Identifying the cause of acute dyspnea in the emergency department is often challenging, even for the most experienced provider. A detailed history may not be obtainable because of extreme dyspnea, and management is often initiated before more standard testing (laboratory results and chest radiography) is available. Additionally, imaging with portable plain film radiographs has been shown to be inaccurate in the differentiation of ADHF (acute decompensated heart failure) from COPD (chronic obstructive pulmonary disease).1
Explore This IssueACEP News: Vol 31 – No 09 – September 2012
A focused bedside ultrasound in conjunction with the clinical exam can be the ideal tool for the emergency physician in the rapid evaluation of the undifferentiated dyspneic patient.2-4
In isolation, focused echocardiography in the ED can determine gross cardiac function. Limited pulmonary ultrasound can determine the presence or absence of pulmonary edema. Inferior vena cava (IVC) collapsibility can be a rough marker for central venous pressure (CVP).
Using specific aspects of each of the previous focused ultrasounds allows the clinician to visualize the lack of forward cardiac flow and its effects on the lungs and the afferent venous vasculature, defining the process of ADHF.2,4-6
A three-view bedside sonographic examination or “triple scan” (focused evaluation of the heart, lungs, and inferior vena cava) is an ideal adjunct in the clinical evaluation and management of the acutely dyspneic patient.
For the novice sonographer, the goal of the exam is not to rule out the various other processes that present as acute dyspnea in the emergency setting (pulmonary embolism, pneumonia, asthma, etc.), but rather to confirm the presence of ADHF and allow the clinician to execute appropriate initial therapies.
Poor systolic cardiac function, edema in the lungs, and congestion of the IVC can confirm clinical findings at the bedside and reduce clinical uncertainty.
The evaluation of the acutely dyspneic patient can be performed with any standard portable ultrasound system. Either a curvilinear low-frequency transducer (5-2 MHz) or a phased-array transducer (5-1 MHz) can be used for various parts of the exam. The patient can remain sitting upright (often the most comfortable position for the acutely dyspneic patient).
Two-View Focused Echocardiography For the more novice sonographer, we recommend using the parasternal long (PSL) and parasternal short (PSS) views in succession to evaluate for gross cardiac function (exclusion of a pericardial effusion can also be performed in this view). Our explanation of the views is different from that of our cardiology colleagues as we consistently maintain probe marker position to the patient’s right on ultrasound exams in the ED.7 As with all ultrasound examinations, certain patients will be difficult to image, and other views (subxiphoid, etc.) that will not be discussed here may be useful.