Sustained low-efficiency dialysis for critically ill patients requiring renal replacement therapy

BACKGROUND

The replacement of renal function for critically ill patients is procedurally complex and expensive, and none of the available techniques have proven superiority in terms of benefit to patient mortality. In hemodynamically unstable or severely catabolic patients, however, the continuous therapies have practical and theoretical advantages when compared with conventional intermittent hemodialysis (IHD).

METHODS

We present a single center experience accumulated over 18 months since July 1998 with a hybrid technique named sustained low-efficiency dialysis (SLED), in which standard IHD equipment was used with reduced dialysate and blood flow rates. Twelve-hour treatments were performed nocturnally, allowing unrestricted access to the patient for daytime procedures and tests.

RESULTS

One hundred forty-five SLED treatments were performed in 37 critically ill patients in whom IHD had failed or been withheld. The overall mean SLED treatment duration was 10.4 hours because 51 SLED treatments were prematurely discontinued. Of these discontinuations, 11 were for intractable hypotension, and the majority of the remainder was for extracorporeal blood circuit clotting. Hemodynamic stability was maintained during most SLED treatments, allowing the achievement of prescribed ultrafiltration goals in most cases with an overall mean shortfall of only 240 mL per treatment. Direct dialysis quantification in nine patients showed a mean delivered double-pool Kt/V of 1.36 per (completed) treatment. Mean phosphate removal was 1.5 g per treatment. Mild hypophosphatemia and/or hypokalemia requiring supplementation were observed in 25 treatments. Observed hospital mortality was 62.2%, which was not significantly different from the expected mortality as determined from the APACHE II illness severity scoring system.

CONCLUSIONS

SLED is a viable alternative to traditional continuous renal replacement therapies for critically ill patients in whom IHD has failed or been withheld, although prospective studies directly comparing two modalities are required to define the exact role for SLED in this setting.

Indications for vancomycin in dialysis patients

Resistance to vancomycin has emerged among Staphylococcus aureus, coagulase-negative staphylococci (CNS), and enterococci, and this emergence has particular prevalence in dialysis units. It has therefore become imperative that physicians use vancomycin judiciously. General recommendations regarding the appropriate use of vancomycin have been developed. Although in theory implementation of these guidelines should not be difficult, the medical community may be unable or unwilling to make the necessary adjustments in practice. The onslaught of cost constraints and bureaucratic encumbrance has occurred simultaneously with the increase in vancomycin resistance among pathogens commonly isolated among the dialysis population. When a patient responds to empiric antibiotic therapy and susceptibility data indicate that an antibiotic other than vancomycin would be appropriate, the clinician far too often does not make the change to this alternative. Previously there was no biological imperative to change the antibiotic. That complacency has infected an entire generation of physicians, and especially nephrologists. Furthermore, there is an active movement against change, driven by concerns such as malpractice accusations and frank errors in the interpretation of medical facts.

Methods used to evaluate the quality of evidence underlying the National Kidney Foundation-Dialysis Outcomes Quality Initiative Clinical Practice Guidelines: description, findings, and implications

This report describes the approach the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) used to assess the strength of published evidence pertinent to individual NKF-DOQI Clinical Practice Guidelines, as well as the relationship between that approach and methods used by the US Preventive Services Task Force, the Cochrane Collaboration, and the Agency for Health Care Policy and Research to rate the quality and/or strength of evidence. We also present the results of an analysis of the strength of evidence underlying the NKF-DOQI Guidelines showing that one cannot infer the quality of evidence reported in a study (rated either on a 0-to-1 scale or categorically as excellent, very good, good, fair, or poor) simply by knowing the type of study design used (randomized trial, nonrandomized trial, natural experiment, cohort study, cross-sectional study, case-control study, case report). Issues related to assessment of the strength of evidence underlying a practice guideline opposed to that reported in an individual study are highlighted.

Impaired biological activity of erythropoietin by cyanate carbamylation

AIMS

During advanced renal failure, particularly in patients with end-stage renal disease (ESRD), proteins are carbamylated as a result of a reaction with cyanate. Some or all of the cyanate is derived from urea. If the carbamylation of proteins adversely alters their biologic activities, then urea must be viewed as an uremic toxin, rather than a surrogate. Therefore, we studied the effect of cyanate carbamylation on the erythropoietic activity of erythropoietin (EPO) in a rodent model.

