Single-dose diclofenac in healthy volunteers can cause decrease in renal perfusion measured by functional magnetic resonance imaging

OBJECTIVES

We investigated changes of renal perfusion after topical and oral diclofenac administration in healthy volunteers using functional magnetic resonance imaging (MRI) with arterial spin labelling (ASL).

METHODS

Twenty-four healthy human participants (21-51 years) underwent 1.5T MRI before and 1 h after a single oral dose of diclofenac (50 mg). Twelve of 24 participants underwent an additional MRI examination following 3-day topical diclofenac administration. For renal perfusion imaging, a flow-sensitive alternating inversion-recovery TrueFISP ASL sequence was applied. Plasma concentrations of diclofenac and serum concentrations of thromboxane were determined.

KEY FINDINGS

After oral diclofenac application, large interindividual differences in plasma concentrations were observed (range <3-4604 nm). Topical diclofenac application did not result in relevant systemic diclofenac levels (range 5-75 nm). MRI showed a significant reduction of renal perfusion in individuals with diclofenac levels ≥225 nm (baseline: 347 ± 7 vs diclofenac: 323 ± 8 ml/min/100 g, P < 0.01); no significant differences were observed in participants with diclofenac levels <225 nm. Diclofenac levels correlated negatively with thromboxane B2 levels pointing towards target engagement.

CONCLUSIONS

Single-dose diclofenac caused a decrease in renal perfusion in participants with diclofenac levels ≥225 nm. We demonstrated that even a single dose of diclofenac can impair renal perfusion, which could be detrimental in patients with underlying chronic kidney disease or acute kidney injury.

Patterns of medication use and the burden of polypharmacy in patients with chronic kidney disease: the German Chronic Kidney Disease study

Background

Patients with chronic kidney disease (CKD) bear a substantial burden of comorbidities leading to the prescription of multiple drugs and a risk of polypharmacy. However, data on medication use in this population are scarce.

Methods

A total of 5217 adults with an estimated glomerular filtration rate (eGFR) between 30 and 60 mL/min/1.73 m² or an eGFR ≥60 mL/min/1.73m² and overt proteinuria (>500 mg/day) were studied. Self-reported data on current medication use were assessed at baseline (2010-12) and after 4 years of follow-up (FU). Prevalence and risk factors associated with polypharmacy (defined as the regular use of five or more drugs per day) as well as initiation or termination of polypharmacy were evaluated using multivariable logistic regression.

Results

The prevalence of polypharmacy at baseline and FU was almost 80%, ranging from 62% in patients with CKD Stage G1 to 86% in those with CKD Stage G3b. The median number of different medications taken per day was eight (range 0-27). β-blockers, angiotensin-converting enzyme inhibitors and statins were most frequently used. Increasing CKD G stage, age and body mass index, diabetes mellitus, cardiovascular disease and a history of smoking were significantly associated with both the prevalence of polypharmacy and its maintenance during FU. Diabetes mellitus was also significantly associated with the initiation of polypharmacy [odds ratio (OR) 2.46, (95% confidence interval 1.36-4.45); P = 0.003].

Conclusion

Medication burden in CKD patients is high. Further research appears warranted to address the implications of polypharmacy, risks of drug interactions and strategies for risk reduction in this vulnerable patient population.

Outcomes of renal dysfunction in patients with acute liver failure

Background

Although acute kidney injury (AKI) often accompanies acute liver failure (ALF), its impact on long-term outcome is unknown.

Objective

This study examines the incidence, severity and outcomes of AKI in patients with ALF.

Methods

A total of 134 ALF patients treated at Hannover Medical School between 1995 and 2013 were retrospectively analyzed.

Results

Fifty-four ALF patients (40.3%) demonstrated AKI, as defined by the acute kidney injury network (AKIN) classification, on intensive care unit (ICU) admission, and 85 patients (63.4%) developed AKI prior to ALF recovery, emergency liver transplantation (ELT) or death. AKI severity was closely associated with other end-organ damage (p < 0.001). Follow-up creatinine levels in survivors were increased compared to baseline levels (76 versus 64 µmol/l, p = 0.003). One-hundred-and-three (76.9%) patients reached the combined endpoint of ELT or death, and 42 (31.3%) patients died within 28 days. AKIN stage 3 at ICU admission was the strongest independent predictor of 28-day overall mortality (hazard ratio 3.48, 95% confidence interval 1.75-6.93, p < 0.001) and ELT or death (hazard ratio 2.52, 95% confidence interval 1.60-3.96, p < 0.001).

