Drug Dosing Considerations in Critically Ill Patients Receiving Continuous Renal Replacement Therapy

Anticoagulants in Children with Renal Impairment: A Narrative Review

Venous thromboembolism is a common cause of morbidity and mortality in children with renal disease. To properly treat and prevent thromboembolism in this patient population, it is important to be familiar with the multitude of anticoagulant agents currently available. Many anticoagulant drugs undergo some extent of renal elimination. There are important considerations for the selection, dosing, and monitoring of anticoagulant drugs for patients with renal impairment due to various pharmacokinetic alterations that may occur. While there are data to help guide dosing and monitoring in adults, evidence regarding renal dose adjustment of many anticoagulant drugs in children are limited. For the clinician, anticoagulation management in children with renal impairment presents unique challenges. In addition to considering overall bleeding risk, the extent of renal impairment may vary by patient, making a one-size-fits-all approach to managing these patients difficult. These factors, combined with limited data, can make managing anticoagulation in children with renal impairment a challenge. Therefore, the focus of this review will be to describe the pharmacokinetics of the following anticoagulants in children with impaired renal function: unfractionated heparin, enoxaparin, dalteparin, rivaroxaban, apixaban, edoxaban, fondaparinux, bivalirudin, argatroban, dabigatran, and warfarin.

Drug dosing optimization in critically ill children under continuous renal replacement therapy: from basic concepts to the bedside model informed precision dosing

INTRODUCTION

Optimizing drug dosage in critically ill children undergoing Continuous Renal Replacement Therapy (CRRT) is mandatory and challenging, given the many factors impacting pharmacokinetics and pharmacodynamics coupled with the vulnerability of this population.

AREAS COVERED

A good understanding of the mechanisms that determine drug elimination via the CRRT technique is useful to avoid prescription pitfalls, however limited by the high between and within subject variability. The developments of population pharmacokinetic and physiologically based pharmacokinetic models derived from in-vivo and in-vitro studies, are challenging, but remain the most appropriate tool to suggest adjusted dosage regimens for every patient, throughout treatment. We searched PubMed using the search string: 'pediatrics OR children' AN 'continuous renal replacement therapy' AND 'pharmacokinetics' AND 'model informed precision dosing' AND, 'physiologically based pharmacokinetics,' AND 'therapeutic drug monitoring' until January 2024, regardless of language or publication status.

EXPERT OPINION

Familiarizing the pediatric intensivists with the therapeutic drug monitoring and providing clinicians the individualized prescribing software such as Model Informed Precision Dosing would be a significant step forward. The clinical benefit for patients remains to be demonstrated.

A narrative review on antimicrobial dosing in adult critically ill patients on extracorporeal membrane oxygenation

The optimal dosing strategy of antimicrobial agents in critically ill patients receiving extracorporeal membrane oxygenation (ECMO) is unknown. We conducted comprehensive review of existing literature on effect of ECMO on pharmacokinetics and pharmacodynamics of antimicrobials, including antibacterials, antifungals, and antivirals that are commonly used in critically ill patients. We aim to provide practical guidance to clinicians on empiric dosing strategy for these patients. Finally, we discuss importance of therapeutic drug monitoring, limitations of current literature, and future research directions.

Linezolid Adsorption on Filters during Continuous Renal Replacement Therapy: An In Vitro Study

Background: Renal replacement therapy (RRT), widely used in the treatment of renal injury during sepsis, aims to eliminate the toxins and proinflammatory cytokines involved in the pathomechanism underlying septic shock. Dialysis filters are characterized by a high adsorption potential for cytokines in RRT in the case of septic renal injury. For the treatment of sepsis with antibiotics, it is of key importance to achieve the desired values of PK/PD indices. Continuous renal replacement therapy (CRRT) may affect antimicrobial clearance, increasing their elimination in some cases. Methods: The aim of this study was to determine the degree of adsorption for linezolid on three different types of filters used in CRRT. In our in vitro study, a continuous veno-venous hemofiltration (CVVH) was conducted using three types of filters: polysulfone (PS), polyethyleneimine-treated polyacrylonitrile (PAN PEI), and non-PEI-treated polyacrylonitrile (PAN). Each type of filter was used in three CVVH cycles, involving the use of 600 mg of linezolid dissolved in 700 mL of bovine blood or in 700 mL of 0.9% NaCl. In each case, the total volume of the obtained solution was 1000 mL. Blood samples were collected at particular time points to measure their drug concentration. The differences in mean drug/NaCl adsorption and drug/blood adsorption were determined using a one-way ANOVA with multiple comparisons via Tukey's post hoc test; a p-value of <0.05 was considered significant. Results: A significant adsorption of linezolid was found for PAN PEI filters, both in samples obtained from bovine blood and 0.9% NaCl solutions, at the endpoint. In PAN PEI samples, the concentration of linezolid in 0.9% NaCl solutions decreased from 594.74 μg/mL to 310.66 μg/mL after 120 min (the difference was established at 52%). In blood samples, the initial concentration was 495.18 μg/mL, which then decreased to 359.84 μg/mL (73% of the beginning value). No significant adsorption was demonstrated on PAN or PS filters. Conclusion: There is a need for in vivo research to confirm the effect of filter type on linezolid concentration in patients undergoing CRRT.