METHODS

EPO was carbamylated by incubation with cyanate at 37 degrees C. The extent of carbamylation was monitored using trinitrobenzenesulfonic acid. In Sprague-Dawley rats the erythrocyte count, hemoglobin concentration, and hematocrit were measured after the twice-weekly subcutaneous injection of either EPO or carbamylated EPO for 3 weeks. Two additional control groups received physiologic saline or 0.2 ml of 1 M cyanate.

RESULTS

The level of carbamylated EPO was increased as the time of exposure to cyanate increased from 1 to 6 h, and as the cyanate concentration increased from 8 to 2,000 mM. EPO injections caused significantly large increases in all erythropoietic measures. Physiologic saline or 1 M cyanate-injected controls and the carbamylated EPO-injected animals demonstrated no change from baseline in erythropoietic parameters.

CONCLUSION

These results support that EPO exposed to high levels of cyanate in vitro demonstrates diminished biologic activity in healthy Sprague-Dawley rats. This effect may be manifested by the carbamylation of EPO by the cyanate. Should this occur in ESRD patients, it may contribute to the suboptimal erythropoietic response to EPO therapy associated with high urea levels, especially related to inadequate dialysis. Targeting dialysis doses specifically to urea concentrations may be more important than previously considered.

Tumour lysis syndrome complicating high-dose treatment in patients with multiple myeloma

Tumour lysis syndrome (TLS), because of its low proliferative activity, is thought to only rarely complicate the treatment of patients with multiple myeloma. However, as more aggressive therapeutic approaches are increasingly used in the management of this disease, it is conceivable that clinicians will encounter this complication more frequently. A retrospective analysis of > 800 patients with multiple myeloma treated at the University of Arkansas identified nine patients who developed a marked tumour lysis syndrome following intermediate- or high-dose chemotherapy. Evaluation of disease characteristics revealed association with high tumour mass, high proliferative activity, increased lactic dehydrogenase levels, plasmablastic morphology, and unfavourable cytogenetic abnormalities. Recognition of multiple myeloma patients at high risk for the development of tumour lysis syndrome and prompt intervention are required especially in the presence of abnormal baseline renal function frequently complicating the clinical course of these patients.

Morbidity and mortality in redefining adequacy of peritoneal dialysis: a step beyond the National Kidney Foundation Dialysis Outcomes Quality Initiative

The National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) Peritoneal Dialysis (PD) Adequacy Work Group intentionally limited the scope of its work to address adequacy in terms of small-solute removal. This decision was based on the need for rigorous evidence and that mortality is the most objective parameter in the literature. This review attempts to more broadly redefine the concept of the adequacy of PD, particularly as it relates to the most common general medical problems that PD patients experience; namely, cardiovascular disease and malnutrition. Whereas we are sensitive to the developmental process of the NKF-DOQI, we are critical that the definition of adequacy may be too narrow, leading clinicians to overlook other important morbidities. We have reiterated the evidence that suggests a weekly solute clearance (Kt/Vurea) of 1.7 or greater is associated with better patient survival. The arguments to target a greater Kt/Vurea of 2.0 are challenged, yet the concept is ultimately supported. Because cardiovascular disease is the cause of death in half of all patients with end-stage renal disease, dialysis adequacy must be defined, in part, by the potential of that therapy to diminish cardiovascular maladies. Blood pressure, volume, left ventricular hypertrophy, and dyslipidemias are discussed in this context. Lastly, assumptions that increasing total solute clearance leads to improved nutrition in PD patients are challenged. We have attempted to expand on what the NKF-DOQI did not include, and we urge the dialysis community to seek the answers to the many controversies that remain. We need to redefine the adequacy of PD in a holistic manner and find outcome parameters that are not as final as death.

Predialysis blood pressure and mortality risk in a national sample of maintenance hemodialysis patients

The role of predialysis blood pressure (BP) as a risk factor for the high mortality in chronic hemodialysis (HD) patients has remained controversial. The objective of the current study was to further explore in a national random sample of 4,499 US hemodialysis patients any relationship of systolic or diastolic and predialysis or postdialysis BP with mortality, while considering subgroups of patients and controlling for other patient characteristics and comorbidities. The main finding of this study is the association of a low predialysis systolic BP with an elevated adjusted mortality risk (relative mortality risk [RR] = 1.86 for systolic BP < 110, P < 0.0001). No association with an elevated mortality risk could be observed for predialysis systolic hypertension (RR = 0.98 to 0.99, not significant [NS]), except for an elevated risk of cerebrovascular deaths. Postdialysis systolic BP was associated with an elevated mortality risk both for low and high BP levels as compared with midrange BP. Further evaluation of the elevated mortality risk associated with low predialysis systolic BP indicated similar patterns for both diabetic and nondiabetic subgroups and for patients with and without congestive heart failure (CHF) or coronary artery disease, although it was more pronounced among those with CHF. The level of predialysis fluid excess did not modify these results substantially. The findings from this historical prospective national study do not argue against the treatment of hypertension and suggest greater attention to postdialysis hypertension. The strikingly elevated mortality risk with low predialysis systolic BP suggests that low predialysis BP needs to be viewed with great concern and avoided where possible.

