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Biomedical subjects

Edward A Ross

Publications and source records attributed to Edward A Ross.

10 recordsLinked to original sources
PubMed2006

Observational study of an Arts-in-Medicine Program in an outpatient hemodialysis unit.

BACKGROUND: Long-term hemodialysis is associated with impaired quality of life (QOL) and depression, which are thought to worsen compliance with the treatment regimen. With the success of our hospital's Arts-in-Medicine Program, we launched a similar set of activities in the long-term dialysis unit and sought to measure their effects. METHODS: At baseline and 6 months, we administered the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and Beck depression scales to 46 patients (44% men; mean age, 52 years) and assessed their percentage of achieved dialysis time, interdialytic weight gain, and predialysis laboratory results. We tested for a relationship between these variables and Arts-in-Medicine Program participation (low and high; 51% and 49%). Arts in Medicine was offered each shift, led by artists, and included artwork, crocheting, crafts, seasonal displays, poetry, and playing musical instruments. RESULTS: At 6 months, the patients, nurses, technicians, and physicians subjectively believed that Arts in Medicine had a positive impact on the unit. In paired comparisons to baseline, there was significant improvement in SF-36 scores for Role-Physical (mean values, 34.4 to 38.7; P = 0.04), less weight gain (3.6 to 3.2 kg; P = 0.02), greater serum carbon dioxide content (20.4 to 22.5 mEq/L [mmol/L]; P < 0.01), greater phosphate levels (5.3 to 5.7 mg/dL [1.71 to 1.84 mmol/L]; P = 0.04), and a trend to less depression (Beck score, 15.3 to 12.1; P = 0.07). Regression analyses showed that high participation correlated with improved SF-36 scores for Social Function (11.1-unit increase; P = 0.01), Bodily Pain (7.6-unit increase; P = 0.04), and Role-Physical (6.6-unit increase; P = 0.06), as well as a trend to greater albumin levels (0.11 g/dL [1.1 g/L]; P = 0.08), but with greater phosphate (0.8 mg/dL [0.26 mmol/L]; P = 0.01) and lower calcium levels (0.3 mg/dL [0.07 mmol/L]; P = 0.07). CONCLUSION: Participation in a new Arts-in-Medicine Program correlated with improved QOL measures, and there were encouraging trends for depression, as well as certain laboratory and hemodialysis parameters.

Depression↗
PubMed2005

Continuous venovenous hemofiltration with citrate-based replacement fluid: efficacy, safety, and impact on nutrition.

BACKGROUND: Citrate-based continuous venovenous hemofiltration (CVVH) replacement fluids provide effective and simple regional anticoagulation. However, concern over toxicity has limited citrate use, especially at the high filtration rates advocated for better outcomes. We used volumes of 72 L/d in patients at high risk for bleeding and investigated the treatment's efficacy, safety, and clinical results, especially with regard to nutrition supplementation. METHODS: A standard replacement solution (trisodium citrate, 13.3 mmol/L) was infused at up to 3 L/h in predilution CVVH, and ultrafiltration was increased further for net fluid removal. Calcium was repleted centrally. We retrospectively evaluated metabolic control, citrate toxicity, circuit patency, hemorrhagic complications, hemodynamics, vasopressor use, nutrition, renal recovery, and mortality. RESULTS: Seventy-six patients with 766 CVVH patient-days were analyzed. Mean replacement fluid rate was 31 mL/kg/h (35 mmol/h of citrate), with hemofiltration of 35 mL/kg/h (67 +/- 11 L/d). No significant bleeding, citrate toxicity, or hypocalcemia was observed, and 74% required additional alkali therapy. Dialyzer patency was 58% at 48 hours. Control of fluid, electrolytes, and azotemia was excellent (serum creatinine level, 1.7 mg/dL [150 micromol/L]; blood urea nitrogen, 42 mg/dL [15 mmol/L]). Fluid removal permitted protein (1.7 g/kg/d) and calorie (30 kcal/kg/d) nutrition in high fluid volumes. Vasopressor use and central pressures decreased significantly. Cumulative 28-day intensive care unit survival was 58%, and 41% of these patients had renal recovery in the intensive care unit. Thirty percent of the entire cohort survived the hospitalization, and 53% of these patients recovered renal function. CONCLUSION: CVVH with 3 L/h of citrate-based replacement fluid is a safe, efficient, and simple technique in patients at high risk for bleeding. It allows superb control of uremia and fluid balance and thereby permits aggressive nutritional support.

