Augmented Renal Clearance in Severe Infections-An Important Consideration in Vancomycin Dosing: A Narrative Review

Therapeutic drug monitoring of vancomycin in the case of augmented renal clearance: a case report of a paediatric patient

Augmented renal clearance (ARC) is a condition in which renal circulation increases, causing drug levels in the blood to remain at subtherapeutic levels in severe trauma patients. Vancomycin, a hydrophilic anti-Gram-positive drug, has been shown in the literature to have its levels fall below the therapeutic range in the case of ARC. However, vancomycin dosing recommendations in the case of ARC are still lacking. Here, we identify an ARC case measured with urinary creatinine clearance in a severe trauma paediatric patient, causing vancomycin blood trough levels to drop. We could not be able to increase the vancomycin trough levels with intermittent dosing; hence, we administered vancomycin with continuous infusion, and this resulted in vancomycin blood trough levels remaining in the therapeutic range. No adverse effect was seen. Continuous infusion of vancomycin can be safely administered to paediatric patients in these cases.

Evaluating the efficiency of a nomogram based on the data of neurosurgical intensive care unit patients to predict pulmonary infection of multidrug-resistant Acinetobacter baumannii

Background

Pulmonary infection caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) is a common and serious complication after brain injury. There are no definitive methods for its prediction and it is usually accompanied by a poor prognosis. This study aimed to construct and evaluate a nomogram based on patient data from the neurosurgical intensive care unit (NSICU) to predict the probability of MDR-AB pulmonary infection.

Methods

In this study, we retrospectively collected patient clinical profiles, early laboratory test results, and doctors' prescriptions (66 variables). Univariate and backward stepwise regression analyses were used to screen the variables to identify predictors, and a nomogram was built in the primary cohort based on the results of a logistic regression model. Discriminatory validity, calibration validity, and clinical utility were evaluated using validation cohort 1 based on receiver operating characteristic curves, calibration curves, and decision curve analysis (DCA). For external validation based on predictors, we prospectively collected information from patients as validation cohort 2.

Results

Among 2115 patients admitted to the NSICU between December 1, 2019, and December 31, 2021, 217 were eligible for the study, including 102 patients with MDR-AB infections (102 cases) and 115 patients with other bacterial infections (115 cases). We randomly categorized the patients into the primary cohort (70%, N=152) and validation cohort 1 (30%, N=65). Validation cohort 2 consisted of 24 patients admitted to the NSICU between January 1, 2022, and March 31, 2022, whose clinical information was prospectively collected according to predictors. The nomogram, consisting of only six predictors (age, NSICU stay, Glasgow Coma Scale, meropenem, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio), had significantly high sensitivity and specificity (primary cohort AUC=0.913, validation cohort 1 AUC=0.830, validation cohort 2 AUC=0.889) for early identification of infection and had great calibration (validation cohort 1,2 P=0.3801, 0.6274). DCA confirmed that the nomogram is clinically useful.

Conclusion

Our nomogram could help clinicians make early predictions regarding the onset of pulmonary infection caused by MDR-AB and implement targeted interventions.

Population pharmacokinetic model of vancomycin in postoperative neurosurgical patients

Objective: Vancomycin is commonly used in postoperative neurosurgical patients for empirical anti-infective treatment due to the low success rate of bacterial culture in cerebrospinal fluid (about 20%) and the high mortality of intracranial infection. At conventional doses, the rate of target achievement for vancomycin trough concentration is low and the pharmacokinetics of vancomycin varies greatly in these patients, which often leads to treatment failure. The objective of this study was to establish a population pharmacokinetic (PPK) model of vancomycin in postoperative neurosurgical patients for precision medicine.

Method: A total of 895 vancomycin plasma concentrations from 560 patients (497 postoperative neurosurgical patients) were retrospectively collected. The model was analyzed by nonlinear mixed effects modeling method. One-compartment model and mixed residual model was employed. The influence of covariates on model parameters was tested by forward addition and backward elimination. Goodness-of-fit, bootstrap and visual predictive check were used for model evaluation. Monte Carlo simulations were employed for dosing strategies with AUC₂₄ targets 400–600.

