Dash and Boston Questionnaire Assessment of Carpal Tunnel Syndrome Outcome: What is the Responsiveness of an Outcome Questionnaire?

This prospective study evaluates if the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire is an adequately responsive outcome measure in carpal tunnel syndrome by comparing it with the disease-specific Boston questionnaire (BQ). To measure responsiveness (sensitivity to clinical change), 57 patients with a clinical diagnosis of carpal tunnel syndrome completed the DASH and BQ preoperatively and again 3 months after open carpal tunnel decompression. A second group of 31 patients completed the questionnaires in the outpatient clinic and again 2 weeks later to assess test–retest reliability. The time to complete all questionnaires was recorded. Responsiveness of the DASH is comparable with the BQ with standardized response means of 0.66, 1.07 and 0.62 for the DASH, BQ-symptoms and BQ-function, respectively. Test–retest data show both questionnaires are reliable. Mean times to complete questionnaires were 6.8 minutes (DASH) and 5.6 minutes (BQ). This study concludes that the DASH questionnaire is a reliable, responsive and practical outcome instrument in carpal tunnel syndrome.

An Evaluation of the Value of Group Education in Recently Diagnosed Diabetes Mellitus

Diabetic patients have a 12% to 25% lifetime risk of developing foot complications leading to significant morbidity and mortality. The objective of this study was to assess the effectiveness of group education in improving patient awareness of foot care. The authors evaluated the effect of group size and areas in which knowledge seemed to be most affected. Patients attending a 2-hour teaching session between November 2005 and March 2006 were recruited. Patients filled in an 18-part questionnaire before and after the teaching session to assess knowledge. Fifty-nine patients recently diagnosed with diabetes mellitus or foot complications were recruited for 7 sessions. Analysis of the data showed a statistically significant improvement in foot care knowledge after the teaching session compared with before (69% to 85%,P < .001). Patients in the smaller group (n< 10) had significantly higher scores compared with the bigger groups (n> 10;P < .025). These data show the benefit of group education about foot care for patients with diabetes. Smaller groups benefited more than larger ones did, which could be attributed to the sizes allowing for better interaction between the tutor and patient. As patient knowledge is variable from individual to individual, smaller teaching sessions may allow patients to address specific concerns.

Acute kidney injury: global health alert

Acute kidney injury (AKI) is increasingly prevalent in developing and developed countries and is associated with severe morbidity and mortality. Most etiologies of AKI can be prevented by interventions at the individual, community, regional and in-hospital levels. Effective measures must include community-wide efforts to increase an awareness of the devastating effects of AKI and provide guidance on preventive strategies, as well as early recognition and management. Efforts should be focused on minimizing causes of AKI, increasing awareness of the importance of serial measurements of serum creatinine in high risk patients, and documenting urine volume in acutely ill people to achieve early diagnosis; there is as yet no definitive role for alternative biomarkers. Protocols need to be developed to systematically manage prerenal conditions and specific infections. More accurate data about the true incidence and clinical impact of AKI will help to raise the importance of the disease in the community, increase awareness of AKI by governments, the public, general and family physicians and other health care professionals to help prevent the disease. Prevention is the key to avoid the heavy burden of mortality and morbidity associated with AKI.

Patient safety systems in the primary health care of diabetes—a story of missed opportunities?

AIMS

Key elements of a patient safety system include mechanisms for identifying errors or safety events, methods for investigating the events and processes for acting on the findings of the investigations. A patient safety system for management of diabetes in primary care might help to reduce adverse outcomes. The aims of this study were to review the current state of research into patient safety systems for people with diabetes in primary care.

METHODS

MEDLINE, EMBASE and nine other biomedical and health management databases were searched for articles published up to April 2009. Selection and review of abstracts were carried out independently by two authors.

RESULTS

Abstracts of 1659 articles were identified, of which only three fulfilled the selection criteria, and these did not appear in mainstream primary care journals. These papers covered the applications of root cause analysis, videoconferencing and automated telephone support to patient safety systems for managing diabetes in primary care.

CONCLUSIONS

There is very little evidence on how patient safety systems for the management of primary care diabetes can be implemented, or on how the effectiveness of such systems can be maximized. If patient safety systems do have potential to improve the processes and outcomes of care, the lack of relevant research may be regarded as a missed opportunity—investigation into the reasons for the situation is needed, with the aim of motivating and enabling further research on a range of problems identified here.

Renal replacement therapy for acute renal failure

Renal replacement therapy became a common clinical tool to treat patients with severe acute kidney injury (AKI) since the 1960s. During this time dialytic options have expanded considerably; biocompatible membranes, bicarbonate dialysate and dialysis machines with volumetric ultrafiltration control have improved the treatment for acute kidney injury. Along with advances in methods of intermittent hemodialysis, continuous renal replacement therapies have gained widespread acceptance in the treatment of dialysis-requiring AKI. However, many of the fundamental aspects of the renal replacement treatment such as indication, timing of dialytic intervention, and choice of dialysis modality are still controversial and may influence AKI patient's outcomes. This review outlines current concepts in the use of dialysis techniques for AKI and suggests an approach for selecting the optimal method of renal replacement therapy.