Implementation of the Peritoneal Dialysis Adequacy Guidelines: a personal perspective

I describe some of the political issues surrounding the National Kidney Foundation-Dialysis Outcomes Quality Initiative project as I perceived them. I then discuss what I would do differently, what I recommend to encourage implementation, and why regulatory concerns are well founded. I close with technical issues including expansion, simplification, and corrections.

Incremental dialysis

The National Kidney Foundation-Dialysis Outcome Quality Initiative Peritoneal Dialysis Adequacy Clinical Practice Guideline 1 and Appendix A offered the first formal in-depth discussion of the concept of incremental dialysis (1). The context of the work group's concern was that it is paradoxical that we nephrologists have focused on optimizing urea clearance for end-stage renal disease patients, but not in pre-end-stage renal disease patients. Because so much evidence from the collective peritoneal dialysis experience suggested that a weekly Kt/Vurea of 2.0 is appropriate, the National Kidney Foundation-Dialysis Outcome Quality Initiative Peritoneal Dialysis Adequacy Work Group recommended that when the residual renal Kt/Vurea drops below 2.0, supplemental Kt/Vurea should be added incrementally by dialysis. This article describes this concept in more detail.

Plasma iohexol clearance in automated peritoneal dialysis--its role in adequacy determination

OBJECTIVE

To compare the relationship of plasma iohexol clearance to standard adequacy measures in an automated peritoneal dialysis (APD) population.

DESIGN

Prospective, nonrandomized, open label, simultaneous clearance studies of novel (iohexol) and traditional (urea and creatinine) markers of dialysis quantitation.

SETTING

Outpatient peritoneal dialysis units associated with tertiary care university hospitals.

PATIENTS

Eighteen stable patients, 13 undergoing continuous cycling peritoneal dialysis (CCPD) and 5 receiving intermittent dialysis, who underwent 24-hour clearance studies were enrolled in and completed the study.

INTERVENTIONS

Each subject received 15 mL of iohexol intravenously the morning of a scheduled dialysis night. Blood was obtained for determination of serum concentrations of urea nitrogen and creatinine, and plasma iohexol concentration. Dialysate and urine were collected over 24 hours.

MAIN OUTCOME MEASURES

Urea and creatinine data from the total pooled dialysate and from the 24-hour urine collection were used to calculate daily Kt/Vurea and normalized total daily creatinine clearance (CrCl). Total plasma iohexol clearance was calculated using a one-compartment model with the Brochner-Mortensen correction.

RESULTS

Normalized [to 1.73 m2 body surface area (BSA)] iohexol clearance correlated very well with normalized CrCl (r2 = 0.777; p < 0.001). A weaker correlation was observed between Kt/Vurea and normalized iohexol clearance (r2 = 0.213; 0.05 < p < 0.1). When data are not normalized using BSA or urea distribution volume, the regressions are improved for both creatinine (r2 = 0.820) and urea (r2 = 0.533). These results were comparable between those on CCPD and those on intermittent therapy.

CONCLUSION

Total plasma iohexol clearance provides a simple assessment for APD adequacy by eliminating collection problems inherent to the methodologies currently employed. Such simplicity allows for more frequent assessments of delivered dialysis dose and efficacy of prescription changes.

Cefazolin as empiric therapy in hemodialysis-related infections: efficacy and blood concentrations

