Have you ever thought about how you would apply your knowledge in an environment that is not in or even close to the security of an emergency department?
Say you are ice climbing in the White Mountains in the middle of winter, and your climbing partner falls 30 feet while leading a climb. He loses consciousness for five minutes and then regains normal mental status. You are in a remote location with no cell service, and the weather is getting worse. It is late in the afternoon, and a storm is rapidly approaching. Do you hike out to an emergency department, or stay and not risk further injury to your partner and rescuers trying to evacuate him during a whiteout?
These are the kind of decisions you have to make in the world of wilderness medicine. It's all about decision-making, reducing risk, and making the wilderness treatment approximate real-world medicine as much as possible.
Without CT imaging, we have no idea what a patient's specific pathophysiology is, and we have to make decisions based solely on clinical assessment. Does your partner have a traumatic brain injury (TBI)? Does he have signs of increasing intracranial pressure (ICP)? Do you need to evacuate? If so, how urgently? Is it time to pull out all the stops and bring in a rescue team with a litter or even a helicopter? Or is this a case that can wait and you can hike him out in the morning when the weather has cleared? These decisions have far-reaching implications for your patient and the rescuers.
It takes someone with good medical and wilderness skills to put it all together and keep the patient safe without risking others to get him to definitive care. It's easy to take care of this patient in the ED, but it's a different story in the middle of the White Mountains. It's mostly about making good decisions.
Signs and Symptoms
TBI comprises multiple etiologies with no accurate method to differentiate the dangerous from the benign in the wilderness. The most sensitive indicator of brain injury in this environment is mental status. The AVPU scale (alert, voice, pain, unresponsive) is a simple and effective method of assessing and communicating a patient's level of consciousness. It assesses whether the patient is awake, responsive to verbal or painful stimulus, and responsive.
Increasing ICP may manifest with deterioration in mental status, seizures, posturing, persistent vomiting, and pupil changes. Significantly elevated blood pressure with bradycardia and respiratory pattern changes (Cushing's triad) can be a concerning sign suggesting brainstem herniation. If the patient sustained head trauma without loss of consciousness or amnesia, it is unlikely he would have a lesion that leads to increased ICP. The patient with head trauma but no evidence of TBI or increasing ICP is safe to observe in the field, with plans to evacuate for concerning signs such as change in mental status or deterioration.
Stabilization and Treatment
What if your partner isn't stable and shows signs of TBI and increasing ICP? First, get the rescuers headed toward you. If he can walk, start moving toward them as well. Different rescue teams have different capabilities and equipment, and you should be aware that the length of travel and the complexity of the terrain determine the number of rescuers and level of wilderness skills necessary to facilitate the evacuation safely.
It's important to maintain your patient's blood pressure above 100 mm Hg for ages 50-69 and above 110 mm Hg for those under 50 or over 69. Intravenous crystalloid can be used if available. Keep it from freezing by putting the bag next to your skin inside your shirt and drawing off boluses to administer. If the patient requires mechanical ventilation during a carryout, which in this case would be bag-valve-mask ventilation by hand, the procedure will require additional tools such as a distal one-way valve and a three-foot piece of respiratory tubing. PCO2 should be targeted at 35-40 mm Hg if end-tidal monitoring is available. Hyperventilation promotes hypocarbia and resultant vasoconstriction, but it should be used only for a severe TBI with significant deterioration indicating increasing ICP or herniation.
An osmotic agent can mitigate the mass effect of cerebral edema for a severe TBI. Hypertonic saline, a volume expander, is preferred over a diuretic such as mannitol (which likely cannot be carried in the field because of storage issues). The patient's head should be elevated at 30 degrees to facilitate jugular venous outflow if there are no concerns for intraabdominal traumatic hemorrhage. Oxygen can be applied if available, and an antiepileptic medication may be given if the patient's neuro exam is not intact or a seizure occurs. The patient should be packaged in the litter on his side, preferably in a vacuum mattress for the carryout, if he is likely to vomit.
In the case mentioned above, our climbing leader who fell 30 feet, it was smart to remain at the scene because he had no change in mental status, no nausea or vomiting, and no severe headache. Frequent reassessments showed no evidence of increasing ICP, and we hiked out the next morning 14 hours after the fall. If he had deteriorated during the night, it would have been worth taking the chance to hike out or evacuate during the storm.
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