Pharmacologic approaches for volume excess in acute kidney injury (AKI)

Volume management is an integral component of the care of patients with acute kidney injury (AKI). Considerable controversy exists regarding the use of pharmacological agents for volume management. Although overt fluid overload is often seen in AKI and may prompt attention for the use of diuretics, often these agents are used in the absence of fluid retention. Over the last decade several new agents have become available for volume removal. We reviewed the literature on this topic and addressed four key questions for the appropriate utilization of these agents. These include the drug targets and mechanism of action of available agents; clinical goals and criteria for timing of intervention; adaptation of therapy for specific clinical settings and measures required for monitoring effectiveness and patient safety. This report details our current knowledge in this area, provides evidence-based clinical practice recommendations where appropriate, and formulates a research agenda to address unanswered questions.

Acid-base disturbances in the intensive care unit: current issues and the use of continuous renal replacement therapy as a customized treatment tool

Continuous renal replacement therapies (CRRT) are often used to manage complex acid-base problems in critically ill patients. These techniques allow a constant manipulation of the plasma composition. Several technical factors from CRRT influence the acid-base status; namely, the effluent rate, the operational characteristics of the technique, the content of the solutions and the metabolic rate of the buffer. This article reviews the common acid base disorders occurring in the intensive care unit, using both the anion gap and the strong ion gap approaches, and describes the influence of CRRT on acid-base physiology. The use of CRRT as a customized therapy for acid-base disorders is discussed, allowing an integration of both physiological and technical concepts.

Mortality after acute renal failure: models for prognostic stratification and risk adjustment

To adjust adequately for comorbidity and severity of illness in quality improvement efforts and prospective clinical trials, predictors of death after acute renal failure (ARF) must be accurately identified. Most epidemiological studies of ARF in the critically ill have been based at single centers, or have examined exposures at single time points using discrete outcomes (e.g., in-hospital mortality). We analyzed data from the Program to Improve Care in Acute Renal Disease (PICARD), a multi-center observational study of ARF. We determined correlates of mortality in 618 patients with ARF in intensive care units using three distinct analytic approaches. The predictive power of models using information obtained on the day of ARF diagnosis was extremely low. At the time of consultation, advanced age, oliguria, hepatic failure, respiratory failure, sepsis, and thrombocytopenia were associated with mortality. Upon initiation of dialysis for ARF, advanced age, hepatic failure, respiratory failure, sepsis, and thrombocytopenia were associated with mortality; higher blood urea nitrogen and lower serum creatinine were also associated with mortality in logistic regression models. Models incorporating time-varying covariates enhanced predictive power by reducing misclassification and incorporating day-to-day changes in extra-renal organ system failure and the provision of dialysis during the course of ARF. Using data from the PICARD multi-center cohort study of ARF in critically ill patients, we developed several predictive models for prognostic stratification and risk-adjustment. By incorporating exposures over time, the discriminatory power of predictive models in ARF can be significantly improved.

The male neck of femur

Fractured neck of femur in elderly is associated with mortality which is reported in literature to vary between 20 and 40%. One of the factors which is suggested to be a risk factor is male sex. We reviewed 83 male necks of femur patients admitted over a period of a year to assess the patient's physical status, influence of co-morbidities, postoperative course and mortality. The in-hospital mortality was 26.5% and 1-year mortality was 44.6%. The in-hospital mortality for female neck of femur patients during the same period was 18%. Increasing age, high ASA category and post-operative chest infections were associated with high peri-operative mortality, and fall sustained in an acute hospital ward was associated with high 1-year mortality in addition to ASA grade and chest infection. Patients who had a chest infection in the post-operative period had in-hospital mortality of 46.2% (P value 0.006) and a 1-year mortality of 73.1% (P value 0.001). Patients who fell in the ward as inpatients under geriatric care had 60% mortality.

Cardiac structural and functional abnormalities in end stage renal disease patients with elevated cardiac troponin T

OBJECTIVES

To identify in a prospective observational study the cardiac structural and functional abnormalities and mortality in patients with end stage renal disease (ESRD) with a raised cardiac troponin T (cTnT) concentration.

METHODS

126 renal transplant candidates were studied over a two year period. Clinical, biochemical, echocardiographic, coronary angiographic, and dobutamine stress echocardiographic (DSE) data were examined in comparison with cTnT concentrations dichotomised at cut off concentrations of < 0.04 microg/l and < 0.10 microg/l.

