High Accuracy, Clinical Relevance With Point-of-Care Lung Sonography

Point-of-care lung sonography can be used to accurately assess a wide range of clinical conditions, creating substantial clinical impact, according to a study published in the Journal of Ultrasound in Medicine.¹

Pulmonologists from the San Paolo Hospital in Milan, Italy, conducted a 2-year prospective, observational study. “Despite the fact that our analysis was targeted to a vast list of pulmonary conditions, reflecting the heterogeneity of real clinical use, we found a good overall accuracy rate, similar to that obtained in the study by Rahman et al,”² the researchers noted.

Point-of-care lung sonography has many advantages over other forms of imaging: it is radiation free, low cost, and provides immediate answers to critical questions regarding early diagnosis and treatment.¹

In addition to pleural effusion, evidence is mounting in favor of the application of lung sonography in the diagnosis and management of pneumothorax, pneumonia, pulmonary congestion, and atelectasis.³ In addition, sonography may be useful in differentiating between an acute exacerbation of chronic obstructive pulmonary disease and acute decompensated heart failure at the bedside.⁴

Giuseppe Francesco Sferrazza Papa, MD, and colleagues examined 1150 consecutive sonographic lung examinations performed on 951 patients at San Paolo Hospital from May 2012 to April 2014.

The clinical indications for lung sonography were most commonly pleural effusion (31%), lung consolidation (28%), acute heart failure (17%), pleural procedures (10%), pneumothorax (5%), and acute exacerbation of chronic obstructive pulmonary disease (3%).

The researchers identified 8 common sonographic patterns, including pleural effusion (32.6%), lung consolidation (14.3%), consolidation with pleural effusion (8.5%), acute cardiogenic pulmonary edema with or without pleural effusion (10.7%), complex pleural effusion (5.7%), atelectasis (4.5%), pulmonary fibrosis (4.0%), and pneumothorax (1%); 18.8% of patients had no abnormality identified.

In those with suspected lung consolidation, the following final diagnoses were made: pneumonia (63.4%), cancer (lung or pleural: 4.7%), bronchiolitis (3.1%), pleuritis (2.8%), acute bronchitis (2.2%), empyema (0.9%), and pulmonary fibrosis (0.6%); 21.1% of patients did not have a pulmonary disease.

The average examination duration was 6 minutes; final diagnostic accuracy (limited to 574 sonographic cases performed as a first evaluation) was 98.3% (95% CI, 96.6%-99.1%). There were 4 false-positives, including 2 pediatric cases of bronchiolitis and 1 asthmatic exacerbation, misdiagnosed as 3 cases of small subpleural lung consolidation, and 1 case of pericardial fat misdiagnosed as lung consolidation. There were 6 false-negatives, including 4 central lesions (3 consolidations and 1 ground glass opacity) and 2 subpleural infarctions that were hidden on chest X-ray but detected on chest computed tomography scan.

To assess the clinical effect of lung sonography, sonography operators were asked whether the test was decisive for making specific clinical decisions, indicated the need for further imaging, or was not helpful in decision making. Results showed lung sonography correctly influenced the clinical decision (including treatment) in 51% of cases and structured the diagnostic workup for additional imaging in 12%. No effect was found for 38% of the cases.

“Lung sonography is a feasible, rapid, and accurate procedure that is applicable to many pathologic conditions, with a substantial clinical impact,” Dr Sferrazza Papa and colleagues concluded.

Study Limitations

• Results of the study may not be generalizable to other institutions.
• The approach of combining a clinical practice audit with prospective evaluation of diagnostic accuracy may have influenced results, as the operator was not blinded to the patient’s clinical data.
• The researchers did not measure the interoperator variability of the diagnostic application of lung sonography. 

References

1. Sferrazza Papa GF, Mondoni M, Volpicelli G, et al. Point-of-care lung sonography: an audit of 1150 examinations [published online April 18, 2017]. J Ultrasound Med. doi:10.7863/ultra.16.09007
2. Rahman NM, Singanayagam A, Davies HE, et al. Diagnostic accuracy, safety and utilisation of respiratory physician-delivered thoracic ultrasound. Thorax. 2010;65(5):449-453. doi:10.1136/thx.2009.128496
3. Volpicelli G1, Elbarbary M, Blaivas M, et al; for the International Liaison Committee on Lung Ultrasound (ILC-LUS) for International Consensus Conference on Lung Ulrasound (ICC-LUS). International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012;38(4):577-591. doi:10.1007/s00134-012-2513-4
4. Liteplo AS, Marill KA, Villen T, et al. Emergency thoracic ultrasound in the differentiation of the etiology of shortness of breath (ETUDES): sonographic B-lines and N-terminal pro-brain-type natriuretic peptide in diagnosing congestive heart failure. Acad Emerg Med. 2009;16(3):201-210. doi:10.1111/j.1553-2712.2008.00347.x