Integrating point-of-care ultrasound in the ED evaluation of patients presenting with chest pain and shortness of breath

Abstract

Objective

The differential diagnoses of patients presenting with chest pain (CP) and shortness of breath (SOB) are broad and non-specific. We aimed to 1) determine how use of point-of-care ultrasound (POCUS) impacted emergency physicians' differential diagnosis, and 2) evaluate the accuracy of POCUS when compared to chest radiograph (CXR) and composite final diagnosis.

Methods

We conducted a prospective observational study in a convenience sample of patients presenting with CP and SOB to the Emergency Department (ED). Treating physicians selected possible diagnoses from a pre-indexed list of possible diagnoses of causes of CP and SOB. The final composite diagnosis from a chart review was determined as the reference standard for the diagnosis. The primary analysis involved calculations of sensitivity and specificity for POCUS identifiable diagnoses in detecting cause of CP and SOB. Additional comparative accuracy analysis with CXRs were conducted.

Results

128 patients with a mean age of 64 ± 17 years were included in the study. Using a reference standard of composite final diagnoses, POCUS had equal or higher specificity to CXR for all indications for which it was used, except for pneumonia. POCUS correctly identified all patients with pneumothorax, pleural effusion and pericardial effusion. In patients with a normal thoracic ultrasound, CXR never provided any actionable clinical information. Adding POCUS to the initial evaluation causes a significant narrowing of the differential diagnoses in which the median differential diagnosis from 5 (IQR 3–6) to 3 (IQR 2–4) p < 0.001.

Conclusion

In evaluation of patients with CP and SOB, POCUS is a highly feasible diagnostic test which can assist in narrowing down the differential diagnoses. In patients with a normal thoracic ultrasound, the added value of a CXR may be minimal.

Introduction

Chest pain (CP) and shortness of breath (SOB) are among the most common chief complaints in the Emergency Department (ED) [1]. The initial management can be challenging due to the broad differential diagnoses, which often includes life-threatening conditions requiring rapid identification and management [2]. With many possible etiologies, understanding the cause of CP and SOB is essential for targeted interventions, and a timely management of patients. Typically, a chest radiograph (CXR) is part of the initial work up for these patients. However, previous studies have challenged the diagnostic utility of CXR for these indications, suggesting that in the evaluation of CP, CXRs yield clinically significant information in as few as 12% of studies [[3], [4], [5]]. Therefore, the limited sensitivity and specificity of CXR in the evaluation of CP and SOB raises questions about the diagnostic accuracy and initial diagnostic tests in patients with CP and SOB.

The use of point-of-care (POCUS) in the evaluation of CP and SOB is growing rapidly and in different clinical settings it shows promise as accurate point-of-care diagnosis is made possible [[4], [5], [6]]. Results of studies have shown that POCUS has excellent diagnostic accuracy for the pathologies most commonly encountered in patients presented with CP and SOB, and often higher than CXR [[6], [7], [8], [9], [10]]. POCUS most often diagnoses pneumothorax, pleural effusion, lung consolidation, pulmonary edema, and pulmonary embolism [[11], [12], [13], [14], [15], [16]]. For example, with respect to pleural effusion, Ünlüer et al. have reported a sensitivity and specificity of bedside ultrasound as 93% and 93%, using CT as the gold standard [1]. With respect to pulmonary edema, Martindale et al. found 74% agreement with CT findings for lung ultrasound (versus 58% with CXR) [8]. In critical care cases, bedside lung ultrasound has been reported to yield a diagnosis for patients with acute respiratory failure in 90.5% percent of cases [1,6,7,17].

Despite being a rapidly evolving initial diagnostic modality, further studies are needed to determine whether POCUS actually increases the proportion of patients with undifferentiated CP and SOB who are correctly diagnosed and treated in the ED. Previous studies of the utility and efficacy of POCUS have largely focused on specific patient populations including ventilated patients, trauma patients and children, who likely have significant difference in incidence of disease, and concomitant pathology [8,18,19].

The objective of this study was to 1) determine how use of POCUS influenced emergency physicians' differential diagnosis, and 2) compare the US findings to chest radiograph and composite final diagnosis to assess relative sensitivities and specificities of each imaging modality in this patient population. Our hypothesis was that the use of POCUS would narrow the overall differential diagnosis of SOB and CP, and increase the proportion of patients who receive a correct presumptive diagnosis in the ED. We also investigated the hypothesis that POCUS would exhibit a comparable diagnostic accuracy compared with CXR in respect to pneumothorax, pleural effusion, pneumonia, and pulmonary edema.