter knowledge have made it possible to access the peritoneal cavity safely and maintain access over an extended period of time. Infection at the exit site remains a major problem, a solution for which is being extensively researched. The successful outcome of a catheter in an individual depends on meticulous care and adherence to sound principles of catheter insertion and management. The guidelines provided in this publication represent the consensus based on the extensive experience of several major centers worldwide.

Catheters, Indwelling↗
PubMed1992

Clinical effects of a sorbent suspension dialysis system in treatment of hepatic coma (the BioLogic-DT).

Fifteen patients with acute deterioration of liver function, high serum ammonium, and an average coma level of 3.9 were identified. Eleven of the patients were on respirator support, and eleven had kidney failure pursuant to the liver failure. The patients were treated for 8-12 hours daily with the BioLogic-DT system, in which membranes of a cellulosic plate dialyzer actively pump blood through a single access at over 200 ml/min, and the dialysate contains a suspension of powdered activated charcoal (300,000 square meters surface area) and cation exchanger (160 meq capacity). No anticoagulant was used. In spite of the declining condition of the patients prior to treatment, there was a statistically significant improvement in neurologic status during individual treatments, and a positive trend over 1-12 (average four) daily treatments. Four patients recovered liver function and another four improved enough to receive a liver transplant operation. The BioLogic-DT system appears to be safe in treatment of patients with hepatic insufficiency and coma. The neurologic improvement of these patients indicates that many toxins of hepatic failure are dialyzable across cellulosic membranes and bound by charcoal.

Acute Disease↗
PubMed1991

A comparison of peritoneal dialysance (D) during CAPD, intermittent peritoneal dialysis (IPD) and tidal PD (TPD) in awake normal dogs.

The important variables which determine peritoneal clearances include: residual volume, cycle volume, and cycle frequency. Various combinations of these variables result in CAPD, IPD, and TPD schedules. We decided to develop an animal model in which the clearances of these modes could be compared, performing dialysis on awake dogs with normal kidney function. In five successive experiments, two silicone catheters were placed in the abdomen of anesthetized dogs, one in the lower abdomen and one between the liver and diaphragm. On successive days, with the dogs awake but lying down, CAPD, IPD, and TPD schedules were performed for 4 hours, using 1.5% Inpersol (Abbott Laboratories, IL.). For CAPD the infused volume was 2 liters, drained at 4 hours. For IPD, 2 liters were infused and drained each hour. For TPD, one liter residual was infused, and another liter infused and drained each 20 minutes, to result in a 3 liter/hour flow-through-rate. The dialysance of glucose (Dglu) was calculated from changes in dialysate and blood glucose concentration. Dglu reproducibly predicted the Durea, with Dglu = 0.6 Durea. Our experiments demonstrated that without efforts to optimize TPD, its dialysance is similar to that of standard TPD. The higher average TP volume of TPD offsets the higher fluid flow rate of TPD schedules. Both IPD and TPD have higher dialysance than CAPD.

Animals↗
PubMed1991

Effect of ethanol perfusion on creatinine removal in a Roux-Y intestinal segment.

Five rats and 2 goats had a bypass operation to allow infusion of sorbents through an inlet ostomy. The sorbents passed through one limb of intestine isolated from food contact to join a food limb which included 30-40% of the original length of small intestine. In goats, serum creatinine levels were elevated by infusion of sterile creatinine solutions intravenously. Twenty-four hour urines were collected before, during and after periods of infusion of sorbents into the inlet ostomy. Infusion of charcoal into the ostomy had little effect on the total daily urinary creatinine excretion (TDUC). However infusion of 4.3 g/kg/day ethanol decreased the TDUC significantly, in both species. In rats, 8.6 g/kg/day ethanol infusion had an even greater effect on TDUC. Studies of intraluminal creatinine concentration in the distal part of the sorbent segment indicated that especially when serum concentration of creatinine is over 2 mg%, ethanol greatly increases the intraluminal creatinine concentration in the intestine. It is concluded that ethanol, in combination with intestinal sorbents or alone, could allow intestinal dialysis to remove considerably more creatinine, and possibly aid transport of other organic substances.

Anastomosis, Roux-en-Y↗
PubMed1988

Evaluation of the sorbent suspension reciprocating dialyser in the treatment of overdose of paracetamol and phenobarbitone.