RESULTS

Left ventricular (LV) size and filling pressure were significantly raised and LV systolic and diastolic function parameters significantly impaired in patients with raised cTnT, irrespective of the cut off concentration. The proportions of patients with diabetes and on dialysis were higher in both groups with raised cTnT. With a cut off cTnT concentration of 0.04 microg/l but not 0.10 microg/l, significantly more patients had severe coronary artery disease and a positive DSE result. The total ischaemic burden during DSE was similar in cTnT positive and negative patients, irrespective of the cut off concentration used. LV end systolic diameter index and E:Ea ratio were independent predictors of cTnT rises > or = 0.04 microg/l and > or = 0.10 microg/l, respectively. Diabetes was independently associated with cTnT at both cut off concentrations. Mortality was higher in all patients with raised cTnT.

CONCLUSIONS

Patients with ESRD with raised cTnT concentrations have increased mortality. Raised concentrations are strongly associated with diabetes, LV dilatation, and impaired LV systolic and diastolic function, but not with severe coronary artery disease.

Prognostic value of the Framingham cardiovascular risk equation and the UKPDS risk engine for coronary heart disease in newly diagnosed Type 2 diabetes: results from a United Kingdom study

AIMS

To determine the prognostic value of the Framingham equation and the United Kingdom Prospective Diabetes Study (UKPDS) risk engine in patients with newly diagnosed Type 2 diabetes.

METHODS

A community-based cohort (n=428; aged 30-74 years) free of clinically evident CVD and newly diagnosed with Type 2 diabetes were studied over a median 4.2 (sd+/-0.62) years. Predicted (using baseline variables at diagnosis) and observed proportions of primary CVD and CHD events were compared using the Framingham equations and the UKPDS risk engine (only CHD events). The discrimination (c-statistic) and calibration (HLchi2) of the risk equations were calculated. The sensitivity and specificity of the Framingham equation at a 15%, 10-year CHD risk threshold (NICE guidelines) was compared with that of the ADA lipid threshold (LDLc>or=2.6 mmol/l or triglycerides>or=4.5 mmol/l).

RESULTS

The Framingham equations underestimated the overall number of cardiovascular events by 33% and coronary events by 32% and showed modest discrimination and poor calibration for CVD [c=0.673; HLchi2=32.8 (P<0.001)] and CHD risk [c=0.657; HLchi2=19.8 (P=0.011)]. Although the overall underestimate was lower and non-significant with the UKPDS risk engine for CHD (13%), its performance in terms of discrimination and calibration were similar [c=0.670; HLchi2=17.1 (P=0.029)]. The 15%, 10-year CHD risk threshold with both the Framingham and UKPDS risk engines had similar sensitivity for primary CVD as the lipid level threshold [85.7 and 89.8% vs. 93.9% (P=0.21 and 0.34)] and both had greater specificity [33.0 and 30.3% vs. 12.1% (P<0.001 and P<0.001)].

CONCLUSIONS

In people with newly diagnosed Type 2 diabetes, both the Framingham equation and UKPDS risk engine are moderately effective at identifying those at high-risk (discrimination) and are poor at quantifying risk (calibration). Nonetheless, at a population level, a 15% 10-year CHD risk threshold using either risk calculator has similar sensitivity as an approach based on a single lipid risk factor level and may have benefits in terms of cost-effectiveness given the improved specificity.

Mucosal expression of cyclooxygenase isoforms 1 and 2 is increased with worsening damage to the gastric mucosa

AIMS

To test the hypothesis that both COX-1 and COX-2 expression in human gastric mucosa is up-regulated in the presence of inflammation as seen in patients with gastritis and gastric ulcers.

METHODS AND RESULTS

We performed immunohistochemistry using COX-1 and COX-2 monoclonal antibodies on gastric biopsies from 59 patients with normal mucosa, gastritis and gastric ulcers. Expression of COX-1 and COX-2 was quantified using an intensity proportion scoring system. Expression of COX-1 was primarily seen in the lamina propria mononuclear cells with some expression in deep gastric glands in the ulcer group. Expression of COX-2 was primarily seen in the deep gastric glands with focal expression in the lamina propria mononuclear cells. We found a stepwise increase in the expression of both COX-1 and COX-2 as mucosal damage progressed from normal to gastritis to gastric ulcer.

CONCLUSIONS

We conclude that both COX-1 and COX-2 expression in the gastric mucosa are increased in the setting of gastritis and gastric ulceration. Although this increased expression may be due, at least in part, to an increase in inflammatory cell numbers, this study raises the possibility that both COX-1 and COX-2 are inducible, contrary to the traditionally held view of only COX-2 being inducible.

Endobronchial ultrasound to assess airway wall thickening: validation in vitro and in vivo

Endobronchial ultrasound (EBUS) allows identification of airway wall structures and could potentially be utilised for in vivo studies of airway thickening in asthma. The present study investigated whether inflation of the fluid-filled balloon sheath over the transducer (necessary to provide sonic coupling with the airway wall) influenced in vitro measurements. In vivo comparability of EBUS with high resolution computed tomography scanning (HRCT), an established method for measuring wall thickness, was determined in control subjects. The airway diameter and wall thickness were studied using EBUS in 24 cartilaginous airways obtained from four sheep, before and after balloon sheath inflation during immersion in saline. To assess EBUS versus HRCT comparability of airway measures in vivo, 12 control subjects underwent imaging of the posterior basal bronchus of the right lower lobe by both techniques. Intra- and interobserver agreement were also assessed. Results with and without the balloon sheath gave comparable measures of airway internal diameter and wall thickness in vitro. Statistical analysis showed agreement between EBUS and HRCT, and intra- and interobserver variability in vivo. The current study concludes that endobronchial ultrasound, which does not present a radiation risk, could be utilised in the in vivo study of cartilaginous airway wall remodelling in respiratory diseases, such as asthma.

