Prevalence and impact of admission hyperfibrinolysis in severely injured pediatric trauma patients

Abstract

Introduction: Hyperfibrinolysis (HF) on admission is associated with increased mortality in adult patients with trauma. Several studies have demonstrated that 9% of severely injured adults present to the emergency department (ED) with HF. Our aim was to (1) define HF in pediatric patients and develop a relevant cut-point for therapeutic intervention (if any); (2) identify the prevalence of HF in severely injured pediatric patients; and (3) determine whether HF on admission is as lethal a phenomenon as it is in adults.

Methods: After approval from the institutional review board (Committee for the Protection of Human Subjects), we identified all pediatric trauma admissions (patients ≤17 years old) who met highest-level trauma activation criteria between January 2010 and December 2013. Fibrinolysis rates were determined with LY-30 by rapid thrombelastography, which represents the percent decrease of the maximal clot amplitude (fibrinolysis) 30 minutes after such amplitude is achieved. HF was defined a priori as an initial LY-30 inflection point that translated to a doubling of mortality. Two previous studies in adults demonstrated an inflection point of ≥3% where mortality doubled from 9 to 20%. We began by identifying a relevant inflection point to define HF and its prevalence, followed by univariate analysis to compare HF and non-HF patients. Finally, a purposeful logistic regression model was developed to evaluate clinically relevant predictors of mortality in severely injured pediatric patients.

Results: A total of 819 patients met study criteria. LY-30 values were plotted against mortality. A distinct inflection point was noted at ≥3%, where mortality doubled from 6 to 14%. Of note, mortality continued to increase as the amount of lysis increased, with a 100% mortality demonstrated at a LY-30 ≥30% (compared with 77% in adults). Using LY-30 ≥3%, we stratified patients into HF (n = 197) and non-HF (n = 622) groups, with prevalence on admission of 24%. With the exception of HF patients being younger (median age 11 vs 15 years; P < .001), there were no differences in demographics, scene vitals, or Injury Severity Scores between the groups. On arrival to the ED, HF patients had a lesser systolic blood pressure (median 118 vs 124 mm Hg) and lesser hemoglobin (median 12.2 vs 12.7 g/dL); both P < .001). Controlling for age, arrival vital signs, admission hemoglobin, and Injury Severity Score, we found that logistic regression identified admission LY30 ≥3% (odds ratio 6.2, 95% confidence interval 2.47-16.27) as an independent predictor of mortality.

Conclusion: Similar to adults, admission HF appears to reach a critical threshold at a LY30 ≥3% in pediatric patients. Admission HF in pediatric patients occurs more frequently than in adults (24 vs 9%) but is associated similarly with a substantial increase in mortality (6-14%). When controlling for additional factors, we found that admission LY-30 ≥3% has an odds ratio of 6.2 (P < .001) for mortality among severely injured pediatric patients. HF on admission may serve to identify rapidly those injured children and adolescents likely to benefit from hemostatic resuscitation efforts and to guide antifibrinolytic therapy.