Continuous Renal Replacement Therapy Device Research Articles

Population Pharmacokinetic Modeling of Unbound Meropenem in Patients Undergoing Continuous Renal Replacement Therapy: An Observational Cohort Study.

The most effective dosing strategy of meropenem for patients undergoing continuous renal replacement therapy (CRRT) remains uncertain. This study aimed to analyze the population pharmacokinetics (popPKs) of unbound meropenem and establish an appropriate dosing approach. This prospective study involved 19 patients for the development of a popPK model and an additional 10 for its validation. Ethical approval was obtained. The clearance of unbound meropenem was influenced by the sequential organ failure assessment (SOFA) score [=2.22 × (SOFA score/12)^1.88] and the effluent flow rate from the CRRT device, with an interindividual variability of 44.5%. The volume of distribution was affected by the simplified acute physiology score II [=23.1 × (simplified acute physiology score II/52)^1.54]. Monte Carlo simulations suggested meropenem doses ranging from 1.0 to 3.0 g/d using continuous infusion to achieve a target time above the 4 times of minimum inhibitory concentration of the unbound form (% f T >4×MIC ) of 100% for definitive therapy. For empirical therapy, a dose of 1.0 g/d using continuous infusion was recommended to target % f T >MIC of 100%. This study developed a popPK model for unbound meropenem in patients undergoing CRRT and formulated dosing guidelines. UMIN000024321.

Metabolic disturbances potentially attributable to clogging during continuous renal replacement therapy

BackgroundClogging is characterized by a progressive impairment of transmembrane patency in renal replacement devices and occurs due to obstruction of pores by unknown molecules. If citrate-based anti-coagulation is used, clogging can manifest as a metabolic alkalosis accompanied by hypernatremia and hypercalcemia, primarily a consequence of Na3Citrate infusion. An increased incidence of clogging has been observed during the COVID-19 pandemic. However, precise factors contributing to the formation remain uncertain. This investigation aimed to analyze its incidence and assessed time-varying trajectories of associated factors in critically ill patients on continuous renal replacement therapy (CRRT).MethodsIn this retrospective, single-center data analysis, we evaluated COVID-19 patients undergoing CRRT and admitted to critical care between March 2020 and December 2021. We assessed the proportional incidence of clogging surrogates in the overall population and subgroups based on the specific CRRT devices employed at our institution, including multiFiltrate (Fresenius Medical Care) and Prismaflex System (Baxter). Moderate and severe clogging were defined as Na > 145 or ≥ 150 mmol/l and HCO3− > 28.0 or ≥ 30 mmol/l, respectively, with a total albumin-corrected calcium > 2.54 mmol/l. A mixed effect model was introduced to investigate factors associated with development of clogging.ResultsFifty-three patients with 240 CRRT runs were analyzed. Moderate and severe clogging occurred in 15% (8/53) and 19% (10/53) of patients, respectively. Twenty-seven percent (37/136) of CRRTs conducted with a multiFiltrate device met the criteria for clogging, whereas no clogging could be observed in patients dialyzed with the Prismaflex System. Occurrence of clogging was associated with elevated triglyceride plasma levels at filter start (p = 0.013), amount of enteral nutrition (p = 0.002) and an increasing white blood cell count over time (p = 0.002).ConclusionsClogging seems to be a frequently observed phenomenon in critically ill COVID-19 patients. The presence of hypertriglyceridemia, combined with systemic inflammation, may facilitate the development of an impermeable secondary membrane within filters, thereby contributing to compromised membrane patency.