Effect of video display on the grading of diabetic retinopathy

PURPOSE

Digital images are increasingly being used in ophthalmology. These may be viewed either on thin-film transistor (TFT) or on cathode-ray tube (CRT) displays. However, there is little data showing which is superior. In this study, we compared the performance of CRT and TFT displays for grading of both compressed and uncompressed images of diabetic retinopathy.

METHODS

A total of 49 35 mm transparencies of diabetic retinopathy were scanned and compressed. The images comprised 17 with no retinopathy, eight with background, five with preproliferative, and 19 with proliferative retinopathy. Four levels of compression were used: 0, 70, 80, and 90%. A total of 196 randomised images were presented to two masked graders using both TFT and CRT displays under uniform lighting conditions, 2 months apart. The grade of retinopathy was assessed. Statistical analysis of grading accuracy was performed using receiver operator characteristic curves of sensitivity and specificity and the Stuart-Maxwell test for paired, nonparametric data.

RESULTS

Both displays showed high sensitivity and specificity for the detection of any retinopathy. For the specific grade of retinopathy, the CRT performed slightly better with a sensitivity of 0.80 for uncompressed images, compared with 0.75 using the TFT. Compression reduced these sensitivities to 0.73 on the CRT and 0.63 on the TFT. Grading of uncompressed images magnified to four times their original size was more accurate on the TFT.

CONCLUSIONS

Grading on both displays met sensitivity and specificity criteria proposed by Diabetes UK (formerly British Diabetic Association) for screening of diabetic retinopathy. The CRT generally performed slightly better than the TFT in relation to the detection of the specific grade of retinopathy.

Clinical benefit and approach of ultrafiltration in acute heart failure

Because of the increasing incidence of acute heart failure admissions to critical care units, nephrologists have been asked to become more involved in the management of these patients. Renal dysfunction is a major element in impeding clinical recovery. In acute heart failure, renal function is often abnormal. The judicious application of ultrafiltration techniques may represent an efficacious adjunct to present conventional practice. In patients with refractory congestive heart failure, the ability to provide continuous, daily, large volume removal not only improves volume status but also the clinical symptoms of the decompensated patient. A thorough literature review supports the premise that starting hemofiltration is an appropriate alternative for difficult and unstable cardiac patients. An optimal strategy utilizing continuous renal replacement therapy can dramatically improve the patient's clinical condition, mitigate the neurohumoral stimulation, increase urinary output and promote absorption of excessive extravascular fluid.

Assessing fluid change in hemodialysis: whole body versus sum of segmental bioimpedance spectroscopy

BACKGROUND

Accurate estimation of extracellular fluid (ECF) is an important factor in assessing dry weight in hemodialysis patients. Bioimpedance spectroscopy (BIS) is a simple method to determine the compartmental distribution of body water in HD patients. Recent studies have shown that sum of segmental BIS (SBIS) is less affected by the change of body position and may be more accurate in measuring ECF change than whole body BIS (WBIS). We have compared SBIS and WBIS in estimating change in fluid volume during hemodialysis.

METHODS

Twenty-eight patients (male 10, female 18) were studied during their regular hemodialysis. ECF changes estimated by both techniques were compared with actual weight change during the inter- and intradialytic periods.

RESULTS

Both techniques tracked fluid changes that correlated well with fluid loss during the dialysis run (WBIS, r = 0.75, P < 0.001; SBIS, r = 0.65, P < 0.001) and fluid gain in the interdialytic period (WBIS, r = 0.73, P < 0.01; SBIS, r = 0.6, P < 0.01). ECF changes estimated by SBIS and WBIS underestimated weight loss 0.78 +/- 0.01 L and 0.6 +/- 0.01 L, respectively; and underestimated weight gain 0.66 +/- 0.18 L and 0.76 +/- 0.18 L, respectively.

CONCLUSIONS

While both WBIS and SBIS can be used to track relative ECF volume changes in HD patients, they are not accurate in quantifying changes in ECF volume. More studies are needed to evaluate the benefit of SBIS over WBIS in clinical practice.

Fluid management in CRRT

Fluid management with CRRT requires an understanding of the principles of fluid removal and fluid balance. Although these appear to be similar to intermittent hemodialysis, there are significant differences. In order to utilize these techniques to their full ability, a variety of strategies can be used. No matter which method is used it is imperative that the goals for fluid management be well defined and monitoring for errors be a part of the protocol.