Acute Kidney Injury↗
PubMed2005

Circulating endothelial cells are associated with future vascular events in hemodialysis patients.

BACKGROUND: Endothelial dysfunction and injury are thought to have a key role in the pathogenesis of cardiovascular disease. We hypothesized that the presence of circulating endothelial cells, as a reflection of ongoing endothelial injury, might provide a novel means for predicting cardiovascular events in hemodialysis subjects who are known to be at marked increased risk for cardiovascular disease. METHODS: Circulating endothelial cell number was determined in 29 hemodialysis patients who were then followed for vascular events for 470 +/- 172 days. In a second cohort of 44 hemodialysis patients, circulating endothelial cell number was correlated with markers of inflammation, namely high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, IL-10, and monocyte chemoattractant protein-1 (MCP-1), and endothelial dysfunction, soluble vascular cellular adhesion molecule-1 (VCAM-1). RESULTS: Seven of the 19 subjects with elevated circulating endothelial cells (defined as >19 cells per mL) had cardiovascular (N= 5) or vascular (N= 5) events during follow-up, whereas no events occurred in subjects with a low number of circulating endothelial cells (</=19 CECs per mL) (P= 0.04 by Fisher Exact Test). In the second cohort, the number of circulating endothelial cells was independent of all markers of inflammation and endothelial dysfunction. CONCLUSION: In this hemodialysis population, an increase in circulating endothelial cells was found to predict the development of cardiovascular and vascular events, and to be independent of other known markers of inflammation or endothelial dysfunction. These studies suggest that circulating endothelial cells may be a novel way to assess endothelial health and cardiovascular risk. Further studies to investigate the utility of circulating endothelial cells in predicting cardiovascular risk are needed.

Adult↗
PubMed2004

Continuous haematocrit monitoring during intradialytic hypotension: precipitous decline in plasma refill rates.

BACKGROUND: Intradialytic hypotension (IDH) during ultrafiltration remains a major source of haemodialysis related morbidity, despite technological advances including continuous haematocrit monitoring and automated blood volume controlled dialysis machines. We hypothesized that studying the relationship between ultrafiltration rate and plasma refill rate (UFR, PRR) before and during IDH would provide insight into its mechanism and possible prevention. METHODS: We retrospectively identified 17 patients (mean age 50 years) with IDH treated solely by turning off the ultrafiltration, none having received hypertonic saline, mannitol or albumin. All patients had archived data for continuous haematocrits, UFR, ultrafiltration goal, vital signs and symptoms. We used the Crit-Line III optical haematocrit monitor to calculate the PRR for intervals preceding and during IDH. RESULTS: Prior to IDH the PRR was 1360+/-550 ml/h; which was less than the UFR of 1471+/-602 ml/h and was associated with a 4.4% rise in haematocrit. However, during IDH the PRR was dramatically lower (P<0.001): only 242+/-151 ml/h. The PRR was not correlated (P>0.05) with the absolute, per cent change or rate of rise in haematocrit, UFR, ultrafiltration goal or heart rate. CONCLUSIONS: On-line haematocrit monitoring allows for the calculation of plasma volume changes, UFR and PRR, and the mismatch in those rates helps explain the physiology of hypotension episodes. The precipitous fall in PRR during sudden IDH supports activation of the cardiodepressor Bezold-Jarisch reflex. As both the UFR and PRR variables can change during a single dialysis session, this supports the use of devices with automated continuous adjustments of the UFR and suggests additional profiling methodologies.