Impact of connecting methods of continuous renal replacement therapy device on patients underwent extracorporeal membrane oxygenation: A retrospectively observational study

ObjectiveThe objective of this study was to compare the safety and efficiency of different extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) connection methods. BackgroundThe number of patients receiving ECMO is increasing, and the fields of application are getting wider. However, patients receiving ECMO are prone to acute kidney injury and fluid overload requiring CRRT. There are few comparative studies of two different systems of connecting CRRT device and ECMO from safety and efficacy perspective. MethodsThis retrospective observational study included patients receiving ECMO in the extracorporeal life support centre of the First Affiliated Hospital of Nanjing Medical University from June, 2015, to December, 2020. Patients were divided into the parallel system group and integrated system group according to the connecting method between ECMO circuit and CRRT line. The outcomes were discharge survival rate, CRRT therapeutic dose completion rate, CRRT catheterisation time, CRRT initiating time, local bleeding at the CRRT catheter site, mean filter life, ECMO circuit thrombosis, ECMO air leakage, or blood leakage due to CRRT. ResultsThirty patients in the parallel system group and 70 patients in the integrated system group were finally included. The discharge survival rate and CRRT therapeutic dose completion rate were not significantly different between the two groups. The parallel system group had significant longer CRRT initiating time (49.0 ± 12.1 min vs. 14.6 ± 2.1 min, P < 0.001) and shorter filter life (11.5 ± 3.2 h vs. 47.3 ± 14.0 h, P < 0.001) than the integrated system group. The occurrence rate of local bleeding was 93.3% in the parallel system group, and there is no bleeding case in the integrated system group. There was no case of ECMO circuit thrombosis from CRRT as well as ECMO air or blood leakage caused by CRRT in either group. ECMO therapy can be adapted by adjusting the position of the CRRT outlet in the integrated system. ConclusionsConnecting CRRT and ECMO as an integrated system might accelerate CRRT initiation, avoid local bleeding, and prolong filter life compared to the parallel system. The chance of developing CRRT-related ECMO circuit leak and thrombosis is manageable.

Constructing a continuous hemodiafiltration-type circulatory model of acute kidney injury in pigs.

IntroductionAnimal‐model experimental systems capable of reflecting the effects of devices for continuous renal replacement therapy (CRRT) on living organisms are limited; thus, aimed to construct an animal model of AKI‐CRRT using pigs.MethodsPigs were subjected to renal artery ischemia–reperfusion injury (IRI) and then to a maximum of 24 h of continuous hemodiafiltration (CHDF)‐type CRRT.ResultsPost‐IRI, pigs' creatinine levels rose threefold, and they exhibited 24 h of anuria and clear aggravation of oxidative stress, demonstrating successful induction of AKI for CRRT. Post‐CRRT, no significant changes in their vital signs or hematological parameters were observed. Creatinine and blood urea nitrogen clearance, as well as suppression of increases in oxidative stress, were also confirmed.ConclusionWe believe that the use of our model can enable the preclinical evaluation of the effects of under‐development CRRT devices on living organisms under conditions similar to those encountered in an actual clinical setting.

Providing Continuous Renal Replacement Therapy in Patients on Extracorporeal Membrane Oxygenation.

A 34-year-old male was admitted for respiratory failure due to H1N1 influenza. His hypoxia worsened despite maximal ventilator support and thus initiated on venovenous extracorporeal membrane oxygenation (VV-ECMO). Whereas this stabilized his respiratory and hemodynamic status, his creatinine

Using additional pressure control lines when connecting a continuous renal replacement therapy device to an extracorporeal membrane oxygenation circuit

BackgroundThe introduction of a continuous renal replacement therapy (CRRT) device into the extracorporeal membrane oxygenation (ECMO) circuit is widely used. However, excessive pressure transmitted to the CRRT device is a major disadvantage. We investigated the effects of using additional pressure control lines on the pressure and the lifespan of the CRRT circuit connected to the ECMO.MethodsThis is an observational study using prospectively collected data from consecutive patients receiving CRRT connected into the ECMO circuit at a university-affiliated, tertiary hospital from January 2013 to December 2016. The CRRT circuit was connected into the ECMO circuit through the Luer Lock connection without an additional pressure control line in 16 patients (9%, no line group), an additional pressure control line on the inlet line in 36 patients (23%, single line group), and additional pressure control lines on both the inlet and outlet lines in 118 patients (77%, double line group). The outcome measures of interest were compared among the three groups.ResultsThe median access pressure was higher in the no line group compared to the groups. However, median filter pressure, effluent pressure, and return pressure were higher in the double line group compared to the other groups. There were no significant differences in platelets, lactate dehydrogenase, and plasma hemoglobin among the 3 groups over the time period studied. Median lifespan of the CRRT circuits in the double line group was 45.0 (29.0–63.7) hours, which was higher compared to 21.8 (11.6–31.8) hours in the no line group and 23.0 (15.0–34.6) hours in the single line group, respectively. In addition, in-hospital mortality was lower in the double line group (48.3%) compared to the no line group (68.8%) and the single line group (75.0%).ConclusionsAdditional tubing can be considered a simple and safe method for pressure control and lengthening circuit survival when connecting the CRRT device to the ECMO circuit.

