Thank you. Thank you for having me. I am a neurointensivist at Massachusetts General Hospital in Boston. And I will be talking about traumatic brain injury in the context of resource-limited settings. I have no disclosures pertaining to this talk. So I'll be outlining the basic pre-hospital management of traumatic brain injury and then special considerations in combat casualty care and also in specific resource-limited settings, for example, absence of imaging or absence of neurophysiologic monitoring that we routinely do in severe TBI. So traumatic brain disease, population health studies have shown that the annual global incidence of traumatic brain injuries is anywhere from 27 to 69 million and among the leading causes of mortality. Up to half of these mortalities happen within the first two hours. And from various records in combat and in the military set up to 70% of these fatalities can happen within the first few minutes, the first hour of traumatic brain injury. Which is why the early resuscitation is critical, not just for the primary brain injury itself, but for the secondary brain injury that ensues within minutes to hours and can significantly increase morbidity or mortality. Just to reiterate or highlight traumatic brain injuries, typically the severity is guided by the Glasgow Coma Scale and it's categorized as mild, moderate, or severe TBI based on the GCS. So what are the key components of resuscitation? And this is pre-hospital first responder resuscitation. The assessments focus primarily on hemodynamics, oxygenation, and blood pressure. And then the neurologic exam, particularly the Glasgow Coma Scale and the pupillary exam, which really clue you into whether the patient has raised intracranial pressure, ongoing or impending herniation. And then the treatments are targeted specifically to these with airway, ventilation, oxygenation, hemodynamics support, c-spine immobilization, and then treatments targeted towards cerebral herniation, if that is evident on the exam. So starting with oxygen and hemodynamics, and I won't go too much into this because I know there's talks coming up on mechanical ventilation and oxygenation. But for TBI patients specifically, hypotension, and there are studies that show even a single episode of hypotension defined as systolic blood pressure less than 90 millimeters of mercury is associated with worse outcomes. Similarly, hypoxemia increases morbidity and mortality, and this is a dose-dependent relationship. So the more hypoxemic a patient is, the higher the likelihood of increased mortality and worse functional outcomes. And so the initial resuscitation, the goal of resuscitation is really to maintain cerebral perfusion and minimize neuronal injury. And so when it comes to hemodynamics, supplemental oxygen, of course, for keeping SADS greater than 90. If a patient is maintaining their saturation greater than 90% with supplemental oxygen or on their own, intubation does not need to be prioritized and focus more on prioritizing intubation in patients where their comatose have a GCS less than 9, unable to ventilate or hypoxemic despite supplemental oxygen. Fluid resuscitation is with isotonic fluids. You can consider hypertonic fluids. There's no data to say hypertonic fluids are better, but there are small studies that show they may improve survival. So if there's concern that there is high ICP or impending herniation, hypertonic fluids can also be considered during resuscitation. And again, I won't delve too much into this because there is additional talks on shock management in the trauma setting. So what I'll focus more on is the neurologic exam and particularly markers for cerebral herniation. And this is critical because for both in the field for first responders or at a first response in low resource settings, the clinical exam is really what clues you in into how severe the TBI is and whether or not there is risk for herniation, especially in scenarios where imaging is not available or not immediately available. Close monitoring of the clinical exam is what helps in triaging and moving these patients. So first and foremost, the Glasgow Coma Scale. The GCS is a very reliable, significant and reliable indicator of outcomes in patients with traumatic brain injury. And it should be assessed on initial assessment and then with serial assessments. The focus, however, the importance is that the GCS is assessed once a patient has been resuscitated. Hypotension, hypoxemia, initial medications, all of these can also confound or impact the GCS. And so after initial resuscitation is when the GCS should be followed and monitored closely. And signs that are concerning for increased intracranial pressure or impending herniation includes decreasing or a decline in the GCS, particularly a decline of two or more points if their starting GCS was nine or higher. Absence of motor responses, posturing and unilateral posturing are all concerning. Unilateral posturing means flexion or extension of one arm and one leg or on one side, which clues us into the possibility of a large structural brain injury or hemorrhage in the opposite hemisphere. Next is the pupillary exam. And again, pupils should be assessed once the patient has been resuscitated and is hemodynamically stable. And what we're looking for is not just evidence of orbital injury, but we're looking for asymmetry, more than one millimeter difference between the pupil's fixed or unreactive pupils. The pupils are not specific, so they can be abnormal in