High-risk adverse drug reactions: consideration of limited dialysis therapy for toxic epidermal necrolysis (TEN)

Toxic epidermal necrolysis (TEN) is a rare but often lethal drug reaction involving the skin. Treatment is often centered around suppurative care, and the mortality rate remains unacceptably high, although the clinical and epidemiological features of TEN have been well documented for decades. Recent studies have placed an emphasis on certain medications in the pathophysiology of severe TEN, and our colleagues previously reported several cases of clinical improvement in TEN patients following hemodialysis. Here, we discuss the major considerations for initiating dialysis in TEN patients. By doing so, we hope to encourage others to explore this potential avenue for treating TEN, one of the most serious medical emergencies in the field of dermatology.

Meropenem extraction by ex vivo extracorporeal life support circuits

BACKGROUND

Meropenem is a broad-spectrum carbapenem-type antibiotic commonly used to treat critically ill patients infected with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. As many of these patients require extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT), it is important to understand how these extracorporeal life support circuits impact meropenem pharmacokinetics. Based on the physicochemical properties of meropenem, it is expected that ECMO circuits will minimally extract meropenem, while CRRT circuits will rapidly clear meropenem. The present study seeks to determine the extraction of meropenem from ex vivo ECMO and CRRT circuits and elucidate the contribution of different ECMO circuit components to extraction.

METHODS

Standard doses of meropenem were administered to three different configurations (n = 3 per configuration) of blood-primed ex vivo ECMO circuits and serial sampling was conducted over 24 h. Similarly, standard doses of meropenem were administered to CRRT circuits (n = 4) and serial sampling was conducted over 4 h. Meropenem was administered to separate tubes primed with circuit blood to serve as controls to account for drug degradation. Meropenem concentrations were quantified, and percent recovery was calculated for each sample.

RESULTS

Meropenem was cleared at a similar rate in ECMO circuits of different configurations (n = 3) and controls (n = 6), with mean (standard deviation) recovery at 24 h of 15.6% (12.9) in Complete circuits, 37.9% (8.3) in Oxygenator circuits, 47.1% (8.2) in Pump circuits, and 20.6% (20.6) in controls. In CRRT circuits (n = 4) meropenem was cleared rapidly compared with controls (n = 6) with a mean recovery at 2 h of 2.36% (1.44) in circuits and 93.0% (7.1) in controls.

CONCLUSION

Meropenem is rapidly cleared by hemodiafiltration during CRRT. There is minimal adsorption of meropenem to ECMO circuit components; however, meropenem undergoes significant degradation and/or plasma metabolism at physiological conditions. These ex vivo findings will advise pharmacists and physicians on the appropriate dosing of meropenem.

Complications Associated with Continuous RRT

Continuous renal replacement therapy (CRRT) is a form of renal replacement therapy that is used in modern intensive care units (ICUs) to help manage acute kidney injury (AKI), end stage kidney disease (ESKD), poisonings, and some electrolyte disorders. CRRT has transformed the care of patients in the ICU over the past several decades. In this setting, it is important to recognize CRRT-associated complications but also up-to-date management of these complications. Some of these complications are minor, but others may be more significant and even life-threatening. Some CRRT complications may be related to dialysis factors and others to specific patient factors. Our overarching goal in this article is to review and discuss the most significant CRRT-related complications at the different stage of management of CRRT. With the advent of newer solutions, there have been newer complications as well.

