Review articleThe role of lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia
Introduction
Lower respiratory tract infections are a major healthcare and economic problem with a considerable impact on morbidity and mortality. Among such infections, community-acquired pneumonia (CAP) is the seventh leading cause of death overall and the most common cause of death from infectious diseases in the United States [1]. The annual incidence rate of CAP is 6/1000 in the 18–39 age groups and 34/1000 in people aged 75 years and over. Between 20 and 40% of CAP patients require hospitalization, and, of these, 5–10% are admitted to an intensive care unit (ICU). Due to the burden of CAP on morbidity and mortality, healthcare providers must adopt practices focused on improving outcomes. One of the most important challenges in the management of pneumonia is correct and early diagnosis.
Section snippets
What are current problems in diagnosing pneumonia?
Based on the latest European Respiratory Society guidelines, CAP is defined as an acute illness with signs or symptoms compatible with a respiratory tract infection supported by X-ray findings of new lung infiltrates [2]. There is a strong consensus among international societies that a chest X-ray should be performed in all patients who are admitted to hospital with suspected pneumonia [2], [3], [4].
Although chest X-ray is widely recognized as a crucial step in the diagnosis of pneumonia, this
How is lung ultrasound performed in patients with suspected pneumonia?
LUS is becoming a widely used imaging technique in several settings. It can be performed with any abdomen-sonography device. Selection of the most suitable probe is critical: vascular probes have the highest resolution in superficial layers, but make artifact identification harder. Convex or microconvex probes (3.5–5 MHz) are the best suited to diagnosing pneumonia by lung ultrasonography. Fine regulation of the sonographer's parameters is not strictly required. Of these parameters, focus can be
Is lung ultrasound helpful in the diagnosis and follow-up of pneumonia?
In most cases, pneumonia affects the peripheral lung tissue. Due to the inflammatory defence reaction of the host against pathogenic microorganisms the peripheral airways and alveoli are flooded by a neutrophil-rich exudate. As a consequence, air is evacuated from the affected tissue, allowing sonographic evaluation if the lesion extends up to the pleura.
Is lung ultrasound better than CXR and/or CT?
In a large multicentre trial [17] baseline results (including unequivocal results) showed that pneumonia was correctly diagnosed by LUS in 211 of 229 cases (92.1%) and by X-ray in 199 of 229 cases (86.9%) (Table 3).
On the other hand, CAP was correctly ruled out by LUS in 127 of 133 patients (95.5%) and by X-ray in 122 of 133 patients (91.7%). X-ray detected 14 cases of CAP that were missed by LUS, whereas 26 cases of LUS-detected CAP were missed by X-ray (Table 3).
In the same study, LUS and
Use in children/pediatric population
CAP is a common disease in the pediatric population with 40 cases annually per 1.000 children under 5 years in Europe and North America. Pneumonia in children may present with fever, cough and tachypnea and hospitalization is often required. Up to 50% of hospitalized pneumonia cases are complicated by parapneumonic effusion, pulmonary necrosis and empyema.
X-ray is currently recommended as the first imaging step for diagnosing pneumonia in children. However, several studies have been performed
What are the future implications of lung ultrasound in pneumonia?
To date no comparisons of the sonomorphology of CAP, hospital acquired pneumonia and ventilator-associated pneumonia have been made, although their sonomorphology may differ. Co-morbidity such as heart failure or pulmonary edema and antibiotic therapy may also influence sonographic features. During the course of pneumonia, the air bronchogram became less pronounced in 79 of 314 patients (23%) [16]. Therefore, in cases of pneumonic lesions under antibiotic therapy, lung cancer, which do not
Learning points
- •
CAP may be diagnosed and followed up by lung sonography.
- •
Lung sonography shows an excellent sensitivity and specificity that is at least comparable with that of chest X-ray in two planes.
- •
Lung sonography may be performed with any abdomen-sonography device.
- •
Lung sonography 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
Conflict of interest statement
All authors assert that there are no conflicts of interest, financial or otherwise, pertaining to this study.
References (44)
- et al.
Guidelines for the management of adult lower respiratory tract infections — full version
Clin Microbiol Infect
(2011) - et al.
Interobserver reliability of the chest radiograph in community-acquired pneumonia. PORT Investigators
Chest
(1996) - et al.
Imaging of the ICU patient
Clin Chest Med
(1991) - et al.
Acute respiratory distress syndrome
Lancet
(1999) - et al.
Bedside lung ultrasound in the assessment of alveolar interstitial syndrome
Am J Emerg Med
(2006) - et al.
Ultrasound imaging of pneumonia
Ultrasound Med Biol
(1995) - et al.
Evaluation of lung ultrasound for the diagnosis of pneumonia in the ED
Am J Emerg Med
(2009) - et al.
Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol
Chest
(2008) Transcutaneous contrast-enhanced sonography of pleural-based pulmonary lesions
EJR
(2007)- et al.
Thoracic ultrasound for diagnosing pulmonary embolism. A prospective multicenter study of 352 patients
Chest
(2005)
Sonography of lung and pleura in pulmonary embolism: sonomorphologic characterization and comparison with spiral CT scanning
Chest
Contrast-enhanced sonography for differential diagnosis of pleurisy and focal pleural lesions of unknown cause
Chest
The dynamic air bronchogram. A lung ultrasound sign of alveolar consolidation ruling out atelectasis
Chest
Lung ultrasound in the evaluation of patients with pleuritic pain in the emergency department
J Emerg Med
Pneumonia and influenza death rates — United States, 1979–1994
MMWR Morb Mortal Wkly Rep
Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults
Clin Infect Dis
BTS guidelines for the management of community acquired pneumonia in adults: update 2009
Thorax
Reliability of the chest radiograph in the diagnosis of lower respiratory infections in young children
Pediatr Infect Dis J
High-resolution computed tomography for the diagnosis of community-acquired pneumonia
Clin Infect Dis
Transthoracic sonography in the diagnosis of pulmonary diseases: a systematic approach
Ultraschall Med
Ultrasound diagnosis of alveolar consolidation in the critically ill
Intensive Care Med
Sonographic diagnosis and follow-up of pneumonia: a prospective study
Respiration
Cited by (80)
Community-acquired pneumonia
2021, The LancetThe Geriatric Patient: The Ideal One for Chest Ultrasonography? A Review From the Chest Ultrasound in the Elderly Study Group (GRETA) of the Italian Society of Gerontology and Geriatrics (SIGG)
2020, Journal of the American Medical Directors AssociationEarly Prediction of Thoracic Diseases Using Rough Set Theory and Machine Learning
2024, Lecture Notes in Networks and SystemsAdvancing healthcare through thoracic ultrasound research in older patients
2023, Aging Clinical and Experimental Research