Diagnostic testing after return of circulation following arrest
By Joshua Easter, MD, MSc
University of Virginia Health System emergency physician and UVA School of Medicine associate professor
Case: A 74-year-old female presents to your ED in circulatory arrest with ongoing chest compressions and ventilations via bag valve mask. EMS notes she was unresponsive and pulseless upon their arrival to her home, and she has had pulseless electrical activity throughout transport to the hospital. They administered two doses of epinephrine without any improvement. EMS does not know any history for the patient. In the ED, after several rounds of advanced cardiac life support and intubation, the patient has return of circulation. She remains unresponsive with a heart rate in the 80s and blood pressure of 105/76. The etiology of her arrest is not clear based on her course or her post-resuscitation EKG, chest radiograph, and labs. Are there any additional diagnostic studies that you should consider performing in the ED before admitting the patient?
The etiology for circulatory arrest is often difficult to ascertain in the ED, as patients are frequently unresponsive, limiting the history. Existing guidelines recommend acquisition of an EKG, echocardiogram, labs, and chest radiograph to assist in the diagnosis and management of patients with return of circulation (Nolan, 2021; Yannopoulos, 2019; Roffi, 2015; ACEP, 2017). However, these studies fail to identify many non-cardiac causes for arrest. Prior studies suggest that CT performed early in the post-resuscitative period may identify diagnoses not otherwise apparent (Petek, 2019; Chelly, 2012; Yang, 2020). However, these studies were small and retrospective.
Branch et al. assessed the diagnostic benefits of early head-to-pelvis CT for patients with return of circulation after an out-of-hospital circulatory arrest (Branch, 2021). They prospectively enrolled a convenience sample of patients at two academic EDs in Seattle between 2015-18. They excluded patients with a clear etiology for their arrest, e.g., STEMI or known non-revascularized coronary artery disease. All patients underwent whole body CT with IV contrast within 6 hours of presentation, utilizing a protocol similar to trauma patients supplemented with an EKG gated scan of the thorax to assess the coronary arteries. Unlike a traditional coronary CTA, they did not administer beta blockers to slow the heart rate due to patients’ relative instability after their arrest. Two radiologists blinded to clinical data reviewed the CT and determined diagnoses apparent on CT by consensus. Meanwhile, an EM physician and cardiologist’s ascertainment of the cause of the arrest based on review of all clinical information represented the criterion standard. The primary outcome was the cause of the arrest determined by CT compared to this criterion standard. Secondary outcomes were the frequency that CT identified a cause not apparent based on clinical information and the incidence of adverse outcomes arising from CT acquisition.
Table.
They enrolled 104 patients with a mean age of 56±15 years. Co-morbidities were rare; less than half had hypertension and less than one quarter had a history of reduced ejection fraction, diabetes, or coronary artery disease. Most CTs were performed promptly, with a mean time to acquisition of 1.8± 0.8 hours. CT independently identified 39% of all adjudicated causes for the arrest and 98% of all critical causes; it missed one cause that was deemed critical- a patient with acute coronary syndrome (Table). CT was able to identify a cause for 13% of cases that were uncertain based on clinical information (Table). CT also identified multiple complications of resuscitation, such as rib fractures and liver lacerations, in 16% of patients.
In terms of safety, there were no significant complications from CT. Slightly over one quarter of patients had an elevated creatinine at 48 hours. For all but one patient their renal function normalized before discharge. The one patient required renal replacement therapy but had a history of chronic kidney disease stage III and received vasopressors during their hospitalization, so it is unclear if CT acquisition was the etiology of their renal failure. No patients had allergic reactions after IV contrast. Similarly, no patients underwent inappropriate therapy based on their CT results.
While this study was small with potential selection bias from their convenience sample, it is the first prospective study of early CT in the ED following return of circulation. It suggests there is a role for early whole body CT acquisition in patients with an unclear etiology for their arrest after return of circulation. Several of the diagnoses that were not apparent based on clinical information and identified only by CT are critical diagnoses that impact management, e.g., massive pulmonary embolism or intracranial hemorrhage. Nevertheless, CT should likely be reserved for select patients. For example, patients with known coronary artery disease might be harmed by a delay in coronary catherization in order to obtain a CT. Similarly, patients with ongoing hemodynamic instability after their arrest might be harmed by CT acquisition.
After successfully resuscitating your patient and acquiring initial diagnostic tests, you are still unclear of the cause for their circulatory arrest. Therefore, you obtain a whole body CT that reveals a massive pulmonary embolism. Based on this new information, you administer thrombolytics and transfer the patient to the ICU.
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