The present study demonstrated that rapid evaluation by lung-cardiac-inferior vena cava (LCI) integrated ultrasound has a higher diagnostic accuracy for differentiating acute dyspnea due to AHFS from pulmonary acute dyspnea (including COPD/asthma, pulmonary fibrosis, and ARDS) compared with lung ultrasound either alone or in combination with plasma BNP assay. These findings suggest that LCI integrated ultrasound has become a fundamental tool for diagnostic evaluation of patients with acute dyspnea and selection of early treatment in the emergency setting.
Rapid and accurate diagnosis and management can be lifesaving for patients with acute dyspnea
. However, making a differential diagnosis and selecting early treatment for patients with acute dyspnea in the ED is a clinical challenge that requires complex decision-making in order to achieve hemodynamic balance, improve functional capacity, and decrease mortality and the length of hospital stay
. Methods for evaluation of emergency patients with possible AHFS include the history, physical examination, chest radiography, 12-lead electrocardiography, and measurement of BNP or N-terminal pro-BNP
[5–10]. Among these methods, chest radiography is a cornerstone in the diagnostic evaluation of acute dyspnea. Although chest radiography serves a vital role in the evaluation of patients with acute dyspnea, including the identification of various causes, the lack of radiographic signs of congestion does not exclude AHFS
[2, 41]. Recently, BNP and N-terminal pro-BNP have been studied extensively and are frequently used in clinical practice. However, some recent randomized trials on the use of BNP to aid in diagnosis or serial BNP levels to dictate therapy in the acute setting found no improvement of diagnostic accuracy or important clinical outcomes because age, sex, and renal dysfunction have an impact on natriuretic peptide levels and need to be considered when test results are interpreted
[42, 43]. Also, patients with a history of decompensated HF can have chronically elevated BNP or N-terminal pro-BNP levels, making the test inconclusive. In addition, it was reported that BNP does not reliably distinguish ARDS from AHFS
. In our study, the BNP level of patients with a history of heart failure who had dyspnea due to pulmonary disease or ARDS showed no significant difference compared to that of patients with acute dyspnea due to AHFS, a finding that is in agreement with prior reports
[42, 43]. Therefore, among patients with acute dyspnea (including those with a history of heart failure and those with ARDS), the baseline BNP level alone could have various limitations for making a differential diagnosis in the emergency setting, and further research is needed to address this issue.
B-lines assessed by lung ultrasound have been proposed as an easy alternative diagnostic tool for monitoring pulmonary congestion in AHFS patients
. Recently, it was reported that B-lines alone or B-lines combined with N-terminal pro-BNP show a high diagnostic accuracy for differentiating AHFS-related acute dyspnea from that due to COPD/asthma in the ED
[3, 41]. However, it is impossible to differentiate AHFS from bilateral pneumonia, pulmonary fibrosis, or ARDS by lung ultrasound alone, because although B-lines are a very sensitive sign of cardiogenic pulmonary edema, this sign is not specific
. However, in the present study, the lung ultrasound in two patients with pure right-sided heart failure, which was not in association with left-sided heart failure, showed a false negative, suggesting that B-lines may not be sensitive for pure right-sided heart failure. Recently, Gargani has suggested that addition of lung ultrasound to echocardiography provides additive information about pulmonary involvement
. Furthermore, Kimura et al. has reported the usefulness of cardiopulmonary-limited ultrasound examination consisting of only 4 ultrasound views, such as LV systolic dysfunction, left atrial enlargement, IVC, and B-lines, for the diagnostic accuracy and prognostic information, although they did not evaluate a diagnostic accuracy for differentiating acute dyspnea due to AHFS from that caused be primary pulmonary disease
. On the basis of these available reports and our findings, it is suggested that LCI integrated ultrasound assists with the rapid and accurate diagnosis and treatment of acute dyspnea in the emergency setting.
Our study had several limitations. First, this was a single-center investigation of a small patient population. Second, assessment of diastolic dysfunction and quantitative analysis of valvular heart disease could not be done with the hand-held ultrasound device employed in this study. Therefore, complete evaluation of acute dyspnea in patients requires comprehensive standard echocardiography after LCI ultrasound evaluation. Third, we could not evaluate the extravascular lung water in AHFS patients because we did not examine the number of B-lines. Therefore, further prospective investigation to evaluate the extravascular lung water by a hand-held device for patients with acute dyspnea in the emergency setting is needed. Fourth, training is needed to interpret the findings of LCI ultrasound.
In conclusion, our study demonstrated that rapid evaluation by lung-cardiac-IVC (LCI) integrated ultrasound has a higher accuracy for differentiating AHFS-related acute dyspnea from pulmonary-related acute dyspnea compared with lung ultrasound alone or lung ultrasound combined with BNP. These findings suggest that LCI integrated ultrasound is a useful tool to expedite the evaluation of patients with acute dyspnea before initiating treatment in the ED. However, further research will be needed to provide more insight into the impact of LCI integrated ultrasound using a portable ultrasound device on diagnosis and decision making in the ED.