Conclusions

AKI is a frequent complication in ALF that correlates with remote organ damage and long-term creatinine levels and independently predicts outcome.

Drugs linked to plasma homoarginine in chronic kidney disease patients—a cross-sectional analysis of the German Chronic Kidney Disease cohort

Background

Elevated plasma concentrations of symmetric and asymmetric dimethylarginine (SDMA and ADMA, respectively) and a lower plasma concentration of the structurally related homoarginine are commonly observed in patients with chronic kidney disease (CKD) and independently predict total mortality as well as progression of renal disease. We aimed to identify drugs that may alter this adverse metabolite pattern in a favourable fashion.

Methods

Plasma ADMA, SDMA, homoarginine and l-arginine were determined by liquid chromatography–tandem mass spectrometry in 4756 CKD patients ages 18–74 years with an estimated glomerular filtration rate (eGFR) of 30–60 mL/min/1.73 m2 or an eGFR &gt;60 mL/min/1.73 m2 and overt proteinuria who were enrolled in the German Chronic Kidney Disease (GCKD) study. Associations between laboratory, clinical and medication data were assessed.

Results

Intake of several commonly used drugs was independently associated with plasma concentrations of homoarginine and/or related metabolites. Among these, the peroxisome proliferator-activated receptor alpha (PPAR-α) agonist fenofibrate was associated with the most profound differences in ADMA, SDMA and homoarginine plasma concentrations: 66 patients taking fenofibrate had a multivariable adjusted odds ratio (OR) of 5.83 [95% confidence interval (CI) 2.82–12.03, P &lt; 0.001] to have a plasma homoarginine concentration above the median. The median homoarginine plasma concentration in patients taking fenofibrate was 2.30 µmol/L versus 1.55 in patients not taking the drug (P &lt; 0.001). In addition, fibrates were significantly associated with lower plasma SDMA and higher l-arginine concentrations. In contrast, glucocorticoids were associated with lower plasma homoarginine, with adjusted ORs of 0.52 (95% CI 0.40–0.67, P &lt; 0.001) and 0.53 (95% CI 0.31–0.90, P = 0.018) for prednisolone and methylprednisolone, respectively.

Conclusions

In a large cohort of CKD patients, intake of fenofibrate and glucocorticoids were independently associated with higher and lower plasma homoarginine concentrations, respectively. Effects on plasma homoarginine and methylarginines warrant further investigation as potential mechanisms mediating beneficial or adverse drug effects.

Early therapeutic plasma exchange in septic shock: a prospective open-label nonrandomized pilot study focusing on safety, hemodynamics, vascular barrier function, and biologic markers

Background

Given the pathophysiological key role of the host response to an infection rather than the infection per se, an ideal therapeutic strategy would also target this response. This study was designed to demonstrate safety and feasibility of early therapeutic plasma exchange (TPE) in severely ill individuals with septic shock.

Methods

This was a prospective single center, open-label, nonrandomized pilot study enrolling 20 patients with early septic shock (onset < 12 h) requiring high doses of norepinephrine (NE; > 0.4 μg/kg/min) out of 231 screened septic patients. Clinical and biochemical data were obtained before and after TPE. Plasma samples were taken for ex-vivo stimulation of human umbilical vein endothelial cells (HUVECs) to analyze barrier function (immunocytochemistry and transendothelial electrical resistance (TER)). Cytokines were measured by cytometric bead array (CBA) and enzyme-linked immunosorbent assays (ELISAs). An immediate response was defined as > 20% NE reduction from baseline to the end of TPE.

Results

TPE was well tolerated without the occurrence of any adverse events and was associated with a rapid reduction in NE (0.82 (0.61–1.17) vs. 0.56 (0.41–0.78) μg/kg/min, p = 0.002) to maintain mean arterial pressure (MAP) above 65 mmHg. The observed 28-day mortality was 65%. Key proinflammatory cytokines and permeability factors (e.g., interleukin (IL)-6, IL-1b, and angiopoietin-2) were significantly reduced after TPE, while the protective antipermeability factor angiopoietin-1 was not changed. Ex-vivo stimulation of HUVECs with plasma obtained before TPE induced substantial cellular hyperpermeability, which was completely abolished with plasma obtained after TPE.

