Effect of Extracorporeal Membrane Oxygenation on the New Vancomycin Dosing Regimen in Critically Ill Patients Receiving Continuous Venovenous Hemofiltration

Antimicrobial Exposures in Critically Ill Patients Receiving Extracorporeal Membrane Oxygenation

Rationale: Data suggest that altered antimicrobial concentrations are likely during extracorporeal membrane oxygenation (ECMO). Objectives: The primary aim of this analysis was to describe the pharmacokinetics (PKs) of antimicrobials in critically ill adult patients receiving ECMO. Our secondary aim was to determine whether current antimicrobial dosing regimens achieve effective and safe exposure. Methods: This study was a prospective, open-labeled, PK study in six ICUs in Australia, New Zealand, South Korea, and Switzerland. Serial blood samples were collected over a single dosing interval during ECMO for 11 antimicrobials. PK parameters were estimated using noncompartmental methods. Adequacy of antimicrobial dosing regimens were evaluated using predefined concentration exposures associated with maximal clinical outcomes and minimal toxicity risks. Measurements and Main Results: We included 993 blood samples from 85 patients. The mean age was 44.7 ± 14.4 years, and 61.2% were male. Thirty-eight patients (44.7%) were receiving renal replacement therapy during the first PK sampling. Large variations (coefficient of variation of ⩾30%) in antimicrobial concentrations were seen leading to more than fivefold variations in all PK parameters across all study antimicrobials. Overall, 70 (56.5%) concentration profiles achieved the predefined target concentration and exposure range. Target attainment rates were not significantly different between modes of ECMO and renal replacement therapy. Poor target attainment was observed across the most frequently used antimicrobials for ECMO recipients, including for oseltamivir (33.3%), piperacillin (44.4%), and vancomycin (27.3%). Conclusions: Antimicrobial PKs were highly variable in critically ill patients receiving ECMO, leading to poor target attainment rates. Clinical trial registered with the Australian New Zealand Clinical Trials Registry (ACTRN12612000559819).

Antibiotic Therapy in the Critically Ill with Acute Renal Failure and Renal Replacement Therapy: A Narrative Review

The outcome for critically ill patients is burdened by a double mortality rate and a longer hospital stay in the case of sepsis or septic shock. The adequate use of antibiotics may impact on the outcome since they may affect the pharmacokinetics (Pk) and pharmacodynamics (Pd) of antibiotics in such patients. Acute renal failure (ARF) occurs in about 50% of septic patients, and the consequent need for continuous renal replacement therapy (CRRT) makes the renal elimination rate of most antibiotics highly variable. Antibiotics doses should be reduced in patients experiencing ARF, in accordance with the glomerular filtration rate (GFR), whereas posology should be increased in the case of CRRT. Since different settings of CRRT may be used, identifying a standard dosage of antibiotics is very difficult, because there is a risk of both oversimplification and failing the therapeutic efficacy. Indeed, it has been seen that, in over 25% of cases, the antibiotic therapy does not reach the necessary concentration target mainly due to lack of the proper minimal inhibitory concentration (MIC) achievement. The aim of this narrative review is to clarify whether shared algorithms exist, allowing them to inform the daily practice in the proper antibiotics posology for critically ill patients undergoing CRRT.

Therapeutic Drug Monitoring of Antibiotic Drugs in Patients Receiving Continuous Renal Replacement Therapy or Intermittent Hemodialysis: A Critical Review

PURPOSE

Antibiotics are frequently used in patients receiving intermittent or continuous renal replacement therapy (RRT). Continuous renal replacement may alter the pharmacokinetics (PK) and the ability to achieve PK/pharmacodynamic (PD) targets. Therapeutic drug monitoring (TDM) could help evaluate drug exposure and guide antibiotic dosage adjustment. The present review describes recent TDM data on antibiotic exposure and PK/PD target attainment (TA) in patients receiving intermittent or continuous RRT, proposing practical guidelines for performing TDM.

METHODS

Studies on antibiotic TDM performed in patients receiving intermittent or continuous RRT published between 2000 and 2020 were searched and assessed. The authors focused on studies that reported data on PK/PD TA. TDM recommendations were based on clinically relevant PK/PD relationships and previously published guidelines.