different conditions, also in the setting of medications or paralytics, for instance. However, abnormal pupil exam in the context of GCS and the injury mechanism is critical and following the pupils and noting a change in pupillary exam is what is critical. Other signs and symptoms that are essential to look for, especially as you're waiting for transfer or if imaging is not immediately available, the Cushing's triad is a physiologic response characterized by systolic hypertension, diastolic hypertension, and a widened pulse pressure, bradycardia, and irregular breathing and is a sign of ongoing or impending herniation. The lucid interval, so this is when a patient is initially comatose and then regains consciousness for minutes to hours, followed by loss of consciousness again. And this is typically seen with expanding epidural hematomas. Ongoing or persistent vomiting, which is a sign of raised intracranial pressure. And then the injury mechanism itself, as well as presence of fractures, depressed skull fractures, all of these raise or put patients at higher risk for having elevated intracranial pressure, as well as cerebral herniation. So if we see any of, sorry, this is jumping. Presence of any of these signs, of course, raise concern for intracranial hypertension. And what are the things that we can do immediately on the field is first ensure the patient's head is midline at 30 degrees. The midline position prevents compression of your venous sinuses, jugular veins, sorry, and which can cause rise in intracranial pressure. And elevation at 30 degrees also helps in lowering intracranial pressure. Hyperventilation should not be instituted prophylactically. There is data showing prolonged hyperventilation in DBI patients is actually associated with worse outcomes. However, it is recommended as a temporizing measure if there is evidence or concern for raised intracranial pressure. And this is typically done by giving about 20 breaths per minute. And if there is an entitled CO2 targeting 30 to 35, again, transiently as a temporizing measure, watching the exam, seeing if the signs concerning four raised intracranial pressure are improving. And as we're waiting or trying to get patients to more definitive management. And then finally, hyperosmolar treatment. This includes mannitol and hypertonic saline ranging anywhere from 3% to 23.4%. There are no large randomized trials comparing one versus the other. There are some studies in DBI specifically that show hypertonic saline can lower the ICP better than mannitol. It's really what's available. In general, particularly for more severe DBI patients where there's concern for other shock or ongoing hemorrhage, hypertonic saline may be a better option as mannitol itself can cause diuresis and can worsen the shock. So if available, using hypertonic saline. Specific considerations. So there are clinical practice guidelines for management of DBI in the battlefield. Level one is the immediate first responder care. And it essentially has the same principles as what I talked about in pre-hospital care, even in the civilian settings. Just to note, specifically for hyperosmolar treatment, for instance, mannitol, it can crystallize in hot and humid environments. So another situation where if we're thinking or considering hyperosmolar treatment, using hypertonic saline. Similarly, when we're using paralytics and sedatives, vacuronium does not require refrigeration and can be considered as a preferred agent, propofol for sedation. And then bolusing paralytics and analgesics as opposed to continuous infusions. So the next step really is where these are the immediate resuscitations for any patient where there's concern for severe DBI, impending herniation, really the next step is getting them to a facility where there's neuroimaging, monitoring, neurosurgical expertise, and then availability for monitoring for secondary brain injury. And what I'll talk about is how to approach this when these resources are not available. So first, if there's no imaging available at all, then of course serial neurologic exams as we talked about, focusing on the GCS. The four score is also an outcome score. It's a little more elaborate where we look at eye exam, motor exam, brainstem reflexes as well as respiratory patterns. It sort of overcomes the limitation of the verbal score for the GCS as it doesn't require that. Monitoring the pupils, assessing for Cushing's triad, and looking for any deterioration in the exam. If x-rays are available, skull x-rays can help particularly if there's a penetrating injury and can help localize the area or help localize the area of potential hemorrhage or structural injury. Invasive monitoring, so ICP monitoring, Brain Trauma Foundation recommends in comatose patients with imaging abnormalities or those who are comatose have no imaging abnormalities but are either over 40 years of age, are posturing, or are hypotensive. And of course, these resources are not available in resource-poor areas and during humanitarian crisis. So how do we monitor? What are the other resources that we can use? We already talked about the exam. There are some non-invasive neuromonitoring devices, ultrasound to measure the optic nerve sheet diameter, transcranial dopplers to measure cerebral blood flow velocity, quantitative pupillometry using portable EEG, which is a small device that can help localize focal areas of slowing and potential hemorrhage. Similarly, near-infrared spectroscopy is also a non-invasive device