Conclusions

Inclusion of early septic shock patients with high doses of vasopressors was feasible and TPE was safe. Rapid hemodynamic improvement and favorable changes in the cytokine profile in patients with septic shock were observed. It has yet to be determined whether early TPE also improves outcomes in this patient cohort. An appropriately powered multicenter randomized controlled trial is desirable.

Trial registration

Clinicaltrials.gov, NCT03065751. Retrospectively registered on 28 February 2017.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2220-9) contains supplementary material, which is available to authorized users.

Higher levels of SDMA and not ADMA are associated with poorer survival of trial patients with systemic ANCA-associated vasculitis

OBJECTIVE

Endothelial dysfunction, increased cardiovascular events (CVE), and accelerated atherosclerosis have been described in patients with small vessel vasculitis and collagen vascular disease. Identifying predictors of cardiovascular risk will help to optimize short- and long-term care of patients with vasculitis. The present study investigates the predictive role of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) and its stereoisomer symmetric dimethylarginine (SDMA) for cardiovascular risk, all-cause mortality, and renal function in patients with anti-neutrophil-cytoplasmic antibodies-associated small vessel vasculitis (AASV) subjected to standardized treatment regimens in four European Vasculitis Study Group trials representing all stages of renal disease.

METHODS

Sera from 89 patients with AASV were available for measuring SDMA, ADMA, and arginine using liquid chromatography/mass spectrometry at the time of active disease and remission. Clinical data on disease activity, remission, relapse rate, and 5-year follow-up data for CVE and renal outcome were collected.

RESULTS

Symmetric dimethylarginine and ADMA levels were not predictive of CVE at 5 years of follow-up. The overall CVE rate was low in the present cohort of AASV (8%). However, SDMA, and not ADMA, levels were significantly associated with poorer survival (death/ESRD) independent of entry glomerular filtration rate.

CONCLUSION

This novel outcome in a well-defined group of patients with AASV might indicate a different mechanism of endothelial response in AASV as compared with atherosclerosis. This should be further explored in a larger cohort of AASV patients with a higher CVE rate and/or a longer follow-up. Moreover, these findings should be correlated to other markers of vascular damage.

Preoperative serum uric acid predicts incident acute kidney injury following cardiac surgery

Background

Acute kidney injury (AKI) following cardiac surgery is a frequent complication and several risk factors increasing its incidence have already been characterized. This study evaluates the influence of preoperative increased serum uric acid (SUA) levels in comparison with other known risk factors on the incidence of AKI following cardiac surgery.

Methods

During a period of 5 month, 247 patients underwent elective coronary artery bypass grafting, valve replacement/ repair or combined bypass and valve surgery. Datas were prospectively analyzed. Primary endpoint was the incidence of AKI as defined by the AKI criteria comparing patients with preoperative serum uric acid (SUA) levels below versus above the median. Multivariate logistic regression analysis was used to identify independent predictors of postoperative AKI.

Results

Thirty (12.1%) of the 247 patients developed postoperative AKI, 24 of 30 (80%) had preoperative SUA- levels above the median (≥373 μmol/l) (OR: 4.680, CI 95% 1.840; 11.904, p = 0.001). In the multivariate analysis SUA levels above the median (OR: 5.497, CI 95% 1.772; 17.054, p = 0.003), cardiopulmonary bypass (CPB) time > 90 min (OR: 4.595, CI 95% 1.587; 13.305, p = 0.005), cardiopulmonary bypass (CPB) > 30 kg/m² (OR: 3.208, CI 95% 1.202; 8.562; p = 0.02), and preoperative elevated serum-creatinine levels (OR: 1.015, CI 95% 1.001; 1.029, p = 0.04) were independently associated with postoperative AKI.

Conclusions

Serum uric acid is an independent risk marker for AKI after cardiac surgery. From all evaluated factors it showed the highest odds ratio.

Pro: High dose of therapeutic plasma exchange-mind the gap!