Cefepime Extraction by Extracorporeal Life Support Circuits

Extracorporeal life support (ECLS) devices are lifesaving for critically ill patients with multi-organ dysfunction. Despite this, patients supported with ECLS are at high risk for ECLS-related complications, including nosocomial infections, and mortality rates are high in this patient population. The high mortality rates are suspected to be, in part, a result of significantly altered drug disposition by the ECLS circuit, resulting in suboptimal antimicrobial dosing. Cefepime is commonly used in critically ill patients with serious infections. Cefepime dosing is not routinely guided by therapeutic drug monitoring and treatment success is dependent upon the percentage of time of the dosing interval that the drug concentration remains above the minimum inhibitory concentration of the organism. This ex vivo study measured the extraction of cefepime by continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO) circuits. Cefepime was studied in four closed-loop CRRT circuit configurations and a single closed-loop ECMO circuit configuration. Circuits were primed with a physiologic human blood-plasma mixture and the drug was dosed to achieve therapeutic concentrations. Serial blood samples were collected over time and concentrations were quantified using validated assays. In ex vivo CRRT experiments, cefepime was rapidly cleared by dialysis, hemofiltration, and hemodiafiltration, with greater than 96% cefepime eliminated from the circuit by 2 hours. In the ECMO circuits, the mean recovery of cefepime was similar in both circuit and standard control. Mean (standard deviation) recovery of cefepime in the ECMO circuits (n = 6) was 39.2% (8.0) at 24 hours. Mean recovery in the standard control (n = 3) at 24 hours was 52.2% (1.5). Cefepime is rapidly cleared by dialysis, hemofiltration, and hemodiafiltration in the CRRT circuit but minimally adsorbed by either the CRRT or ECMO circuits. Dosing adjustments are needed for patients supported with CRRT.

Research on the Application Effect of Strengthening Risk Management in Continuous Renal Replacement Therapy Nursing of Critically Ill Patients

Objective

To evaluate the efficacy of risk management in the nursing of critically ill patients on continuous renal replacement therapy (CRRT).

Methods

In this retrospective study, 80 critically ill patients on continuous renal replacement therapy in our hospital from February 2020 to February 2021 were recruited. They were randomly assigned to receive either the risk management treatment (risk management group) or the conventional management treatment (conventional management group) via the random number table method. Outcome measurements included the occurrence of adverse events, complications, psychological status, quality of life, treatment compliance, duration of CRRT, and nursing satisfaction.

Results

Risk management treatment was associated with lower incidence of adverse events compared to conventional management treatment (P value < 0.05). The risk management group also resulted in a lower incidence of complications compared to the conventional management group (P value < 0.05). Patients who received risk management treatments demonstrated a significantly lower anxiety/depression level and a higher World Health Organization Quality of Life Brief Version (WHOQOL-BREF) (P value < 0.05). The risk management group resulted in more cases with high compliance and fewer cases with moderate and poor compliance (P < 0.05). Risk management was associated with more cases with a CRRT duration less than 36 hours and 36–48 hours and fewer cases with a duration longer than 48 h (X² = 2.999, P value < 0.05). Patients who were given a risk management treatment had a higher nursing satisfaction compared to conventional management treatment (X² = 4.501, P value < 0.05).

Conclusion

Risk management treatment in caring of critically ill patients on CRRT shows better efficacy than conventional management treatments.

Trends, Advantages and Disadvantages in Combined Extracorporeal Lung and Kidney Support From a Technical Point of View

Extracorporeal membrane oxygenation (ECMO) provides pulmonary and/or cardiac support for critically ill patients. Due to their diseases, they are at high risk of developing acute kidney injury. In that case, continuous renal replacement therapy (CRRT) is applied to provide renal support and fluid management. The ECMO and CRRT circuits can be combined by an integrated or parallel approach. So far, all methods used for combined extracorporeal lung and kidney support present serious drawbacks. This includes not only high risks of circuit related complications such as bleeding, thrombus formation, and hemolysis, but also increase in technical workload and health care costs. In this sense, the development of a novel optimized artificial lung device with integrated renal support could offer important treatment benefits. Therefore, we conducted a review to provide technical background on existing techniques for extracorporeal lung and kidney support and give insight on important aspects to be addressed in the development of this novel highly integrated artificial lung device.

Chinese ICU physicians' knowledge of antibiotic pharmacokinetics/pharmacodynamics (PK/PD): a cross-sectional survey

BACKGROUND

Patients with sepsis have a high mortality rate, accumulated evidences suggest that an optimal antibiotic administration strategy based on pharmacokinetics/pharmacodynamics (PK/PD) can improve the prognosis of septic patients. Therefore, we assessed Chinese intensive care unit (ICU) physicians' knowledge about PK/PD.

METHODS

In December 2019, we designed a questionnaire focused on Chinese ICU physicians' knowledge about PK/PD and collected the questionnaires after 3 months. The questionnaire was distributed via e-mail and WeChat, and was distributed to ICU doctors in 31 administrative regions of China except Hong Kong, Macao and Taiwan. The passing score was corrected by the Angoff method, and the ICU physicians' knowledge about PK/PD was analysed accordingly.