Adult↗
PubMed2004

Insect repellent [correction of repellant] interactions: sunscreens enhance DEET (N,N-diethyl-m-toluamide) absorption.

Toxicology studies are typically performed on single compounds, which we hypothesized would miss adverse synergies from chemical mixtures. This hypothesis was tested using an insect repellant and sunscreens because both groups include known permeation enhancers, with prior pediatric reports of toxicity from highly concentrated DEET (N,N-diethyl-m-toluamide). Using real-time mass spectroscopy in a hairless mouse skin model, we confirmed substantial penetration of a 20% DEET standard. Despite a lower (10%) DEET content, a commercially marketed sunscreen formulation had a 6-fold more rapid detection (5 versus 30 min) and 3.4-fold greater penetration at steady state. We also tested the efficacy of DEET microemulsion products and confirmed that one successfully slowed the onset of absorption, but not the steady-state permeation. Risks from mixtures of potential toxins are worthy of routine testing, which can be accomplished by simple assays, and are of utmost importance for pediatric applications.

Animals↗
PubMed2003

Tissue adhesion to bioactive glass-coated silicone tubing in a rat model of peritoneal dialysis catheters and catheter tunnels.

BACKGROUND: Silicone peritoneal dialysis catheters do not develop tissue ingrowth, lack a mechanical barrier to periluminal bacterial migration and need cuffs for anchorage. We hypothesized that a bioactive glass coating composed of silicon, calcium, sodium and phosphorous oxides would cause a beneficial tissue reaction causing catheter adhesion, and tested this in a rat model. METHODS: A hexane solvent-based method of coating silicone tubes with Bioglass powder was used, which maintained flexibility, and then the ultrastructure was confirmed with scanning electron microscopy (EM). Segments 2.5 cm were implanted subcutaneously in 8 Sprague-Dawley rats, with uncoated tubes as a contralateral control, and histology was done at 2, 4 and 6 weeks, including special stains and EM. RESULTS: The uncoated segments grossly had no adherence to surrounding tissue, and were physically separate from a thin fibrous capsule of approximately 50 micro width. Trichrome stains demonstrated the capsule was rich in collagen. There was minimal adjacent tissue reaction. In contrast, the coated tubes were palpably fixed to the soft tissues, and sections demonstrated an adjacent prominent layer of macrophages and multinucleated giant cells. Small numbers of lymphocytes were noted. This cellular reaction increased over the 6-week implant duration, and was also associated with neovascularization of the tissue adjacent to the segments (33 vessels in coated vs. 20 in controls per x 200 field, P < 0.0001). Many refractile silicone particles and prominent multinucleated giant cells were present, with small numbers of lymphocytes and macrophages. Stains showed scattered discontinuous calcific deposits. These findings are consistent with reports that the Bioglass(R) silicon oxide leads to the formation of a layer of hydroxyapatite, which binds to collagen and induces a tissue cellular reaction. CONCLUSIONS: In summary, bioactive glass coatings can improve the tissue retention of silicone tubing by promoting adhesion by collagen and cell proliferation, and are promising for future studies of peritoneal dialysis catheters.

Animals↗
PubMed2002

Prospective validation of an algorithm to maximize native arteriovenous fistulae for chronic hemodialysis access.