Concern about the increasing incidence of vancomycin-resistant organisms has tempered the enthusiasm for indiscriminate vancomycin use. Cefazolin has an antibacterial activity profile similar to vancomycin against most pathogens encountered in the hemodialysis (HD) population. We evaluated the clinical efficacy and serum concentrations that were achieved during empiric cefazolin use. Fifteen consecutive HD patients (five, conventional HD; five, high-efficiency HD; and five, high-flux HD) with suspected or documented infections warranting antibiotic intervention, including access-related, respiratory tract, urinary tract, or wound infections, were enrolled. Each patient received intravenous cefazolin (20 mg/kg actual body weight rounded to the nearest 500-mg increment [range, 1 to 2 g]) after each dialysis treatment for at least three doses. Cefazolin concentrations were obtained before and immediately after the next three consecutive dialysis treatments. Thirteen patients were evaluated for efficacy and all 15 were evaluated for toxicity and cefazolin blood concentrations. All patients showed at least a short-term (3-week) clinical resolution of infection with cefazolin treatment. No central nervous system toxicities were noted and no other adverse events were expressed by the patients during the course of cefazolin treatment. Predialysis cefazolin concentrations, as determined by high-performance liquid chromatography, were 70.2 +/- 42.7 (conventional HD), 45.6 +/- 18.9 (high-efficiency HD), and 41.6 +/- 23.9 mg/L (high-flux HD) over the three dialysis sessions. Cefazolin at doses of approximately 20 mg/kg administered post-HD appears to be a safe and effective empiric therapy and yields predialysis cefazolin concentrations of 2.5 times or greater than those considered to be the minimum inhibitory concentration breakpoint (16 mg/L) for susceptible organisms. These data support the broader use of cefazolin for empiric treatment in the HD population, allowing vancomycin to be reserved for confirmed resistant organisms.

Quality of life during and between hemodialysis treatments: role of L-carnitine supplementation

End-stage renal disease affects every aspect of a patient's life, including perception of health and quality of life. It is likely that a hemodialysis patient's perceptions of health-related quality of life directly influence compliance with medical, nursing, and nutritional prescriptions. Because L-carnitine supplementation is known to enhance muscle strength and energy in hemodialysis patients, we hypothesized that L-carnitine supplementation would enhance a hemodialysis patient's perception of health-related quality of life. To test this hypothesis, 1 g L-carnitine or placebo was administered orally to 101 patients immediately before and after every hemodialysis treatment for 6 months. To assess health-related quality of life from the patient's perspective, the Medical Outcomes Study Short Form 36 instrument was administered before the study and at 1.5-month intervals for the duration of the study. In addition, a 10-item questionnaire designed to assess common intradialytic symptoms was administered at the end of each dialysis treatment. Other parameters analyzed included Kt/V(urea) and level of nutrition. In the 6-month group, oral L-carnitine supplementation had an early positive effect on general health (P < 0.02) and physical function (P < 0.03), but the perceived effect was not sustained throughout the 6 months of the study. In the 3-month group, L-carnitine supplementation improved vitality (P < 0.02) and general health (P < 0.01). There was no association between Kt/V(urea) and perceived health-related quality of life. Serum albumin concentration was directly correlated to how patients perceived the quality of their lives.

Noncompliance in hemodialysis: predictors and survival analysis

Noncompliance with hemodialysis (HD), depending on the definition, occurs in 2% to more than 50% of patients. To better understand predictors and outcomes of noncompliance, we evaluated patient characteristics associated with noncompliance and the impact of noncompliance on survival. Using data from two USRDS special studies, we identified 6,251 patients who were on dialysis for more than 1 year for inclusion in this study. Noncompliance was defined in four ways: skipping one or more HD sessions in a month, shortening by 10 or more minutes one or more HD sessions in a month, an interdialytic weight gain (IWG) of more than 5.7% of dry weight, or a serum phosphate (PO4) of greater than 7.5 mg/dL. Sociodemographic predictors of noncompliance were identified using logistic regression. Survival analysis was done using Cox proportional hazards models with adjustments for sociodemographics, comorbid conditions, and dose of HD. Overall, 8.5% of patients skipped HD, 20% shortened HD (7% three or more times), 10% had more than a 5.7% IWG, and 22% had a PO4 greater than 7.5. There was a significant correlation among the measures of noncompliance. Blacks (adjusted odds ratio [AOR] = 2.10), patients aged 20 to 39 years (AOR = 1.62), and smokers (AOR = 1.34) were significantly more likely to skip HD than whites, patients aged 40 to 59 years, and nonsmokers, respectively (P < 0.01 for each). Similar results were seen for the other measures of noncompliance, except for PO4, in which blacks were significantly less likely to be noncompliant (NC) (AOR = 0.85, P < 0.05). Compared with compliant patients, those who skipped one or more HD sessions in a month had a 25% higher risk of death (P < 0.01). Those who had greater than a 5.7% IWG had a 35% higher risk of death (P < 0.001), whereas those with a PO4 > 7.5 had a 13% higher risk of death (P < 0.05). Overall, patients who shortened HD sessions did not have a higher risk of death, but those who shortened three or more in 1 month had a 20% higher risk of death (P < 0.05). Compliance with a medical regimen is a complex issue. Noncompliance in HD often, but not always, is associated with a higher risk of an adverse outcome. This is a US government work. There are no restrictions on its use.

