Heart Rate Variability in Children with Moderate and Severe Traumatic Brain Injury: A Prospective Observational Study

Objective: To assess feasibility of continuous monitoring of heart rate variability (HRV) in children with traumatic brain injury (TBI) hospitalized in a Pediatric Intensive Care Unit (PICU) and collect preliminary data on the association between HRV, neurological outcome and complications. Method: Prospective observational cohort study in a tertiary academic PICU. Children are admitted to the PICU 24 h after moderate or severe TBI were included. Children suspected of brain death at PICU entry or with a pacemaker were excluded. Children underwent continuous monitoring of electrocardiographic (ECG) waveforms over 7 days post TBI. HRV analysis was performed retrospectively, using a standardized, validated HRV analysis software (CIMVA). The occurrence of medical complications (“event”: intracranial hypertension, cerebral hypoperfusion, seizure and cardiac arrest) was prospectively documented. Outcome of children 6 months post TBI was assessed using the Glasgow Outcome Scale – Extended Pediatric (GOS-E Peds). Results: Fifteen patients were included over a 20-month period. Thirteen patients had ECG recordings available and 4 had >20% missing ECG data. When ECG was available, HRV calculation was feasible (average 88%; range 70-97%). Significant decrease in overall HRV Coefficient of variation and Poincaré SD2 (p<0.05) at 6 hours post-PICU admission was associated with an unfavorable outcome (defined as GOS-E Peds ≥3, or a deterioration of ≥2 points over baseline score). Several HRV metrics exhibited significant and non-significant variation in heart rate variability during event. Conclusions: This study demonstrates that it is feasible to monitor HRV in the PICU provided available ECG data, however missing ECG data is not uncommon. These preliminary data suggest that altered HRV is associated with unfavorable neurological outcome and in-hospital medical complications. Larger prospective studies are needed to confirm these findings and to explore if HRV offers reliable and clinically useful prediction data that may help clinical decision making.