A randomized clinical trial of continuous versus intermittent dialysis for acute renal failure

BACKGROUND

Acute renal failure (ARF) requiring dialysis in critically ill patients is associated with an in-hospital mortality rate of 50 to 80%. The worldwide standard for renal replacement therapy is intermittent hemodialysis (IHD). Continuous hemodialysis and hemofiltration techniques have recently emerged as alternative modalities. These two therapies have not been directly compared.

METHODS

A multicenter, randomized, controlled trial was conducted comparing two dialysis modalities (IHD vs. continuous hemodiafiltration) for the treatment of ARF in the intensive care unit (ICU). One hundred sixty-six patients were randomized. Principal outcome measures were ICU and hospital mortality, length of stay, and recovery of renal function.

RESULTS

Using intention-to-treat analysis, the overall ICU and in-hospital mortalities were 50.6 and 56.6%, respectively. Continuous therapy was associated with an increase in ICU (59.5 vs. 41.5%, P < 0.02) and in-hospital (65.5 vs. 47.6%, P < 0.02) mortality relative to intermittent dialysis. Median ICU length of stay from the time of nephrology consultation was 16.5 days, and complete recovery of renal function was observed in 34.9% of patients, with no significant group differences. Despite randomization, there were significant differences between the groups in several covariates independently associated with mortality, including gender, hepatic failure, APACHE II and III scores, and the number of failed organ systems, in each instance biased in favor of the intermittent dialysis group. Using logistic regression to adjust for the imbalances in group assignment, the odds of death associated with continuous therapy was 1.3 (95% CI, 0.6 to 2.7, P = NS). A detailed investigation of the randomization process failed to explain the marked differences in patient assignment.

CONCLUSIONS

A randomized controlled trial of alternative dialysis modalities in ARF is feasible. Despite the potential advantages of continuous techniques, this study provides no evidence of a survival benefit of continuous hemodiafiltration compared with IHD. This study did not control for other major clinical decisions or other supportive management strategies that are widely variable (for example, nutrition support, hemodynamic support, timing of initiation, and dose of dialysis) and might materially influence outcomes in ARF. Standardization of several aspects of care or extremely large sample sizes will be required to answer optimally the questions originally posed by this investigation.

What do American nephologists think about dialysis modality selection?

In the United States, 87.3% of the patients with end-stage renal disease (ESRD) requiring dialysis are treated with hemodialysis (HD) and 12.7% with peritoneal dialysis (PD). This represents a greater use of HD than in many other nations. We mailed a survey questionnaire to members of the National Kidney Foundation Council on Dialysis to better understand the attitudes of American nephrologists toward dialysis modality decisions. We received responses from 240 of 507 nephrologists (47.3%). The respondents were heavily involved in clinical dialysis work. Results showed that decisions regarding modality selection were strongly based on patient preference (4.54 on a scale of 1 to 5), quality of life (4.18), morbidity (4.02), and mortality (3.90), whereas the least important factors reported were facility reimbursement (2.09) and physician reimbursement (1.98). When asked about the current use of modalities, hospital-based HD and full-care HD were believed to be overused (2.63 for each on a scale of 1 [vastly overused] to 5 [vastly underused]), whereas home HD (4.29), continuous ambulatory PD (3.71), and cycler PD (3.59) were underused. A hypothetical question about optimal modality distribution to maximize survival or cost-effectiveness showed that HD should constitute 71% or 66% of dialysis (with 11% or 14% in the form of home HD, respectively). PD use would increase between two- and threefold over current practices. Our results suggest that American nephrologists believe home therapies are underused. Because modality distribution is an important determinant of costs and possibly outcomes in patients with ESRD, there is an urgent need for further research in this area.

Current status of renal replacement therapy for acute renal failure. A survey of US nephrologists. The National Kidney Foundation Council on Dialysis

Although the management of acute renal failure (ARF) constitutes a major component of the activities of practicing nephrologists, minimal information is available on the dialysis techniques utilized to treat ARF in the USA. It is evident from several recent publications that there are wide variations in the dialytic and nondialytic management of ARF. In order to obtain a better understanding of the current practice for dialytic management of ARF, the National Kidney Foundation (NKF) Council on Dialysis commissioned a survey of NKF members. This article describes the results of this survey and provides a snapshot of the current management practices for ARF. It is our hope that this information will provide a baseline for further research in this area.

Attitudes of Canadian nephrologists toward dialysis modality selection

OBJECTIVE

To determine the opinions and attitudes of Canadian nephrologists about dialysis modality decisions and optimal dialysis system design.

PARTICIPANTS

Members of the Canadian Society of Nephrology.

INTERVENTION

A mailed survey questionnaire.