RESULTS

We received a total of 1,309 questionnaires and retained 1,240 valid questionnaires. The passing score was 90.8, and the overall pass rate was 56.94%. The pass rate for tertiary and secondary hospitals was 59.07% and 37.19%, respectively. ICU physicians with less than 5 years of work experience and resident physician accounted for the highest pass rate, while those with between 5 to 10 years of work experience and attending accounted for the lowest pass rate. The majority of participants in the Chinese Critical Care Certified Course (5C) were from Jiangsu and Henan provinces, and they had the highest average scores (125.8 and 126.5, respectively). For Beijing and Shanghai, the average score was only 79.4 and 90.9, respectively.

CONCLUSIONS

Chinese ICU physicians' knowledge about PK/PD is unsatisfactory. Therefore, it is essential to strengthen ICU physicians' knowledge about PK/PD.

Antiretrovirals for People with HIV on Dialysis

In the era of widespread use of antiretroviral therapy (ART), people with HIV (PWH) have a near-normal life expectancy. However, PWH have high rates of kidney diseases and progression to end-stage renal disease at a younger age. PWH have multiple risks for developing acute and chronic kidney diseases, including traditional risk factors such as diabetes, hypertension, and HIV-related factors such as HIV-associated nephropathy and increased susceptibility to infections and exposure to nephrotoxic medications. Despite an improvement in access to kidney transplant among PWH, the number of PWH on dialysis continues to increase. The expansion of the number of antiretrovirals (ARVs) and kidney replacement modalities, the absence of pharmacokinetic data, and therapeutic drug monitoring make it very challenging for providers to dose ARVs appropriately leading to medication errors, adverse events, and higher mortality. Most of the recommendations are either based on small sample size studies or extrapolated based on physiochemical characteristics of ART. We aim to review the most available and most current literature on ART in PWH with renal insufficiency and ART dosing recommendations on dialysis to ensure that PWH are provided with the safest and most effective ART regimen.

Imipenem/Relebactam Ex Vivo Clearance during Continuous Renal Replacement Therapy

(1) Purpose of this study: determination of adsorption and transmembrane clearances (CL_TM) of imipenem and relebactam in ex vivo continuous hemofiltration (CH) and continuous hemodialysis (CHD) models. These clearances were incorporated into a Monte Carlo Simulation (MCS), to develop drug dosing recommendations for critically ill patients requiring continuous renal replacement therapy (CRRT); (2) Methods: A validated ex vivo bovine blood CH and CHD model using two hemodiafilters. Imipenem/relebactam and urea CL_TM at different ultrafiltrate/dialysate flow rates were evaluated in both CH and CHD. MCS was performed to determine dose recommendations for patients receiving CRRT; (3) Results: Neither imipenem nor relebactam adsorbed to the CRRT apparatus. The CL_TM of imipenem, relebactam, and urea approximated the effluent rates (ultrafiltrate/dialysate flow rates). The types of hemodiafilter and effluent rates did not influence CL_TM except in a dialysis flow rate of 1 L/h and 6 L/h in the CHD with relebactam (p < 0.05). Imipenem and relebactam 200 mg/100 mg every 6 h were sufficient to meet the standard time above the MIC pharmacodynamic targets in the modeled CRRT regimen of 25 kg/mL/h. (4) Conclusions: Imipenem and relebactam are not removed by adsorption to the CRRT apparatus, but readily cross the hemodiafilter membrane in CH and CHD. Dosage adjustment of imipenem/relebactam is likely required for critically ill patients receiving CRRT.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

Adsorption of vancomycin, gentamycin, ciprofloxacin and tygecycline on the filters in continuous renal replacement therapy circuits: in full blood in vitro study

The aim of this study was to assess the in vitro adsorption of antibiotics: vancomycin, gentamicin, ciprofloxacin and tigecycline on both polyethyleneimine-treated polyacrylonitrile membrane of AN69ST filter and polysulfone membrane of AV1000 filter using porcine blood as a model close to in vivo conditions. The porcine blood with antibiotic dissolved in it was pumped into hemofiltration circuit (with AN69ST or AV1000 filter), ultrafiltration fluid was continuously returned to the reservoir containing blood with antibiotic. Blood samples to determine antibiotic concentrations were taken at minutes 0, 5, 15, 30, 45, 60, 90 and 120 from the pre- blood pump of the hemofiltration circuit. To assess possible spontaneous degradation of the drug in the solution there was an additional reservoir prepared for each antibiotic, containing blood with the drug, which was not connected to the circuit. In the case of vancomycin, ciprofloxacine and tigecycline, a statistically significant decrease in the drug concentration in the hemofiltration circuit in comparison to initial value as well as to the concentrations in the control blood was observed, both for polyacrylonitrile and plolysulfone membrane. In the case of gentamicin, significant adsorption was noted only on polyacrylonitrile membrane. Our studies demonstrated that in full blood adsorption of antibiotics may be big enough to be of clinical significance. In particular in the case of polyacrylonitrile membrane.