Canadian survey of clinical status at dialysis initiation 1998-1999: a multicenter prospective survey

AIMS

The current growth in end-stage kidney disease populations has led to increased efforts to understand the impact of status at dialysis initiation on long-term outcomes. Our main objective was to improve the understanding of current Canadian nephrology practice between October 1998 and December 1999.

METHODS

Fifteen nephrology centers in 7 provinces participated in a prospective data collection survey. The main outcome of interest was the clinical status at dialysis initiation determined by: residual kidney function, preparedness for chronic dialysis as measured by presence or absence of permanent peritoneal or hemodialysis access, hemoglobin and serum albumin. Uremic symptoms at dialysis initiation were also recorded, however, in some cases these symptom data were obtained retrospectively.

RESULTS

Data on 251 patients during 1-month periods were collected. Patients commenced dialysis at mean calculated creatinine clearance levels of approximately 10 ml/min, with an average of 3 symptoms. 35% of patients starting dialysis had been known to nephrologists for less than 3 months. These patients are more likely to commence without permanent access and with lower hemoglobin and albumin levels. Even of those known to nephrologists, only 66% had permanent access in place.

CONCLUSIONS

Patients commencing dialysis in Canada appear to be doing so in relative concordance with published guidelines with respect to timing of initiation. Despite an increased awareness of kidney disease, a substantial number of patients continues to commence dialysis without previous care by a nephrologist. Of those who are seen by nephrologists, clinical and laboratory parameters are suboptimal according to current guidelines. This survey serves as an important baseline for future comparisons after the implementation of educational strategies for referring physicians and nephrologists.

Cardiovascular disease in patients with chronic kidney disease: getting to the heart of the matter

The high prevalence of cardiovascular disease (CVD) in patients with kidney disease is well described. This Canadian, multicenter, observational cohort study reports the prevalence and risk factors of CVD associated with kidney disease, in a cohort of patients with established chronic kidney disease (CKD), who are followed-up by nephrologists. This analysis sought to answer 2 questions: (1) in patients with established CKD, are the prevalence and progression of CVD accounted for by conventional or uremia-related risk factors, and (2) to what extent can progression to renal replacement therapy (RRT) be explained by CVD versus traditional risk factors for kidney disease? This study population consists of 313 patients (predominantly men) who had a mean age of 56 years and a mean creatinine clearance of 36 mL/min. Thirty percent were diabetic. The overall prevalence of CVD was 46%, and was independent of severity of kidney dysfunction (P = 0.700). The median follow-up time was 23 months, for a total of 462 patient years. We note the overall incidence of CVD events (new CVD or worsening of CVD) was 47/244 (20%). The best predictors of new CVD events among those without preexisting CVD were diabetes (odds ratio [OR] = 5.35, P = 0.018) and age (OR = 1.26, P = 0.08). In those with preexisting CVD, low diastolic pressure (DP) (OR =.72, P = 0.004) and high triglycerides (OR = 1.48, P = 0.019) at baseline were independent predictors of progression of CVD. We could not determine an independent impact of kidney function on CVD in the overall cohort. Furthermore, we determined that the presence of CVD itself confers an increased risk for progression to RRT (relative risk [RR] = 1.58, P = 0.047), adjusted for kidney function. This is the first in-depth analysis of CVD in a cohort of patients with established chronic kidney disease who are not on dialysis. The question regarding the impact of the altered biology of uremia in contributing to CVD progression remains unanswered, and clearly needs further study. However, the findings do raise the issue of whether aggressive treatment of CVD and risk factors might, in fact, reduce progression to RRT. Further large-scale, observational studies as well as interventional studies are needed to more clearly understand the complex biology of cardiovascular and kidney disease progression.

Topological analysis and role of the transmembrane domain in polar targeting of PilS, a Pseudomonas aeruginosa sensor kinase

In Pseudomonas aeruginosa, synthesis of pilin, the major protein subunit of the pili, is regulated by a two-component signal transduction system in which PilS is the sensor kinase. PilS is an inner membrane protein found at the poles of the bacterial cell. It is composed of three domains: an N-terminal hydrophobic domain; a central cytoplasmic linker region; and the C-terminal transmitter region conserved among other sensor kinases. The signal that activates PilS and, consequently, pilin transcription remains unknown. The membrane topology of the hydrophobic domain was determined using the lacZ and phoA gene fusion approach. In this report, we describe a topological model for PilS in which the hydrophobic domain forms six transmembrane helices, whereas the N- and C-termini are cytoplasmic. This topology is very stable, and the cytoplasmic C-terminus cannot cross the inner membrane. We also show that two of the six transmembrane segments are sufficient for membrane anchoring and polar localization of PilS.