RESULTS

A 66% response rate was obtained. Decisions about modality are reported to be based most strongly on patient preference (4.4 on a scale from 1 to 5), followed by quality of life (4.06), morbidity (3.97), mortality (3.85), and rehabilitation (3.69), while neither facility (1.78) nor physician (1.62) reimbursement are important. When asked about the current relative utilization of each modality, nephrologists felt that hospital-based hemodialysis (HD) is slightly overutilized (2.53), continuous ambulatory peritoneal dialysis (CAPD) is about right (3.00), while cycler peritoneal dialysis (PD) (3.53), community-based full (3.83) and self-care HD (3.91), and home HD (4.02) are underutilized. A hypothetical question about optimal distribution to maximize survival revealed that a type of HD should constitute 62.8% of the mix, with more emphasis on cycler PD (14.9%), community-based full care HD (13.8%), self-care HD (14.5%), and home HD (9.0%) than is current practice. However, when the goal was to maximize cost effectiveness, HD fell slightly to 57.8%.

CONCLUSIONS

These survey results suggest that the current national average 66%/34% HD/PD ratio is reasonable. However, there appears to be a consensus that Canada could evolve to a more cost-effective, community-based dialysis system without compromising patient outcomes.

Assessment of dry weight in hemodialysis: an overview

Fluid balance is an integral component of hemodialysis treatments to prevent under- or overhydration, both of which have been demonstrated to have significant effects on intradialytic morbidity and long-term cardiovascular complications. Fluid removal is usually achieved by ultrafiltration to achieve a clinically derived value for "dry weight." Unfortunately, there is no standard measure of dry weight and as a consequence it is difficult to ascertain adequacy of fluid removal for an individual patient. Additionally, there is a lack of information on the effect of ultrafiltration on fluid shifts in the extracellular and intracellular fluid spaces. It is evident that a better understanding of both interdialytic fluid status and fluid changes during hemodialysis is required to develop a precise measure of fluid balance. This article describes the current status of dry weight estimation and reviews emerging techniques for evaluation of fluid shifts. Additionally, it explores the need for a marker of adequacy for fluid removal.

Comorbidity of substance use disorders with mood and anxiety disorders: results of the International Consortium in Psychiatric Epidemiology

This article reports the results of a cross-national investigation of patterns of comorbidity between substance use and psychiatric disorders in six studies participating in the International Consortium in Psychiatric Epidemiology. In general, there was a strong association between mood and anxiety disorders as well as conduct and antisocial personality disorder with substance disorders at all sites. The results also suggest that there is a continuum in the magnitude of comorbidity as a function of the spectrum of substance use category (use, problems, dependence), as well as a direct relationship between the number of comorbid disorders and increasing levels of severity of substance use disorders (which was particularly pronounced for drugs). Finally, whereas there was no specific temporal pattern of onset for mood disorders in relation to substance disorders, the onset of anxiety disorders was more likely to precede that of substance disorders in all countries. These results illustrate the contribution of cross-national data to understanding the patterns and risk factors for psychopathology and substance use disorders.

Acute renal failure in the 21st century: recommendations for management and outcomes assessment

Acute renal failure (ARF) remains a common and potentially devastating disorder affecting as many of 5% of all hospitalized patients, with a higher prevalence in patients in critical care units. ARF is more frequently observed in the setting of multiorgan dysfunction syndrome (MODS) and in elderly patients with complex disease, where mortality is high. Numerous technical advances have not yet impacted favorably on this high mortality rate. This report summarizes recommendations from participants at the National Institutes of Health Conference: "Acute Renal Failure in the 21st Century," May 6 to 8, 1996, in Bethesda, MD. The focus is on categorizing recent clinically relevant developments in the field and on identification of new research initiatives to transfer a new body of knowledge derived from fundamental studies and laboratory investigation to the management of ARF in the new millennium. The development of a multicenter database through cooperative multicenter studies is advocated. Future studies should define the appropriate outcome measures to assess and emphasize the impact of hemodynamic monitoring, adjunctive agents, and adequacy and modality of renal replacement therapy on outcomes in ARF.

Continuous renal replacement therapies in the acute renal failure setting: current concepts

Several new methods of renal replacement therapy are now available for the treatment of acute renal failure in the intensive care unit (ICU) setting. Continuous dialysis techniques have evolved over the last decade and are now increasingly used in the ICU. This review provides a framework for the evaluation of these therapies and discusses the emerging indications for their use.

Determination of fluid shifts during chronic hemodialysis using bioimpedance spectroscopy and an in-line hematocrit monitor

Effective ultrafiltration in hemodialysis requires a plasma refilling rate (PRR) sufficient to support blood volume. Knowledge of PRR and compartment shifts helps in understanding intradialytic events and may improve fluid removal. Simultaneous measurements with in-line hematocrit and bioimpedance spectroscopy were done in eight patients (17 runs) and extended for 15-60 min beyond the end of hemodialysis to determine fluid shifts and evaluate the relationship between changes in blood volume, extracellular fluid volume, and PRR. Absolute blood volumes, plasma refilling rates, and interstitial fluid volumes were calculated. Significant correlations were noted between different compartment volumes and the change in weight and estimates of plasma refilling. Pooling all runs, the change in interstitial fluid volume from beginning to end of hemodialysis correlated with the change in weight (r = 0.63, p = 0.01). Changes in PRR tracked changes in interstitial fluid volume for patients with two or more runs. In conclusion, the combination of in-line hematocrit and bioimpedance spectroscopy allows the quantification of different compartment volumes and PRR. Interstitial fluid volume may be a major determinant of PRR. This information would permit the development of strategies to reduce intradialytic morbidity.

