Arun Chopra

Pharmacokinetics of continuous-infusion meropenem in a pediatric patient receiving extracorporeal life support.

Meropenem, a broad‐spectrum carbapenem, is commonly used for empirical and definitive therapy in the pediatric intensive care unit (ICU). Pharmacokinetic data to guide dosing in children, however, are limited to healthy volunteers or patients who are not in the ICU. Adult data demonstrate that pharmacokinetic parameters such as the volume of distribution and clearance can be significantly altered in individuals receiving extracorporeal membrane oxygenation (ECMO). Alterations in the volume of distribution and clearance of antimicrobials in patients with sepsis and septic shock have also been documented, and these patients have demonstrated lower than expected antimicrobial serum concentrations based on standard dosing regimens. Therefore, an understanding of the pharmacokinetic changes in critically ill children receiving ECMO is crucial to determining the most appropriate dose and dosing interval selection for any antimicrobial therapy. In this case report, we describe the pharmacokinetics of a continuous infusion of meropenem in a pediatric cardiac ICU patient who was receiving concurrent extracorporeal life support. The patient was an 8‐month‐old male infant who underwent a Glenn procedure and pulmonary artery reconstruction. Postoperatively, he required ECMO with a total run of 21 days. On day 11 of ECMO, a bronchoalveolar lavage was performed, and blood cultures from days 11 and 12 of ECMO grew Pseudomonas aeruginosa, with a meropenem minimum inhibitory concentration (MIC) of 0.5 μg/ml. On ECMO day 13, meropenem was initiated with a loading dose of 40 mg/kg and infused over 30 minutes, followed by a continuous infusion of 200 mg/kg/day. A meropenem serum concentration measured 8 hours after the start of the infusion was 46 μg/ml. Repeat levels were measured on days 3 and 9 of meropenem therapy and were 39 and 42 μg/ml, respectively. Repeat blood and respiratory cultures remained negative. This meropenem regimen (40‐mg/kg bolus followed by a continuous infusion of 200 mg/kg/day) was successful in providing a target attainment of 100% for serum and lung concentrations above the MIC for at least 40% of the dosing interval and was associated with a successful clinical outcome.

Procalcitonin use in a pediatric intensive care unit.

We evaluated whether procalcitonin (PCT) might aid diagnosing serious bacterial infections in a general pediatric intensive care unit population. Two-hundred and one patients accounted for 332 PCT samples. A PCT ≥1.45 ng/mL had a positive predictive value of 30%, a negative predictive value of 93% and a sensitivity of 72% and a specificity of 75%. These data suggest PCT can assist in identifying patients without serious bacterial infections and limit antimicrobial use.

Pharmacokinetics of Continuous Infusion Meropenem With Concurrent Extracorporeal Life Support and Continuous Renal Replacement Therapy: A Case Report.

Pharmacokinetic parameters can be significantly altered for both extracorporeal life support (ECLS) and continuous renal replacement therapy (CRRT). This case report describes the pharmacokinetics of continuous-infusion meropenem in a patient on ECLS with concurrent CRRT. A 2.8-kg, 10-day-old, full-term neonate born via spontaneous vaginal delivery presented with hypothermia, lethargy, and a ~500-g weight loss from birth. She progressed to respiratory failure on hospital day 2 (HD 2) and developed sepsis, disseminated intravascular coagulation, and liver failure as a result of disseminated adenoviral infection. By HD 6, acute kidney injury was evident, with progressive fluid overload >1500 mL (+) for the admission. On HD 6 venoarterial ECLS was instituted for lung protection and fluid removal. On HD 7 she was initiated on CRRT. On HD 12, a blood culture returned positive and subsequently grew Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) for meropenem of 0.25 mg/L. She was started on vancomycin, meropenem, and amikacin. A meropenem bolus of 40 mg/kg was given, followed by a continuous infusion of 10 mg/kg/hr (240 mg/kg/day). On HD 15 (ECLS day 9) a meropenem serum concentration of 21 mcg/mL was obtained, corresponding to a clearance of 7.9 mL/kg/min. Repeat cultures from HDs 13 to 15 (ECLS days 7-9) were sterile. This meropenem regimen was successful in providing a target attainment of 100% for serum concentrations above the MIC for ≥40% of the dosing interval and was associated with a sterilization of blood in this complex patient on concurrent ECLS and CRRT circuits.