RESULTS

In total, 2383 reports were retrieved. After excluding nonrelevant publications, 139 articles were selected. Overall, 107 studies reported PK/PD TA for 24 agents. Data were available for various intermittent and continuous RRT techniques. The study design, TDM practice, and definition of PK/PD targets were inconsistent across studies. Drug exposure and TA rates were highly variable. TDM seems to be necessary to control drug exposure in patients receiving intermittent and continuous RRT techniques, especially for antibiotics with narrow therapeutic margins and in critically ill patients. Practical recommendations can provide insights on relevant PK/PD targets, sampling, and timing of TDM for various antibiotic classes.

CONCLUSIONS

Highly variable antibiotic exposure and TA have been reported in patients receiving intermittent or continuous RRT. TDM for aminoglycosides, beta-lactams, glycopeptides, linezolid, and colistin is recommended in patients receiving RRT and suggested for daptomycin, fluoroquinolones, and tigecycline in critically ill patients on RRT.

Pharmacokinetics of Commonly Used Antimicrobials in Critically Ill Adults During Extracorporeal Membrane Oxygenation: A Systematic Review

PURPOSE

Adequate dosing of antimicrobials is critical to properly treat infections and limit development of resistance and adverse effects. Limited guidance exists for antimicrobial dosing adjustments in patients requiring extracorporporeal membrane oxygenation (ECMO) therapy. A systematic review was conducted to delineate the pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobials in critically ill adult patients requiring ECMO.

METHODS

Medline, EMBASE, Global Health, and All EBM Reviews databases were searched. Grey literature was examined. All studies reporting PK/PD parameters of antimicrobials in critically ill adults treated with ECMO were included, except for case reports and congress abstracts. Ex vivo studies were included. Two independent reviewers applied the inclusion and exclusion criteria. Reviewers were then paired to independently abstract data and evaluate methodological quality of studies using the ROBINS-I tool and the compliance with ClinPK guidelines. Patients' and studies' characteristics, key PK/PD findings, details of ECMO circuits and co-treatments were summarized qualitatively. Dosing recommendations were formulated based on data from controlled studies.

RESULTS

Thirty-two clinical studies were included; most were observational and uncontrolled. Fourteen ex vivo studies were analysed. Information on patient characteristics and co-treatments was often missing. The effect of ECMO on PK/PD parameters of antimicrobials varied depending on the studied drugs. Few dosing recommendations could be formulated given the lack of good quality data.

CONCLUSION

Limited data exist on the PK/PD of antimicrobials during ECMO therapy. Rigorously designed and well powered populational PK studies are required to establish empiric dosing guidelines for antimicrobials in patients requiring ECMO support.

PROSPERO REGISTRATION NUMBER

CRD42018099992 (Registered: July 24th 2018).

Effects of continuous venovenous hemofiltration on vancomycin trough concentrations in critically ill children

Background

Vancomycin trough concentrations are associated with clinical outcomes and drug adverse effects. This study investigates the effects of continuous venovenous hemofiltration (CVVH) on vancomycin trough concentrations in critically ill children with a vancomycin dosage of 40–60 mg/kg/day.

Methods

Children with steady-state vancomycin trough concentrations admitted to the pediatric intensive care unit (PICU) between January 2016 and December 2019 were retrospectively enrolled. Patients were divided into CVVH and non-CVVH groups according to treatment differences and renal function. Vancomycin trough concentrations were then compared between the groups, and risk factors for supratherapeutic trough concentrations (>20 mg/L) were analyzed with logistic regression.