Anticoagulation during continuous renal replacement therapy

Proper anticoagulation is an important factor in the function and life of the filter in CAVH or CAVHD and is the Achilles heel for CRRT. Several options now exist for anticoagulation and can be selected based on individual patient characteristics, availability of various anticoagulants, and local expertise. The choice of anticoagulant should be based on multiple factors, including A) the access site and whether an external pump is being used; B) the nature and geometry of the membrane; C) whether enhancements for ultrafiltration, such as predilution, are used; and D) the clinical status of the patient and preexisting coagulation abnormalities. Since anticoagulation in continuous therapy lasts longer than in intermittent hemodialysis, careful selection and monitoring are essential to prevent complications.

Synthetic peptides of human CD4 enhance binding of immunoglobulins to monocyte/macrophage cells. II. Mechanisms of enhancement

We have previously shown that a synthetic peptide corresponding to amino acid residues 21-49 of the first extracellular domain of human CD4 binds immunoglobulins (Ig) and antibody: antigen (Ab:Ag) complexes, and greatly enhances the uptake of aggregated Ig by monocyte/macrophage U937 cells. In this report, we investigated the mechanisms of enhanced uptake, and the contribution of different receptors present on the surface of monocyte/macrophage cells to this phenomenon. Our results indicate that both Fc receptor (FcR) and cell surface CD4 participate in the enhanced uptake of Ig promoted by the synthetic peptide of CD4. The involvement of these two receptors was demonstrated in experiments using monoclonal antibodies to FcR and CD4, as well as monosialoganglioside GM1, a substance known to modulate surface CD4. The participation of CD4 was further confirmed using the CD4 monocyte/macrophage cell line MM-6. Together, the results of these experiments indicate that surface CD4 may cooperate with FcR in handling aggregated Ig and Ab:Ag complexes. The implications of these findings for immunoregulation by Ab:Ag and idiotype:anti-idiotype (Id:anti-Id) complexes, and infection of macrophages by HIV, are discussed.

Identification of novel heparin-releasable proteins, as well as the cytokines midkine and pleiotrophin, in human postheparin plasma

The heparin-releasable proteins are a group of proteins that are targeted to the endothelial surface by attachment to glycosaminoglycans and may have functions specific to the endothelium-blood interface. In this study, heparin-affinity chromatography of human postheparin plasma was used as a method to identify and study novel heparin-releasable proteins. Six proteins seen on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels have increased levels in plasma after intravenous heparin. The six proteins are platelet factor 4, midkine, pleiotrophin, and several novel proteins. Midkine and pleiotrophin are related cytokines that are developmentally regulated, neurotrophic, and mitogenic. Additional studies show that levels of midkine and pleiotrophin peak at 10 to 30 minutes after injection of heparin. Heparin-releasable midkine and pleiotrophin do not originate from blood cells or the kidney. Heparin-releasable midkine may originate from endothelial cells. Soft agar culture of an adenocarcinoma cell line (SW-13) demonstrates growth-stimulating activity similar to that described for pleiotrophin in the heparin-agarose eluate of postheparin plasma but not in the heparin-agarose eluate of preheparin plasma. It is concluded there are more heparin-releasable proteins than previously identified, including midkine and pleiotrophin, and that heparin-affinity chromatography of postheparin plasma is a useful technique for identifying novel heparin-releasable proteins.

Extracorporeal management of acute renal failure patients at high risk of bleeding

The incidence of systemic bleeding events and extracorporeal clotting was studied in 57 critically ill acute renal failure patients treated with intermittent hemodialysis (IHD) and/or continuous arteriovenous hemodialysis (CAVHD), using heparin (Hep), saline-flush (Sal, no anticoagulant), and citrate (Cit) anticoagulation protocols. Thirty-seven patients received a single dialysis modality, and 20 changed modalities one or more times, each change of dialysis type (IHD or CAVHD) or anticoagulant protocol being considered as a new course of treatment. The study was non-randomized, with a demonstrable bias towards using Hep for patients at lower risk of bleeding, and Sal or Cit for higher risk patients. Despite this bias, new bleeding events occurred during 26% of 35 courses of HepIHD and HepCAVHD, and during 0% of 24 courses of CitIHD and CitCAVHD (P < 0.009). Troublesome dialyzer/filter clotting occurred during one course of HepCAVHD, and during 12% of 129 SalIHD procedures; 28% of 29 courses of SalIHD were terminated for this reason. CitCAVHD was well tolerated and proved superior to other modalities in freedom from bleeding events and clotting problems. Alternatives to heparin anticoagulation should be made available for high risk patients requiring acute extracorporeal therapy.

