In Vivo Evaluation of Customized Aortic Repair Using a Novel Survival Model.

OBJECTIVE: The aim of the study was to evaluate the feasibility and mid-term biological behavior of the novel customized aortic repair (CAR) method for endovascular aneurysm treatment. METHODS: CAR consists of exclusion of an aneurysm from the circulation using a custom-designed dog bone-shaped balloon, followed by aneurysm sac filling with an in situ curing polymer. After curing and balloon deflation, the circulation is restored through a patent cast neolumen. A liquid two-component polymer was injected via a small bore catheter under X-ray control into a surgically created aneurysm. In 50% of the procedures, a self expanding bare metal stent was placed in the polymer cast lumen. A novel animal model was established involving creation of an aneurysm by anastomosing a venous interposition graft into the common carotid artery of eight adult sheep. Two animals were excluded because of non-device related complications. The remaining six animals were monitored for 20 weeks with duplex sonograms performed monthly to assess blood flow and polymer cast lumen patency. After the animals were sacrificed the polymer cast, common carotid artery, and the brain in the carotid outflow tract were removed for histological assessment. RESULTS: In four of the six animals, the aneurysm was successfully excluded using CAR with uneventful follow up. The aneurysm sac was filled incompletely in two animals, resulting in a stent malpositioning and cast lumen occlusion after 12 weeks in one case, and a type 1 endoleak in the other. All six animals survived for 20 weeks. Neither migration nor expansion of the polymer cast was observed and the polymer was demonstrated to be biocompatible and non-thrombogenic. Polymer emboli were not detected in the brain or meninges after sacrifice. CONCLUSIONS: The feasibility and mid-term biological safety of the CAR method for minimally invasive aneurysm repair was demonstrated using a simulated aneurysm survival model.

The need for a new animal model for chronic rejection after lung transplantation.

The single most important cause of late mortality after lung transplantation is obliterative bronchiolitis (OB), clinically characterized by a decrease in lung function and morphologically by characteristic changes. Recently, new insights into its pathogenesis have been acquired: risk factors have been identified and the use of azithromycin showed a dichotomy with at least 2 different phenotypes of bronchiolitis obliterans syndrome (BOS). It is clear that a good animal model is indispensable to further dissect and unravel the pathogenesis of BOS. Many animal models have been developed to study BOS but, so far, none of these models truly mimics the human situation. Looking at the definition of BOS, a good animal model implies histological OB lesions, possibility to measure lung function, and airway inflammation. This review sought to discuss, including pros and cons, all potential animal models that have been developed to study OB/BOS. It has become clear that a new animal model is needed; recent developments using an orthotopic mouse lung transplantation model may offer the answer because it mimics the human situation. The genetic variants among this species may open new perspectives for research into the pathogenesis of OB/BOS.

Change in donor profile influenced the percentage of organs transplanted from multiple organ donors.

We hypothesized that the change in donor profile over the years influenced the percentage of transplantations. We reviewed medical records for all multiple-organ donors (MODs) within our network. The percentage of transplanted organs was compared between 1991-1992 (A) and 2006-2007 (B). In period A, 156 potential MODs were identified compared with 278 in period B. Fifteen potential donors (10%) in period A and 114 (41%) in period B were rejected because they were medically not suitable (40% vs 75%) or there was no family consent (60% vs 25%). Of the remaining effective MODs (141 in period A and 164 in period B), mean (standard deviation = SD) age was 34 (5) years vs 49 (17) years (P < .001). Brain death resulted from craniocerebral trauma in 69% vs 39%, cerebrovascular disease in 24% vs 46%, hypoxia in 4% vs 15%, and brain tumor in 2% vs 0.6% (P < .001). Chest trauma was present in 19% vs 9% (P < .01). The percentage of MODs who received mechanical ventilation for more than 5 days was 8% vs 24% (P < .001). The percentage of organs transplanted in periods A vs B was kidneys, 97% vs 79%; livers, 64% vs 85%; hearts, 60% vs 26%; lungs, 7% vs 35%; and pancreas, 6% vs 13% (P < .001). The number of referred potential MODs increased by 80%, resulting in a small increase in effective MOD organs (17%), mainly because of medical contraindications. The MOD profile changed to older age, fewer traumatic brain deaths, and longer ventilation time. We transplanted more livers, lungs, and pancreases but fewer kidneys and hearts.