Results

Of the 119 patients included, 35 were enrolled in the CVVH group and 84 in the non-CVVH group. Median vancomycin trough concentrations were significantly higher in the CVVH group than those in the non-CVVH group [14.9 (IQR =9.6–19.6) vs. 9.3 (IQR =7.0–13.4), P<0.001] and the proportion of therapeutic trough concentrations (10–20 mg/L) was similar between CVVH and non-CVVH groups (54.3% vs. 39.3%, P=0.133). However, CVVH therapy patients had a significantly higher proportion of supratherapeutic trough concentrations (20.0% vs. 1.2%, P=0.001) compared to the non-CVVH group. Multivariate analysis demonstrated that the Pediatric Risk of Mortality (PRISM) III score ≥28 (OR =13.7; 95% CI, 1.4–137.0; P=0.026] was an independent risk factor for supratherapeutic trough concentrations in critically ill patients.

Conclusions

CVVH therapy affects vancomycin trough concentrations and is associated with supratherapeutic concentrations with a 40–60 mg/kg/day vancomycin dosage. PRISM III scores ≥28 may serve as an independent risk factor for supratherapeutic trough concentrations in children receiving CVVH therapy.

Prospective Cohort Study of Population Pharmacokinetics and Pharmacodynamic Target Attainment of Vancomycin in Adults on Extracorporeal Membrane Oxygenation

The aim of this study was to develop a population pharmacokinetics (PK) model for vancomycin and to evaluate its pharmacodynamic target attainment in adults on extracorporeal membrane oxygenation (ECMO). After a single 1,000-mg dose of vancomycin, samples were collected 9 times per patient prospectively. A population PK model was developed using a nonlinear mixed-effect model. The probability of target attainment (PTA) of vancomycin was evaluated for various dosing strategies using Monte Carlo simulation. The ratio of the area under the vancomycin concentration-time curve at steady state over 24 h to the MIC (AUC/MIC ratio) was investigated by applying the vancomycin breakpoint distribution of MICs for methicillin-resistant Staphylococcus aureus A total of 22 adult patients with 194 concentration measurements were included. The population PK was best described by a three-compartment model with a proportional residual error model. Vancomycin clearance and steady-state volume of distribution were 4.01 liters/h (0.0542 liters/h/kg) and 29.6 liters (0.400 liters/kg), respectively. If the treatment target AUC/MIC value was only ≥400, a total daily dose of 3 to 4 g would be optimal (PTA of ≥90%) for patients with normal renal function (estimated glomerular filtration rate [eGFR] = 60 to 120 ml/min/1.73 m²) when the MIC was presumed to be 1 mg/liter. However, AUC/MIC values of 400 to 600 were difficult to attain with any dosing strategy regardless of MIC and eGFR. Thus, it is hard to achieve efficacy and safety targets in patients on ECMO using the population dosing approach with Monte Carlo simulations, and therapeutic drug monitoring should be implemented in these patients.

Antibiotic dosing during extracorporeal membrane oxygenation: does the system matter?

PURPOSE OF REVIEW

The aims of this review are to discuss the impact of extracorporeal membrane oxygenation (ECMO) on antibiotic pharmacokinetics and how this phenomenon may influence antibiotic dosing requirements in critically ill adult ECMO patients.

RECENT FINDINGS

The body of literature describing antibiotic pharmacokinetic and dosing requirements during ECMO support in critically adult patients is currently scarce. However, significant development has recently been made in this research area and more clinical pharmacokinetic data have emerged to inform antibiotic dosing in these patients. Essentially, these clinical data highlight several important points that clinicians need to consider when dosing antibiotics in critically ill adult patients receiving ECMO: physicochemical properties of antibiotics can influence the degree of drug loss/sequestration in the ECMO circuit; earlier pharmacokinetic data, which were largely derived from the neonatal and paediatric population, are certainly useful but cannot be extrapolated to the critically ill adult population; modern ECMO circuitry has minimal adsorption and impact on the pharmacokinetics of most antibiotics; and pharmacokinetic changes in ECMO patients are more reflective of critical illness rather than the ECMO therapy itself.

SUMMARY

An advanced understanding of the pharmacokinetic alterations in critically ill patients receiving ECMO is essential to provide optimal antibiotic dosing in these complex patients pending robust dosing guidelines. Antibiotic dosing in this patient population should generally align with the recommended dosing strategies for critically ill patients not on ECMO support. Performing therapeutic drug monitoring (TDM) to guide antibiotic dosing in this patient population appears useful.