Mathematical formulation to help identify the patient at risk of ischemic tissue necrosis--a potentially lethal complication of chronic renal failure

Ischemic tissue necrosis (ITN) has been described as a complication of hyperparathyroidism (HPT) in patients with end-stage renal disease (ESRD) and is associated with a mortality rate of up to 80%. Early recognition of ITN is important but difficult. Optimal treatment is controversial. Based on an analysis of the English literature and a recent clinical experience, a mathematical expression to aid in the identification of high-risk patients (2 x [CaPO(4) - 5] x alkaline phosphatase x PTH ratio) was developed. The values for this expression were calculated in 3 recently reported cases and our case (n = 4). The values were compared with those of a group of 54 hyperparathyroid chronic hemodialysis patients (controls); the mean values were significantly different (p < 0.001). The expression, consisting of 4 easily measured laboratory values, appears to differentiate patients with this complication of ITN from patients with only severe HPT. Ten new additional cases were evaluated using the equation; the sensitivity of the equation was 80% and the specificity 92%, positive predictive value was 66% and the negative predictive value 96%. Long-term validation of this equation is required but it appears to be discriminatory and, thus, promising, given the potentially lethal consequences of ITN.

Synthetic peptides of human CD4 enhance binding of Ig to monocyte/macrophage cells. I. Characterization and mapping studies

Human T cell glycoprotein CD4 binds to class II MHC molecules and to HIV envelope protein gp120. We have shown that CD4 and synthetic peptides corresponding to amino acid residues 21-49 of the first extracellular domain of CD4, also bind Ig and, with greater avidity, antibody:Ag complex. We investigated the effect of CD4 synthetic peptides on the binding and uptake of human Ig by monocyte/macrophage U937 cells. We found that a synthetic peptide corresponding to amino acid residues 21-49 enhanced binding to U937 cells of both aggregated and nonaggregated Ig. The enhancement was concentration dependent, occurred both in normal and low ionic strength conditions, and varied with the time and the temperature of the preincubation step. The enhancement was maximal after preincubation for 3 h at 37 degrees C. A peptide concentration of 20 micrograms/ml was sufficient for optimal binding of both nonaggregated and aggregated Ig. CD4 peptide 21-49 also enhanced binding of Ig to Staphylococcus aureus protein A. These studies open a new perspective in the way monocyte/macrophage cells handle Ig, antibody:Ag or Id:anti-Id complex, in particular when present at threshold amounts in a nonprecipitating form.

Synthetic peptides of human CD4 enhance binding of Ig to monocyte/macrophage cells. I. Characterization and mapping studies

Human T cell glycoprotein CD4 binds to class II MHC molecules and to HIV envelope protein gp120. We have shown that CD4 and synthetic peptides corresponding to amino acid residues 21-49 of the first extracellular domain of CD4, also bind Ig and, with greater avidity, antibody:Ag complex. We investigated the effect of CD4 synthetic peptides on the binding and uptake of human Ig by monocyte/macrophage U937 cells. We found that a synthetic peptide corresponding to amino acid residues 21-49 enhanced binding to U937 cells of both aggregated and nonaggregated Ig. The enhancement was concentration dependent, occurred both in normal and low ionic strength conditions, and varied with the time and the temperature of the preincubation step. The enhancement was maximal after preincubation for 3 h at 37 degrees C. A peptide concentration of 20 micrograms/ml was sufficient for optimal binding of both nonaggregated and aggregated Ig. CD4 peptide 21-49 also enhanced binding of Ig to Staphylococcus aureus protein A. These studies open a new perspective in the way monocyte/macrophage cells handle Ig, antibody:Ag or Id:anti-Id complex, in particular when present at threshold amounts in a nonprecipitating form.

Interactions of the beta carboline abecarnil with the high pressure neurological syndrome in a primate model

The neurophysiological interactions between the high pressure neurological syndrome (HPNS) and a new beta carboline, abecarnil, were studied in the non-human primate Papio anubis. Abecarnil is a partial agonist at the benzodiazepine site on the GABA/benzodiazepine receptor. Six animals were exposed on two occasions to pressures of 91 ATA in an environment of helium and oxygen. One exposure was pretreated with a total dose of abecarnil 1.0 mg/kg, the other with an equivalent volume of vehicle. Treatment with abecarnil prevented the severe signs of HPNS occurring between 51 and 91 ATA. Onset pressures of the various signs were unaffected. Some signs, e.g. myoclonus, became more frequent when abecarnil was used. A residual protective effect of abecarnil was present 4 weeks after the dose was given, active at pressures less than 71 ATA. Changes with pressure in the EEG were recorded primarily from the frontal cortex, but were also present in the parietal and occipital areas of the left cortex. Amplitude and frequency spectra were calculated and changes with pressure in the four conventional wavebands, plus two others, analysed. The most striking change was the prevention by abecarnil of the pressure-induced 100% increase in alpha wave amplitude in the frontal region. It is concluded that modulation of GABA transmission is important in controlling the expression of HPNS.