The Pre-brief
Traumatic brain injuries (TBIs) are caused by blunt and or penetrating forces that impact the brain and disrupt its function. According to CDC data, more than 64000 Americans died in 2020 from TBI, and many more experience long-term sequelae, making them one of the major causes of mortality and morbidity across all age groups. While anyone can experience a TBI, the available data suggests that the social determinants of health have a substantive impact on the outcomes associated with them. Marginalized and disadvantaged groups including racial and ethnic minorities, individuals experiencing houselessness, survivors of domestic abuse and intimate partner violence, incarcerated people, as well as service members and veterans all experience increased death and disability when suffering from TBI
When a TBI occurs, the injury transpires in 2 phases. At the moment the traumatic force impacts the brain, the primary injury occurs and there is immediate structural damage to the brain, surrounding tissues, and bones. Even if the injury occurs in front of a fully staffed trauma bay, the damage is instantaneous and unavoidable. Secondary TBI happens after the initial injury and is caused by poor blood flow to the central nervous system and cellular hypoxia in the cerebral neurons. In many cases, secondary brain injuries associated with TBI can be mitigated by the care that is provided in the prehospital setting.
The Excellence in Prehospital Injury (EPIC) Study
The EPIC TBI study ran from 2007 to 2019 and involved an EMS and public health partnership in Arizona. It included the statewide implementation of the Brain Trauma Foundation and the NAEMSP guidelines for prehospital management of TBI. Their findings strongly indicate that the care provided in the field by EMS providers can have a substantial impact on TBI patient survival.
The study occurred in 3-phases which included retrospective analysis, staff training and protocol implementation, and finally prospective analysis with ongoing education. In total, about 22,000 patients were enrolled including approximately 4,000 patients who were intubated in the field. The data was collected from 2007 until 2015, analyzed from 2015 until 2019, and then published in 2019. Since then, their recommendations are quickly becoming the ubiquitous standard of care for prehospital TBI management.
On November 1, 2021, the Commonwealth of Pennsylvania joined a growing group of states that have adopted the EPIC findings as part of a statewide TBI management protocol.
The training associated with the EPIC program is low cost, low tech, and incredibly high yield. The program focuses on avoiding hypoxia, hyperventilation, and hypotension. There are no major changes in equipment or treatment paradigms. They bring attention to detail and slightly adjusted clinical parameters to the standard treatment modalities already used by prehospital clinicians. The results after implementation were nothing short of astonishing. Among adult TBI patients the adjusted survival doubled among patients with severe TBI and tripled among the patients that experienced severe TBI and were intubated. In 2020 the EPIC4Kids study was published and the findings among pediatric TBI patients were similar to that of adults. Among children with severe TBI, the implementation of the new guidelines leads to a substantial improvement in adjusted survival to hospital admission as well as survival to discharge.
- Hypoxia must be prevented. If hypoxia occurs and the patient experiences an SPO2 of less than 90%, even if corrected quickly, the likelihood of mortality is doubled. Every patient with a TBI should receive at a minimum high flow oxygen via non-rebreather mask. If indicated aggressive BLS airway management with positive pressure ventilation (PPV) is appropriate. Advanced airway management should be approached with caution. Frequently, prehospital advanced airway management is associated with hypoxia, even when it is successful on the first attempt, which is extremely deleterious to the TBI patient. Advanced airway management should only be considered when BLS airway management is ineffective, there is an extended transport time, or the patient is at high risk for aspiration. When providers do decide to attempt intubation or even the placement of a supraglottic airway then the patient must be pre-oxygenated as well as possible. Do not forget that a low pulse oxygenation is lagging indicator of overall tissue hypoxia and once the patient’s SPO2 begins to drop you are already in danger of increasing secondary brain injury.
- Hyperventilation must be avoided. Unintentional hyperventilation often occurs and among all patients receiving positive pressure ventilation. When a TBI patient experiences hyperventilation it has been shown to increase mortality by 6 times. To avoid this strict attention to detail must be maintained. When an adult patient is ventilated appropriately, they should only receive 10 breaths per minute which will inevitably feel incredibly slow to the clinician providing the PPV. A few ways to improve compliance with strict normo-ventilation parameters include using a ventilation metronome like the one pictured which presents the ventilator with a light that flashes once every 6 seconds, the use of pressure-controlled BVMs which prevent the delivery of excessive tidal volume with each squeeze of the bag, continuous ETCO2 monitoring with a target of 40 mmHg (35-45mmHg range), and finally the use of a ventilation spotter to observe the primary ventilator and provide real-time feedback and coaching. It has been past practice to encourage EMS providers to hyperventilate patients with suspected cerebral herniation. There is very little evidence to support this practice. If true herniation has occurred in the field, then the patient has a poor prognosis. The signs and symptoms of herniation that are typically observed in the field such as unilateral pupil dilation, hemiparesis, posturing, and unusual respiratory patterns can all be mimicked by patients with severe TBI that have not experienced herniation. For patients that have experienced herniation, hyperventilation is unlikely to help and for those who present with a mimic, it will cause significant harm.
- Hypotension is deadly for TBI patients. Even a single episode of hypotension where the patient’s systolic blood pressure is less than 90 mmHg is associated with at least a 2-fold increase in the mortality associated with TBI. Multiple episodes or persistent hypotension can increase the risk of death by 8 times. To prevent hypotension manageable causes such as hemorrhage should be identified and managed. Blood products should be administered if available. If crystalloids are the only product available to treat hypotension then adults should receive a 1000mL saline solution bolus, followed up with 500mL boluses up to a max of 2000mL. Pediatric patients should receive 20mL/kg of saline solutions repeated as needed with a maximum dose of 60mL/kg.
The Debrief
- The prehospital care provided to patients with severe TBI can help prevent secondary brain injury and increase the patient’s chances of survival and meaningful recovery.
- All patients with known or suspected TBI should receive 100% oxygen via a non-rebreather mask and or appropriate airway management with positive pressure ventilation (PPV) and 100% oxygen.
- Hyperventilation must be prevented when providing PPV. Adults, 15-years or older should receive 10 breaths per minute, children from 2-14 years old should receive 20 breaths per minute, and infants from 0 to 2 years old should receive 25 breaths per minute. Adjuncts like a metronome or ventilation spotter should be used to prevent unconscious hyperventilation.
- Hypotension must be avoided. While permissive hypotension has been shown to be beneficial for many trauma patients, when a TBI is present it can be deadly. Fluid boluses should be used to ensure that the patient maintains a systolic blood pressure of 90mmHg or greater.