Outcomes of single organism peritonitis in peritoneal dialysis: gram negatives versus gram positives in the Network 9 Peritonitis Study

The use of the "peritonitis rate" in the management of patients undergoing peritoneal dialysis is assuming importance in comparing the prowess of facilities, care givers and new innovations. For this to be a meaningful outcome measure, the type of infection (causative pathogen) must have less clinical significance than the number of infections during a time interval. The natural history of Staphylococcus aureus, pseudomonas, and fungal peritonitis would not support that the outcome of an episode of peritonitis is independent of the causative pathogen. Could this concern be extended to other more frequently occurring pathogens? To address this, the Network 9 Peritonitis Study identified 530 episodes of single organism peritonitis caused by a gram positive organism and 136 episodes caused by a single non-pseudomonal gram negative (NPGN) pathogen. Coincidental soft tissue infections (exit site or tunnel) occurred equally in both groups. Outcomes of peritonitis were analyzed by organism classification and by presence or absence of a soft tissue infection. NPGN peritonitis was associated with significantly more frequent catheter loss, hospitalization, and technique failure and was less likely to resolve regardless of the presence or absence of a soft tissue infection. Hospitalization and death tended to occur more frequently with enterococcal peritonitis than with other gram positive peritonitis. The outcomes in the NPGN peritonitis group were significantly worse (resolution, catheter loss, hospitalization, technique failure) compared to coagulase negative staphylococcal or S. aureus peritonitis, regardless of the presence or absence of a coincidental soft tissue infection. Furthermore, for the first time, the poor outcomes of gram negative peritonitis are shown to be independent of pseudomonas or polymicrobial involvement or soft tissue infections. The gram negative organism appears to be the important factor. In addition, the outcome of peritonitis caused by S. aureus is worse than that of other staphylococci. Thus, it is clear that all peritonitis episodes cannot be considered equivalent in terms of outcome. The concept of peritonitis rate is only meaningful when specific organisms are considered.

Peritoneal dialysis-related peritonitis treatment recommendations: 1996 update

The recommendations provided in this document represent a distillation of various experiences, as well as data obtained from published studies in the setting of substantial changes in antibiotic sensitivity. It is hoped that this revised compilation will provide a basis upon which future developments and advances can be made in the therapeutic approach to infectious complications of peritoneal dialysis.

Risk factors for peritonitis in long-term peritoneal dialysis: the Network 9 peritonitis and catheter survival studies. Academic Subcommittee of the Steering Committee of the Network 9 Peritonitis and Catheter Survival Studies

To determine factors involved in peritoneal dialysis-associated peritonitis and catheter loss, all point prevalent peritoneal dialysis patients in Health Care Finance Administration (HCFA) end-stage renal disease (ESRD) Network 9 were followed throughout 1991 for peritonitis events and throughout 1991 to 1992 for catheter survival. Data were collected by questionnaires compiled by the dialysis facility and validated by network staff. Peritonitis was reported 1,168 times in 729 of the 1,930 patients. By gamma-Poisson regression, a significantly increased risk for peritonitis was observed for patients with previous peritonitis, black race, and those dialyzing with standard connectors or cyclers compared with disconnect systems. Decreased risks were observed for patients with longer ESRD experience and when prophylactic antibiotics were administered before catheter insertion. Postinsertion leakage, diabetes, visual problems, previous or current immunosuppression, and physical activity were not risk factors. Infection of any kind caused the removal of 68% of the 414 catheters lost. Patients with downward-directed tunnels were less likely to experience concomitant exit site/tunnel infections associated with peritonitis. Peritonitis episodes with Staphylococcus epidermidis-like organisms were more likely to resolve with a single course of antibiotics. Perhaps because of their higher infection rate, blacks were more likely than whites to use a disconnect system. In general, the outcome of peritonitis in blacks was similar to that in whites, except that blacks were less likely to be hospitalized and were less likely to die.