Result: Estimated glomerular filtration rate (eGFR), body weight (BW) and mannitol had significant influence on vancomycin clearance (CL). eGFR(mL/min)=144×(Scr/a)b×0.993age, for female, a = 0.7, Scr ≤ 0.7 mg/dl, b = −0.329, Scr > 0.7 mg/dl, b = −1.209; for male, a = 0.9, Scr ≤ 0.9 mg/dl, b = −0.411, Scr > 0.9 mg/dl, b = −1.210. Vancomycin clearance was accelerated when co-medicated with mannitol and increased with eGFR and BW. In the final model, the population typical value is 7.98 L/h for CL and 60.2 L for apparent distribution volume, CL (L/h)=7.98×(eGFR/115.2)0.8×(BW/70)0.3×eA, where A = 0.13 when co-medicated with mannitol, otherwise A = 0. The model is stable and effective, with good predictability.

Conclusion: In postoperative neurosurgical patients, a higher dose of vancomycin may be required due to the augmented renal function and the commonly used mannitol, especially in those with high body weight. Our vancomycin PPK model could be used for individualized treatment in postoperative neurosurgical patients.

Risk factors associated with augmented renal clearance in a mixed intensive care unit population: a retrospective study

BACKGROUND

Augmented renal clearance is increasingly recognized in critically ill patients. This condition may lead to suboptimal dosing of renally excreted medications.

AIM

Our primary objective was to identify demographic and clinical factors associated with augmented renal clearance in a mixed critically ill population.

METHOD

This retrospective single center observational cohort study evaluated patients admitted in a mixed adult intensive care unit for augmented renal clearance, defined as a creatinine clearance of ≥ 130 ml/min/1.73m²_, through weekly 24-h urine collection. Variables associated with augmented renal clearance were identified using univariate analysis, then served as covariates in a backward stepwise logistic regression. Goodness-of-fit of the model was assessed and receiver operating characteristic curve was generated.

RESULTS

Augmented renal clearance was observed in 25.3% of the study cohort (n = 324). Age below 50 years (adjusted odds ratio 7.32; 95% CI 4.03-13.29, p < 0.001), lower serum creatinine at intensive care admission (adjusted odds ratio 0.97; 95% CI 0.96-0.99, p < 0.001) and trauma admission (adjusted odds ratio 2.26; 95% CI 1.12-4.54, p = 0.022) were identified as independent risk factors. Our model showed acceptable discrimination in predicting augmented renal clearance (Area under receiver operating characteristic curve (0.810; 95% CI 0.756-0.864, p < 0.001)).

CONCLUSION

We identified age below 50 years, lower serum creatinine upon intensive care admission and trauma as independent risk factors for augmented renal clearance, consistent with the literature suggesting that patients with low serum creatinine upon admission could have a higher risk of developing augmented renal clearance.

Risk Factors Associated With Prolonged Antibiotic Use in Pediatric Bacterial Meningitis

Objectives: To determine the risk factors associated with a prolonged antibiotic course for community-acquired bacterial meningitis (BM) in children.

Methods: This retrospective cohort study included children aged 1 month to 18 years with community-acquired BM due to a confirmed causative pathogen from 2011 to 2021. Patients were divided into an antibiotic prolongation group and a nonprolongation group according to whether the antibiotic course exceeded 2 weeks of the recommended course for the causative pathogen. Associations of important clinical characteristics and laboratory and other parameters with antibiotic prolongation were assessed using univariate and multivariable regression logistic analyses.

Results: In total, 107 patients were included in this study. Augmented renal clearance (ARC) (OR, 19.802; 95% CI, 7.178–54.628; p &lt; 0.001) was associated with a prolonged antibiotic course; however, septic shock, causative pathogen, preadmission antibiotic use, peripheral white blood cell (WBC) count, initial cerebrospinal fluid (CSF) WBC count, CSF glucose, CSF protein, and surgical intervention were not associated with the prolonged antibiotic course. Patients with ARC had more total fever days (median time: 14 vs. 7.5 days), longer hospitalization (median time: 39 vs. 24 days), higher rates of complications (72.34% vs. 50.00%) and antibiotic adjustments (78.723% vs. 56.667%) than patients with normal renal function.

Conclusion: ARC is an independent risk factor for prolonged antibiotic use in children with community-acquired BM. ARC may be associated with longer fever and hospitalization durations, higher rates of complications and antibiotic adjustments.