Background: Unfractionated heparin (UFH) dosing may need to be adjusted when used in obese patients. The prevalence of pediatric obesity is increasing and, to our knowledge, no data exist to determine the effect of obesity on UFH therapy in children.
Objective: To determine whether obese pediatric patients who receive a weight-based dose of UFH in the cardiac catheterization laboratory exhibit an enhanced response compared with those of normal body habitus.
Methods: The records of pediatric patients who underwent a cardiac catheterization procedure from September 2006 to September 2010 at Texas Children's Hospital were reviewed. Patients were included if they had received a bolus dose of UFH during their procedure, and had pre- and post-UFH bolus activated clotting time (ACT) values determined. Patients were identified as obese if their body mass index (BMI) was at the 95th percentile or more for age and sex and were matched by age, sex, and catheterization procedure to a control group of patients with a BMI lower than the 95th percentile. Differences in demographic, UFH, and ACT variables were compared between obese and nonobese paired groups.
Results: Seventy-eight patients (39 obese) met study criteria; 46 (58.9%) patients were male. The primary catheterization procedure was radiofrequency ablation (n = 32). There was no statistically significant difference in the mean (SD) dose per kilogram of UFH administered (72.3 [24.9] vs 63.6 [23.6] units/kg; p = 0.12) and no statistically significant difference in the time after the UFH bolus that the ACT was measured (52  vs 56  minutes; p = 0.59) between the 2 groups. No statistically significant difference was noted in the percent change in ACT after UFH bolus in obese compared to nonobese pediatric patients (196%  vs 165% ; p = 0.17).
Conclusions: No significant difference in response to UFH was identified in obese pediatric patients compared to nonobese pediatric patients as measured by ACT in the cardiac catheterization laboratory.