Relationship of dose of hemodialysis and cause-specific mortality

A number of studies have found a relationship of lower all-cause mortality risk for ESRD patients treated with increasing dose of dialysis. The objective of this study was to determine the relationship of delivered dose of dialysis with cause-specific mortality. Data from the USRDS Case Mix Adequacy Study, which includes a national random sample of hemodialysis patients, were utilized. To minimize the contribution of unmeasured residual renal function, the sample used in this analysis (N = 2479) included only patients on dialysis for one year or more. Cox proportional hazards models, stratified for diabetes, were used to analyze the effect of delivered dose of dialysis (measured and reported by both Kt/V and URR) on major causes of death and withdrawal from dialysis, adjusting for other covariates including demographics, comorbid diseases present at start of study, functional status, laboratory values and other dialysis parameters. Patient follow-up for mortality was censored at the earliest of time of transplantation, 60 days after a switch to peritoneal dialysis or at the time of data abstraction. For each 0.1 higher Kt/V, the adjusted relative risk of death due to coronary artery disease was 9% lower (RR = 0.91, P < 0.05), due to other cardiac causes was 12% lower (RR = 0.88, P < 0.01), due to cerebrovascular disease (CVD) was 14% lower (RR = 0.86, P < 0.05), due to infection was 9% lower (RR = 0.91, P = 0.05), and due to other known causes was 6% lower (RR = 0.94, P < 0.05). There was no statistically significant relationship of Kt/V and risk of death among patients who died of malignancy (RR = 0.84, P = 0.10) or among patients whose death cause was missing (RR = 0.95, P = 0.41). The risk of withdrawal from dialysis prior to death due to any cause was 9% lower (RR = 0.91, P < 0.05) for each 0.1 higher Kt/V. The relationships of delivered dose of dialysis, as measured by URR, and cause-specific mortality were essentially similar in relative magnitude and statistical significance as the relationships observed using Kt/V as the measurement of dialysis dose, with the exception that the relationship was less significant for cerebrovascular disease and withdrawal from dialysis. The relationship of dialysis dose with risk of death due to each cause of death category except other cardiac causes and "other" causes appeared to be of greater magnitude and of greater statistical significance among diabetics than non-diabetics. These results indicate that low dose of dialysis is not associated with mortality due to just one isolated cause of death, but rather is due to a number of the major causes of death in this population. This study is consistent with hypotheses that low doses of dialysis may promote atherogenesis, infection, malnutrition and failure to thrive through a variety of pathophysiologic mechanisms. Further study is necessary to confirm these results and to test hypotheses that are developed.

Pseudomonas peritonitis in peritoneal dialysis patients: the Network #9 Peritonitis Study

To determine risk factors for the development of Pseudomonas peritonitis (PsP) and outcomes of PsP, the authors compared peritoneal dialysis patients who developed PsP with peritoneal dialysis patients who developed non-Pseudomonas bacterial peritonitis (non-PsP). The authors also sought to determine if there were differences in patients who had resolution of PsP compared with those patients whose PsP did not resolve. The data were derived from the prospective Tristate Renal Network Peritonitis and Catheter Survival Study. Resolution in this study was defined as clearing of peritoneal dialysate on visual inspection, with up to three courses of antibiotic therapy allowed. Catheter removal, switch to hemodialysis, or death were outcomes that were considered separately from resolution because of the study design. There were 31 cases of PsP in 28 patients and 886 cases of non-PsP identified in 667 adult patients. There were no differences in race, gender, age, or incidence of diabetes between the groups. The PsP group had a 25% incidence of previous exposure to immunosuppressive agents, whereas it was 10.6% in the non-PsP group (P = 0.028). PsP infections were more frequently associated with concomitant exit and tunnel infections, higher hospitalization rates, increased incidence of catheter loss, switch to hemodialysis, and a worse rate of resolution when compared with non-PsP (all, P < 0.05). Logistic regression could not identify patients at increased risk of PsP. PsP resolved with antibiotic therapy only in 10 of 31 episodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Quality control in a peritoneal dialysis program

A reliable and effective quality-control program in the peritoneal dialysis (PD) unit requires a team effort. Historically, the nursing staff has been responsible for PD program development, and in some programs the physicians are frankly uninvolved. An enthusiastic, knowledgeable, and committed physician is necessary. In the early days of continuous ambulatory peritoneal dialysis in the United States, lack of physician understanding and commitment tarnished the image of this promising, evolving therapy. After recognizing this problem, Baxter embarked on an intensive effort to upgrade the expertise of the physicians. Concurrently, PD programs were identified with successful outcomes and "best demonstrated practice" techniques were promulgated. The key to quality control is the involvement of all members of the team, including physicians, nurses, dietitians, social workers, technicians, administrators, and patients. A commitment is needed for continuing education, continuing reevaluation of policies and procedures, and the empowerment of all team members to achieve the programmatic goals.

