Helen Dickie

Renal replacement therapy in critically ill patients with acute kidney injury--when to start.

BACKGROUND Despite the frequent use of renal replacement therapy (RRT) for patients with acute kidney injury (AKI) in the intensive care unit (ICU), there is no accepted consensus on the optimal indications and timing. METHODS The aim of this paper is to identify optimal triggers for RRT in critically ill patients with AKI. RESULTS We examined data from 2 randomized controlled trials, 2 prospective studies and 13 retrospective trials and found large variation in the different parameters and cut-offs for initiation of RRT. No single biochemical parameter was adequate to define the optimal indication and time to commence RRT. Degree of fluid overload, oliguria and associated non-renal organ failure appeared to be more appropriate parameters for initiation of RRT. We propose a clinical algorithm based on regular assessment of the patients condition and trends in these parameters. It is intended to aid the process of deciding when to start RRT in critically ill adult patients with AKI. CONCLUSION Available evidence suggests that the decision when to start RRT in critically ill patients with AKI should be based on trends in the patients severity of illness, presence of oliguria and fluid overload and associated non-renal organ failure rather than specific serum creatinine or urea values.

Management of sodium disorders during continuous haemofiltration

In patients with acute kidney injury and concomitant severe hyponatraemia or hypernatraemia, rapid correction of the serum Na+ concentration needs to be avoided. The present paper outlines the principles of how to adjust the Na+ concentration in the replacement fluid during continuous renal replacement therapy to prevent rapid changes of the serum Na+ concentration.

Heparin algorithm for anticoagulation during continuous renal replacement therapy

Premature circuit clotting is a problem during continuous renal replacement therapy. We describe an algorithm for individualised anticoagulation with unfractionated heparin based on the patients risk of bleeding and previous circuit life. The algorithm allows effective and safe nurse-led anticoagulation during continuous renal replacement therapy.

Maintaining Normal Levels of Ionized Calcium during Citrate-Based Renal Replacement Therapy Is Associated with Stable Parathyroid Hormone Levels

Background/Aims: Citrate is an effective anticoagulant during continuous renal replacement therapy (CRRT). Previous studies showed raised parathyroid hormone (PTH) levels when aiming for serum ionized calcium [Cai] between 0.8 and 1.1 mmol/l. Our objective was to assess whether citrate-based CRRT with physiologic target systemic [Cai] between 1.12 and 1.20 mmol/l could maintain stable PTH levels. Methods: Measurement of intact PTH (PTHi) in 30 consecutive critically ill patients treated with citrate-based CRRT. Results: Thirty patients [mean age: 70.4 (SD 11.3) years; 56.7% males] were enrolled. Mean serum [Cai] was 1.16 mmol/l (SD 0.09), 1.13 mmol/l (SD 0.09), 1.17 mmol/l (SD 0.05) and 1.16 mmol/l (SD 0.04) at baseline, 12, 24 and 48 h, respectively (p = 0.29). Median PTHi levels (interquartile range) at baseline, 12, 24 and 48 h were 66.5 (43-111), 109 (59.5-151.5), 88.5 (47-133) and 85 pg/ml (53-140), respectively. The differences between baseline and 12 h and across all time points were statistically not significant (p = 0.16 and p = 0.49, respectively). In a mixed-effects model, each 0.1 mmol/l increase in serum [Cai] was associated with a 31.2% decrease in PTHi (p < 0.001). Results were unchanged after adjustment for age, gender, magnesium, phosphate, arterial pH and time spent on CRRT. Conclusions: Maintaining systemic [Cai] within the physiologic range was associated with stable PTHi levels.

Correction of Hyper- and Hyponatraemia during Continuous Renal Replacement Therapy

Background: Severe hyper- and hyponatraemia is associated with significant risks, yet its correction can also have serious consequences when implemented too fast or inadequately. The safe correction of serum sodium levels is particularly challenging when renal replacement therapy (RRT) is required. Methods: Using 2 case scenarios, we aim to illustrate a simple method of correcting hyper- and hyponatraemia safely by step-wise manipulation of the dialysate/replacement fluid. Results: During continuous RRT, hypernatraemia can be corrected effectively and safely by adding small pre-calculated amounts of 30% NaCl to the dialysate/replacement fluid bags aiming for a [Na+] in the fluid that allows safe equilibration and correction of the serum [Na+]. To correct hyponatraemia safely, pre-calculated amounts of sterile water can be added in a step-wise manner to achieve a fluid [Na+] that equals the desired target serum [Na+]. Conclusion: During continuous RRT, the step-wise adjustment of [Na+] of dialysate/replacement fluids offers a safe and reliable method to correct sodium disorders.

Beyond the randomized clinical trial: citrate for continuous renal replacement therapy in clinical practice.

Background: Premature circuit clotting is a major problem during continuous renal replacement therapy (CRRT). Six randomized controlled trials confirmed that regional anticoagulation with citrate is superior to heparin. Our objective was to compare circuit patency with citrate, heparin and epoprostenol in routine clinical practice. Methods: We retrospectively analysed data on circuit patency of all circuits used in a single centre between September 2008 and August 2009. We differentiated between premature filter clotting, elective discontinuation and waste. Results: 309 patients were treated with CRRT (n = 2,059 circuits). The mean age was 65.7; 63.8% were male. The methods to maintain circuit patency were unfractionated heparin (42.3%), epoprostenol (23.0%), citrate (14.7%), combinations of different anticoagulants (14.6%) and no anticoagulation (4.7%). Premature clotting was the most common reason for circuit discontinuation among circuits anticoagulated with heparin, epoprostenol or combinations of different anticoagulants (59-62%). Among circuits anticoagulated with citrate the main reason for discontinuation was elective (61%). Hazard regression analysis confirmed significantly better circuit survival with citrate. Changing from heparin to citrate decreased the risk of premature circuit clotting by 75.8%. Conclusion: In routine clinical practice, regional anticoagulation with citrate is associated with significantly better circuit patency than heparin or epoprostenol.

Association between type of anticoagulation and blood transfusion requirements during renal replacement therapy in the ICU

Renal replacement therapy (RRT) is an essential component of modern critical care. Anticoagulation is necessary to prevent premature clotting of the extracorporeal circuit. We aimed to determine whether regional anticoagulation with citrate is associated with the reported reduced need for blood transfusions compared with heparin or epoprostenol.

Addition of prostacyclin to heparin does not prolong circuit life during continuous haemofiltration

Premature circuit clotting is a major problem during continuous venovenous haemofiltration (CVVH). Some studies have suggested that circuit life can be improved by adding epoprostenol to heparin.