Retrospective analysis of the diagnostic accuracy of lung ultrasound for pulmonary embolism in patients with and without pleuritic chest pain

Accuracy of transthoracic lung ultrasound for diagnosing pulmonary embolism: An updated systematic review and meta-analysis

BACKGROUND

Computed tomography pulmonary angiography (CTPA) simplifies the diagnosis of pulmonary embolism (PE) but is not suitable for all patients. Transthoracic lung ultrasound (LUS) is a potential alternative; this meta-analysis evaluates its accuracy for diagnosing PE.

METHODS

We systematically searched PubMed, Embase and Cochrane Library from the inception of each database up to April 2024 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Diagnostic Test Accuracy Studies guidelines. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, and a bivariate random effects model was used to pool sensitivity and specificity.

RESULTS

A total of 18 studies with 2158 patients were analyzed. Lung ultrasound showed a sensitivity of 0.80 (95 %, confidence interval (CI): 0.71-0.86; I2 = 85.2 %) and specificity of 0.87 (95 %, CI: 0.81-0.92; I2 = 87.3 %). The diagnostic score was 3.27 (95 %, CI: 2.75-3.78; I2 = 61.9 %), and the diagnostic odds ratio was 26 (95 %, CI: 16-44; I2 = 100.0 %). The pooled positive likelihood ratio was 6.2 (95 %, CI: 4.2-9.1; I2 = 79.2 %), and the negative likelihood ratio was 0.24 (95 %, CI: 0.16-0.34; I2 = 83.7 %). The summary area under the curve was 0.91 (95 %, CI: 0.88-0.93). Significant heterogeneity was observed, which may impact the generalisability of the results, and no publication bias was detected.

CONCLUSION

Transthoracic LUS shows potential as an alternative to CTPA for PE diagnosis, but further research is needed to improve its accuracy and establish standardised diagnostic criteria. The observed heterogeneity highlights the need for a cautious interpretation of the results.

The Diagnostic Role of Lung Ultrasound and Contrast-Enhanced Ultrasound in Pulmonary Embolism

The diagnosis of pulmonary embolism (PE) relies essentially on a probabilistic approach that requires careful clinical assessments, targeted laboratory tests, and the use of appropriate imaging tools. Nowadays, the diagnostic gold standard is computed tomographic pulmonary angiography. Lung ultrasound (LUS) can play a role in the diagnosis of PE mainly by allowing the visualization of peripheral lung infarctions. Hypoechoic, pleural-based parenchymal consolidation is the most typical and common finding of pulmonary infarction. More than 85% of infarct lesions are wedge-shaped, extending to the pleural surface and are localized to where the patient complains of pleuritic chest pain. Contrast-enhanced ultrasound can be performed in addition to basic ultrasound examination to ascertain nonvascularization of the consolidation, thus confirming that the lesion is an infarct. The aim of this narrative review is to summarize the latest evidence on the application of LUS to the diagnosis of PE, focusing purely on thoracic/lung signs.

Lung, Pleura, and Diaphragm Point-of-Care Ultrasound

Thoracic Ultrasonography involves the ultrasonographic examination of the lungs, pleura, and diaphragm. This provides a plethora of clinical information during the point of care assessment of patients. The air filled lungs create consistent artifacts and careful examination and understanding of these artefactual signs can provide useful information on underlying clinicopathologic states. This review aims to provide a review of the ultrasound signs and features that can be seen in horacic ultrasonography and summarize the clinical evidence to support its use.

Comparison of international guideline recommendations for the diagnosis of pulmonary embolism

Pulmonary embolism is one of the leading causes of death due to cardiovascular disease. Timely diagnosis is crucial, but challenging, as the clinical presentation of pulmonary embolism is unspecific and easily mistaken for other common medical emergencies. Clinical prediction rules and D-dimer measurement allow stratification of patients into groups of expected prevalence and are key elements in adequate selection of patients for diagnostic imaging; however, the strengths and weaknesses of the multiple proposed prediction rules, when to measure D-dimer, and which cutoff to apply might be elusive to a significant proportion of physicians. 13 international guidelines authored by medical societies or expert author groups provide recommendations on facets of the diagnostic investigations in suspected pulmonary embolism, some of which are hallmarked by pronounced heterogeneity. This Review summarises key recommendations of each guideline, considers the most recent evidence on the topic, compares guideline recommendations on each facet of the diagnosis of pulmonary embolism, and provides a synthesis on the most common recommendations.

Lung ultrasound monitoring: impact on economics and outcomes

PURPOSE OF REVIEW

This review aims to summarize the impact of lung ultrasonography (LUS) on economics and possible impact on patients' outcomes, proven its diagnostic accuracy in patients with acute respiratory failure.

RECENT FINDINGS

Despite some previous ethical concerns on LUS examination, today this technique has showed several advantages. First, it is now clear that the daily use of LUS can provide a relevant cost reduction in healthcare of patients with acute respiratory failure, while reducing the risk of transport of patients to radiological departments for chest CT scan. In addition, LUS reduces the exposition to x-rays since can replace the bedside chest X-ray examination in many cases. Indeed, LUS is characterized by a diagnostic accuracy that is even superior to portable chest X-ray when performed by well trained personnel. Finally, LUS examination is a useful tool to predict the course of patients with pneumonia, including the need for hospitalization and ICU admission, noninvasive ventilation failure and orotracheal intubation, weaning success, and mortality.

SUMMARY

LUS should be implemented not only in Intensive Care Units, but also in other setting like emergency departments. Since most data comes from the recent coronavirus disease 2019 pandemic, further investigations are required in Acute Respiratory Failure of different etiologies.

Lung ultrasound: are we diagnosing too much?

The clinical use of lung ultrasound (LUS) has made more efficient many diagnostic processes at bedside. The great power of LUS is a superior diagnostic sensitivity in many applications, when compared to chest radiography (CXR). The implementation of LUS in emergency is contributing to reveal a growing number of radio-occult pulmonary conditions. In some diseases, the superior sensitivity of LUS is a great advantage, like for pneumothorax and pulmonary edema. Diagnosing at bedside pneumothoraxes, pulmonary congestions, and COVID-19 pneumonia that are visible by LUS but undetected by CXR may be decisive for appropriate management, and even for saving lives. However, in other conditions, like bacterial pneumonia and small peripheral infarctions due to subsegmental pulmonary embolism, the high sensitivity of LUS does not always lead to advantages. Indeed, we doubt that it is always necessary to treat by antibiotics patients suspected of lower respiratory tract infection, who show radio-occult pulmonary consolidations, and to treat by anticoagulation patients with small subsegmental pulmonary embolism. The possibility that we are overtreating radio-occult conditions should be investigated with dedicated clinical trials.