In this real-life study, an almost perfect concordance was observed between the point-of-care ultrasound POCUS-guided diagnosis conducted in the emergency department and the final diagnosis given at discharge for patients presenting with shock, acute coronary syndrome, or acute decompensated heart failure. This finding highlights the utility of POCUS as an effective tool for evaluating patients in these clinical scenarios and the high confidence that should be placed on a multiorgan ultrasound evaluation alongside clinical exam.
In every case, the categorization of individuals with acute heart failure was accurate. Gallard et al. (17) conducted a study involving a cohort of 130 patients to assess the diagnostic accuracy of heart failure. Their findings indicated a diagnostic accuracy of 90% which aligns with our research. Baid et al. (13) found a sensitivity of 77% in diagnosing left ventricular systolic dysfunction. Previous research has indicated that emergency physicians have achieved a detection rate of 82%. The agreement observed in our study, using multimodal Point-of-care ultrasound was found to be 0.98. This result contrasts with the findings reported by Baid et al., who reported agreement values of 0.59 for systolic dysfunction and 0.83 for pulmonary edema.
These findings may be due to differences in observations made by various observers and the population being studied. Similarly, the assessment methods for evaluating left ventricular systolic function may vary in the POCUS approach. Previous studies have evaluated a specific finding in an ultrasound exam. Our study aimed to analyze a global clinical-ultrasound approach that combines clinical reasoning using POCUS. In a systematic review conducted by Albaroudi et al (18) eyeballing was associated with a Kappa of 0.46–0.79, suggesting substantial variations but with at least moderate diagnostic accuracy. The high concordance found in our research may be influenced by a global clinical evaluation. Conducting a complete clinical history, identifying clinical signs of congestion, and confirming these findings with a well-executed ultrasound evaluation form the basis of a well-founded diagnosis.
In the ACS group adequate classification was performed on 61 patients diagnosed with non-ST segment elevation myocardial infarction (NSTEMI), yielding a Kappa agreement value of 0.98. Prior studies have shown variability in the accuracy of POCUS diagnosing acute coronary syndrome. Zanobetti et al. established a concordance of 0.70 between the initial diagnosis of acute coronary syndrome and the final diagnosis in emergency department patients presenting with dyspnea (19). This study evaluated POCUS diagnoses versus ED diagnoses, but our study evaluated a different diagnosis stage: initial using POCUS versus final diagnosis. Our work showed better performance of a clinical approximation to patients including cardiac ultrasound and integrating findings to clinical diagnosis. We are aware that focused cardiac ultrasound neither confirms nor discards a patient having ACS. Identifying patients with left ventricle dysfunction, regional wall abnormalities and/or ruling out other critical conditions such as acute aortic dissection (no patients were found in this study), pulmonary embolism, pneumothorax and pericardial effusion could be very valuable to make a decision in an emergency care situation.
Regional wall motion abnormalities (RWMA) are considered an advanced ability in focused cardiac ultrasound. Farsi et al. (20) previously reported a correlation Kappa of 0.83 between trained residents and the formal echocardiogram conducted by a cardiologist. In our investigation, we identified segmental contractility disorders in 82.1% of cases, with 5 false positives and 5 false negatives, yielding a Kappa of 0.40 in this ACS group of patients. This underscores the importance of accurate diagnosis and the potential consequences of inappropriate interventions based on inaccurate observations from ultrasound. Croft et al evaluated the diagnostic potential of RWMA in individuals with ST elevation myocardial infarction in the WAMAMI study (21) reporting a Kappa 0.79 after specific training of emergency medicine residents. Again, not a clinical diagnosis but a specific ultrasound finding. Another study conducted by Saglam (22) in patients with suspected non-ST myocardial infarction reported a good agreement of 0.84 after a 3-hour training. The variability observed in these studies may be attributed to the varying levels of training of point-of-care ultrasound (POCUS) operators and different studied populations. Our data shows a low agreement, thus, reflecting the high variability of this specific ultrasound finding and the need to not rely only on RWMA to diagnose or treat a patient with chest pain.
The acquisition of RWMA viewing skill needs thorough training, and the existence of abnormalities does not invariably indicate the presence of acute coronary syndrome, nor is it exclusive to this pathology. The American Society of Echocardiography (ASE) has issued a recommendation concerning POCUS and the interpretation of these conditions as an advanced skill. Its implementation may limit the widespread utilization of the tool (23).
