Original Contribution
Accuracy of lung ultrasound for the diagnosis of consolidations when compared to chest computed tomography,☆☆,,★★

https://doi.org/10.1016/j.ajem.2015.01.035Get rights and content

Abstract

Objectives

Despite emerging evidences on the clinical usefulness of lung ultrasound (LUS), international guidelines still do not recommend the use of sonography for the diagnosis of pneumonia. Our study assesses the accuracy of LUS for the diagnosis of lung consolidations when compared to chest computed tomography (CT).

Methods

This was a prospective study on an emergency department population complaining of respiratory symptoms of unexplained origin. All patients who had a chest CT scan performed for clinical reasons were consecutively recruited. LUS was targeted to evaluate lung consolidations with the morphologic characteristics of pneumonia, and then compared to CT.

Results

We analyzed 285 patients. CT was positive for at least one consolidation in 87 patients. LUS was feasible in all patients and in 81 showed at least one consolidation, with a good inter-observer agreement (k = 0.83), sensitivity 82.8% (95% CI 73.2%-90%) and specificity 95.5% (95% CI 91.5%-97.9%). Sensitivity raised to 91.7% (95% CI 61.5%-98.6%) and specificity to 97.4% (95% CI 86.5%-99.6%) in patients complaining of pleuritic chest pain. In a subgroup of 190 patients who underwent also chest radiography (CXR), the sensitivity of LUS (81.4%, 95% CI 70.7%-89.7%) was significantly superior to CXR (64.3%, 95% CI 51.9%-75.4%) (P< .05), whereas specificity remained similar (94.2%, 95% CI 88.4%-97.6% vs. 90%, 95% CI 83.2%-94.7%).

Conclusions

LUS represents a reliable diagnostic tool, alternative to CXR, for the bedside diagnosis of lung consolidations in patients with respiratory complains.

Introduction

Pneumonia is a common disease characterized by an infection that involves alveoli, distal airways, and interstitium, and leads to lung inflammatory consolidations. Chest computed tomography (CT) is considered the gold standard imaging test for the diagnosis of pulmonary consolidations, but its routine application for the diagnosis of pneumonia is limited by concerns about the high radiation exposure and high costs [1], [2]. In clinical practice, the diagnosis of pneumonia is based on clinical signs and supported by the visualization of typical opacities on chest radiography (CXR). However, in patients evaluated in the emergency department (ED), CXR showed a poor sensitivity (43.5%) when compared to CT [3]. Therefore, reliance on CXR to diagnose pneumonia may lead to significant rates of misdiagnosis.

Lung ultrasonography (LUS) is a bedside diagnostic tool that showed high sensitivity for the diagnosis of various pulmonary conditions, including pneumonia [4], [5], [6], [7], [8], [9]. However, an important limitation of some of these previous studies is that not always CT was used as the gold standard to confirm a pulmonary consolidation.

The aim of our study was to define the diagnostic performance of LUS in detecting pulmonary consolidations with the morphologic characteristics of pneumonia, using chest CT as the gold standard.

Section snippets

Study subjects and design

This was a prospective accuracy study, approved by the local institutional review board. Written informed consent was obtained for inclusion in the study. The patients were recruited from December 2011 to August 2012 in the ED of an Italian university hospital with an annual census of 120000 visits. Consecutive patients aged > 18 years with at least one unexplained respiratory complaint among dyspnea, chest pain, cough or hemoptysis, for which the attending emergency physician ordered a chest CT

Baseline characteristics

A total of 308 patients with respiratory complains underwent chest CT in the ED during the study period. Four patients did not consent to participate. In 19 patients LUS was not performed before chest CT or within the time limit. Thus, 285 patients were included in the final analysis (Fig. 1). These patients had a mean age of 71±14 years (range, 23-100) and 152 (53.3%) were women. Chest CT was positive for at least one consolidation in 87 patients (30.5%), with an almost perfect agreement

Discussion

This study demonstrates that LUS is a reliable tool for the diagnosis of pneumonia-related lung consolidations, when chest CT imaging is used as the gold standard, in adults with respiratory complains of unexplained origin. Our data showed that LUS rules in consolidations with the radiologic characteristics of pneumonia with a high positive likelihood ratio (+ LR = 18.2, 95% CI 9.6-34.7) and rules out this condition with a moderate negative likelihood ratio (− LR = 0.18, 95% CI 0.1-0.3).

These

Conclusions

LUS is a reliable method for the diagnosis of pulmonary consolidations when compared to chest CT in patients with respiratory complains of unexplained origin. Ultrasonography has certain advantages over CXR and may be considered a valid alternative for the diagnosis of pneumonia. LUS is highly feasible and its application in the ED may be extended to physicians with different levels of expertise, still maintaining a high diagnostic accuracy.

The following are the supplementary data related to

References (37)

  • D.A. Lichtenstein et al.

    Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol

    Chest

    (2008)
  • G. Volpicelli et al.

    A comparison of different diagnostic tests in the bedside evaluation of pleuritic pain in the ED

    Am J Emerg Med

    (2012)
  • G. Volpicelli et al.

    Lung ultrasound in the evaluation of patients with pleuritic pain in the emergency department

    J Emerg Med

    (2008)
  • G. Soldati et al.

    Chest ultrasonography in lung contusion

    Chest

    (2006)
  • D.J. Brenner et al.

    Computed tomography—an increasing source of radiation exposure

    N Engl J Med

    (2007)
  • Y. Esayag et al.

    Diagnostic value of chest radiographs in bedridden patients suspected of having pneumonia

    Am J Med

    (2010)
  • F. Cortellaro et al.

    Lung ultrasound is an accurate diagnostic tool for the diagnosis of pneumonia in the emergency department

    Emerg Med J

    (2012)
  • D.A. Lichtenstein et al.

    Ultrasound diagnosis of alveolar consolidation in the critically ill

    Intensive Care Med

    (2004)
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    Author contributions: Dr. Nazerian is the guarantor of the manuscript.

    Dr Nazerian: contributed to study conception and design and data acquisition, analysis and interpretation, drafted the manuscript, edit the manuscript for important intellectual and scientific content; served as the principal author; edited the revision; and approved the final draft.

    Dr Volpicelli: contributed to study design, drafted and edited for important intellectual and scientific content, edit the revision and approved the final draft.

    Dr Vanni: contributed to study conception and design, conduct statistical analysis, drafted the manuscript, edited the revision and approved the final draft.

    Dr Betti: contributed to data acquisition, conducted statistical analysis, edited the revision and approved the final draft.

    Dr Gigli: contributed to data acquisition, conducted statistical analysis, edited the revision, and approved the final draft.

    Dr Bartolucci: contributed to data acquisition, and approved the final draft.

    Dr Zanobetti: contributed to data acquisition, analysis and interpretation, drafted and edited for important intellectual and scientific content and approved the final draft.

    Dr. Ermini: contributed to data acquisition, edited the revision, and approved the final draft.

    Dr. Iannello: edited the revision and approved the final draft.

    Dr Grifoni: contributed to data analysis and interpretation and approved the final draft.

    ☆☆

    All the authors have participated in the preparation of and read and approved the final manuscript.

    Funding Sources: none.

    ★★

    Disclosures: the authors have no potential conflict of interest to disclose

    The article has never been presented.

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