Diagnosis of Acute Aortic Dissection

Reference: Gibbons et al. The sonographic protocol for the emergent evaluation of aortic dissections (SPEED protocol): A multicenter, prospective, observational study. AEM February 2024. Date: February 28, 2024 Guest Skeptic: Dr. Neil Dasgupta is an emergency medicine physician and ED intensivist from Long Island, NY.  He is the Vice Chair of the Emergency Department at Nassau University Medical Center in East Meadow, NY, the safety net hospital for Nassau County. Case: A 59-year-old man walks into your community emergency department (ED) complaining of chest pain. It is described as a ripping sensation that radiates to his back. His vital signs are all normal and the ECG done at triage does not show an occlusive myocardial infarction. The chest x-ray is unremarkable, and his troponin is not elevated. You suspect an acute aortic dissection (AoD). However, your CT scanner is offline for two hours of scheduled maintenance. He will need to be transferred to the tertiary care center which is 35 minutes away by ground EMS if it is a dissection. Your Spidey senses are tingling, and you don't want to wait for the CT scanner to be back online to make the diagnosis. Arrangements are made for him to be transferred stat to the tertiary hospital while he is still stable. You wonder if a quick POCUS examination looking for three sonographic findings while waiting for the paramedics could help determine the likelihood of this being an AoD. Background: We recently covered acute aortic syndrome (AAS) on SGEM#430. AAS has been called the lethal triad and includes aortic dissection (AD), intramural hematoma (IMH), and penetrating aortic ulcer [1]. It is a rare but deadly condition that can present in atypical ways leading to delays in diagnosis and an associated increase in mortality. This episode is going to focus on acute aortic dissection (AoD) which is classified into two major types according to the Stanford classification system: Type A and Type B. This system is based on the location of the tear and helps guide treatment strategies. Type A dissections Involves the ascending aorta and may extend into the descending aorta. It's more common and more dangerous than Type B, as it can lead to serious complications like rupture into the pericardial space leading to cardiac tamponade, aortic valve insufficiency, or myocardial infarction. Symptoms may include more severe chest pain radiating to the back, loss of consciousness, or symptoms of stroke if the blood supply to the brain is affected. Type A AoDs generally require an emergent trip to the operating room as soon as they are identified to reduce the likelihood of a terrible outcome. Type B dissections occur in the descending aorta only, after it has passed the arteries that supply blood to the arms and head. They are less common than Type A and usually less immediately life-threatening, but still serious and potentially fatal if not treated properly. Symptoms can include sudden onset of pain in the back or abdomen, depending on the exact location and extent of the dissection. The pain is often described as tearing or ripping. Speed is important in making the diagnosis of an AoD due to the associated increase in mortality with delays [2,3]. We know from last week that clinical decision tools (CDTs) are not ready for prime time. This is consistent with the American College of Emergency Physicians (ACEP) which does not recommend the routine use of clinical decision rules in suspected cases of AoD [4]. Clinical Question: What is the diagnostic accuracy of three sonographic findings for acute aortic dissection? Reference: Gibbons et al. The sonographic protocol for the emergent evaluation of aortic dissections (SPEED protocol): A multicenter, prospective, observational study. AEM February 2024. Population: A convenience sample of adult patients with clinically suspected Stanford type A or B AoDs before performing a POCUS or CTA from January 2010 to December 20...