Serial prealbumin levels as predictors of outcomes in a retrospective cohort of peritoneal and hemodialysis patients.

OBJECTIVE: Although earlier research has suggested that baseline prealbumin level is an independent predictor of outcome among dialysis patients, the prognostic importance of serial prealbumin levels is less clear. The present study had 3 objectives: first, to determine if prealbumin (a marker of visceral protein stores with a relatively short half-life) predicts subsequent albumin levels taken at least 1 month later; second, to examine the association between serial prealbumin levels and clinical outcome; and third, to examine the association between changes in prealbumin level and outcome. DESIGN: The prognostic value of serial prealbumin levels was examined by linear regression analysis and Cox hazard models in an observational cohort study using a repeated measures design and time-dependent covariates. SETTING: Patients were followed by a tertiary care center, receiving hemodialysis (HD; at either an in-center dialysis unit or one of several satellite units operated by the hospital) or home peritoneal dialysis (PD). PATIENTS: A retrospective cohort was identified consisting of 268 incident and prevalent chronic HD and PD patients receiving dialysis from June 1998 to September 1999. MAIN OUTCOME: The study examined the association between serial prealbumin measurements and future laboratory and clinical outcomes (albumin, hospitalization, and death). RESULTS: Serial prealbumin values were independent predictors of future albumin levels among HD patients (P =.04), but not PD patients. Independent predictors of hospitalization included diabetes for PD patients (P =.0012) and advanced age for HD patients (P =.0008). Advanced age and diabetes were independent predictors of death for both HD (P =.0001 and P =.0368) and PD patients (P =.0014 and P =.0164). Serial prealbumin values, measured as time-dependent covariates, did not predict hospitalization or death. Further analyses examined the prognostic value of changes in prealbumin and albumin values as time-dependent covariates. The final multivariate analysis identified low baseline albumin level as an independent predictor of hospitalization among HD patients (P =.0282), whereas low baseline prealbumin was an independent predictor of death for HD patients (P =.0001). Interestingly, negative changes in serial prealbumin measurements were also independent predictors of death among HD patients (P =.0025). CONCLUSION: Serial prealbumin measurements predict subsequent albumin values among HD patients. As well, low baseline prealbumin level is an independent predictor of adverse outcome among HD patients. Although repeated prealbumin measurements in and of themselves were of no added prognostic value, falling prealbumin values identified by repeated measurements were additional independent predictors of death. These results support the clinical utility of regular prealbumin monitoring among HD patients.

Tissue plasminogen activator (t-PA) efficacy in the restoration of hemodialysis catheter function.

Thrombus formation within hemodialysis catheters contributes to inadequate dialysis and adverse patient outcomes. A thrombolytic agent may be required to restore patency and improve blood flow. This study evaluates the efficacy of instilling low dose (1 mg/ml) t-PA in catheter lumens to restore patency in malfunctioning catheters. t-PA was utilized to treat suspected catheter thrombus over a four-month period. Seventeen patients with 21 catheters (12 temporary, 9 permanent) received 40 doses of t-PA. Catheter function was restored in 39 of 40 cases (97.5%). Significant improvement in blood flow was confirmed by paired t-test (p < 0.001). Sustained improvement in blood flow was confirmed by ANOVA (p < 0.001). The mean primary patency of all catheters was 29.7 days (SD = 27.0 days). No adverse patient effects were noted. These results demonstrate that t-PA can safely and effectively restore blood flow and extend patency in hemodialysis catheters.

The pathophysiology and management of renal bone disease in dialysis patients.

As renal function declines, changes in mineral metabolism occur including phosphate retention, calcitriol deficiency, and the development of secondary hyperparathyroidism. Renal bone disease related to disordered mineral metabolism may result in increased patient morbidity and mortality. Uncontrolled parathyroid hormone (PTH) secretion will result in osteitis fibrosa, a high turnover bone disease. The use of calcium and aluminum-based phosphate binders and vitamin D sterols may contribute to the development of low turnover bone diseases such as osteomalacia and aplastic bone disease. Prevention and control of renal bone disease is an important goal for the interdisciplinary health care team. This paper discusses disordered mineral metabolism and its relationship to renal bone disease. Case studies illustrate the development and treatment of renal bone disease related to secondary hyperparathyroidism and aluminum intoxication.

