Heparin Dosing in Obese Pediatric Patients in the Cardiac Catheterization Laboratory

Unfractionated heparin using actual body weight without dose capping in obese pediatric patients-Subgroup analysis from an observational cohort study

To evaluate the correlation between an uncapped, actual body weight-based unfractionated heparin dosing strategy, we performed a body mass index-based subanalysis of a previously reported pediatric cohort. Nearly half (45%) of obese patients were supra-therapeutic on initial anti-FXa assessment. Obese patients achieved therapeutic anti-FXa significantly faster than nonobese patients (median 4 vs 12 hours, P = .0192) and were more likely to have any supra-therapeutic anti-FXa levels (77% vs 35%; P = .0021). There was no statistically significant difference in major or clinically relevant nonmajor bleeding rates between weight categories (P = .69). Prospective pediatric studies are warranted to confirm our findings.

Dosing Common Medications in Hospitalized Pediatric Patients with Obesity: A Review

Medication management in children and adolescents with obesity is challenging because both developmental and pathophysiological changes may impact drug disposition and response. Evidence to date indicates an effect of obesity on drug disposition for certain drugs used in this population. This work identified published studies evaluating drug dosing, pharmacokinetics (PK), and effect in pediatric patients with obesity, focusing on 70 common medications used in a pediatric network of 42 US medical centers. A PubMed search revealed 33 studies providing PK and/or effectiveness data for 23% (16 of 70) of medications, 44% of which have just one study and can be considered exploratory. This work appraising 4 decades of literature shows several promising approaches: greater use of PK models applied to prospective clinical studies, dosing recommendations derived from both PK and safety, and multiyear effectiveness data on drugs for chronic conditions (e.g., asthma). Most studies make dose recommendations but are weakened by retrospective study design, small study populations, and no controls or historic controls. Dosing decisions continue to rely on extrapolating knowledge, including targeting systemic drug exposure typically achieved in adults. Optimal weight-based dosing strategies vary by drug and warrant prospective, controlled studies incorporating PK and modeling and simulation to complement clinical assessment.

Development and Implementation of a Standardized Heparin Protocol for Left-Sided Pediatric Electrophysiology Procedures

Heparin is used to decrease the risk of thromboembolic complications during electrophysiology studies (EPS); however, there is wide practice variation and minimal evidence to guide heparin dosing, particularly in pediatric patients. This study retrospectively analyzed heparin dosing and response, measured via activated clotting time (ACT), in patients undergoing EPS and used these data (pre-protocol cohort, n = 40), as well as guidance from available literature to implement a standardized heparin protocol (phase 1, n = 43). We utilized quality improvement methodology to refine this protocol (phase 2, n = 40) to improve therapeutic heparin response. Prior to the protocol, patients achieved therapeutic ACT levels (250-350 s) only 35% of the time which improved to 60% during phase 1 (p < 0.05) and to 73% during phase 2 (p < 0.001 compared to pre-protocol). There were no thromboses or significant adverse events in any group. These results demonstrate the effectiveness of a standardized heparin protocol in achieving effective antithrombotic therapy during left-sided pediatric EPS.

Assessment of inpatient admissions and top 25 medications for obese pediatric patients at two academic hospitals

PURPOSE

Inpatient admissions and the top 25 medications for obese pediatric patients at two academic hospitals were assessed.

METHODS

Children age 2-17 years were included if they were obese and admitted to either hospital on or after January 1, 2011, and discharged before December 31, 2011. Obesity was defined as a body mass index of ≥95th percentile for age and sex. The objectives of this study were to determine the percentage of hospital admissions involving obese children and compile a list of medications prescribed to these patients. The top 25 medications prescribed were further evaluated to determine their pharmacokinetic disposition in obese patients.

RESULTS

Obese children accounted for 18.8% of the 15,119 admissions for children age 2-17 years at the two study hospitals. No significant difference was noted in the number of obese pediatric children admitted between institutions. A total of 28,234 medications were ordered for this population, with a median number of 8 medications prescribed per admission. Sixteen of the same medications (64.0%) ranked in the top 25 at each facility. The most commonly prescribed medications for these patients included analgesics, antimicrobials, corticosteroids, bronchodilators, and gastrointestinal agents.

CONCLUSION

Obese children accounted for 18.8% of admissions for patients age 2-17 years at two academic hospitals over a 1-year period. The most commonly prescribed medications for these children included analgesics, antimicrobials, corticosteroids, bronchodilators, and gastrointestinal agents. The literature guiding the dosing of these medications in this population was limited to seven studies, representing just three medications.

Evaluation of weight-based dosing of unfractionated heparin in obese children

OBJECTIVE

To determine whether pediatric patients with obesity receiving weight-based dosages of unfractionated heparin (UFH) exhibit an enhanced response when dosed by actual body weight compared with nonobese patients as assessed primarily by the frequency of supratherapeutic anticoagulation. Secondary measures included UFH doses associated with therapeutic anticoagulation.

STUDY DESIGN

This single-institution retrospective case-matched study included children with and without obesity, matched on a 1:1 basis, who received a weight-based continuous infusion of UFH. Therapeutic monitoring values were defined for activated partial thromboplastin time (aPTT) level (70-101 seconds) and anti-activated factor X (Xa) level (0.35-0.7 U/mL).

RESULTS

The study included 50 children. The percentage of patients with supratherapeutic anticoagulation at any point in the study, as measured by either aPTT or anti-Xa level, was similar in the obese and nonobese groups (76% vs 72%; P = 1.0). However, compared with patients without obesity, those with obesity received a lower mean starting dose (17.4 vs 20.2 U/kg/hour; P = .013) and a lower mean maintenance dose (19.1 vs 24.3 U/kg/hour; P = .033) to achieve stable therapeutic monitoring test values. There was no difference in mean initial post-UFH aPTT between the 2 groups, but the mean initial anti-Xa level was higher in the obese group (0.45 vs 0.29 U/mL; P = .045).

CONCLUSION

Compared with children without obesity, those with obesity who received actual body weight-based continuous UFH infusions did not exhibit a higher frequency of supratherapeutic anticoagulation, but did require lower dosages to achieve comparable anticoagulation. Our results highlight recognized discrepancies between aPTT and anti-Xa monitoring assays.