Veno-venous continuous renal replacement therapy for burned patients with acute renal failure

From 1995 to 1998, 12 burned patients with acute renal failure (ARF) were treated by veno-venous continuous renal replacement therapy (CRRT) at the Burn Unit of Hôtel-Dieu de Montréal. Their mean (+/-SD) age was 51+/-12 years, and the mean burned surface covered 48.6+/-15.8% of total body surface area. All patients were mechanically ventilated and presented evidence of sepsis. The mean delay before occurrence of ARF was 15+/-6 days and ARF was mainly related to sepsis and hypotension. Main reasons for CRRT initiation were azotemia and fluid overload. A total of 15 CRRT modalities were applied (12 continuous veno-venous hemodiafiltration, CVVHDF; two continuous veno-venous hemofiltration, CVVH; and one continuous veno-venous hemodialysis, CVVHD) over 14+/-13 days. For CRRT, nine patients received heparin and three were not anticoagulated. Mean values for dialysate and reinjection flow rates were 1134+/-250 ml/h and 635+/-327 ml/h, respectively. Admission weight was 78.8+/-12.7 kg with a mean weight gain before CRRT initiation of 10.0+/-5.8 kg and a mean weight loss during CRRT of 8.9+/-5.5 kg. Nine patients received enteral plus parenteral nutrition, and three, parenteral nutrition only; the total caloric intake was 31.5+/-7.0 kcal/kg/day and protein intake, 1.8+/-0.4 g/kg/day. The normalized protein catabolic rate (nPCR) was evaluated at 2.28+/-0.78 g/kg/day during CRRT. The mortality rate was 50%. The six survivors all recovered normal renal function with four of them requiring intermittent hemodialysis for short periods. In conclusion, veno-venous CRRT is particularly well suited for this selected population allowing smooth fluid removal and aggressive nutritional support.

Extreme diuretic dependence in idiopathic edema: mechanisms, prevention and therapy

Idiopathic edema patients abusing diuretics are occasionally becoming dependent to such a degree on increasing doses of diuretics that their withdrawal results in severe cardiorespiratory failure, occasionally even pulmonary edema. Two such patients are described and 1 is investigated in depth as to the mechanism of the diuretic abuse-induced excessive tubular avidity for sodium. An extreme diuretic-induced secondary hyperaldosteronism and atrial natriuretic factor suppression, although tapering off when diuretics are stopped, results in a continuous tubular sodium hyper-reabsorption. Since the most affected patient was deprived of the benefits of converting enzyme inhibitors because of their side effects, the only way to partially overcome this condition was a generous combination of several diuretics acting at several segments of the nephron. This contrasted with a similar patient who was relatively well controlled by a converting enzyme inhibitor combined with lower dose diuretics. Diuretic abuse-induced secondary hyperaldosteronism and diuretic resistance are apparently best prevented by converting enzyme inhibitors. When nonpharmacological preventive measures fail, converting enzyme inhibitors are preferable to diuretics as the first-choice treatment of idiopathic edema patients.

Elevated levels of serum creatinine: recommendations for management and referral

BACKGROUND

The potential benefits of earlier referral to a nephrologist of patients with elevated levels of serum creatinine include identifying and treating reversible causes of renal failure, slowing the rate of decline associated with progressive renal insufficiency, managing the coexisting conditions associated with chronic renal failure and facilitating efficient entry into dialysis programs for all patients who might benefit.

METHODS

A subcommittee of the Canadian Society of Nephrology, which included representatives from family practice and internal medicine, conducted a MEDLINE search for the period 1966 to 1998 using the key words referral and consultation, dialysis, hemodialysis, peritoneal dialysis, renal replacement therapy and kidney diseases. Where published evidence was lacking, conclusions were reached by consensus.

GUIDELINES

Earlier referral to nephrologists of patients with elevated creatinine levels is expected to lead to better health care outcomes and lower costs for both the patients and the health care system. All patients with newly discovered renal insufficiency (as evidenced by serum creatinine elevated to a level above the upper limit of the normal range of that laboratory, adjusted for age and height in children) must undergo investigations to determine the potential reversibility of disease, to evaluate the prognosis and to optimize planning of care. All patients with an established, progressive increase in serum creatinine level should be followed with a nephrologist. Adequate preparation for dialysis or transplantation (or both) requires at least 12 months of relatively frequent contact with a renal care team. Nephrologists should provide consultation in a timely manner for any patient with an elevated serum creatinine level. In addition, they should provide advice about what aspects of the condition require particularly urgent or emergency assessment.

SPONSORS

This clinical practice guideline has been endorsed by the Canadian Society of Nephrology and the College of Family Physicians of Canada. Meeting, teleconference and travel expenses of the Referral Guideline Subcommittee were covered by The Momentum Program, a collaboration between Baxter Corp. and Janssen-Ortho Inc. However, the authors are solely responsible for the editorial content of this article.