'Mind the gap' is a recorded warning phrase used in the London Tube since 1969. The following article is meant to be a warning of an increasing knowing-doing gap in routine practice of therapeutic plasma exchange (TPE), a treatment method that is used more and more throughout the world. The American Society of Apheresis recommendations, including the most recent ones from 2016, suggest using a TPE volume of 1.0-1.5 times the actual calculated plasma volume of the patient. There are only a few exceptions to that rule, such as the recommnded exchange volume in vasculitis or mushroom poisoning. The published literature suggests that in routine clinical practice in many institutions in several countries the exchanged volume might in fact be lower than recommended by the guidelines. In the following article we argue for a high dose of exchanged plasma volume, yet sketch different scenarios on how this time-averaged high dose can be delivered in various ways depending on the underlying disease, refuting a one-size-fits-all strategy that might facilitate the procedure but may result in 'underpheresis' in many patients. Further, the objectives underlying the use of smaller exchange volumes, especially the gap between the cost of blood products and the reimbursement of TPE are discussed. Lastly, the knowing-guiding gap is described, which can only be overcome by collecting high-quality data and conducting prospective clinical trials in the field of TPE.

[Prevention of acute kidney injury in critically ill patients : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

BACKGROUND

Acute kidney injury (AKI) has both high mortality and morbidity.

OBJECTIVES

To prevent the occurrence of AKI, current recommendations from the renal section of the DGIIN (Deutschen Gesellschaft für Internistische Intensivmedizin und Notfallmedizin), ÖGIAIN (Österreichischen Gesellschaft für Internistische und Allgemeine Intensivmedizin und Notfallmedizin) and DIVI (Deutschen Interdisziplinären Vereinigung für Intensiv- und Notfallmedizin) are stated.

MATERIALS AND METHODS

The recommendations stated in this paper are based on the current Kidney Disease Improving Global Outcomes (KDIGO) guidelines, the published statements of the "Working Group on Prevention, AKI section of the European Society of Intensive Care Medicine" and the expert knowledge and clinical experience of the authors.

RESULTS

Currently there are no approved clinically effective drugs for the prevention of AKI. Therefore the mainstay of prevention is the optimization of renal perfusion by improving the mean arterial pressure (>65 mm Hg, higher target may be considered in hypertensive patients). This can be done by vasopressors, preferably norepinephrine and achieving or maintaining euvolemia. Hyperhydration that can lead to AKI itself should be avoided. In patients with maintained diuresis this can be done by diuretics that are per se no preventive drug for AKI. Radiocontrast enhanced imaging should not be withheld from patients at risk for AKI; if indicated, however, the contrast media should be limited to the smallest possible volume.

Population pharmacokinetics of vancomycin in critically ill patients receiving prolonged intermittent renal replacement therapy

OBJECTIVES

The aim of this study was to describe the population pharmacokinetics of vancomycin during prolonged intermittent renal replacement therapy (PIRRT) in critically ill patients with acute kidney injury.

METHODS

Critically ill patients prescribed vancomycin across two sites had blood samples collected during one to three dosing intervals during which PIRRT was performed. Plasma samples were assayed with a validated immunoassay method. Population pharmacokinetic analysis and Monte Carlo simulations were performed using Pmetrics^®. The target vancomycin exposures were the area under the concentration-time curve within a 24-h period (AUC_0-24)/minimum inhibitory concentration (MIC) ratio of 400 for efficacy and AUC_0-24 700 for toxicity.

RESULTS

Eleven critically ill patients (seven male) were enrolled and contributed 192 plasma samples. The patient's mean ± standard deviation (SD) age, weight and body mass index (BMI) were 57 ± 13 years, 98 ± 43 kg and 31 ± 9 kg/m², respectively. A two-compartment linear model adequately described the data. The mean ± SD population pharmacokinetic parameter estimates were PIRRT clearance (CL) 3.47 ± 1.99 L/h, non-PIRRT CL 2.15 ± 2.07 L/h, volume of distribution of the central compartment (Vc) 41.85 ± 24.33 L, distribution rate constant from central to peripheral compartment 5.97 ± 7.93 per h and from peripheral to central compartment 5.29 ± 6.65 per h. Assuming a MIC of 1 mg/L, vancomycin doses of 25 mg/kg per day are suggested to be efficacious, whilst minimising toxic, exposures.

CONCLUSIONS

This is the first population pharmacokinetic study of vancomycin in patients receiving PIRRT and we observed large pharmacokinetic variability. Empirically, weight-based doses that are appropriate for the duration of PIRRT, should be selected and supplemented with therapeutic drug monitoring.