Therapeutic drug monitoring of continuous-infusion acylovir for disseminated herpes simplex virus infection in a neonate receiving concurrent extracorporeal life support and continuous renal replacement therapy.

Disseminated herpes simplex virus (HSV) infection in neonates represents a devastating entity that yields high mortality. Acyclovir is the primary antiviral agent used to treat life‐threatening HSV infections in neonates; however, even though the agent has reduced morbidity overall from these infections, mortality with disseminated disease remains high. Currently, to our knowledge, no data exist regarding therapeutic drug monitoring of acyclovir in the setting of extracorporeal life support (ECLS) or continuous renal replacement therapy (CRRT) coupled with ECLS. We describe the case of a 14‐day‐old female with disseminated HSV‐1 infection that progressed to fulminant hepatic and renal failure, necessitating the use of ECLS for hemodynamic support and CRRT as a treatment modality for hepatic and renal failure. The standard dosage of acyclovir 20 mg/kg/dose intravenously every 8 hours had been initiated, but after conversion to ECLS and CRRT, the patients dosage was increased to 30 mg/kg/dose every 8 hours. After a repeat viral load remained unchanged from the initial viral load at 1 × 108 copies/ml, the patient was transitioned from intermittent dosing to a continuous infusion of acyclovir added to the dialysate solution for CRRT at a concentration of 5.5 mg/L. To provide an optimal outcome, dosing was designed to maintain acyclovir plasma concentrations of at least 3 mg/L in order to maintain an acyclovir concentration of at least 1 mg/L in the cerebrospinal fluid. The patients acyclovir serum concentrations measured at 24 and 72 hours after starting continuous‐infusion acyclovir via the dialysate were 8.8 and 5.3 mg/L, respectively, allowing for a continuous serum concentration above 3 mg/L. Unfortunately, before a repeat viral load could be obtained to assess the efficacy of the continuous infusion acyclovir, the patient experienced an intracerebral hemorrhage as a complication related to ECLS after which technological support was withdrawn. This is the first report to describe the pharmacokinetics of continuous‐infusion acyclovir in a neonate receiving ECLS with concurrent CRRT. These data suggest that adding acyclovir to the dialysate fluid during CRRT is effective in achieving therapeutic drug concentrations despite the complications of adding ECLS and CRRT circuits to a small patient.

Pharmacokinetics of Continuous-Infusion Meropenem for the Treatment of Serratia marcescens Ventriculitis in a Pediatric Patient