Continuous renal replacement therapy: understanding circuit hemodynamics to improve therapy adequacy.

The utilization of continuous renal replacement therapy (CRRT) increases throughout the world. Technological improvements have made its administration easier and safer. However, CRRT remains associated with numerous pitfalls and issues. Even if new-generation CRRT devices have built-in safety features, understanding basic concepts remains of primary importance. CRRT circuits' maximum recommended lifespan (72 h) can often not be achieved. Such early artificial kidney failures are typically related to two processes: circuit clotting and membrane clogging. Although these processes are to some degree inevitable, they are facilitated by poor therapy management. Indeed, the majority of device-triggered alarms are associated with blood pump interruption, which through blood stasis, enhance clotting and clogging. If the underlying issue is not adequately managed, further alarms will rapidly lead to prolonged stasis and complete circuit clotting or clogging making its replacement mandatory. Hence, rapid recognition of issues triggering alarms is of paramount importance. Because most alarms are related to circuit's hemodynamics, a thorough understanding of these concepts is mandatory for the staff in charge of delivering the therapy.This review describes CRRT circuits, measured and calculated pressures and the way their knowledge might improve therapy adequacy.

Continuous renal replacement therapy during extracorporeal membrane oxygenation: why, when and how?

The use of extracorporeal membrane oxygenation (ECMO) is increasing rapidly. Patients on ECMO have a high risk of developing acute kidney injury (AKI) and needing renal replacement therapy (RRT). The aim of this review is to describe different strategies of combining RRT and ECMO and to outline their advantages and drawbacks. Fluid overload is the most common indication for RRT during ECMO, and continuous renal replacement therapy (CRRT) is the most commonly used modality. The optimal timing for initiation of CRRT should be individualized based on degree of fluid overload and severity of AKI-related metabolic derangements. In ECMO patients, CRRT can be provided via an integrated approach (i.e. in-line haemofilter or a fully integrated CRRT device) or a parallel system with separate ECMO and RRT circuits. In-depth knowledge of the resulting intra-circuit pressure changes, risks of air entrapment and haemolysis, and implications for ultrafiltration and solute clearance are essential. There is no evidence that the different methods of combining ECMO and CRRT impact mortality. In patients on ECMO, CRRT can be provided via an integrated approach or independently via parallel systems. An in-depth understanding of the advantages and drawbacks of the different techniques is required.

Comparison of the Accuracy of the Novel PrisMax Continuous Renal Replacement Therapy System to the Classic Prismaflex System

Background/Aims: We assessed how the novel PrisMax continuous renal replacement therapy (CRRT) system performed in an international multicentre setting. The system has multiple novel tools aiming to increase accuracy and dose delivery. Methods: Data was prospectively collected from 7 intensive care units in 6 countries. The PrisMax device data logs constituted the raw material and last generation Prismaflex data was used as comparison. Clinical parameters like treatment time, filter life span, downtime as well as prescribed and delivered dose were recorded. Results: PrisMax delivered/prescribed effluent ratios (mean ± SD) 0.92 ± 0.15 vs. Prismaflex ratios 0.85 ± 0.21, p < 0.001; delivered effluent dose (mL/kg/h) was 18.16 ± 12.93 vs. 10.95 ± 10.96, p < 0.0001; and (Kt/V) 0.76 ± 0.52 vs. 0.44 ± 0.44, p < 0.0001. Moreover, downtime was 27 minutes less for the newer device. Conclusion: The PrisMax CRRT device outperforms its predecessor with regard to dose delivery and accuracy.