Reducing complications during hemodialysis using gradient ultrafiltration with gradient sodium dialysate.

The objective of this study was to determine if patient complications and nursing interventions during hemodialysis could be reduced using gradient ultrafiltration and gradient sodium dialysate. Twenty outpatients who had been on hemodialysis for at least 3 months, and using gradient sodium dialysate for at least 1 month, participated. Patients received either ultrafiltration at a constant hourly rate or gradient ultrafiltration, in which the ultrafiltration rate was set higher initially, then decreased step-wise mid-dialysis. Patients received each protocol for 3 months, using a randomized cross-over design. Both protocols used gradient sodium dialysate (150 mEq/L x 3 hrs, 140 mEq/L x 1 hr). There were significantly fewer complications and interventions using gradient ultrafiltration, as compared to constant ultrafiltration. No differences were found in interdialytic weight gain, intradialytic weight loss, or orthostatic blood pressure. These results indicate that gradient ultrafiltration combined with gradient sodium dialysate enhances patient well-being and reduces nursing interventions during hemodialysis.

Urokinase efficacy in the restoration of hemodialysis catheter function.

Thrombus formation is a common cause of hemodialysis catheter malfunction. When thrombus or fibrin sheath restrict the flow of blood through one or both lumens, the catheter may need to be replaced. A less invasive, potentially lower cost option may be the instillation of low dose urokinase to degrade fibrin and restore catheter function. This study examines the efficacy of urokinase in improving blood flow and maintaining catheter patency. In a one-year period, urokinase was utilized in 25 dual lumen hemodialysis catheters (20 temporary, five permanent) in 22 patients. Blood flow and arterial and venous pressures were monitored before and after instillation. Urokinase administration successfully restored function in 20 catheters (80%). Paired t-tests demonstrated a significant improvement in blood flow and arterial pressure (p < 0.01) following urokinase. Catheter patency was extended for a mean of 18.0 days (range 0-90 days). The cost effectiveness of urokinase was evaluated in terms of direct costs, such as the cost of urokinase or materials to replace catheters, and indirect costs such as nursing and physician time and delays in dialysis scheduling. The results of this study suggest that judicious use of urokinase is a cost-effective, non-invasive method of restoring blood flow and extending patency in hemodialysis catheters.

Quantity of dialysis: quality of life--what is the relationship?

Health related quality of life (HRQOL) is increasingly being used to evaluate physical and psychosocial parameters in patients receiving dialysis. In patients with chronic illness, these indices are important adjuncts to biochemical measurements. Inadequate dialysis with low urea clearance (Kt/Vurea) has been linked to adverse outcomes in dialysis patients. Little is known about the relationship between dialysis adequacy and patient reported HRQOL. We evaluated HRQOL in 55 hemodialysis and 60 peritoneal dialysis patients using the RAND 36 Item Health Survey 1.0, measuring the following: physical functioning; role limitations (physical); role limitations (emotional); social functioning; emotional well being; pain; energy; and general health perceptions. Kt/V was also calculated for each patient. Mean HD Kt/V was 1.44 +/- 0.31 (range, 0.5-2.0); mean weekly PD Kt/V was 2.28 +/- 0.90 (range, 1.13-6.02). The relationship between Kt/V and HRQOL was tested using Pearson's correlation. No significant association was found for either treatment group between Kt/V and any of the domains of HRQOL. Thus, HRQOL seems to be influenced by factors other than dialysis adequacy, enhancing its role as an independent measure of patient problems otherwise undetected by traditional objective parameters.

Self-delivery of hemodialysis care: a therapy in itself.

Patient autonomy, sense of control, and well-being are thought to be enhanced by self-care hemodialysis as a therapy for end-stage renal disease. Dialysis in a satellite setting reduces travel time and can diminish therapy intrusiveness. Health-related quality of life (HRQOL), in terms of functional status and well-being, was measured in a group of patients trained for self-care, and then measured again after these patients were transferred to a satellite unit. Comparison was made with an age- and comorbidity-matched cohort of full-care patients. Patients trained for self-care tended to score higher than the full-care patients in the psychosocial domains of HRQOL, such as role function, social function, and emotional well-being, before and after transfer to the satellite unit. Physiological measurements did not differ significantly between groups at any time during the study, indicating that differences in HRQOL were not attributable to differences in metabolic stability. We conclude that patients trained for self-care hemodialysis experience better subjective quality of life than their full-care counterparts. This study highlights both the usefulness of measuring HRQOL as an outcome of hemodialysis therapy and the potential benefits of therapies such as self-care and satellite dialysis.