Left ventricular mass index increase in early renal disease: impact of decline in hemoglobin

Cardiovascular disease occurs in patients with progressive renal disease both before and after the initiation of dialysis. Left ventricular hypertrophy (LVH) is an independent predictor of morbidity and mortality in dialysis populations and is common in the renal insufficiency population. LVH is associated with numerous modifiable risk factors, but little is known about LV growth (LVG) in mild-to-moderate renal insufficiency. This prospective multicenter Canadian cohort study identifies factors associated with LVG, measured using two-dimensional-targeted M-mode echocardiography. Eight centers enrolled 446 patients, 318 of whom had protocol-mandated clinical, laboratory, and echocardiographic measurements recorded. We report 246 patients with assessable echocardiograms at both baseline and 12 months with an overall prevalence of LVH of 36%. LV mass index (LVMI) increased significantly (>20% of baseline or >20 g/m2) from baseline to 12 months in 25% of the population. Other than baseline LVMI, no differences in baseline variables were noted between patients with and without LVG. However, there were significant differences in decline of Hgb level (-0.854 v -0.108 g/dL; P = 0.0001) and change in systolic blood pressure (+6.50 v -1.09 mm Hg; P = 0.03) between the groups with and without LVG. Multivariate analysis showed the independent contribution of decrease in Hgb level (odds ratio [OR], 1.32 for each 0.5-g/dL decrease; P = 0.004), increase in systolic blood pressure (OR, 1.11 for each 5-mm Hg increase; P = 0.01), and lower baseline LVMI (OR, 0.85 for each 10-g/m2; P = 0.011) in predicting LVG. Thus, after adjusting for baseline LVMI, Hgb level and systolic blood pressure remain independently important predictors of LVG. We defined the important modifiable risk factors. There remains a critical need to establish optimal therapeutic strategies and targets to improve clinical outcomes.

Preliminary findings from a teleultrasound study in Alberta

BACKGROUND AND OBJECTIVES

Ultrasound practice in Alberta requires direct supervision by an ultrasound-accredited specialist physician (sonologist). This requirement limits access to ultrasound examinations in many rural communities. A prospective study was performed to evaluate the adequacy of teleultrasound service in High Level, Alberta, with remote sonologist supervision from Edmonton, Alberta.

METHODS

A total of 146 patients were evaluated in two groups. Group A (72 patients) was evaluated by both an on-site radiologist in High Level and a remote supervising radiologist in Edmonton. Group B (74 patients) was evaluated only by the remote supervising radiologist in Edmonton. The teleultrasound service included digital store-and-forward capabilities using a commercially available teleradiology system, with videoconferencing review for real-time scanning.

RESULTS

The teleultrasound service was helpful to the referring physician. It made transfer unnecessary in 42% of patients, and the results of the ultrasound assessment influenced management in 59% of patients. The sonographer on site and the remote radiologists agreed on the quality of the images. The information required for diagnosis was available from the sonographer's study in the majority of cases, with second-look scanning by the on-site radiologist or videoconferencing by the remote radiologist providing a major new diagnosis in only 1% of patients.

CONCLUSION

Teleultrasound service to High Level could be provided reliably with remote supervision, comparable to direct on-site supervision.

Lithium poisoning treated by high-performance continuous arteriovenous and venovenous hemodiafiltration

Intermittent hemodialysis is considered the modality of choice when enhanced lithium removal is indicated. However, postdialysis rebound in serum lithium concentration is frequently observed after the dialysis sessions and results from incomplete intracellular removal. Continuous renal replacement therapy could provide a more gradual and complete lithium removal since it is performed over longer time periods, thus avoiding rebound following therapy. Seven patients presenting with symptomatic lithium intoxication were treated by continuous renal replacement therapy (continuous arteriovenous and venovenous hemodiafiltration [CAVHDF and CVVHDF]). For CAVHDF, the dialysate flow rate was increased to 4 L/hr to optimize solute clearances. Five intoxicated patients (four acute and one chronic) were treated by high dialysate flow rate (HDFR) (4 L/hr) CAVHDF and two patients with chronic poisoning were treated by CVVHDF, one with a dialysate flow rate of 1 L/hr and one with a dialysate flow rate of 2 L/hr. Serum lithium concentrations for the four acute poisoning cases were 4.0, 4.6, 4.4, and 3.2 mEq/L, at initiation of HDFR CAVHDF, and decreased respectively to 1.2, 0.8, 1.2, and 1.1 mEq/L after 15, 19, 35, and 21 hours of treatment. No lithium rebound was observed over 24 to 36 hours following CAVHDF. For the three chronic intoxication cases, serum lithium concentrations dropped from 1.7, 2.2, and 3.8 mEq/L to 0.7, 0.17, and 0.4 mEq/L, respectively, after 18, 42, and 44 hours of HDFR CAVHDF or CVVHDF. The chronic case treated for only 18 hours presented a slight rebound in lithium level (0.3 mEq/L), whereas no significant rebound was observed for the two other cases treated for longer periods. Mean +/- SEM dialyser urea, lithium, and creatinine clearance during HDFR CAVHDF were 50.5 +/- 5.0, 41.4 +/- 4.6, and 37.6 +/- 3.7 mL/min, respectively (number of measurements = 41). Dialyser lithium clearance during CVVHDF was 48.4 +/- 1.4 mL/min (n = 10) and 61.9 +/- 2.3 mL/min (n = 7), with dialysate flow rates of 1 and 2 L/hr, respectively. Mean dialyzer lithium removal for the seven cases was 106.4 mEq, while mean renal lithium removal was 21.5 mEq during the same period. We conclude that HDFR CAVHDF and CVVHDF are effective alternatives to intermittent hemodialysis for treatment of lithium poisoning. They provide excellent lithium clearances (60 to 85 L/d); in addition, because of their continuous nature, they prevent posttherapy lithium rebound by allowing a more gradual and complete removal from intracellular compartments, and they may be particularly useful in chronic poisoning in which intracellular lithium accumulation is more extensive.