The Novel PrisMax Continuous Renal Replacement Therapy System in a Multinational, Multicentre Pilot Setting

Background/Aims: We assessed how the novel PrisMax continuous renal replacement therapy (CRRT) system performed in a prospective international multicentre setting. We compared this device to its predecessor, the Prismaflex, with regards to multiple treatment parameters. Additionally, we performed a survey, aiming to measure user satisfaction. Methods: Data was prospectively collected from 7 intensive care units (ICU) in 6 countries. The PrisMax device data logs constituted the raw material. Clinical parameters like treatment time, filter life span, downtime, delivered dose and number and type of alarms were recorded. A user questionnaire was sent out to 3 of the participating ICUs. Results: Filter life, downtime, blood pump stops, bag changing time and number of malfunction alarms showed significantly improved values compared to the historic Prismaflex data. The survey showed high scores with regards to user friendliness. Conclusion: The PrisMax CRRT device is safe and outperformed its’ previous generation counterpart in virtually all aspects. Video Journal Club “Cappuccino with Claudio Ronco” at http://www.karger.com/?doi=489213.

Continuous Renal Replacement Therapy Quality Control and Performance Measures.

Continuous renal replacement therapy (CRRT) is one of the most predominant forms of renal replacement therapy (RRT) currently in use now, this therapy being the initial RRT modality in most critically ill patients. However, in general, the quality of CRRT is still suboptimal. The quality of CRRT is affected by many factors, including the optimal prescription and precision delivery, the CRRT providers' professional level, and the CRRT device used. Establishment of a comprehensive quality control system covering all the aspects and procedures of CRRT is essential. Quality measures for structure, process, and outcome of CRRT need to be developed, evaluated, and implemented to ensure the high quality of CRRT. Some CRRT quality improvement methods such as the professional education and specialized team and the application of citrate anticoagulation to extend filter lifespan have been found to be potentially beneficial but need further validation. After all, much work is needed in this field because of the heterogeneity in CRRT practice. More evidence is needed to improve the CRRT quality control system. These are challenges that will need to be addressed in the future.

Continuous Renal Replacement Therapy Applications on Extracorporeal Membrane Oxygenation Circuit.

Background and Aims:Continuous venovenous hemofiltration or hemodiafiltration is used frequently in pediatric patients, but experience of continuous renal replacement therapy (CRRT) application on extracorporeal membrane oxygenation (ECMO) circuit is still limited. Among several methods used for applying CRRT on ECMO patients, we aim to share our experience on inclusion of a CRRT device in the ECMO circuit which we believe is easier and safer to apply.Materials and Methods:The data were collected on demographics, outcomes, and details of the treatment of ECMO patients who had CRRT. During the study period of 3 years, venous cannula of ECMO circuit before pump was used for CRRT access for both the filter inlet and outlet of CRRT machine to minimize the thromboembolic complications. The common indication for CRRT was fluid overload.Results:CRRT was used in 3.68% of a total number of patients admitted and 43% of patients on ECMO. The patients have undergone renal replacement therapy for periods of time ranging between 24 h and 25 days (260 h mean). The survival rate of this group of patients with multiorgan failure was 33%. Renal recovery occurred in all of the survivors. Complications such as electrolyte imbalance, hypothermia, and bradykinin syndrome were easily managed.Conclusions:Adding a CRRT device on ECMO circuit is a safe and effective technique. The major advantages of this technique are easy to access, applying CRRT without extra anticoagulation process, preventing potential hemodynamic disturbances, and increased clearance of solutes and fluid overload using larger hemofilter.

