Pediatric Pneumonia: Sensitivity of Lung Ultrasound vs Chest Radiography

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Lung ultrasound was more effective in diagnosing pediatric community-acquired pneumonia than chest radiography.
Lung ultrasound was more effective in diagnosing pediatric community-acquired pneumonia than chest radiography.

Lung ultrasound was more effective in diagnosing pediatric community-acquired pneumonia (pCAP) than chest radiography, with significantly better sensitivity and similar specificity, according to the results of a meta-analysis published in Pediatric Pulmonology.

Although pCAP is diagnosed clinically, radiologic confirmation is often used in complicated or uncertain cases. Chest radiography has a high false-negative rate, exposes patients to ionizing radiation, and can be difficult to obtain in areas with limited resources. Computed tomography of the chest exposes children to considerable radiation and is expensive. Provider-performed point-of-care lung ultrasound is a promising alternative: portable and radiation-free.

Daniel S. Balk, MD, from the Department of Emergency Medicine, Beth Israel Deaconess Medical Center in Boston, Massachusetts, and colleagues conducted a systematic review of PubMed, EMBASE, and Web of Science and included all literature through August 2017. The investigators identified 12 studies, which included a total of 1510 patients.

Lung ultrasound had a pooled sensitivity of 95.5% and a pooled specificity of 95.3%, and it had a positive predictive value of 99.0% and a negative predictive value of 63.1%. In contrast, chest radiography had a pooled sensitivity of 86.8% and a pooled specificity of 98.2%, whereas the positive predictive value for chest radiography was 99.6%, and the negative predictive value was 43.6%.

The study is limited by the use of a select population with a high suspicion of pCAP, which does not reflect the general population of pediatric patients. Furthermore, there is significant heterogeneity in the positive predictive and negative predictive values found here, and thus they would only be applicable to a patient population in which there is a high clinical suspicion of pCAP, and not to pediatric patients in general.

Another major limitation is the reference standard. There is considerable difficulty in differentiating bacterial pCAP, viral pneumonia, and bronchiolitis based on clinical presentation, and radiologic studies are often used to help differentiate these conditions and guide treatment. Computed tomography is usually considered the gold standard of imaging, but routine use may expose children to unnecessary radiation. Thus, chest radiography is often used to diagnose pCAP.

Limitations aside, these results suggest the utility of lung ultrasound and demonstrate its superior sensitivity over chest radiography. However, although the evidence to support the use of lung ultrasound over chest radiography is growing, the authors noted that additional research is necessary to help differentiate bacterial from viral pneumonia.

Reference

Balk DS, Lee C, Schafer J, et al. Lung ultrasound compared to chest X-ray for diagnosis of pediatric pneumonia: a meta-analysis [published online April 26, 2018]. Pediatr Pulmonol. doi:10.1002/ppul.24020

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