Assessment of health status in peritoneal dialysis patients: a potential outcome measure.

OBJECTIVES: To determine the feasibility and practicality of measuring general health status (GHS) in an outpatient peritoneal dialysis population. To determine whether GSH correlated intuitively with biochemical, socio-demographic and co-morbidity measurements. DESIGN: The Medical Outcomes Study 20-item short form was administered on a voluntary basis in the outpatient setting. Demographic and current biochemical data were extracted from the medical record. The effects of the socio-demographic, biochemical and physiologic variables on the six subscales of GHS generated by the questionnaire were estimated using multivariate linear regression analysis resulting in the development of six separate models. SETTING: Peritoneal dialysis program of a University Hospital. PATIENTS: Sixty stable patients on home peritoneal dialysis completed the GHS questionnaire during regularly scheduled outpatient visits. Ages ranged from 13 to 81 years. The study group included 14 diabetics (23%). RESULTS: Administering the questionnaire caused no logistical difficulties in the outpatient setting. Regression models for predicting GHS were both significant and intuitively correct. The presence of co-morbidities such as diabetes mellitus (p = 0.002; Social Subscale) and peripheral vascular disease (p = 0.016: General Health Subscale) had the most significant negative impact on GHS. An increased length of time on dialysis was associated with a higher GHS (p = 0.002; Physical Subscale). CONCLUSION: General Health Status questionnaires can be readily administered to peritoneal dialysis patients in the outpatient setting. They have face validity as a measurement of wellness and functioning. The longitudinal use of such instruments in conjunction with clinical and laboratory findings may identify both medical and non-medical factors impacting on our peritoneal dialysis population.

Health-related quality of life assessment in clinical practice.

Assessment of biochemical responses to therapy is routine in the management of patients with end stage renal disease (ESRD). Assessment of health-related quality of life (HRQOL), however, is less common. Previous research indicates that HRQOL is a meaningful indicator that should be integrated into clinical practice. HRQOL is longitudinally evaluated in in-centre hemodialysis patients using the RAND 36-item Health Survey 1.0. Caregivers incorporate scores from this instrument into their assessment of patient functioning and well-being. HRQOL scores can be utilized to evaluate responses to changes in therapy, and to direct clinical decision-making, adding an important dimension to holistic, quality care for ESRD patients.

Specializing in nursing: nephrology certification and recertification: benefits and barriers.

The diversity and complexity of nephrology is increasing and specialized knowledge and skills are required to practise this subspeciality. As a result, specialization and certification by the Canadian Nurses' Association (CNA) in nephrology nursing has become a reality. Specialization benefits patients, nurses and employers by ensuring high professional standards, providing an increased sense of professional achievement and innovative ways of providing quality care. Maintaining these high standards requires continuing education and recertification. A number of educational opportunities meet these needs. Recognition of speciality services would motivate more nurses to commit to nephrology certification. Specialization demands a greater commitment from the health care system, but provides significant dividends to both the health care system and the patient.

Measuring and predicting outcomes in ESRD patients.

To test the feasibility of using general health status as a practical dialysis outcome measure, in a longitudinal pilot study, two well-validated instruments were administered to patients from our dialysis unit or clinic. The instruments were administered three times, at eight-week intervals for seven months to 41 hemodialysis (HD) patients. Forty-five transplant (Tx) patients were surveyed once as a validating control. Sociodemographic, imaging and biochemical data were tested as outcome predictors. Unexpected hospitalizations and adverse intercurrent events were used as additional outcome measures. Preliminary analysis shows HD patients scoring low, while Tx patients scored higher (healthier). These preliminary results suggest that assessment of general health status is a valid and practical outcome measure.

Noncompliance in chronic hemodialysis patients: an assessment approach for care planning.

Noncompliance is a nursing diagnosis frequently encountered by nephrology nurses in their practice. Patient assessment, as part of the nursing process, gives us insight into the numerous factors contributing to noncompliance. An assessment approach has been developed to assist nurses in acquiring the knowledge, empathy and understanding to plan effective care for the noncompliant patient.