Neither guidelines nor best practices for the treatment of external ventricular drain (EVD) and ventriculoperitoneal shunt infections exist. An antimicrobial regimen with a broad spectrum of activity and adequate cerebrospinal fluid (CSF) penetration is vital in the management of both EVD and ventriculoperitoneal infections. In this case report, we describe the pharmacokinetics of continuous‐infusion meropenem for a 2‐year‐old girl with Serratia marcescens ventriculitis. A right frontal EVD was placed for the management of a posterior fossa mass with hydrocephalus and intraventricular hemorrhage. On hospital day 6, CSF specimens were cultured, which identified a pan‐sensitive Serratia marcescens with an initial cefotaxime minimum inhibitory concentration of 1 μg/ml or less. The patient was treated with cefotaxime monotherapy from hospital days 6 to 17, during which her CSF cultures and Grams stain remained positive. On hospital day 26, Serratia marcescens was noted to be resistant to cefotaxime (minimum inhibitory concentration > 16 μg/ml), and the antimicrobial regimen was ultimately changed to meropenem and amikacin. Meropenem was dosed at 40 mg/kg/dose intravenously every 6 hours, infused over 30 minutes, during which, simultaneous serum and CSF meropenem levels were measured. Meropenem serum and CSF levels were measured at 2 and 4 hours from the end of the infusion with the intent to perform a pharmacokinetic/pharmacodynamic analysis. The resulting serum meropenem levels were 12 μg/ml at 2 hours and “undetectable” at 4 hours, with CSF levels of 1 and 0.5 μg/ml at 2 and 4 hours, respectively. On hospital day 27, the meropenem regimen was changed to a continuous infusion of 200 mg/kg/day, with repeat serum and CSF meropenem levels measured on hospital day 33. The serum and CSF levels were noted to be 13 and 0.5 μg/ml, respectively. The serum level of 13 μg/ml corresponds to an estimated meropenem clearance from the serum of 10.2 ml/kg/minute. Repeat meropenem levels from the serum and CSF on hospital day 37 were 15 and 0.5 μg/ml, respectively. After instituting the continuous‐infusion meropenem regimen, only three positive CSF Grams stains were noted, with the CSF cultures remaining negative. The continuous‐infusion dosing regimen allowed for 100% probability of target attainment in the serum and CSF and a successful clinical outcome.

Acetazolamide therapy for metabolic alkalosis in critically ill pediatric patients.

Objective: Despite a paucity of supporting literature, acetazolamide is commonly used in critically ill children with metabolic alkalosis (elevated plasma bicarbonate [pHco–3] and pH). The objective of this study was to assess the change in 18 hours after initiation of acetazolamide therapy. Design: Retrospective study. Setting: PICU of an urban, tertiary-care children’s hospital. Patients: Mechanically ventilated children (⩽ 17 yr) with metabolic alkalosis (pHco–3 ≥ 35 mmol/L). Interventions: None. Measurements and Main Results: Of 153 consecutively screened patients, 61 patients (29 female patients) were enrolled: 18 cardiac patients (after congenital heart disease repair) and 43 noncardiac patients. The cardiac patients were younger than the noncardiac patients (median [interquartile range] age, 0.6 mo [0.3–2.5 mo] vs 7.4 mo [2.8–39.9 mo]; p < 0.00001) and had higher preacetazolamide baseline diuretic scores and urine output. The pHco–3 levels 18 hours after initiation of acetazolamide were reduced in the cohort as a whole (40.2 ± 4.8 to 36.2 ± 5.6 mmol/L; p < 0.001) and in the noncardiac patients, but they were unchanged in the cardiac patients. The PCO2 remained unchanged after acetazolamide in both subgroups. Because young age and presence of cardiac disease were potential confounders, the 20 noncardiac patients who are 6 months old or younger were compared with the cardiac subgroup and demonstrated reduced pHco–3 after acetazolamide and lower preacetazolamide baseline diuretic score and urine output. Conclusion: Acetazolamide reduces pHco–3 concentration in critically ill, mechanically ventilated children overall, but it did not do so in cardiac patients in our cohort, even in comparison with noncardiac patients of a similar age. These findings do not support the current use of acetazolamide for metabolic alkalosis in critically ill children with congenital heart disease. Further study is required to determine why these cardiac patients respond differently to acetazolamide than noncardiac patients and whether this response impacts important clinical outcomes, for example, weaning mechanical ventilation.

IV enoxaparin in pediatric and cardiac ICU patients.