Proinflammatory cytokines and hemofiltration membranes

To determine whether the clinical improvement noted in some septic patients undergoing hemofiltration is in part due to the removal of proinflammatory mediators, in vitro hemofiltration of a 1% albumin solution containing recombinant human tumor necrosis factor alpha and interleukin-1 was performed through a variety of hemofilters. Observed sieving coefficients of these cytokines was much higher (up to 0.35) than expected, considering their molecular weights of 17 kd. In addition, binding of up to 32% of the total mass to selected membranes (polyamide and AN69) was noted. These data are consistent with the concept that either the convective or adsorptive removal of proinflammatory cytokines may play role in the clinical efficacy of hemofiltration in sepsis.

Case report: an unexpected intravenous pyelogram appearance in an azotemic patient

The authors discuss the unusual intravenous pyelogram (IVP) findings in a patient with blunt abdominal trauma. Although the patient had apparent renal dysfunction, both nephrogram and pyelogram were seen clearly after a moderate dose of iothalamate. This may be explained by the fact that the underlying complete obstruction was relieved by his traumatic bladder rupture, prior to the contrast study. Alternatively, evidence of azotemia may be an artifact, resulting from resorption of urea and creatinine after rupture. Thus, the nephro-pyelogram may accurately reflect his renal function.

Indications, technical considerations, and strategies for renal replacement therapy in the intensive care unit

Renal replacement therapy in the intensive care unit can vary from simple procedures to very complex technologies. I discuss the factors that contribute to the decisions regarding the selection of a specific therapy. These factors include immediate and intermediate therapeutic goals (e.g., solute removal, dehydration), hemodynamic stability and other clinical conditions, and the technical requirements obligate to specific therapies. The differences between convective and diffusive solute removal are described, as well as the rationale for choosing one over the other. This choice is particularly relevant to and dependent on the therapeutic goal. Spontaneous blood flow versus pumped blood flow is debated. Lastly, the removal of middle molecular weight molecules is discussed in the context of toxic cytokines or bacterial products.

The effect of tobramycin on the renal handling of vancomycin

Studies in experimental animals and humans have suggested that enhanced renal and auditory toxicity occur with concurrent vancomycin and aminoglycoside treatment. In volunteers, systemic vancomycin clearance at steady-state was measured simultaneously with renal clearances of vancomycin, creatinine, inulin, and para-aminohippurate. Group 1 (n = 9) received vancomycin 5 mg/kg IV for 1 hour, then 1.1 mg/kg/hr for 3 hours. Group II (n = 7) received vancomycin plus tobramycin (2 mg/kg IV over 30 min). Groups did not differ demographically. Audiograms were obtained before and after vancomycin. Plasma samples were collected serially for vancomycin and tobramycin pharmacokinetic studies. Serum concentration versus time data were fit to a two-compartment model for vancomycin and a one-compartment model for tobramycin. For all volunteers, creatinine, inulin and para-aminohippurate clearance, and audiograms were not altered from baseline and were not statistically different between groups. No significant effect of tobramycin on vancomycin pharmacokinetics was observed. conversely, vancomycin had no significant effect on tobramycin pharmacokinetics. The nephrotoxic synergism of vancomycin and tobramycin is not explained by short-term differences in renal handling.

Response of continuous peritoneal dialysis patients to subcutaneous recombinant human erythropoietin differs from that of hemodialysis patients

The hematologic response of 65 continuous ambulatory peritoneal dialysis (CAPD) patients to subcutaneous recombinant human erythropoietin (rHuEPO) was compared with that of 369 hemodialysis patients (HD). Pretherapy transfusions were more common in HD than CAPD. The response was measured as the change in hematocrit after 70 or more days of therapy (or as the hematocrit change normalized by a weekly dose) in CAPD patients. The weekly rHuEPO dose did not differ, but the dosing frequency was less in CAPD than in HD patients. Hematologic response parameters were greater in CAPD. Multivariate analysis showed that the response in both groups varied inversely with the frequency of dosing and with pretherapy baseline hematocrit. In HD subjects, the response also varied inversely with previous transfusion history. The authors concluded that CAPD patients responded better to rHuEPO than HD patients. This may be a result, in part, of lower ongoing blood losses. Patients with more severe anemias responded less well, whereas more sensitive patients were dosed less frequently.

