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46 JANUARY 2018 | EMSWORLD.com CONTINUING EDUCATION • Psychiatric conditions • Seizure or postictal More questions: 8. What is the definition of sepsis? 9. What endocrine gland produces cortisol? 10. How does cyanide act as a poison? Hallmark findings may lead prehospital providers to suspect a particular cause for each of the above conditions based on inci- dent history, physical exam, field diagnostic tests, and medical background. Back to the Case The man in the alley requires a thorough trauma assessment to determine if he has signs of a head injury or internal bleeding. Assault or fall can't be ruled out, neces- sitating a detailed thoracic and abdominal assessment. An irregular heartbeat could indicate atrial fibrillation, increasing stroke risk in a man who's not compliant with antico- agulation medication, and anticoagulation increases the risk of intracerebral bleed- ing. Motor assessment should indicate bilateral withdrawal to painful stimulus; unilateral findings would suggest cerebro- vascular accident. Following a trauma survey, you place the man on a stretcher in the warm and well-lit ambulance. Diagnostic tests reveal a blood pressure of 95/55 and a respiratory rate of 10, with 96% oxygen saturation on room air. His temperature is cold, atrial fibrillation is at a rate of 55 with no STEMI, and blood glucose is normal. A detailed physical exam reveals the scent of alcohol on the man's breath. A hematoma is felt beneath the hair on the right side of his head. His pupils remain equal and reactive, air entry is clear, and the abdomen is soft and not tender. You find no rash, no track marks, and no medi- cal ID bracelet. More questions: 11. What are the diagnostic criteria for atrial fibrillation? 12. Why can atrial fibrillation cause a stroke? 13. Name the two organs in the abdomen most likely to cause significant bleed- ing in cases of abdominal trauma. Prehospital Management Supportive care of the ABCs is of the utmost importance until a definitive diag- nosis can be determined. Airway management may consist of manual maneuvers such as the head tilt and jaw thrust, which may improve ventila- tion and oxygenation. Attempt naso- and oropharyngeal lumens before intubation, as advanced airway management may be postponed until hospital arrival unless oxy- Blood in the Brain The Monro-Kellie hypothesis states that the brain is a closed space (the cranial vault) with a single outlet where the spinal cord exits. The vault has three contents: blood, brain, and cerebrospinal fluid (CSF). If the volume of one of these increases, the volume of the other two must decrease for pressure to stay the same. As brain volume cannot change, CSF must be expelled from the vault through the spinal canal if blood accumulates. There are four types of bleeds that occur inside the cranial vault. A careful history and physical can often determine which type of bleed is most likely long before CT scans can be performed. Epidural bleeds—Epidural bleeds are arterial and tend to be associated with a direct blow to the temple. The middle meningeal artery is the culprit in most cases; it rapidly pumps blood into the epidural space. The classic presentation is an initial loss of consciousness caused by the blow, followed by a period of lucid behavior, followed by deteriorating GCS as the blood accumulates and the brain is compressed. Subdural bleeds—Subdural bleeds are venous in nature and often accumulate slowly, sometimes over a matter of weeks. They tend to bleed when stretched, as is the case where there has been brain atrophy followed by a good shaking. A textbook presentation would be a patient who is older or has alcoholism—both have slightly shrunken brains that can rattle around when the head shakes—with a history of falls. The trauma doesn't necessarily have to be significant, as the smaller brain can tug at the veins and cause small, slow bleeds. Subarachnoid bleeds—Subarachnoid bleeds are often arterial and caused by malformations or aneurysms that were pre-existing. They tend to affect middle- aged people and classically present as a "thunderclap" headache—a sudden, "worst-ever" headache. The blood irritates the meninges, and patients often complain of stiff necks, photophobia, and nausea. Hypertension is often witnessed before and after the bleeding begins. Intraparenchymal bleeds—Finally, intraparenchymal bleeds, or intracerebral bleeds, occur inside the brain matter itself, beneath the pia mater. They can be caused by trauma, tumors, or hypertension. They often present similarly to an isch- emic stroke in that a territory of the brain is disabled and focal neurologic deficits can be observed. Obtain a thorough patient history in suspected cases of blood in the brain. Patients on antiplatelet medications such as ASA and clopidogrel and antico- agulant medications such as warfarin or dabigatran are at higher risk of bleeding. Afford additional clinical suspicion to patients on these medications who suffer head trauma. A CT is often warranted even in the absence of headache and neuro- logic deficit. And don't forget to ask about blood thinners. —Blair Bigham, MD, MSc, EMT-P