Hypoxia-induced long non-coding RNA Malat1 is dispensable for renal ischemia/reperfusion-injury

Renal ischemia-reperfusion (I/R) injury is a major cause of acute kidney injury (AKI). Non-coding RNAs are crucially involved in its pathophysiology. We identified hypoxia-induced long non-coding RNA Malat1 (Metastasis Associated Lung Adenocarcinoma Transcript 1) to be upregulated in renal I/R injury. We here elucidated the functional role of Malat1 in vitro and its potential contribution to kidney injury in vivo. Malat1 was upregulated in kidney biopsies and plasma of patients with AKI, in murine hypoxic kidney tissue as well as in cultured and ex vivo sorted hypoxic endothelial cells and tubular epithelial cells. Malat1 was transcriptionally activated by hypoxia-inducible factor 1-α. In vitro, Malat1 inhibition reduced proliferation and the number of endothelial cells in the S-phase of the cell cycle. In vivo, Malat1 knockout and wildtype mice showed similar degrees of outer medullary tubular epithelial injury, proliferation, capillary rarefaction, inflammation and fibrosis, survival and kidney function. Small-RNA sequencing and whole genome expression analysis revealed only minor changes between ischemic Malat1 knockout and wildtype mice. Contrary to previous studies, which suggested a prominent role of Malat1 in the induction of disease, we did not confirm an in vivo role of Malat1 concerning renal I/R-injury.

Therapeutic plasma exchange in a tertiary care center: 185 patients undergoing 912 treatments - a one-year retrospective analysis

BACKGROUND

Therapeutic plasma exchange (TPE) is increasingly used throughout the world. Although the procedure itself is fairly standardized, it is yet unknown how the underlying disease entities influence the key coordinates of the treatment.

METHODS

Retrospective chart review. The treatment indications were clustered into four categories. Data are presented as median and interquartile (25-75%) range [IQR].

RESULTS

Within 1 year, 912 TPE treatments were performed in 185 patients (90 female, 48.6%). The distribution of the treatment numbers to the pre-specified disease categories were as follows: transplantation (35.7%), neurology (31.9%), vasculitis and immunological disease (17.3%), and others including thrombotic microangiopathy (8.1%), critical care related diseases (5.4%), hematology [multiple myeloma] (1.1%), and endocrine disorders (0.5%). The calculated plasma volume was significantly higher in patients with vasculitis and immunological diseases (3984 [3433-4439] ml) as compared to patients treated for transplant related indications (3194 [2545-3658] ml; p = 0.0003) and neurological diseases (3058 [2533-3359] ml; p < 0.0001). This was mainly due to the differences in the hematocrit which was 30.5 [27.0-33.6] % in the vasculitis/immunological disease patients and 40.2 [37.5-42.9] % in the neurological patients; p < 0.0001. Interestingly, treatment time using a membrane based technology was significantly longer than TPE using a centrifugal device 135.0 [125.0-140.0] min vs. 120.0 [112.5-135.0] min. Furthermore, the relative exchanged plasma volume was significantly lower in the treatment of vasculitis and immunological diseases as compared to treatments of transplant related indications and neurological diseases.

CONCLUSION

Patients with low hematocrit and high body weight do not receive the minimum recommended dose of exchange volume. Centrifugal TPE allowed faster plasma exchange than membrane TPE.

Enhanced elimination of cyclophosphamide by high cut-off haemodialysis: single-dose pharmacokinetics in a patient with cast nephropathy

High cut-off (HCO) haemodialysis removes free light chains in patients with multiple myeloma. This is possible as HCO dialysers allow clearance of molecules up to a molecular weight of 65 kDa. In contrast, high-flux dialysers, which are used in routine haemodialysis, only remove molecules up to a molecular weight of 20 kDa. Even though patients with advanced myeloma frequently need dialysis and alkylating agents, drug dosing recommendations in this patient population are scarce at best or absent as for cyclophosphamide dosing in patients with myeloma undergoing HCO dialysis. Therefore, we aimed to determine pharmacokinetics of cyclophosphamide in a 52-year-old man (height 172 cm, weight 80 kg) with cast nephropathy. Intermittent 4-hour haemodialysis was started ~6 hours after the end of a 70 min cyclophosphamide infusion containing 1700 mg of this drug. Blood/dialysate flow rates were 300/500 mL/hour, respectively. Peak concentration of cyclophosphamide was 24.7 mg/L. Using HCO dialysis, plasma concentration of cyclophosphamide decreased from 10.8 mg/L to 3.7 mg/L during the treatment. The calculated whole blood dialyser clearance was 166 mL/min. HCO dialysis led to a marked decrease of cyclophosphamide resulting in a a 50% reduction in half-life as compared with the half-life before dialysis. This removal has to be accounted for in dosing cyclophosphamide.