Low-dose recombinant human erythropoietin therapy in chronic hemodialysis patients

To test the hypothesis that low-dose recombinant human erythropoietin (r-HuEpo) would be effective and safe therapy for the anemia of end-stage renal failure, we studied 37 chronic hemodialysis patients for 3 months before and 6 months after beginning treatment with r-HuEpo, 3,000 U, administered initially intravenously (IV) three times weekly. Hematocrit increased from a mean of 25.2 vol% into the target range (mean, 32.2 vol%, a 28% increase) by 4 months. Transfusion requirements were dramatically reduced. Eight patients (22%) had exacerbated or new development of hypertension, while in trials using higher doses this occurred in 35%. Vascular access thrombosis, dialyzer clotting, and seizures were not seen more frequently during r-HuEpo therapy. Dialyzer reuse was not affected. Low-dose r-HuEpo therapy is effective in most hemodialysis patients and may be associated with less adverse effects because of the slower increase in blood viscosity. As targets are reached, downward dosage adjustments need to be smaller when using an initial low-dose regimen.

Continuous arteriovenous hemofiltration in the critically ill patient

Continuous arteriovenous hemofiltration (CAVH) is a simple extracorporeal treatment for fluid overload, electrolyte imbalances, and removal of uremic toxins. The CAVH technique can be initiated rapidly and allows effective fluid removal without compromising cardiovascular status. This article describes two illustrative cases where CAVH was used to treat fluid overload accompanying in one case cardiogenic shock and in the other case septic shock. CAVH may have contributed to the removal of sepsis-related vasodilators as well as excess fluid. This therapy is an attractive alternative to hemodialysis in the critical care setting and may be the treatment of choice in hemodynamically unstable patients.

Multicenter trial of L-carnitine in maintenance hemodialysis patients. I. Carnitine concentrations and lipid effects

Previous studies have reported conflicting results of carnitine supplementation on plasma lipids in patients with chronic renal failure. We therefore performed a four center, double-blind placebo controlled trial to evaluate the effects of post-hemodialysis intravenous injection of L-carnitine in ESRD patients on maintenance hemodialysis. Thirty-eight patients received up to six months of L-carnitine infusions (20 mg/kg) post-dialysis and 44 patients received placebo infusions. In both groups of patients, baseline pre-dialysis plasma and red blood cell total carnitine levels were normal, but pre-dialysis plasma-free carnitine concentrations and free/total ratios were subnormal, and plasma acyl levels were elevated. Post-dialysis plasma free and total carnitine concentrations were also subnormal. Plasma and red blood cell total carnitine levels rose eightfold in carnitine recipients, but were unchanged from baseline in those receiving placebo. There were no significant changes observed in plasma triglycerides, HDL-cholesterol or other lipoprotein parameters in either the carnitine or placebo treated groups. We conclude that carnitine metabolism is altered in uremia. Furthermore, in a randomly-selected hemodialysis population, L-carnitine injection at the dose of 20 mg/kg results in significant increases in blood (and perhaps tissue) carnitine levels, but this is not associated with any major effects on lipid profiles.

Multicenter trial of L-carnitine in maintenance hemodialysis patients. II. Clinical and biochemical effects

Since carnitine deficiency has been reported in some patients undergoing maintenance hemodialysis, we studied the effects of intravenous infusion of L-carnitine or placebo at the end of each dialysis treatment. The trial, which lasted seven months (one month baseline, 6 months treatment) was multicenter, double blind, placebo controlled, and randomized. Eighty-two long-term hemodialysis patients, who were given either carnitine (N = 38) or placebo (N = 44), completed this study. In each group, clinical and biochemical parameters during treatment were compared with baseline values. Intra-dialytic hypotension and muscle cramps were reduced only in the carnitine treated group, while improvement in post-dialysis asthenia was noticed in both carnitine and placebo groups. Maximal oxygen consumption, measured during a progressive work exercise test, improved significantly in the carnitine group (111 +/- 50 ml/min. P less than 0.03) and was unchanged in the placebo group. L-carnitine treatment was associated with a significant drop in pre-dialysis concentrations of serum urea nitrogen, creatinine and phosphorus (means +/- SEM, 101 +/- 4.5 to 84 +/- 3.9, 16.7 +/- 0.67 to 14.7 +/- 0.64, and 6.4 +/- 0.3 to 5.5 +/- 0.4 mg/dl, respectively, P less than 0.004). No significant changes in any of these variables were noticed in the placebo group. Mid-arm circumference and triceps skinfold thickness were measured in 11 carnitine and 13 placebo treated patients. Calculated mid-arm muscle area increased in the carnitine patients (41.37 +/- 2.68 to 45.6 +/- 2.82 cm2, P = 0.05) and remained unchanged in the placebo patients.(ABSTRACT TRUNCATED AT 250 WORDS)