Clinical application of transthoracic ultrasonography in inpatients with pneumonia

Performance of lung ultrasonography in children with community-acquired pneumonia

Background

There are few prospective evaluations of point-of-care ultrasonography (US) for the diagnosis of pediatric community-acquired pneumonia (CAP). In particular, there are very few data concerning the efficiency of US in comparison with that of chest radiography (CR) in defining different kinds of lung alterations in the various pulmonary sections. The aim of this study was to bridge this gap in order to increase our knowledge of the performance of US in diagnosing CAP in childhood.

Methods

A total of 103 children (56 males, 54.4%; mean age ± standard deviation 5.6 ± 4.6 years) admitted to hospital with a clinical diagnosis of suspected CAP were prospectively enrolled and underwent CR (evaluated by an independent expert radiologist) and lung US (performed by a resident in paediatrics with limited experience in US). The performance of US in diagnosing CAP (i.e. its sensitivity, specificity, and positive and negative predictive values) was compared with that of CR.

Results

A total of 48 patients had radiographically confirmed CAP. The sensitivity, specificity, and positive and negative predictive values of US in comparison with CR were respectively 97.9%, 94.5%, 94.0% and 98.1%. US identified a significantly higher number of cases of pleural effusion, but the concordance of the two methods in identifying the type of CAP was poor.

Conclusion

US can be considered a useful means of diagnosing CAP in children admitted to an Emergency Department with a lower respiratory tract infection, although its usefulness in identifying the type of lung involvement requires further evaluation.

Transthoracic ultrasound in the assessment of pleural and pulmonary diseases: use and limitations

Interest in transthoracic ultrasound (US) procedures increased after the availability of portable US equipment suitable for use at the patient's bedside. It is possible to detect space-occupying lesions of the pleura, pleural effusion, focal or diffuse pleural thickening and subpleural lesions of the lung, even in emergency settings. Transthoracic US is useful as a guidance system for thoracentesis and peripheral lesion biopsy, where it minimises the occurrence of pneumothorax and haemorrhage. Transthoracic US imaging is strongly influenced by physical interaction of the ultrasonic beam at the tissue/air interface, which gives rise to reverberations classified as simple (A-line), "comet tail" and "ring down"(B-line) artifacts. Although these artifacts can be suggestive of a disease condition, they are essentially imaging errors present even in normal subjects and in empty-pleura post-pneumonectomy patients. In order to clarify some confusion and to report on the state of the art, we present a review of the literature on transthoracic US in diseases of the pleura and peripheral lung regions and our own clinical experience over 3 decades. The review focuses on quality assurance procedures and their value in diagnostic imaging and patient monitoring and warns against possible inappropriate indications and misleading information. Thoracic US is much more than "fishing for the moon in the well".

Lung ultrasound in community-acquired pneumonia and in interstitial lung diseases

Lung ultrasound (LUS) is an accurate tool for the diagnosis and follow-up of pneumonia in adults as well as in children. LUS is at least as accurate as chest radiography in diagnosing pneumonia. The most important parenchymal criterion is the positive air bronchogram within an echopoor area. Among pleural criteria, basal effusion was most often detected. The presence of multiple diffuse bilateral B-lines on lung examination indicates the interstitial syndrome (IS). For further differential diagnosis, an integrated consideration of history, clinical examination, LUS and echocardiography should be performed. LUS is an excellent tool for IS screening. Repeated LUS control examinations may reflect the dynamics of IS under therapy and so LUS may serve as a therapy guide. .

Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: a prospective, multicenter, diagnostic accuracy study

BACKGROUND

The aim of this prospective, multicenter study was to define the accuracy of lung ultrasound (LUS) in the diagnosis of community-acquired pneumonia (CAP).

METHODS

Three hundred sixty-two patients with suspected CAP were enrolled in 14 European centers. At baseline, history, clinical examination, laboratory testing, and LUS were performed as well as the reference test, which was a radiograph in two planes or a low-dose CT scan in case of inconclusive or negative radiographic but positive LUS findings. In patients with CAP, follow-up between days 5 and 8 and 13 and 16 was scheduled.