Dimethylarginines in patients with intracerebral hemorrhage: association with outcome, hematoma enlargement, and edema

BACKGROUND

Asymmetric dimethylarginine (ADMA)--the most potent endogenous NO-synthase inhibitor, has been regarded as mediator of endothelial dysfunction and oxidative stress. Considering experimental data, levels of ADMA and its structural isomer symmetric dimethylarginine (SDMA) might be elevated after intracerebral hemorrhage (ICH) and associated with clinical outcome and secondary brain injury.

METHODS

Blood samples from 20 patients with acute ICH were taken at ≤ 24 h and 3 and 7 days after the event. Nine patients had favorable (modified Rankin Scale (mRS) at 90 days 0-2) outcome, and 11 patients unfavorable outcome (mRS 3-6). Patients' serum ADMA, SDMA, and L-arginine levels were determined by high-performance liquid chromatography-tandem mass spectrometry. Levels were compared to those of 30 control subjects without ICH. For further analysis, patients were grouped according to outcome, hematoma and perihematomal edema volumes, occurrence of hematoma enlargement, and cytotoxic edema as measured by computed tomography and serial magnetic resonance imaging.

RESULTS

Levels of ADMA--but not SDMA and L-arginine--were elevated in ICH patients compared to controls (binary logistic regression analysis: ADMA ≤ 24 h, p = 0.003; 3 days p = 0.005; 7 days p = 0.004). If patients were grouped according to outcome, dimethylarginines were increased in patients with unfavorable outcome. The binary logistic regression analysis confirmed an association of SDMA levels ≤ 24 h (p = 0.048) and at 3 days (p = 0.028) with unfavorable outcome. ADMA ≤ 24 h was increased in patients with hematoma enlargement (p = 0.003), while SDMA ≤ 24 h was increased in patients with large hematoma (p = 0.029) and perihematomal edema volume (p = 0.023).

CONCLUSIONS

Our data demonstrate an association between dimethylarginines and outcome of ICH. However, further studies are needed to confirm this relationship and elucidate the mechanisms behind.

International registry on the use of the CytoSorb® adsorber in ICU patients : Study protocol and preliminary results

INTRODUCTION

The aim of this clinical registry is to record the use of CytoSorb® adsorber device in critically ill patients under real-life conditions.

METHODS

The registry records all relevant information in the course of product use, e. g., diagnosis, comorbidities, course of the condition, treatment, concomitant medication, clinical laboratory parameters, and outcome (ClinicalTrials.gov Identifier: NCT02312024). Primary endpoint is in-hospital mortality as compared to the mortality predicted by the APACHE II and SAPS II score, respectively.

RESULTS

As of January 30, 2017, 130 centers from 22 countries were participating. Data available from the start of the registry on May 18, 2015 to November 24, 2016 (122 centers; 22 countries) were analyzed, of whom 20 centers from four countries provided data for a total of 198 patients (mean age 60.3 ± 15.1 years, 135 men [68.2%]). In all, 192 (97.0%) had 1 to 5 Cytosorb® adsorber applications. Sepsis was the most common indication for CytoSorb® treatment (135 patients). Mean APACHE II score in this group was 33.1 ± 8.4 [range 15-52] with a predicted risk of death of 78%, whereas the observed mortality was 65%. There were no significant decreases in the SOFA scores after treatment (17.2 ± 4.8 [3-24]). However interleukin-6 levels were markedly reduced after treatment (median 5000 pg/ml before and 289 pg/ml after treatment, respectively).

CONCLUSIONS

This third interim report demonstrates the feasibility of the registry with excellent data quality and completeness from 20 study centers. The results must be interpreted with caution, since the numbers are still small; however the disease severity is remarkably high and suggests that adsorber treatment might be used as an ultimate treatment in life-threatening situations. There were no device-associated side effects.

[Hot rods in the ICU : What is the antibiotic mileage of your renal replacement therapy?]

