Lee McChesney | EM PGY3
The Article:
The Idea:
To determine the feasibility and diagnostic accuracy of bedside emergency ultrasound in the management of ED patients presenting with acute dyspnea.
The Study:
A prespecified subanalysis of the ADvISED multicenter prospective study from 5 centers in 4 countries in which 839 patients with suspected acute aortic syndromes (AAS) had transthoracic focused cardiac ultrasound (FoCUS) to find either direct or indirect signs of AAS to assist in clinical judgement. Using the aortic dissection risk score (ADD-RS) to determine clinical probability of AAS, which the European Society of Cardiology endorses as the bedside tool to use in suspected AAS, patients can be defined as low or high probability. Those in high probability warrant a CTA/TOE and low probability need additional testing. FoCUS can quickly recognize those who need CTA/TOA despite low clinical probability and be used to safely rule-out those low risk patients with additional negative D-dimer testing. The aim of the study was to give additional validation to the algorithm endorsed by the ESC. Patients were included if AAS was included in the ED attending differential diagnoses and they were able to undergo FoCUS before any advanced cardiac imaging was performed. FoCUS was looking for direct and indirect signs of AAS. Direct signs looked for were intimal flap, intramural aortic hematoma or a penetrating aortic ulcer. Indirect signs included thoracic aorta dilatation greater than 4cm, pericardial effusion or tamponade, or aortic valve regurgitation.
The Findings:
A total of 864 patients were eligible and a total of 839 were included in the study after exclusion criteria. 170 patients had FoCUS performed by a cardiologist and 669 were performed by a non-cardiologist. Direct signs of AAS were found in 84 patients and any signs of AAS were found in 307 patients. Using FoCUS in addition to clinical assessment tool like ADD-RS, greatly increased the diagnostic accuracy of AAS. Using just the ADD-RS, a total of 671 were considered low probability of having AAS, but 67 patients had AAS. Using the tool, less than/equal to 1, with a negative FoCUS, the sensitivity to rule out AAS was 93.8%. D-Dimer testing was available in 812 of the patients, including 652 which were considered low probability. There was only false negative of 2 patients with AAS who had direct or indirect signs of AAS.
The Takeaway:
Making the clinical decision to obtain immediate CTA/TOE in stable patients in which ASS is considered, can be difficult and lead to misdiagnoses, wrong treatment choices, ED discharge and over-testing. In those patients with low probability of AAS, using US in conjunction with clinical assessment and D-Dimer testing, can provided a safe and effective way to make the decision regarding CTA/TOE. It can be inferred that in those patients with only indirect signs of AAS and a negative D-Dimer, CTA/TOE can be avoided by a case-by-case basis.