The use of continuous arteriovenous hemodialysis in the management of patients with oliguria associated with multiple organ failure

Mitochondrial Haplogroup and the Risk of Acute Kidney Injury Following Cardiac Bypass Surgery

Although mitochondrial dysfunction plays a key role in the pathophysiology of acute kidney injury (AKI), the influence of mitochondrial genetic variability in this process remains unclear. We explored the association between the risk of post-cardiac bypass AKI and mitochondrial haplotype - inherited mitochondrial genomic variations of potentially functional significance. Our single-centre study recruited consecutive patients prior to surgery. Exclusions included stage 5 CKD, non-Caucasian race and subsequent off-pump surgery. Haplogroup analysis allowed characterisation of the study population using the common mutations and by phylogenetic supergroup (WXI and HV). Chi-square tests for association allowed the identification of potential predictors of AKI for use in logistic regression analysis. AKI occurred in 12.8% of the study population (n = 881; male 69.6%, non-diabetic 78.5%, median (interquartile range) age 68.0 (61.0-75.0) years). The haplogroup profile comprised H (42.7%), J (12.1%), T (10.9%), U (14.4%) and K (7.6%). Although the regression model was statistically significant (χ² = 95.483, p < 0.0005), neither the phylogenetic supergroups nor any individual haplogroup was a significant contributor. We found no significant association between common European haplogroups and the risk of post-cardiac bypass AKI. However, given the major role of mitochondrial dysfunction in AKI, there is a need to replicate our findings in other cohorts and with other aetiologies of AKI.

Regional citrate anticoagulation for continuous venovenous hemodiafiltration using calcium-containing dialysate

BACKGROUND

Regional anticoagulation with trisodium citrate for continuous venovenous hemodiafiltration (CVVHDF) is an effective and safe alternative to heparin, especially in patients at high risk for bleeding. However, regional citrate anticoagulation is not used widely because current protocols are complex, labor intensive, and cumbersome. Existing protocols require the use of calcium-free dialysate with a continuous systemic calcium infusion to prevent hypocalcemia. We evaluated Anticoagulant Citrate Dextrose Formula A (ACD-A) solution for regional anticoagulation in CVVHDF in combination with a commercially available calcium-containing dialysis solution.

METHODS

Thirty-eight patients in the intensive care units underwent citrate-based CVVHDF using low-calcium peritoneal dialysis solution (calcium, 5.0 mg/dL [1.25 mmol/L]). ACD-A infusion rate was adjusted to maintain postfilter ionized calcium (iCa++) levels at 1.0 to 2.0 mg/dL (0.25 to 0.5 mmol/L). Calcium chloride (10%) solution was administered intravenously every 6 hours on an as-needed basis to maintain systemic serum iCa++ levels at 3.5 to 4.0 mg/dL (0.88 to 1.0 mmol/L).

RESULTS

CVVHDF was performed for a total of 394 days using 149 hemofilters. Mean hemofilter life span was 63.5 +/- 27.1 hours. Seventy-five percent, 61%, and 49% of hemofilters were patent at 24, 48, and 72 hours, respectively. No patient experienced a change in clinical status caused by hypocalcemia and/or signs and symptoms of citrate toxicity. Four patients developed metabolic alkalosis requiring 0.1 N of hydrochloric acid infusion.

CONCLUSION

Our simplified technique of regional citrate anticoagulation for CVVHDF using calcium-containing dialysate is not associated with increased hemofilter clotting and obviates the need for a continuous systemic calcium infusion and calcium-free dialysate.

Regional citrate anticoagulation in continuous venovenous hemofiltration in critically ill patients with a high risk of bleeding

BACKGROUND

Systemic heparinization is associated with a high rate of bleeding when used to maintain patency of the extracorporeal circuit during continuous renal replacement therapy (CRRT) in critically ill patients. Regional anticoagulation can be achieved with citrate, but previously described techniques are cumbersome and associated with metabolic complications.

METHODS

We designed a simplified system for delivering regional citrate anticoagulation during continuous venovenous hemofiltration (CVVH). We evaluated filter life and hemorrhagic complications in the first 17 consecutive patients who received this therapy at our institution. Blood flow rate was set at 180 ml/min. Ultrafiltration rate was maintained at 2.0 liters/hr and citrate-based replacement fluid (trisodium citrate 13.3 mM, sodium chloride 100 mM, magnesium chloride 0.75 mM, dextrose 0.2%) was infused proximal to the filter to maintain the desired fluid balance. Calcium gluconate was infused through a separate line to maintain a serum-ionized calcium level of 1.0 to 1.1 mM.

RESULTS

All patients were critically ill and required mechanical ventilation and vasopressor therapy. Systemic heparin anticoagulation was judged to be contraindicated in all of the patients. A total of 85 filters were used, of which 64 were lost because of clotting, with a mean life span of 29.5 +/- 17.9 hours. The remaining 21 filters were discontinued for other reasons. Control of fluid and electrolyte balance and azotemia was excellent (mean serum creatinine after 48 to 72 hr of treatment was 2.4 +/- 1.2 mg/dl). No bleeding episodes occurred. Two patients, one with septic shock and the other with fulminant hepatic failure, developed evidence for citrate toxicity without a significant alteration in clinical status. Nine patients survived (52.9%).

CONCLUSION

Our simplified technique of regional anticoagulation with citrate is an effective and safe form of anticoagulation for CVVH in critically ill patients with a high risk of bleeding.

Solute clearances with high dialysate flow rates and glucose absorption from the dialysate in continuous arteriovenous hemodialysis

The purpose of this study was to determine the effects of high inlet dialysate flow rates (IDFR) on the clearances of urea and creatinine and to measure the absorption of glucose through the dialyzer in continuous arteriovenous hemodialysis (CAVHD). Ten anuric acute renal failure patients in the intensive care unit were studied. Increasing the IDFR from 0 to 33.3 mL/min (0 to 2 L/h) produced linear increments in the clearances of urea and creatinine, whereas further increases in the IDFR from 33.3 to 66.7 mL/min (2 to 4 L/h) produced less important, but still significant, increases in the clearances. At 66.7 mL/min, the clearances for urea and creatinine were 48.5 +/- 3.4 and 42.2 +/- 2.5 mL/min, respectively. Using a dialysate with a glucose concentration of 25.3 mmol/L (0.5 g/dL), the net transfer of glucose through the dialyzer did not change significantly, from 16.7 to 66.7 mL/min of IDFR. Increasing the inlet dialysate glucose concentration from 25.3 to 75.8, 126.3, and 214.6 mmol/L (0.5 to 1.5, 2.5, and 4.25 g/dL) at a fixed IDFR of 16.7 mL/min produced linear increments in the net glucose transferred to the patient, from 0.12 +/- 0.02 to 0.67 +/- 0.05, 1.25 +/- 0.06 and 2.30 +/- 0.14 mmol/min, respectively (21.4, 121.0, 225.7, and 414.5 mg/min). No significant changes in the ultrafiltration and plasma flow rates through the dialyzer were recorded at these different IDFR or inlet dialysate glucose concentrations. Ten patients were treated for 4 days or more with 16.7 mL/min (1 L/h) IDFR CAVHD with excellent control over kidney function parameters.(ABSTRACT TRUNCATED AT 250 WORDS)