Objectives: To report our experience with the use of IV enoxaparin in neonatal and pediatric patients in the ICU. Design: We performed a case control from January 1, 2009, to June 30, 2012, comparing patients that received IV enoxaparin to controls that received subcutaneous enoxaparin. Cases were matched to controls in a 1:2 manner. IV enoxaparin doses were infused over 30 minutes and anti-Factor Xa levels were drawn 4 hours after the start of the IV infusion or 4 hours after a subcutaneous dose. Setting: The pediatric and cardiac ICUs of a tertiary/quaternary, free-standing, academic children’s hospital. Patients: Forty-five neonatal and pediatric patients receiving prophylactic or therapeutic enoxaparin. Interventions: None. Measurements and Main Results: Fifteen cases and 30 controls were included. Of 15 patients, 13 received IV enoxaparin for treatment and two received IV enoxaparin for prophylaxis as compared with 25 of 30 controls receiving subcutaneous enoxaparin for treatment and five receiving subcutaneous enoxaparin for prophylaxis. The ages for the cases ranged from 21 days to 16 years with a median weight of 5 kg, and the ages for controls ranged from 10 days to 23 years with a median weight of 31 kg. The median duration of IV therapy was 11 days (range, 1–120 d) and the median duration for subcutaneous therapy was 15 days (range, 3–85 d). The mean initial IV dose was 1.14 ± 0.38 mg/kg/dose q12h, and the mean initial subcutaneous dose was 0.85 ± 0.2 mg/kg/dose subcutaneous q12h (p = 0.003). The mean therapeutic IV dose was 1.31 ± 0.52 mg/kg/dose q12h, and the mean therapeutic subcutaneous dose was 0.9 ± 0.3 mg/kg/dose q12h (p = 0.016). There were no adverse events reported related to bleeding, thrombosis, or hypersensitivity in any of the cases or controls evaluated. Conclusion: The pharmacodynamics of a 30-minute IV enoxaparin infusion was found to produce therapeutic 4 hour anti-Factor Xa levels similar to subcutaneous doses. Although this was a small study, there were no adverse events, suggesting the safety profile of IV enoxaparin may be similar to subcutaneous dosing with the added benefit of less pain associated with IV dosing. These findings suggest that IV enoxaparin may be a viable option for anticoagulating critically ill children and its use warrants further study.

Association of procalcitonin values and bacterial infections in pediatric patients receiving extracorporeal membrane oxygenation

Objective: There is increasing data in pediatrics demonstrating procalcitonin (PCT) is more sensitive and specific than other biomarkers in the setting of bacterial infections. However, the use of PCT in neonatal and pediatric extracorporeal membrane oxygenation (ECMO) is not well described. Therefore, the purpose of this study was to describe the clinical utility of PCT in determining the absence or presence of bacterial infections in neonatal and pediatric patients on ECMO. Methods: This was a retrospective electronic medical record (EMR) review of data between January 1, 2010 to June 30, 2016 at a single, free-standing, children’s hospital. All patients on ECMO with ≥1 PCT level obtained while receiving ECMO support were eligible for inclusion. The EMR was searched for chest radiographs (CXR) and bacterial culture results (urine, blood, cerebrospinal fluid (CSF), bronchoalveolar lavage (BAL) and respiratory cultures). All bacterial and viral cultures obtained within 5 days of PCT levels being obtained were analyzed. PCT levels of 0.5, 0.9, 1.0, 1.4 and 2.0 were used as the initial cut-off values for the analysis. The sensitivity, specificity, positive predictive value (PPV), negative predictive values (NPV) and likelihood ratios were calculated for each of the PCT levels. Results: Twenty-seven patients met the inclusion criteria and contributed 193 PCT values for the analysis. The median age was 8 months (range 0 days to 18 years). Linear regression analysis demonstrated that a PCT cut-off of 0.5, 0.9 and 1.4 predicted the presence of a bacterial infection. The PCT value with the most utility was 0.5, with a sensitivity of 92%, a specificity of 43%, a positive predictive value of 60% and a negative predictive value (NPV) of 86%. Conclusion: This is the largest data set evaluating PCT in neonatal and pediatric patients on ECMO. A PCT value of 0.5 ng/mL had the most utility for determining the absence or presence of a bacterial infection in the setting of ECMO with a high sensitivity and NPV.

