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Age-related carbon dioxide reactivity in children after moderate and severe traumatic brain injury
Tensing Maa1, Keith Owen Yeates2, Melissa Moore-Clingenpeel3
1Nationwide Children's Hospital and.
Insights
Carbon dioxide reactivity (CO2R) is often impaired in children after traumatic brain injury (TBI), with younger children showing lower CO2R. Impaired CO2R is linked to poorer outcomes in pediatric TBI patients.
Area of Science:
- Pediatric Neurology
- Neurocritical Care
- Physiology
Background:
- Traumatic brain injury (TBI) in children can significantly impact neurological function.
- Assessing cerebral autoregulation, such as carbon dioxide reactivity (CO2R), is crucial for managing pediatric TBI.
- Age-related differences in CO2R following TBI are not well understood.
Purpose of the Study:
- To evaluate carbon dioxide reactivity (CO2R) in mechanically ventilated children with moderate to severe TBI.
- To investigate age-specific variations in CO2R among pediatric TBI patients.
- To determine the association between CO2R and patient outcomes.
Main Methods:
- A prospective observational study involving 38 mechanically ventilated children (<18 years) with TBI.
- Daily CO2R testing using transcranial Doppler (TCD) to measure changes in middle cerebral artery flow velocity.
- Patients were stratified into three age groups: <2 years, 2-5 years, and >5 years.
Main Results:
- Children younger than 2 years demonstrated lower mean CO2R over time.
- The 2-5 year age group exhibited significantly higher CO2R compared to both younger (<2 years) and older (>5 years) children.
- Lower minimum CO2R values were significantly associated with worse discharge outcomes (p=0.0413).
Conclusions:
- Abnormal CO2R is common in pediatric TBI, with varying degrees of impairment across different age groups.
- No specific clinical or laboratory risk factors for impaired CO2R were identified.
- Reduced CO2R, particularly lower minimum values, correlates with adverse outcomes in pediatric TBI.
Abstract:
OBJECTIVE The objective of this study is to assess carbon dioxide reactivity (CO2R) in children following traumatic brain injury (TBI). METHODS This prospective observational study enrolled children younger than 18 years old following moderate and severe TBI. Thirty-eight mechanically ventilated children had daily CO2R testing performed by measuring changes in their bilateral middle cerebral artery flow velocities using transcranial Doppler ultrasonography (TCD) after a transient increase in minute ventilation. The cohort was divided into 3 age groups: younger than 2 years (n = 12); 2 to 5 years old (n = 9); and older than 5 years (n = 17). RESULTS Children younger than 2 years old had a lower mean CO2R over time. The 2-5-year-old age group had higher mean CO2R than younger patients (p = 0.01), and the highest CO2R values compared with either of the other age groups (vs > 5 years old, p = 0.046; vs < 2 years old, p = 0.002). Having a lower minimum CO2R had a statistically significant negative effect on outcome at discharge (p = 0.0413). Impaired CO2R beyond Postinjury Day 4 trended toward having an effect on outcome at discharge (p = 0.0855). CONCLUSIONS Abnormal CO2R is prevalent in children following TBI, and the degree of impairment varies by age. No clinical or laboratory parameters were identified as risk factors for impaired CO2R. Lower minimum CO2R values are associated with worse outcome at discharge.
