Lung Ultrasonography is Fast and Accurate for Diagnosing Pneumonia

A recent review by Yang Xia from the Second Affiliated Hospital of Zhejiang University School of Medicine in Hangzhou, China, and colleagues of methods used for diagnosing pneumonia found that lung ultrasound (LUS) presents an effective alternative to more traditional methods, including thoracic computed tomography (CT) scanning and chest radiograph. The authors evaluated this novel use of LUS in adults through a meta-analysis of 14 articles published in English on PubMed and EMBASE and published their findings in the Journal of Thoracic Disease.¹ The review included 1911 enrolled participants and found that LUS offered rapid, highly accurate diagnosis of pneumonia.

Previous studies indicated that up to 30% of chest radiographs performed in emergency departments (EDs) yield false-positive or false-negative results.² The authors reviewed 9 studies that used chest radiographs in 1343 patients (782 with pneumonia, 561 controls) and found the pooled sensitivity with LUS was far greater in comparison (92.8% vs 75.1%, respectively). Pooled specificity when LUS was compared with chest radiograph was 89.7% and 90.5%, respectively.

Pooled sensitivity with LUS was also high when compared with 6 studies using the gold standard of CT alone (90.9%; 89.7% specificity) or with the addition of clinical presentation (95%; 91.3% specificity). Comparison of LUS in 2 studies that reviewed the diagnostic accuracy of microbiological analysis in ventilator-associated pneumonia demonstrated a sensitivity of 53.3% and specificity of 67.9%.

The investigators reported that, in all cases, LUS was efficient in accurately diagnosing pneumonia, with a general pooled sensitivity of 90.4% and specificity of 88.4%. Accuracy was higher in cases identified in the ED than in the intensive care unit (ICU), which the researchers attributed to differences in the types of pneumonia seen in those settings: cases presenting in the ED were more likely to be community-acquired pneumonia, while those occurring in the ICU were usually hospital acquired or ventilator associated.

Placing the patient in a supine, semirecumbent, or sitting position during sonography improved the diagnostic power of LUS. The researchers suggested that as this modality offers a low-cost, noninvasive, rapid method of diagnosing pneumonia that can be conducted at bedside, it is suitable in both ICU and ED settings and should be implemented whenever possible. The consistency and accuracy of results across the studies the investigators evaluated indicated that LUS is a relatively easy procedure to learn.

References

1. Xia Y, Ying Y, Wang S,  Li W, Shen H. Effectiveness of lung ultrasonography for diagnosis of pneumonia in adults: a systematic review and meta-analysis. J Thorac Dis. 2016;8:2822-2831. doi: 10.21037/jtd.2016.09.38
2. Claessens YE, Debray MP, Tubach F, et al. Early chest computed tomography scan to assist diagnosis and guide treatment decision for suspected community-acquired pneumonia. Am J Respir Crit Care Med. 2015;192:974-982. doi: 10.1164/rccm.201501-0017OC