Study design and settings
This prospective observational study was conducted in the Emergency Department of All India Institute of Medical Sciences, Rishikesh, Uttarakhand, between November 2019 and April 2021 (patient recruitment period from January 2020 to January 2021).
Selection of patients
The chief complaint of acute onset shortness of breath
Age group: greater than 18 years of age
Individuals referred from an outside hospital with a known diagnosis
Dyspnea due to traumatic cause
All patients presenting to the ED with acute onset dyspnea were included if they met the inclusion criteria during the study’s recruitment phase. A total of 237 patients were enrolled.
The enrolling emergency physician recorded the patient’s medical history, vital signs, and systemic examination. The patient then was planned for relevant routine tests (chest x-ray, ECG, CBC, KFT, etc.) as deemed fit by the primary treating emergency physician. A provisional diagnosis was made from the provided list of differentials by the treating emergency physician.
Each point of care ultrasound examination was performed with a multiprobe machine (SONOSITE M Turbo) by following a systematic, standardized sequence—lung ultrasound, transthoracic echocardiography, and inferior vena cava (IVC) evaluation according to a predefined ultrasound protocol.
It was performed with a 6- to 13-MHz linear probe. The lungs were examined by using longitudinal scans on the anterolateral aspect as per the BLUE protocol  and posterior thoracic area—between the posterior axillary line and spine The anterolateral examination was performed with the patient in the supine or near-to-supine position; whenever possible, dorsal areas were scanned in the sitting position or by turning the patient in the lateral decubitus on both sides in case of forced supine position.
Lung examination was targeted to detect specific ultrasound patterns identified according to international recommendations for pulmonary edema, pneumonia, pleural effusion, pulmonary embolism, acute exacerbation of chronic obstructive pulmonary disease (AECOPD)/bronchial asthma, pneumothorax, and acute respiratory distress syndrome (ARDS)/acute lung injury (ALI).
Pulmonary edema was diagnosed with the bilateral diffuse alveolar syndrome (presence of multiple B lines throughout the entire pulmonary surface symmetrically) .
Pneumonia was diagnosed by the presence of either pleural shredding, irregular pleural line, lung consolidation, and air bronchogram(s) with or without the focal interstitial syndrome .
Pleural effusion was diagnosed by an anechoic space between the parietal and visceral pleura, confirmed with the presence of a thoracic spine sign .
Pulmonary embolism was considered with two or more triangular or rounded pleural-based lesions indicating a pulmonary infarction or absence of any lung findings in the presence of suggestive history and evidence of RV strain .
AECOPD/asthma was diagnosed in the absence of any pattern mentioned above or presence of A-lines and lung sliding in a patient with suggestive medical history [8, 14].
Pneumothorax was diagnosed as the absence of lung sliding, B lines, and lung pulse with the presence of lung point .
ARDS/ALI was diagnosed as subpleural anterior consolidations with the absence or reduction of lung sliding, spared areas of normal parenchyma, pleural line abnormalities such as irregularly thickened or fragmented pleural line, and non-homogeneous distribution of B lines [8, 14].
Transthoracic echo was performed with a 1- to 5-MHz curved array probe to visualize the heart in two windows—an apical four-chamber view and a subcostal long-axis view.
The assessment was done for qualitative estimation of left ventricular ejection fraction by eye-balling method, right ventricular strain, pericardial effusion, acute coronary syndrome (ACS), pulmonary embolism, any visible left ventricular hypertrophy, and valvular abnormalities.
Right ventricular strain was diagnosed with the presence of right ventricular dilation (right/left ventricular end-diastolic diameter ratio > 1 at the level of atrioventricular valve annulus).
ACS was diagnosed indirectly in the presence of regional wall motion abnormalities (RWMA) in the form of any hypokinesia or dyskinesia of the left ventricular wall in the apical four-chamber view .
IVC was evaluated using the 2–5-MHz curvilinear probe. The maximum and minimum diameters and the IVC collapsibility index were measured in the subcostal view in M-mode at 2 cm from the right atrial junction. The IVC collapsibility index was considered reduced if < 50%, normal, or increased if more than 50%.
The consolidated findings were recorded on a standardized form for each patient.
The study investigators were Emergency Medicine Residents who had received training in PoCUS for 2 months. For all eligible patients, the initial treating emergency physician was clinically evaluated in detail, and investigations were ordered as necessary. A provisional diagnosis was made, initial treatment started, and one study investigator was informed. The study investigator then performed PoCUS, blinded to the laboratory investigations but not to the clinical evaluation parameters, and made a provisional diagnosis based on them and the findings of PoCUS. The information was then given to the treating physician about the results of PoCUS. For each patient, the time of entry to the ED, the time at the end of the performance of the PoCUS, and the time to formulate the final composite diagnosis were recorded. Additional clinical parameters, final diagnosis, and patient outcome were obtained retrospectively and noted. Ultimately, the ultrasound diagnosis was compared with the final composite diagnosis (the gold standard) for accuracy and benefit in time. The final composite diagnosis was formulated by two Emergency Medicine consultants, who had access to the history, examination, and investigations performed on the patient during the ED stay. Up to four concurrent diagnoses were permitted to be made for each patient.
The study flow can be depicted in Fig. 1.
The data was entered in an Excel sheet and analyzed with the help of SPSS software Version 23.
Categorical variables were presented in number and percentage (%), and continuous variables were presented as mean (SD) and median (IQR) depending on the distribution of the data. Sensitivity and specificity analysis was done to study the diagnostic accuracy of PoCUS with the gold standard keeping a confidence interval of 95%. Kappa statistics was used to measure the concordance of the PoCUS diagnosis and the final composite diagnosis. Paired T-test was applied to compare the time taken to make the PoCUS diagnosis and final diagnosis.