Poisoning with paracetamol (acetaminophen) and phenobarbitone is a common occurrence in the United States and Europe. The removal efficiency of these drugs by a sorbent suspension reciprocating dialyser (SSRD) has been investigated. The SSRD is a parallel plate dialyser with a reciprocating blood flow and free mobile sorbent suspension composed of charcoal and zeolites. This arrangement provided a system with minimal sorbent saturation. High performance liquid chromatography was used for the quantification of the drugs in aqueous and serum fluids. The in-vitro removal efficiency of the dialyser was studied by dialysing a large volume of the drug in solution for 12 to 16 h. The removal efficiency remained relatively constant up to 10 h of dialysis. The in-vivo dialysis studies were performed using normal dogs. Large doses of the drugs were administered orally or intravenously to achieve high blood levels. The clearance values obtained from these studies were comparable with, or in excess of, the values reported in the literature for conventional dialysers. The major advantage of the SSRD is the ability of the unit to be used for prolonged dialysis and to provide a system with minimal sorbent saturation due to mixing and interchange of sorbent granules next to the membrane surface.

Acetaminophen↗
PubMed1986

Portable and desktop microcomputers for patient care charting.

Microcomputers are perfectly suited for the input, storage, display, and printing of medical information. The most efficient method of data input and verification is by health professionals themselves, at the bedside or in the exam room. Battery-powered microcomputers are now available with all the power and function of desktops. One patient-care software package [Smart-Chart(tm)] allows entry of clinical data into battery-powered computers such as the Epson Geneva or Data General One, and two-way communication of such data with IBM-PC compatibles. This system inexpensively places a complete computer system in the hands of health professionals in all locations of practice (even at home for use during telephone calls). A dozen or so floppy disks can allow primary physicians to have immediate access to current information on all patients in their practice. Medical notation by computer may now achieve its full potential for clarifying medical records, improving patient care, and diminishing the frustration of medical practice.

Attitude to Computers↗
PubMed1986

Phosphate binding gels: balancing phosphate adsorption and aluminum toxicity.

The phosphate binding capacity of five commercial aluminum hydroxide phosphate-binding gels and two crystalline forms of aluminum hydroxide was studied by an in vitro procedure which simulated passage through the stomach to the small intestine. The potential for aluminum toxicity was estimated by determining the fraction of the dose which was converted into soluble aluminum species by acid neutralization at pH 3, 37 degrees C. The commercial products varied widely both in phosphate binding capacity and production of soluble aluminum species. The evidence suggests that the ideal phosphate binder will have a surface area small enough to minimize the formation of soluble aluminum species during the gastric residence time but also large enough to adsorb a clinically significant amount of phosphate.

Aluminum↗
PubMed1984

Assessment of biomaterials as components of a reciprocating dialyser during canine dialysis.

A recently reported device, the sorbent suspension reciprocating dialyser (SSRD), was investigated for use as a test system for biocompatibility of dialyser components. The device is easy to assemble and operate, and allows minimal blood contact with foreign material outside of dialyser components. Its constant pressure/variable flow rate operation allows quantification of degree of clotting of dialyser versus time. The effect of heparinization of the blood distribution gaskets (BDG) of the device on performance and dialyser lifetime was investigated. Heparin was bound to the surface of polyethylene gaskets by immersion in a solution of tridodecylmethylammonium chloride (TDMAC)--heparin complex for several hours. Gaskets were then assembled in an SSRD which was then used for experimental dialysis in dogs with AV shunts. Dialysers assembled using non-heparinized gaskets were used as controls. Blood coagulation tendency was quantified by the activated clotting time (ACT) and partial thromboplastin time (PTT), and these values correlated with the rate of clotting of the device. Heparinization of the gaskets resulted in the prevention of clotting in the dialyser until the final minutes of dialysis in all cases, in contrast to the constant decay of blood fill volume and evidence of clotting in the non-heparinized cases. However, dialyser lifetime was not significantly increased by gasket heparinization. At normal initial values of ACT (80-95 s) dialyser clotting occurred in 10-15 min. In tests with non-heparinized gaskets and systemically heparinized dogs, values obtained in the ACT test were observed to decrease during dialysis, indicating the disappearance of heparin from the blood. Both ACT and PTT tests show promise as predictors of dialyser lifetime.

Animals↗