We would neither be disappointed nor upset if the gas mileage on the sticker of a car didn't match our personal, real-life fuel consumption. Depending on our daily route to work, our style of accelerating and the number of passengers in our carpool, the gas mileage will vary. As soon as the falcon wing door of our car is closed and entrance to the ICU is granted, we tend to forget all of this, even though another hot rod is waiting there for us. Renal replacement therapy is like a car; it fulfills goals, such as the removal of uremic toxins and accumulated fluids, but it also "consumes" (removes) antibiotics. Unlike catecholamines, where we have the mean arterial pressure on our ICU dashboard, we do not have a gauge to measure antibiotic "consumption", i.e. elimination by renal replacement therapy. This manuscript describes the principles and basic knowledge to improve dosing of antibiotics in critically ill patients undergoing renal replacement therapy. As in modern cars, we briefly touch on hybrid therapies combining renal replacement therapy with extracorporeal lung support or adsorbent technologies that remove cytokines or bacteria. Further, the importance of considering body size and body composition is addressed, especially for choosing the right initial dose of antibiotics. Lastly we point out the dire need to increase the availability of timely and affordable therapeutic drug monitoring on the most commonly used antiinfectives, ideally using point-of-care devices at the bedside.

[Role of plasmapheresis and immunoadsorption in salvage therapy of rheumatological diseases]

Many rheumatological diseases are either caused by specific known proteins, such as antibodies or mediated by a plethora of cytokines. Both the unspecific immunosuppressive therapy and the specific action of biologics usually require time to be effective; therefore, extracorporeal forms of treatment are increasingly being employed in severe forms of rheumatological diseases as well as in patients who cannot tolerate pharmacological treatment or where the risk of pharmacological treatment may outweigh the potential benefits. Therapeutic plasma exchange (TPE) removes not only pathogenic substances, such as autoantibodies, lipoproteins and circulating immune complexes from the plasma but also cytokines. The removed plasma that is discarded has to be substituted by blood products, e.g. human albumin or fresh frozen plasma. Fresh frozen plasma is always used when missing plasma components must be replenished, such as ADAMTS-13 in thrombotic thrombocytopenic purpura (TTP). The separated plasma can be further processed by pumping into a hollow fiber filter (cut-off of ~700 kD) and in this way low-density lipoprotein cholesterol and IgM can be eliminated. This treatment mode, called cascade filtration is used to treat diseases, such as Waldenström's macroglobulinemia and cryoglobulinemia. A specific way to remove antibodies is by immunoadsorption in which the antibodies are specifically removed by an adsorber. For this procedure there is no need to substitute blood products. This review article describes the principles of the two different treatment methods, the advantages and disadvantages and also summarizes the current evidence for their use in rheumatological diseases.

A comparative study of bone biopsies from the iliac crest, the tibial bone, and the lumbar spine

BACKGROUND

Patients with an impaired renal function show a high incidence of bone and mineral disturbances. These 'chronic kidney disease - mineral and bone disorders' (CKD-MBD) range from high turnover osteoporosis to adynamic bone disease. Currently, the histomorphometric analysis of a bone biopsy taken from the iliac crest is viewed as the gold standard for CKD-MBD subtype differentiation. However, the clinical relevance of such a biopsy is questionable since iliac crest fractures are an extremely rare finding. Therefore, we aimed to elucidate if the histomorphometric parameter 'trabecular bone volume (BV/TV)' from the iliac crest is representative for other biopsy locations. We chose two skeletal sites of higher fracture risk for testing, namely, the tibial bone and the lumbar spine, to examine if the current gold standard of bone biopsy is indeed golden.

METHODS

Bone biopsies were taken from 12 embalmed body donors at the iliac crest, the proximal tibia, and the lumbar vertebral body, respectively. Masson-Goldner stained sections of methyl methacrylate embedded biopsies were used for trabecular bone volume calculation. Furthermore, exemplary μ-computed tomography (XtremeCT) scans with subsequent analysis were performed.

RESULTS

Median values of trabecular bone volume were comparable between all body donors with median (interquartile range, IQR) 18.3% (10.9-22.9%) at the iliac crest, 21.5% (9.5-40.1%) at the proximal tibia, and 16.3% (11.4-25.0%) at the lumbar spine. However, single values showed extensive intra-individual variation, which were also confirmed by XtremeCT imaging.

CONCLUSIONS

Distinct intra-individual heterogeneity of trabecular bone volume elucidate why a bone biopsy from one site does not necessarily predict patient relevant endpoints like hip or spine fractures. Physicians interpreting bone biopsy results should know this limitation of the current gold standard for CKD-MBD diagnostic, especially, when systemic therapeutic decisions should be based on it.