The purpose of this study was to evaluate application of standard therapy guidelines and recognize other risk factors with regard to the management of severe pediatric TBI in the ED. Two key findings from this study relate to metrics outlined in current TBI guidelines; timeliness for retrieval of first PCO2, and indications for hyperosmolar therapy. Two non-guideline metrics showed that the HOB was not elevated in a large majority of our patients, and an inconsistent presence of physicians with airway expertise accompanying patients to the CT scanner.
One of the deficiencies we reported was a timely retrieval of PCO2. Cerebral blood flow varies proportionally with PCO2 and is the most important factor that balances ICP exacerbation with adequate cerebral oxygenation [9]. Although most patients received EtCO2 monitoring within fifteen minutes of ED admission, a blood gas was obtained in only 34% of our patients during this time, and even fewer received corrections to maintain target normocapnia. Targeted ventilation in the ED has been well documented for optimal discharge outcomes in patients with normocarbia (PaCO2 = 36–45 mmHg), and increased mortality with hypocapnia and hypercapnia (PaCO2 ≤ 35 mmHg, and ≥ 46 mmHg, respectively) [9]. As important, EtCO2 is not an adequate initial surrogate for PCO2 in pediatric patients with severe TBI, but its trend can be useful between PCO2 retrieval times [10, 11].
This study also gathered data around hyperosmolar therapy administration based on clinical and radiological signs of raised ICP. Although the gold standard for ICP monitoring is placement of an intracranial monitor, it is obviously not feasible during the initial resuscitation in the ED [12, 13]. The most challenging part of targeted hyperosmolar therapy in severe TBI has been the proper identification of increased ICP. Thirteen of our patients received hyperosmolar therapy, with an even split between CT and clinical indication for its use. Clinically changes in Glasgow Coma Scale, pupillary reactivity, and herniation syndrome are often late signs of raised ICP. Radiographically, a CT scan can be inconclusive in quantifying ICP after severe TBI [13, 14], unless obvious criteria have been met. Together, they point to the utility of more novel techniques of reliably and rapidly estimating ICPs, such as transcranial dopplers or ultrasonography of optic nerve sheath diameters [12].
Adult ED management guidelines by the Seattle International Brain Injury Consensus Conference included elevation of HOB to 30-45o as an intervention [15]. HOB elevation can have beneficial effects on raised ICP by facilitating cerebral blood flow, increasing cerebrospinal fluid drainage, and maximizing cerebral venous return [16, 17]. Although our study found that only 4% of patients had their HOB elevated, current pediatric TBI guidelines do not address this potential therapy. Interestingly, the wide range of HOB elevation recommendations in adults is likely indicative of patient height variations and consequential hydrostatic differences between skull base and heart level [17]. Given the known beneficial effects of elevating the HOB including lowering ICP as well as other multisystem effects in severe TBI [18, 19], we recommend it as a high-level priority in the initial ED management with normotensive patients.
Finally, we identified that brain CT in the ED may require further considerations. Our study found that 5% of patients experienced adverse events during CT scan, with only 65% of patients being accompanied by a physician with airway expertise. However, a recent national study examined CT practice standards for severe pediatric TBI across tertiary care centers in Canada, and found that over half of the respondents experienced an adverse event in CT [20]. These events, including airway complications may be avoided with the correct care team at bedside.
Major limitations in this study included the small population cohort, the nature of chart reviews, as well as variability in pre-hospital care. Inherent in a chart-review, data collection relies on accurate chronicling, thus calling to question the certainty regarding absence of the expected management versus failure of documentation. This limitation was especially important regarding HOB position. Lastly, patients arrived to the tertiary care hospital with previous management outside of our documentation parameters. The scope of this study did not include pre-hospital management that may have affected ED management protocols on arrival.