In patients with symptoms suggestive of thoracic aortic emergency, blood pressure and pulse should be assessed for symmetry in both arms, and bilateral femoral pulses should be assessed. Discrepancy in blood pressure of greater than 20 mmHg between the arms is suggestive of aortic involvement. Hypotension is an ominous finding and may be the result of excessive vagal tone, cardiac tamponade or hypovolemia from rupture of the dissection. Neurologic deficits may be present, and syncope is also sometimes a presenting complaint.
Prehospital care should consist of ensuring adequate airway and breathing. Administer high-concentration oxygen, and assess for muffled heart sounds and jugular venous distension. ALS care involves starting two large-bore intravenous lines, as well as continuous EKG monitoring and assessment for evolving cardiac ischemia. Contact medical control for potential orders regarding blood pressure and heart rate management, as well as to authorize bypassing a nearby hospital in favor of a center with rapid surgical and intensive care capabilities.
Abdominal Aortic Aneurysm
The abdominal aortic aneurysm (AAA) is a relatively common, potentially life-threatening condition. It has a wide spectrum of presentations and should be considered in the differential diagnosis for a number of symptoms. Ruptured AAA is the 13th-leading cause of death in the U.S., causing an estimated 15,000 deaths per year. White males have the highest incidence of AAA, with more than three-fourths of patients with AAA older than 60 years.5
Expanding AAA causes sudden, severe and constant low back, flank, abdominal or groin pain. Syncope may be the chief complaint, and pain may be a less significant symptom to the patient. Patients with a ruptured AAA may present in frank shock, as evidenced by cyanosis, mottling, altered mental status, tachycardia and hypotension.
At least 65% of patients with ruptured AAA die from sudden cardiovascular collapse before arriving at a hospital.5
Presence of a pulsatile abdominal mass is found in less than half of cases. It is more commonly seen with a ruptured aneurysm. In an obese abdomen, an AAA is more difficult to palpate. Even in 25% of patients known to have an aneurysm, vascular surgeons are unable to palpate a pulsatile mass while preparing the patient for surgery. Providers need not be afraid of properly palpating the abdomen, because no evidence exists that aortic rupture can be precipitated by this maneuver.5
Misdiagnosis is fairly common, because the classic presentation of pain associated with hypotension, tachycardia and a pulsatile abdominal mass is present in fewer than 30%–50% of cases. The leading misdiagnosis is renal colic, as dissection of the renal artery may produce flank pain and hematuria.
Prehospital care includes initiation of airway and breathing support as necessary. Use of military antishock trousers (MAST) to reverse shock due to ruptured AAA may seem beneficial, but it may actually be detrimental. While their application theoretically offers temporary stabilization by compressing the leaking AAA and expanding hematoma, an undesirable reduction in cardiac output also occurs.5 Local protocol and medical direction should be followed. ALS care involves the initiation of two large-bore intravenous lines with isotonic fluid. Transport to a facility with rapid surgical ability is warranted.
The skull is the bony protective covering of the brain. After the bone is removed, the brain is protected by three layers of tissue called meninges. The first layer, closest to the skull, is the dura mater, which is Latin for “hard mother.” Hence, bleeding between the skull and the dura mater is an epidural hematoma. Peeling away the dura mater, you find the arachnoid mater, named because it resembles a spider’s web spread out over the brain. Bleeding between the dura mater and this arachnoid mater is termed subdural hematoma. Below the arachnoid mater is the pia mater, the brain’s final layer of protection, which is actually in contact with brain tissue. Bleeding in the space between the arachnoid mater and the pia mater is termed subarachnoid hemorrhage (SAH).
SAH comprises half of spontaneous atraumatic intracranial hemorrhages. SAH is a devastating condition with high morbidity and mortality, and, in the United States, it is associated with an annual cost of $1.75 billion. The annual incidence of aneurysmal SAH in the United States is 6–16 cases per 100,000 population, with approximately 30,000 episodes occurring each year. An estimated 15% of patients die before reaching the hospital. Approximately 25% of patients die within 24 hours, with or without medical attention. The mortality rate at the end of one week approaches 40%. Half of all patients die in the first six months.6