Analyzing the shock population we found good agreement between initial POCUS-guided diagnosis and final diagnosis. A recent systematic review conducted by Yoshida et al (6) highlights the diagnostic efficacy of point-of-care ultrasound (POCUS) in this set of patients, showing over 95% of diagnostic accuracy. We correctly identified the type of shock in 84.6% of our patients. It is important to say that our patients had similar basal characteristics compared to those included in the systematic review previously mentioned. If we separate cardiogenic shock in this study, all patients were classified correctly. No false positives or false negatives. In septic shock group, we had two patients with inconclusive findings at admission. Septic shock is an entity with no specific ultrasound finding. Clinical history and reasoning are crucial to correct diagnosis. According to our results, a clinician should always be aware of septic shock and interpret the whole clinical picture, including POCUS, to give a shock type diagnosis.
Previously, Javali et al (24) demonstrated that in cases of undifferentiated shock in the emergency department, the diagnostic accuracy for identifying the type of shock increased from 45–89% with the addition of point-of-care ultrasound. A kappa value of 0.89 was reported and is consistent with similar findings by Vaidya et al (25) and our data. The findings of these studies depict a scenario akin to the one outlined in our study, where clinical data was integrated with POCUS information. Kanji et al. (2) previously presented evidence of a potential effect on mortality in patients with hypotension when treatment was oriented by ultrasound findings. Current initiatives are underway to standardize assessment protocols (26).
An examination of the MIMIC III database indicates a significant effect on mortality (odds ratio = 0.78, 95% CI 0.68–0.90, p < 0.001) among patients with septic shock in the intensive care unit who underwent echocardiography for diagnostic and therapeutic guidance (27). The strong diagnostic capability of point-of-care ultrasound (POCUS) described in our study underscores the importance of its integration into routine clinical practice.
We had 12 patients with a non-conclusive POCUS at admission, explaining most patients with wrong diagnosis. Analyzing these patients, we found 6 with pneumonia not diagnosed adequately. We explain these findings considering the limited sensitivity of lung ultrasound in certain scenarios. It is required that lung consolidation involves pleura and to be in an area susceptible to visualization (BLUE points), this could be a limitation for a given diagnosis. This highlights the need of an extensive lung ultrasound evaluation if BLUE points are non-conclusive, and the clinical picture is consistent with a lower respiratory tract infection. The other 6 non-conclusive were a hypertensive angina, 2 septic shock, 1 non-cardiovascular chest pain, 1 obstructive sleep apnea and 1 soft tissue infection. Patients with a wrong diagnosis were followed during hospitalization, all of them had an expected clinical evolution with no mortality. There should be more research on missed diagnoses with POCUS and clinical impact on prognosis and mortality to comprehensively evaluate ultrasound errors.
Limitations and advantages
This study was conducted at a single center within a university hospital, involving a specific population, which may limit the generalizability of the findings. Although a varied population, representative of a given usual ED population, caution should be taken when applying the results. Similarly, using images captured by a single provider may limit the application of our study, it reduces the potential for differences in interpretation among observers.
The study's strengths lie in its real-life depiction of typical conditions in the emergency department, where point-of-care ultrasound (POCUS) information is integrated into the diagnostic process. This integration enables real-time decision-making for patients with potentially life-threatening pathologies. We had a comorbid population, consulting to the ED with the most common symptoms in clinical practice, evaluated with ultrasound and diagnosed with clear parameters at discharge. All patients had POCUS and gold standard clinical diagnosis. Statistical analyses were performed following adequate procedures and sample size was achieved giving enough power to our study.
Finally, we think POCUS should be at the center of clinical evaluation in every emergency department considering our results. Nonetheless, we find a caution message in our findings that lead us to always integrate ultrasound with clinical evaluation. The results of this study demonstrate a strong correlation with definitive diagnosis, emphasizing the significance of integrating these findings into the assessment of patients with potentially life-threatening conditions. It is essential to consider using POCUS to shorten the time for diagnosis and subsequent treatment, thereby possibly impacting mortality. This should be evaluated in well-design prospective studies.