Benefit of continuous renal replacement therapy in subgroups of acutely ill patients: a retrospective analysis.

AIMS: Acute renal failure in the intensive care setting is common and impacts on patient's outcome. Continuous hemodialysis or hemofiltration offers theoretical benefit for patients with acute renal failure, but the clinical benefit has not been demonstrated in randomized trials. ICU patients with acute renal failure are a heterogeneous population and we hypothesize that patients with increased illness severity would benefit from continuous renal replacement therapy. METHODS: From a comprehensive ICU database, we identified patients with acute renal failure exposed to continuous or intermittent renal replacement therapy. We a priori identified a subgroup of patients with multiple organ dysfunction syndrome, then used survival analysis to assess the effect of dialysis modality in the overall acute renal failure population and in the subgroup with increased illness severity. RESULTS: We identified 66 patients treated with intermittent and 36 patients treated with continuous renal replacement therapy. Patients with severe illness were preferentially selected for treatment with continuous dialysis (p = 0.01). Overall, there was no significant difference in survival between patients treated with intermittent or continuous dialysis. The relative risk of in-hospital mortality was significantly decreased in patients with multiple organ dysfunction syndrome (relative risk = 0.42+/-0.22, p = 0.027) treated with continuous therapy as compared with intermittent therapy. Among the survivors, continuous dialysis did not appear to hasten the return of renal function. CONCLUSIONS: This retrospective study suggests that continuous dialysis may be beneficial in a subgroup of ICU patients with multiple organ dysfunction syndrome or severe sepsis. Further randomized trials of dialysis modality should, if possible, concentrate on this population.

The clinical utility of Doppler ultrasound prior to arteriovenous fistula creation.

Arteriovenous fistula (AVF) is the preferred access for long-term hemodialysis, with superior long-term patency rates; however, early failure rates are significant. Recent evidence has brought into question the preferred site of AVF creation in many patient groups. A preoperative test that could reliably predict the outcome of a proposed AVF would be of great benefit. Doppler ultrasound has been the most extensively studied and widely used test to guide access creation. Accurate and validated measurements of internal vessel diameter, both arterial and venous, and blood flow in the upper extremity are obtainable by Doppler ultrasound. Studies evaluating the utility of Doppler ultrasound prior to AVF creation suggest that vessel size and blood flow are predictive of AVF outcome. An AVF created using a cephalic vein and/or radial artery smaller than 1.5-2.0 mm is likely to fail; such preoperative data may indicate that an upper arm AVF should be the primary access attempted. Further prospective studies are needed to evaluate the utility of Doppler ultrasound.

Peritoneal membrane transport and hypoalbuminemia: cause or effect?

OBJECTIVE: Peritoneal membrane transport has been associated with serum albumin and clinical outcome. We examined the relationship between serum albumin and peritoneal membrane transport status before and after the initiation of peritoneal dialysis. SETTING: Patients were followed at a tertiary-care regional nephrology program at St. Joseph's Hospital, McMaster University, Hamilton, Ontario, Canada. METHODS: Incident peritoneal dialysis patients between 1 January 1995 and 31 May 1998 were eligible if there was a peritoneal equilibration test within 180 days of starting dialysis, and a serum albumin value measured within 90 days prior to, and 20 to 70 days after initiating dialysis. MAIN OUTCOME MEASURES: Serum albumin, before and after the initiation of dialysis, and the presence of proteinuric renal disease were compared with the peritoneal equilibration test results. RESULTS: Among 67 identified patients, there were 7 high, 27 high-average, 26 low-average, and 7 low transporters and the mean serum albumin values before dialysis were 35.1, 37.4, 37.8, and 40.4 g/L, respectively (p < 0.001). Serum albumin values prior to the initiation of dialysis correlated significantly with the 4-hour D/P creatinine ratio (r = -0.251, p = 0.040). After initiation of dialysis, the correlation was stronger (r= -0.447, p< 0.001). Serum albumin prior to initiation of dialysis was lower for those with proteinuric than nonproteinuric renal disease (36.4 g/L vs 38.8 g/L, p = 0.04). The trend to lower serum albumin in high transporters was seen in patients with both proteinuric and nonproteinuric renal disease. CONCLUSION: The association between higher peritoneal membrane transport and lower serum albumin is present before initiation of dialysis in both proteinuric and nonproteinuric renal disease. The poor outcomes associated with low serum albumin and higher peritoneal membrane transport might be explained by other underlying factors. The contribution of inflammation, malnutrition, and fluid overload requires further study.