that can help localize an area of cerebral hemorrhage. Now these are non-invasive. The caveat here is there's no large trials. They're not validated in randomized controlled trials. There can be operator dependency, for example, in dopplers or ultrasound, potential for false positive results. They are smaller and more compact, and therefore, it may be easier to bring them to areas where you can't bring a large CT scanner or other resources. Some of these, for instance, portable EEG and NIRS have been field tested in some of the larger military bases and are available to be deployed in certain areas. But again, these come with their own limitations, but that they may not be immediately available. And then in the absence of any data, how do we manage these patients? So the medical management, we talked about the immediate medical management with brief temporizing hyperventilation, hyperosmolar agents. If there is a patient where there's a high concern for cerebral herniation, there's no imaging available, we can't immediately transport these patients to get them to a place for definitive care. One possibility is to use just scheduled treatment. So scheduled hyperosmolar, intensifying sedation, intensifying analgesia, using paralytics. Of course, there has to be an end point, and giving these medications overuse can have their own adverse effects. So sort of balancing what the threshold or concern for high ICP is with how soon they can be transferred and using that as a guide for how long to schedule these treatments. What about surgical considerations in this patient population, particularly in the absence of imaging? And this was a recent publication by Goddard and Ravenstein, and really drawn from lower middle-income countries and low-resource settings in how to approach these patients. And I'll quickly walk us through some of these, and then I'll be done. So if you have a severe TBI patient, after resuscitation is the key, they have fixed dilated pupils, GCS less than three, then these are the patients that really have a poor prognosis. When we are thinking of triaging, we look at patients that have a GCS of three to eight. If they have a normal motor response, normal pupils, if there is availability of non-invasive monitoring determining if they have intracranial pressure elevation or not. If their exam has normal motor pupil responses, and if we don't have a non-invasive monitoring but their exam seems to be stable and not deteriorating, continuing to monitor these patients as we try to get them to a place of higher level of care. If there's any clinical sign or concern or non-invasive concern for raised intracranial pressure, we institute medical management that I just talked about. If despite medical management, or if their exam is worsening and they have now posturing and other signs, surgical considerations in low-resource settings where there is no imaging available can include performing exploratory burr holes with a neurosurgeon, by a neurosurgeon or a trained non-neurosurgeon and really using that to guide care. If the burr hole shows evidence of hemorrhage, performing a craniectomy if that resource is available versus drainage through the craniotomy and then transferring those patients out. Typically in combat casualty considerations level two is where you have more advanced medical care available and this is where initial emergency life-saving surgery or craniotomies can be considered and there's clinical practice guidelines for this considering surgery only if there is, in consultation with a neurosurgeon, if there's clinical signs that are concerning for herniation and despite medical management and there's inability to get this patient transferred out within the next four hours and there's trained personnel available then these emergency craniotomies can be considered. And then finally, is there any data on to prevent hemorrhage expansion and this is based from the CRASH-3 trial which was a large randomized trial randomizing patients to tranexemic acid versus placebo and they included patients that had a low GCS of less than 12 or intracranial hemorrhage, no major extracranial breeding and treatment had to be instituted within three hours and what they found was that overall there was a slight reduction in the risk for death, the outcome here was death in patients that received tranexemic acid where they found the greatest impact was in patients with mild to moderate TBI where there was a relative risk reduction of about two points especially if it was instituted early and the TXA was safe, there was no significant difference in adverse outcomes and so it's a consideration, it should be administered early and in temporizing patients as we're trying to move them out. So in summary, early resuscitation to maintain cerebral perfusion is the key in limited resources, the clinical exam is key in helping to guide and triage these patients and ultimately when we're transferring these patients out there we have to, if there's concern for high ICP, if there's a monitor available keep it in, if there's no ICP monitor scheduling treatments to transfer them out safely, if there's evidence of pneumocephalus you want to consider holding off an air transfer as that can be worsened due to pressure changes, so just additional considerations in moving these patients out once that is available. Thank you for listening, I hope I'm on time.

Traumatic brain injury

resuscitation

cerebral perfusion

intracranial pressure

neuromonitoring devices