Survey of continuous renal replacement therapy application status

Objective: To investigate the condition of implementation of continuous renal replacement therapy (CRRT) in quality control center of critical care medicine. Methods: Questionnaire mails were issued to all of the quality control respondents to survey the application of CRRT in June 2015 from Jiangsu quality control center of critical care medicine. Results: Among the 69 quality control respondents, 62 were equipped with CRRT devices, and in 58 of which patients were treated with CRRT. There were 195 doctors and 253 nurses in 62 quality control respondents attended CRRT training at or above the provincial level; the proportions of hospitals in southern, central and northern regions of Jiangsu were 63%, 79% and 86% respectively with trained doctors (more than 2), and 34%, 38% and 43% respectively with trained nurses (more than 3). The preferred material for CRRT filter were AN69 and acrylic, accounting for 48% and 45% respectively. The average life span was less than 12 h for 21% filters, 12-24 h for 34% filters, and more than 72 h for only 2% filters. Manual displacement liquids were currently mainly used in our province, accounting for 75%. Heparin is the most frequently used anticoagulants, accounting for 48%. Citrate and low molecular weight heparin used for anticoagulation accounted for 31% and 21% respectively. Bleeding was the most common clinical complication (43%) in patients with CRRT, followed by low temperature (22%). The average hospitalization expenses for patients with CRRT amounted to 69 643 yuan RMB per person, in which the cost for CRRT accounted for 19 525 yuan RMB per person. Conclusion: The application of CRRT varies in filter materials, anticoagulants, replacement frequencies and dilution mode. Bleeding is the most common clinical complication in patients with CRRT. Besides, the proportion of trained doctors and nurses at the provincial level is still very low. It will be improved with intensive training and reasonable implementation for us to prolong the lifespan of the filters and reduce the cost for patients with CRRT.

Effects of the Schematized Alarm-managing Manual for Continuous Renal Replacement Therapy on the Alarm Resolution Rate and Nursing Competence of Nurses in Intensive Care Units

Purpose: This study was done to develop a schematized alarm-managing manual for continuous renal replacement therapy (CRRT) and to investigate its effects in maintaining continuity in the patients’ treatment and promptly resolving alarms when CRRT is being carried out. Methods: Sixtynurses from two medical intensive care units (ICUs) (one experimental and one control) at one hospital were asked to answer a questionnaire including their CRRT nursing competency and satisfaction with the manual. Data on alarm resolution rate were collected by analyzing existing data, such as the details of each alarm and the number of resolutions around the clock in the CRRT device. Results: The alarm resolution rate and some of CRRT nursing competency scores in the experimental group were higher than those in the control group. The experimental group was also satisfied with the manual. Conclusion: The study confirmed that the schematized alarm-managing manual can be useful for ICU nurses to resolve alarms and can be used as a guideline. Application of this manual to clinical practices and its use can therefore, be encouraged through continuous educationand promotion.

Design and validation of a diaphragm pump for pediatric CRRT during ECMO

Children requiring artificial heart-lung support through extracorporeal membrane oxygenation (ECMO) are at increased risk of developing acute kidney injury (AKI). Continuous renal replacement therapy (CRRT) is the preferred method of treatment in pediatric AKI patients. CRRT devices are noted to provide inaccurate fluid balance (FB) when operated under low flow rates seen in children. We present the design and validation of a novel pump concept to provide accurate pediatric CRRT during ECMO. A diaphragm pump was prototyped with a working stroke volume (SV) of 7 mL. Fluid transport occurs by periodic expansion and contraction of a flexible membrane due to pressure fluctuations of hydraulic fluid contained below its surface. Comparison of intravenous (IV) pumps to the diaphragm pump was conducted in vitro across the range of pressures observed during CRRT in ECMO. The pump was integrated into a CRRT circuit parallel with ECMO and FB accuracy was evaluated. The pump design improved efficiency of fluid transport, with flow rate errors as low as 1-5 ml/hr as compared to IV pumps (15-50 ml/hr). The SV of IV pumps increased with source pressure in a nearly linear manner compared to the minimal variation produced by the diaphragm pump. Inclusion of the diaphragm pump in a conventional CRRT circuit with ECMO improved the FB accuracy. A novel diaphragm pump concept has been presented for providing CRRT during ECMO in the pediatric population. Improvement of the pump accuracy compared to currently used CRRT pumps was demonstrated via in vitro testing.

