The effect of regional citrate anti-coagulation on the coagulation system in critically ill patients receiving continuous renal replacement therapy for acute kidney injury - an observational cohort study

Background

Regional anticoagulation with citrate is the recommended first line treatment for patients receiving continuous renal replacement therapy (CRRT). There is wide variability in filter patency which may be due to differences in patient characteristics and local practice. It is also possible that citrate has effects on primary and secondary haemostasis, fibrinolysis and platelet function that are still unknown. The primary aim of the study is to describe the effect of citrate on coagulation and fibrinolysis pathways in both the patient and the haemodialysis circuit.

Methods

The study will recruit 12 adult patients admitted to the intensive care unit, requiring CRRT with regional citrate anticoagulation for acute kidney injury. Patients with pre-existing thrombotic or bleeding tendencies will be excluded. Thrombin generation, clot lysis and platelet function will be measured at baseline and at 12, 24, 36, 48 and 72 h after commencing CRRT (from the patient and from the circuit). We will describe the evolution of parameters over time as well as the differences in parameters between the patient and the circuit.

Discussion

The study will provide new data on the effects of citrate during continuous renal replacement therapy which is not currently available. We will minimise confounding factors through the use of tight exclusion criteria and accept that this will slow down recruitment. Depending on the results, we hope to incorporate the findings into existing clinical guidelines and clinical practice with the aim to prevent premature filter clotting and interruptions in treatment.

Trial registration

The study was registered with clinicaltrials.gov on 10th June 2015 (NCT02486614).

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.

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 [Ca(i)] 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 [Ca(i)] 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 [Ca(i)] 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 [Ca(i)] within the physiologic range was associated with stable PTHi levels.

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 patient's 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 patient's 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 patient's risk of bleeding and previous circuit life. The algorithm allows effective and safe nurse-led anticoagulation during continuous renal replacement therapy.

The development of a method for comparative costing of individual intensive care units. The Intensive Care Working Group on Costing

Intensive care is one of the most costly areas of hospital care. Unfortunately, because of the diversity of case mix, costing intensive care is difficult. Many described costing methods previously are limited by being cumbersome, laborious to apply and expensive. The aim of this study was to develop a method for costing intensive care which can be applied with ease but facilitate meaningful cost comparisons between intensive care units. The method developed was based on cost blocks where the major components were identified and costed in a 'top-down' manner. Using strict definitions, the cost blocks attempted to measure the costs of equipment, estates, nonclinical support services (such as hospital management costs), clinical support services (such as physiotherapy, laboratory services), consumables (such as drugs, fluids and disposables) and staff. The study found that clinical support services, consumables and staff costs accounted for approximately 85% of the total costs.

Relationship between TISS and ICU cost

OBJECTIVE

To determine whether the therapeutic intervention scoring system (TISS) reliably reflects the cost of the overall intensive care unit (ICU) population, subgroups of that population and individual ICU patients.

DESIGN

Prospective analysis of individual patient costs and comparison with TISS.

SETTING

Adult, 12 bedded general medical and surgical ICU in a university teaching hospital.

SUBJECTS

Two hundred fifty-seven consecutive patients including 52 coronary care (CCU), 99 cardiac surgery (CS) and 106 general ICU (GIC) cases admitted to the ICU during a 12-week period in 1994. A total of 916 TISS-scored patient days were analysed

MAIN OUTCOME MEASURES

A variable cost (VC) that included consumables and service usage (nursing, physiotherapy, radiology and pathology staff costs) for individual patients was measured daily. Nursing costs were calculated in proportion to a daily nursing dependency score. A fixed cost (FC) was calculated for each patient to include medical, technical and clerical salary costs, capital equipment depreciation, equipment and central hospital costs. The correlation between cost and TISS was analysed using regression analysis.

RESULTS

For the whole group (n = 257) the average daily FC was pound sterling 255 and daily VC was pound sterling 541 (SEM 10); range pound sterling 23-pound sterling 2,806. In the patient subgroups average daily cost (FC + VC) for CCU was pound sterling 476 (SEM 17.5), for CS pound sterling 766 (SEM 13.8) and for GIC pound sterling 873 (SEM 13.6). In the group as a whole, a strong correlation was demonstrated between VC and the TISS for each patient day (r = 0.87, p < 0.001) and this improved further when the total TISS score was compared with the total VC of the entire patient episode (r = 0.93, p < 0.001). This correlation was maintained in CCU, CS and GIC patient cohorts with only a small median difference between actual and predicted cost (2.2 % for GIC patients). However, in the individual patient, the range of error was up to +/- 65 % of the true variable cost. For the whole group the variable cost per TISS point was pound sterling 25.

CONCLUSION

These results demonstrate that TISS reliably measures overall ICU population costs as well as those of the subgroups CCU, CS and GIC. However, the relationship between TISS and cost is less reliable for the individual patient.

Relationships between prednisone therapy, disease activity, and the total serum IgE level in allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an unusual syndrome caused by hypersensitivity to Aspergillus spores growing in the bronchii. Previous investigators have suggested that the IgE levels and precipitating antibodies may vary according to disease activity. We have been able to closely follow 12 out of a group of 40 ABPA patients with IgE and serum precipitating antibody measurements. Our results confirm that both the total serum IgE and the precipitin response vary according to ABPA disease activity. In particular the IgE trend appears to mirror the disease activity in that a rising level may portend a flare, while a stable or declining value implies disease remission.

Lymphocyte subpopulations in the peripheral blood of patients with farmer's lung

The numbers of mononuclear cells having receptors for sheep red blood cells (T lymphocytes) or complement (B lymphocytes) in the peripheral blood of farmer's lung patients were determined. In patients recovering from a clinical episode of farmer's lung or exposed to moldy hay or fodder, both the percentage of T lymphocytes and the T lymphocytes per mm3 were reduced, whereas the number of B lymphocytes remained within normal limits. Farmer's lung patients having no exposure to moldy hay or fodder had T and B lymphocyte numbers similar to a normal population.