Antimicrobial Dosing Recommendations in Pediatric Continuous Renal Replacement Therapy: A Critical Appraisal of Current Evidence

Ceftriaxone Pharmacokinetics and Pharmacodynamic Target Attainment for Three Pediatric Patients Receiving Continuous Kidney Replacement Therapy

Ceftriaxone is used commonly for sepsis, including in children requiring continuous kidney replacement therapy (CKRT). No reports exist of pharmacokinetic (PK) parameters for children receiving ceftriaxone on CKRT. We enrolled children admitted to our pediatric intensive care unit (PICU) who received CKRT for >24 hours and received >1 dose of ceftriaxone while on and off CKRT. We measured free ceftriaxone -concentrations from residual blood samples then used Bayesian estimation with PK modeling software to generate concentration-time profiles and determine PK parameters and the percentage of time free ceftriaxone concentrations were above 1× or 4× MIC (% fT >MIC). Three patients aged 2 to 17 years were included; all were anuric at CKRT initiation and received 50 mg/kg (max 2000 mg) ceftriaxone every 12 to 24 hours. Total ceftriaxone clearance (CL) was 0.50 to 3.67 L/hr while receiving CKRT and 0.29 to 2.71 L/hr while off, indicating CKRT provided 25% to 42% of total ceftriaxone CL. All achieved 100% fT >1× and 4× MIC using an estimated MIC (1 mg/L) for patients 1 to 2 (no culture data) and a measured MIC (0.016 mg/L) for patient 3. Therefore, CKRT contributed significantly to total ceftriaxone clearance in 3 children though the dosing strategies used in each patient attained PD targets.

Anti-infective prescribing practices in critically ill children on continuous renal replacement therapy: a multicenter survey of French-speaking countries

BACKGROUND

Use of continuous renal replacement therapy in children receiving anti-infective drugs may lead to inappropriate concentrations with risks related to treatment failure, toxicity and emergence of multidrug-resistant bacteria. We aimed to describe anti-infective prescribing practices in critically ill children undergoing continuous renal replacement therapy.

METHODS

An online survey to assess continuous renal replacement therapy, anti-infective prescribing and therapeutic drug monitoring practices was sent by e-mail to physicians working in pediatric intensive care units through the French-speaking Group of Pediatric Intensive Care and Emergency medicine (GFRUP).

RESULTS

From April 1st, 2021 to May 1st, 2021, 26/40 pediatric intensive care units participated in the survey, corresponding to a response rate of 65%. Twenty-one were located in France and five abroad. All pediatric intensive care units administered continuous renal replacement therapy, primarily with Prismaflex™ System. Anti-infective prescriptions were adjusted to the presence of continuous renal replacement therapy in 23 (88%) pediatric intensive care units mainly according to molecular weight in 6 (23%), molecule protein binding in 6 (23%) and elimination routes in 15 (58%) including residual diuresis in 9 (35%), to the continuous renal replacement therapy flow in 6 (23%) and to the modality of continuous renal replacement therapy used in 15 (58%), pediatric intensive care units. There was broad variability among pediatric intensive care units and among physicians within the same unit. Barriers to therapeutic drug monitoring were mainly an excessive delay in obtaining results in 11 (42%) and the lack of an on-site laboratory in 8 (31%) pediatric intensive care units.

CONCLUSIONS

Our survey reported wide variability in anti-infective prescribing practices in children undergoing continuous renal replacement therapy, thus highlighting a gap in knowledge and the need for education and recommendations.

Interaction of ceftazidime and clindamycin with extracorporeal life support

BACKGROUND

Ceftazidime and clindamycin are commonly prescribed to critically ill patients who require extracorporeal life support such as ECMO and CRRT. The effect of ECMO and CRRT on the disposition of ceftazidime and clindamycin is currently unknown.

METHODS

Ceftazidime and clindamycin extraction were studied with ex vivo ECMO and CRRT circuits primed with human blood. The percent recovery of these drugs over time was calculated to determine the degree of interaction between these drugs and circuit components.

RESULTS

Neither ceftazidime nor clindamycin exhibited measurable interactions with the ECMO circuit. In contrast, CRRT cleared 100% of ceftazidime from the experimental circuit within the first 2 h. Clearance of clindamycin from the CRRT circuit was slower, with about 20% removed after 6 h.

CONCLUSION

Clindamycin and ceftazidime dosing adjustments are likely required in patients who are supported with CRRT, and future studies to quantify these adjustments should consider the pathophysiology of the patient in combination with the clearance due to CRRT. Dosing adjustments to account for adsorption to ECMO circuit components are likely unnecessary and should focus instead on the pathophysiology of the patient and changes in volume of distribution. These results will help improve the safety and efficacy of ceftazidime and clindamycin in patients requiring ECMO and CRRT.

Cefepime pharmacokinetics in critically ill children and young adults undergoing continuous kidney replacement therapy

OBJECTIVES

Cefepime is an antibiotic commonly used to treat sepsis and is cleared by renal excretion. Cefepime dosing requires adjustment in patients with decreased kidney function and in those receiving continuous kidney replacement therapy (CKRT). We aimed to characterize cefepime PK in a diverse cohort of critically ill paediatric patients on CKRT.

METHODS

Patients were identified from an ongoing pharmacokinetic/pharmacodynamic (PK/PD) study of beta-lactam antibiotics, and were included if they had received at least two cefepime doses in the ICU and were on CKRT for at least 24 h. PK parameters were estimated using MwPharm++ with Bayesian estimation and a paediatric population PK model. Target attainment was assessed as time of free cefepime concentrations above minimum inhibitory concentration (fT > 1× or 4 × MIC).

RESULTS

Seven patients were included in the study (ages 2 to 20 years). CKRT indications included liver failure (n = 1), renal failure (n = 4) and fluid overload (n = 2). Total effluent flow rates ranged from 1833 to 3115 (mean 2603) mL/1.73 m2/h, while clearance was 2.11-3.70 (mean 3.0) L/h/70 kg. Effluent flows were lower, but clearance and fT > MIC were similar to paediatric data published previously. Using Pseudomonas aeruginosa MIC breakpoints, all patients had 100% of dosing interval above MIC, but only one had 100% of dosing interval above 4× MIC.

CONCLUSIONS

Since most patients failed to attain stringent targets of 100% fT > 4×  MIC, model-informed precision dosing may benefit such patients.

β-lactam precision dosing in critically ill children: Current state and knowledge gaps

There has been emerging interest in implementing therapeutic drug monitoring and model-informed precision dosing of β-lactam antibiotics in critically ill patients, including children. Despite a position paper endorsed by multiple international societies that support these efforts in critically ill adults, implementation of β-lactam precision dosing has not been widely adopted. In this review, we highlight what is known about β-lactam antibiotic pharmacokinetics and pharmacodynamics in critically ill children. We also define the knowledge gaps that present barriers to acceptance and implementation of precision dosing of β-lactam antibiotics in critically ill children: a lack of consensus on which subpopulations would benefit most from precision dosing and the uncertainty of how precision dosing changes outcomes. We conclude with opportunities for further research to close these knowledge gaps.