Simulating continuous renal replacement therapy: usefulness of a new simulator device

Simulation allows the training of life-support procedures without patient risk. We analyzed the performance and usefulness of a new device that makes feasible the external control of continuous renal replacement therapy (CRRT) machines in order to realistically generate clinical conditions and problems in simulated patients. A simple mechanical device was designed according to training needs and then hand made. This device permits the control of all monitorable pressures and therefore allows simulation of a range of clinical situations and eventual complications that might occur in real patients. We tested its performance in vitro and then during 16 high-fidelity patient-simulation scenarios included in the program of pediatric CRRT courses. Student and teacher satisfaction was assessed through an anonymous survey. Quick, accurate, real-time monitor of pressure changes, concordant with the usual clinical problems to be simulated (catheter complications, filter coagulation, inadequate CRRT device settings), were easily achieved with the new device. Instructors rated the device as user friendly and well adapted to the reality being simulated. During scenarios, students were not aware of the simulator and considered that simulated clinical conditions were realistic. Our device may be very useful for training healthcare professionals in CRRT management, thus avoiding risk to patients.

Development of an Accurate Fluid Management System for a Pediatric Continuous Renal Replacement Therapy Device

Acute kidney injury is common in critically ill children, and renal replacement therapies provide a life-saving therapy to a subset of these children. However, there is no Food and Drug Administration-approved device to provide pediatric continuous renal replacement therapy (CRRT). Consequently, clinicians adapt approved adult CRRT devices for use in children because of lack of safer alternatives. Complications occur using adult CRRT devices in children because of inaccurate fluid balance (FB) between the volumes of ultrafiltrate (UF) removed and replacement fluid (RF) delivered. We demonstrate the design and validation of a pediatric fluid management system for obtaining accurate instantaneous and cumulative FB. Fluid transport was achieved via multiple novel pulsatile diaphragm pumps. The conservation of volume principle leveraging the physical property of fluid incompressibility along with mechanical coupling via a crankshaft was used for FB. Accuracy testing was conducted in vitro for 8 hour long continuous operation of the coupled UF and RF pumps. The mean cumulative FB error was <1% across filtration flows from 300 to 3000 ml/hour. This approach of FB control in a pediatric-specific CRRT device would represent a significant accuracy improvement over currently used clinical implementations.

Newly Designed CRRT Membranes for Sepsis and SIRS—A Pragmatic Approach for Bedside Intensivists Summarizing the More Recent Advances

In recent years, after all the attention has been focused on the dose for continuous renal replacement therapy (CRRT) in sepsis and systemic inflammation response syndrome (SIRS), the relatively negative results of all those studies did urge our expectations on new approaches regarding CRRT in sepsis and SIRS. So far, after the failure of the major randomized studies on dose, attention is now drawn to new membranes that could better eliminate massive amounts of unbound mediators in wider spectrum and also in greater magnitude Nevertheless, for septic acute kidney injury, the recommended dose will remain 35 ml/kg/h until the IVOIRE (hIgh VOlume in Intensive Care) study will be published. In this new armamentarium, we have distinguished the first tools that can still be called membranes ranging from AN69 Surface Treated (ST), SEPTEX, polymethylmetacrylate, to Oxiris that can still run with a CRRT device. Polymyxin B is still a kind of membrane although it has a larger surface, but it can run in a hemoperfusion system and is also much more selective. Adsorptive columns and sorbents are not anymore membranes but are seen as cartridges as the surface is extremely huge when compared with that of membranes (more than 500 m). They can still run in a hemoperfusion device. At the very end, we do have apheresis or selective plasma exchange (also very close to sorbents and columns) but we have very few data up to now regarding sepsis. Regarding spectrum, CytoSorb seems to be very promising although it is not able to capture endotoxin and IL-10. Oxiris is also promising as it can capture endotoxin and cytokines. AN69 ST is very powerful to capture numerous cytokines and especially high-mobility group box 1 protein (a very upstream cytokine). Polymethylmetacrylate has also the power to capture endotoxin and numerous other cytokines probably with a larger magnitude than Oxiris although this is not proven. Lastly, high-porosity membranes (Septex) may play a role especially when used in continuous venovenous hemodialysis mode. At the end, if we look for a more enlarged spectrum and a higher magnitude, CytoSorb might be seen as the most promising although not having the ability to fix endotoxin. Future studies will tell us which membrane or sorbent will be most useful in the adjunctive treatment for sepsis.