RESULTS

CAP was confirmed in 229 patients (63.3%). LUS revealed a sensitivity of 93.4% (95% CI, 89.2%-96.3%), specificity of 97.7% (95% CI, 93.4%-99.6%), and likelihood ratios (LRs) of 40.5 (95% CI, 13.2-123.9) for positive and 0.07 (95% CI, 0.04-0.11) for negative results. A combination of auscultation and LUS increased the positive LR to 42.9 (95% CI, 10.8-170.0) and decreased the negative LR to 0.04 (95% CI, 0.02-0.09). We found 97.6% (205 of 211) of patients with CAP showed breath-dependent motion of infiltrates, 86.7% (183 of 211) an air bronchogram, 76.5% (156 of 204) blurred margins, and 54.4% (105 of 193) a basal pleural effusion. During follow-up, median C-reactive protein levels decreased from 137 mg/dL to 6.3 mg/dL at days 13 to 16 as did signs of CAP; median area of lesions decreased from 15.3 cm2 to 0.2 cm2 and pleural effusion from 50 mL to 0 mL.

CONCLUSIONS

LUS is a noninvasive, usually available tool used for high-accuracy diagnosis of CAP. This is especially important if radiography is not available or applicable. About 8% of pneumonic lesions are not detectable by LUS; therefore, an inconspicuous LUS does not exclude pneumonia.

Assessment of ultrasound acoustic artifacts in patients with acute dyspnea: a multicenter study

BACKGROUND

Recent reports indicate that numerical assessment of B-lines during transthoracic ultrasound may aid the differential diagnosis of acute diffuse pleuropulmonary disorders.

PURPOSE

To determine whether B-lines are different in normal and diseased lungs and whether they can be used to discriminate between different types of pulmonary disorders in acutely ill patients.

MATERIAL AND METHODS

In this multicenter study, transthoracic ultrasonography was performed on 193 patients with acute dyspnea, 193 healthy non-smokers, and 58 patients who had undergone pneumonectomy for lung cancer. Examinations were done with a low-medium frequency (3.5-5.0 MHz) convex probe and a high-frequency (8-12.5 MHz) linear probe. Video recordings were re-examined by a second set of examiners. In each participant, we measured the number of B-lines observed per scan.

RESULTS

B-lines counts were higher in dyspnoic patients (means: 3.11 per scan per linear probe scan vs. 1.93 in healthy controls and 1.86 in pneumonectomized patients; P < 0.001 for all); all counts were higher when convex probes were used (5.4 in dyspnoic patients and 2 in healthy controls; P < 0.001 vs. the linear probe). Subgroups of dyspnoic patients defined by cause of dyspnea displayed no significant differences in the number of B-lines.

CONCLUSION

Our results demonstrate that there are a significant higher number of B-lines in the lungs of patients with dyspnea compared to healthy subjects and to pneumonectomized patients. Nevertheless, the quantification of B-lines does not make any significant contribution to the differential diagnosis of dyspnea.

The role of lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia

CAP may be diagnosed and followed up by lung sonography (LUS), a technique that shows excellent sensitivity and specificity that is at least comparable with that of chest X-ray in two planes. LUS may be performed with any abdomen-sonography device. Therefore, LUS is a readily available diagnostic tool that does not involve radiation exposure and has wide applications especially in situations where X-ray is not available and/or not applicable. An X-ray or CT of the chest should be performed in cases of negative lung sonography and if other differential diagnoses or complications are suspected.

Thoracic ultrasound

Dyspnea and hypotension often present a diagnostic challenge to the emergency physician. With limitations on traditional methods of evaluating these patients, lung ultrasound has become an essential assessment tool. With the sensitivity of lung ultrasound approaching that of CT scan for many indications, it is quickly becoming a fundamental technique in assessing patients with thoracic emergencies. This article reviews the principles of thoracic ultrasound; describes the important evidence-based sonographic features found in pneumothorax, pleural effusion, pneumonia, and pulmonary edema; and provides a framework of how to use thoracic ultrasound to aid in assessing a patient with severe dyspnea.