OBJECTIVE: The purpose of this study was to evaluate an algorithm to maximize native arteriovenous fistulae (AVF) for hemodialysis access. METHODS: The prospective study design was set in an academic, tertiary care medical center. The study subjects were adults referred for permanent, upper extremity hemodialysis access between April 1999 and May 2001. Intervention included Doppler arterial pressures/waveforms and duplex imaging of the basilic, cephalic, and central veins. The optimal configuration for an AVF was determined (criteria: vein >3 mm, no arterial inflow stenosis, no venous outflow stenosis) on the basis of the noninvasive studies, and unilateral arteriography/venography was performed to confirm the choice. Permanent hemodialysis access was created on the basis of the imaging studies, and remedial imaging/intervention was performed if the AVF failed to mature. Outcome measures included impact of the noninvasive/invasive imaging, perioperative morbidity/mortality, incidence of successful AVF, time to cannulation, and predictors of AVF failure with multivariate analysis. RESULTS: A total of 139 new access procedures was performed in 131 patients (age, 53 +/- 16 years; male, 51%; white, 60%; diabetic, 49%; actively undergoing dialysis, 50%; prior permanent access, 26%). The noninvasive imaging showed that 83% of the patients were candidates for AVF, with a mean of 2.7 +/- 2.1 possible configurations. Invasive imaging was abnormal in 38% (forearm arterial disease > central vein stenosis > inflow stenosis) and impacted the operative plan in 19%. AVF were performed in 90% of the cases (brachiobasilic > brachiocephalic > radiocephalic > radiobasilic), with prosthetic AVF performed primarily because of inadequate veins. Among the patients who underwent AVF, the 30-day mortality rate was 1%, the complication rate was 20% (wound, 10%; hand ischemia, 8%), and 24% needed a remedial procedure. The AVF matured sufficiently for cannulation in 84% of those with sufficient follow-up and was suitable for cannulation by 3.4 +/- 1.8 months. On the basis of an intention to treat approach, an AVF sufficient for cannulation developed in 71% of the 139 cases referred for access. The multivariate analysis predicted that female gender (odds ratio, 9.7; 95% CI, 2.2 to 43.5) and the radiocephalic configuration (odds ratio, 4.6; 95% CI, 1.1 to 18.6) were both independent predictors of failure of the fistula to mature. CONCLUSION: With the aggressive algorithm, the construction of native AVF is possible in the overwhelming majority of patients presenting for new hemodialysis access.

Adult↗
PubMed2000

Minimizing hemodialysis vascular access trauma with an improved needle design.

The maintenance and longevity of hemodialysis vascular access remains one of the most problematic topics in the care of dialysis patients. Although much attention has focused on neointimal hyperplasia, the repetitive trauma to vessel walls by dialysis needles causes significant cumulative damage that has undergone little investigation. Commercial needles have beveled tips with intentional cutting surfaces to ease insertion. It was hypothesized that a pencil-point conical-shaped needle would cause less damage by taking advantage of the elasticity of native fistulae and produce an improved hole configuration in synthetic materials with minimal ability to stretch. A needle was subsequently designed with a removable pencil-point trocar and a side arm for the dialysis tubing. Once the trocar is removed, the blunt-ended cannula can be advanced or can be subject to inadvertent motion without causing damage to the luminal surface of the access. The new design as well as standard 15-gauge hemodialysis needles were tested on Gore-Tex graft material and two bovine carotid artery preparations. Scanning electron microscopy was used to study the hole patterns. For all materials, the commercial needle holes had typical crescent shapes, and the cuts sliced sequentially through the various layers. For grafts, the new design caused a linear defect parallel to the axis of the graft that may preserve longitudinal strength. Interestingly, that tear line was nearly perpendicular to the linear hole in the thin polytetrafluoroethylene overwrap, which would be consistent with maintenance of hoop integrity. It is believed that these nonoverlapping defects would also improve hemostasis. The bovine specimens tested the importance of tissue stretching : Fresh carotid artery had experimental holes dramatically smaller than those from standard needles. In the denatured tissue, the experimental needle provided less benefit than that observed in fresh tissue, which is likely due to limited elasticity of the preserved artery. Improvement in needle design thus provides distinct advantages for native vessels and unique less traumatic holes in current synthetic materials. Pencil-point needle designs may be particularly applicable to the development of new elastomeric graft material.

Animals↗