What is responsible for the diurnal variation in potassium excretion?

Potassium excretion exhibits a diurnal pattern, with most excretion occurring close to noon in humans. Each component of the K+ excretion rate [urinary K+ concentration ([K+]) and flow rate] was measured and back-calculated to reflect events in the cortical collecting duct (CCD). Our purpose was to determine to what extent each component contributed to this diurnal variation in each 2-h portion of the day. In humans, K+ excretion rose threefold from nadir (0600 h) to peak (1200-1400 h), 18 h after the principal intake of K+. The variation in K+ excretion was due almost exclusively to changes in [K+] in the terminal CCD ([K+]CCD) rather than via changes in flow rate. In rats, the bulk of K+ excretion occurred shortly after eating. Both components of K+ excretion rose after meals; the rise in the [K+]CCD (3.3-fold) predominated at earlier times, and the rise in flow rate occurred later and was primarily a result of a higher rate of excretion of urea. The rise in [K+]CCD did not correlate with aldosterone levels or administration. A very large rise in the [K+]CCD only occurred in the presence of bicarbonaturia; the transtubular potassium concentration gradient was now close to 15 in the morning and evening.

Renal function recovery in end-stage renal disease

Renal function recovery (RFR) is a rare event in patients with end-stage renal disease (ESRD). Although some predictive factors have been described, there are still unresolved questions. We have analyzed the Canadian Organ Replacement Register data for the 1981 to 1989 period to assess the incidence and factors predictive of RFR in a large ESRD population as well as the outcome after recovery. Renal function recovery was defined as the interruption of renal replacement therapy (RRT) for more than 3 months. Patients on RRT for < or = 45 days were excluded. Of 14,318 registered ESRD patients, 342 (2.4%) experienced RFR after 8.9 +/- 0.5 months of RRT (mean +/- SEM); 52.3% of the recoveries occurred within 6 months of initiating RRT, while 23.7% were only observed after 12 months or more. By Cox regression, patients within the following diagnostic groups had a significantly higher rate of RFR than those with primary glomerulonephritis, who are considered to comprise the reference group: myeloma (relative rate [RR] = 6.00; P < 0.001), drug-induced disease (RR = 4.21; P < 0.001), vascular/hypertensive disease (RR = 2.60; P < 0.001), and systemic disease (RR = 2.58; P < 0.001). Inversely, patients with polycystic kidneys (RR = 0.06; P = 0.004) and diabetic patients (RR = 0.56; P = 0.024) had a lower rate of RFR than those with glomerulonephritis. Men younger than 45 years had a lower rate of RFR than older men and women of all ages (P < or = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Rotavirus infection in a geriatric population

An outbreak of gastroenteritis affected 19 of 34 geriatric patients and four of 23 staff assigned to the ward in a period of 3 1/2 weeks in January 1980. Fourteen of the 19 patients with gastroenteritis (17 were tested properly) and four of the ten asymptomatic patients (five asymptomatic patients were not tested) showed evidence of rotavirus infection by virus positivity and/or a significant antibody response to rotavirus. One of the four staff members with gastroenteritis showed serologic evidence (three were tested) of rotavirus infection. Nine of the 18 asymptomatic staff members (two remaining staff members were not tested) showed a fourfold rise in antibody to rotavirus but four had antibody titers of 1:32 or more. The patients had diarrhea for a mean of 2.6 days. Most of them had five or fewer diarrheal stools in one day. Six patients had a severe illness and two died. Thirteen of 15 symptomatic patients who had serum samples, collected during the acute and convalescent phases, tested manifested high titers (greater than or equal to 1:32) of complement-fixing antibody to rotavirus antigen.