Respiratory care in familial dysautonomia: Systematic review and expert consensus recommendations

BACKGROUND Familial dysautonomia (Riley-Day syndrome, hereditary sensory autonomic neuropathy type-III) is a rare genetic disease caused by impaired development of sensory and afferent autonomic nerves. As a consequence, patients develop neurogenic dysphagia with frequent aspiration, chronic lung disease, and chemoreflex failure leading to severe sleep disordered breathing. The purpose of these guidelines is to provide recommendations for the diagnosis and treatment of respiratory disorders in familial dysautonomia. METHODS We performed a systematic review to summarize the evidence related to our questions. When evidence was not sufficient, we used data from the New York University Familial Dysautonomia Patient Registry, a database containing ongoing prospective comprehensive clinical data from 670 cases. The evidence was summarized and discussed by a multidisciplinary panel of experts. Evidence-based and expert recommendations were then formulated, written, and graded using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system. RESULTS Recommendations were formulated for or against specific diagnostic tests and clinical interventions. Diagnostic tests reviewed included radiological evaluation, dysphagia evaluation, gastroesophageal evaluation, bronchoscopy and bronchoalveolar lavage, pulmonary function tests, laryngoscopy and polysomnography. Clinical interventions and therapies reviewed included prevention and management of aspiration, airway mucus clearance and chest physical therapy, viral respiratory infections, precautions during high altitude or air-flight travel, non-invasive ventilation during sleep, antibiotic therapy, steroid therapy, oxygen therapy, gastrostomy tube placement, Nissen fundoplication surgery, scoliosis surgery, tracheostomy and lung lobectomy. CONCLUSIONS Expert recommendations for the diagnosis and management of respiratory disease in patients with familial dysautonomia are provided. Frequent reassessment and updating will be needed.

Pharmacokinetics of the Meropenem Component of Meropenem-Vaborbactam in the Treatment of KPC-producing Klebsiella pneumoniae Bloodstream Infection in a Pediatric Patient

Meropenem‐vaborbactam is a new β‐lactam/β‐lactamase inhibitor combination designed to target Klebsiella pneumoniae carbapenemase (KPC)‐producing Enterobacteriaceae. Meropenem‐vaborbactam was United States Food and Drug Administration–approved for complicated urinary tract infections in patients 18 years of age or older. An understanding of the pharmacokinetics of meropenem when given in combination with vaborbactam is important to understanding the dosing of meropenem‐vaborbactam. In addition, the safety and efficacy of meropenem‐vaborbactam in a pediatric patient have yet to be described in the literature. The authors conducted a retrospective single‐patient chart review for a 4‐year‐old male patient with short bowel syndrome, colostomy and gastrojejunal tube, bronchopulmonary dysplasia, and a central line for chronic total parenteral nutrition and hydration management, complicated with multiple central line–associated bloodstream infections (BSIs). The patient was brought to our medical center with fever concerning for a BSI. On day 2, the patient was started on meropenem‐vaborbactam at a dosage of 40 mg/kg every 6 hours infused over 3 hours for KPC‐producing K. pneumoniae BSI. Meropenem serum concentrations obtained on day 5 of meropenem‐vaborbactam therapy, immediately following the completion of the infusion and 1 hour after the infusion, were 51.3 and 13.6 μg/ml, respectively. Serum concentrations correlated to a volume of distribution of 0.59 L/kg and a clearance of 13.1 ml/min/kg. Repeat blood cultures remained negative, and meropenem‐vaborbactam was continued for a total of 14 days. A meropenem‐vaborbactam regimen of 40 mg/kg every 6 hours given over 3 hours was successful in providing a target attainment of 100% for meropenem serum concentrations above the minimum inhibitory concentration for at least 40% of the dosing interval and was associated with successful bacteremia clearance in a pediatric patient.