Recommended β-lactam regimens are inadequate in septic patients treated with continuous renal replacement therapy

IntroductionSepsis is responsible for important alterations in the pharmacokinetics of antibiotics. Continuous renal replacement therapy (CRRT), which is commonly used in septic patients, may further contribute to pharmacokinetic changes. Current recommendations for antibiotic doses during CRRT combine data obtained from heterogeneous patient populations in which different CRRT devices and techniques have been used. We studied whether these recommendations met optimal pharmacokinetic criteria for broad-spectrum antibiotic levels in septic shock patients undergoing CRRT.MethodsThis open, prospective study enrolled consecutive patients treated with CRRT and receiving either meropenem (MEM), piperacillin-tazobactam (TZP), cefepime (FEP) or ceftazidime (CAZ). Serum concentrations of these antibiotics were determined by high-performance liquid chromatography from samples taken before (t = 0) and 1, 2, 5, and 6 or 12 hours (depending on the β-lactam regimen) after the administration of each antibiotic. Series of measurements were separated into those taken during the early phase (< 48 hours from the first dose) of therapy and those taken later (> 48 hours).ResultsA total of 69 series of serum samples were obtained in 53 patients (MEM, n = 17; TZP, n = 16; FEP, n = 8; CAZ, n = 12). Serum concentrations remained above four times the minimal inhibitory concentration for Pseudomonas spp. for the recommended time in 81% of patients treated with MEM, in 71% with TZP, in 53% with CAZ and in 0% with FEP. Accumulation after 48 hours of treatment was significant only for MEM.ConclusionsIn septic patients receiving CRRT, recommended doses of β-lactams for Pseudomonas aeruginosa are adequate for MEM but not for TZP, FEP and CAZ; for these latter drugs, higher doses and/or extended infusions should be used to optimise serum concentrations.

Intra-abdominal hypertension can be monitored with femoral vein catheters during CRRT and may cause access recirculation

Intra-abdominal hypertension (IAH) is an increasingly recognized disorder, and its diagnosis depends on accurate pressure monitoring. Bladder-based protocols are favored, but are not always clinically feasible. Abdominal venous (i.e. vena cava) pressure measurements are an alternative but are logistically challenging. We hypothesized that for patients suffering acute kidney injury, transducers built into renal replacement therapy (RRT) machines offer a simple opportunity to monitor pressures using catheters inserted via femoral veins. We performed in vitro testing of the accuracy of pressure transducers incorporated into continuous RRT devices, using highly calibrated instrumentation in the IAH-relevant range of 0 to +50 mmHg. We developed a protocol for using this modality in vivo, by stopping all pumps so as to allow equilibration of pressures: clinical application in a patient with femoral vein catheters and IAH was then described. In vitro analyses showed accuracy of the extracorporeal pressure transducers with an r² of 0.998, p < 0.001. In the patient case, the pressure transduced at the RRT device was identical to those obtained from bladder catheters. IAH also led to access recirculation and ineffective therapy. Pressure sensors incorporated into continuous RRT machines can be accurate in the IAH physiologic range, and thus may be used to easily measure intra-abdominal pressure via appropriate-length femoral vein-inserted access catheters. If not relieved, IAH can be an under-appreciated cause of access recirculation and ineffective clearance for any RRT modality (continuous or intermittent) using femoral catheters.