Pediatric Lung Ultrasound

Indications

Bedside lung ultrasound can be particularly useful in the pediatric population as a tool for rapid diagnosis of respiratory distress while simultaneously limiting pediatric exposure to ionizing radiation. 

How to scan 

While almost any probe can be used to look for pulmonary pathology, some choices provide advantages over others. 

High frequency linear and microconvex probes provide a higher resolution and are usually the preferred choice for scanning children.  In adults, a low frequency curved probe is often a better choice to evaluate deeper lung tissue, as the increased depth of penetration provides better views in patients with a larger body habitus. It allows the evaluation of multiple rib spaces at a time. 

A thorough lung exam involves scanning the upper and lower portions of the anterior, lateral, and posterior chest wall bilaterally. 

Basic findings 

• Normal lung "A lines"

• Pneumothorax - absent lung sliding 

• Pneumothorax - transition point 

• B lines

• Consolidation

• Pleural Effusion 

Decision Tree

Image from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

Case Comparisons 

Case 1. A 2 yo F presented to ED with 3 days of cough and fever. 

Vitals:  110/60   140   35   95%RA   38.3C rectal

Physical Exam: Increased respiratory effort with intercostal retractions. Slight crackles in the bilateral lung bases and soft expiratory wheezing.

Is this a case of pneumonia, bronchiolitis, or reactive airway disease with URI? 

Use ultrasound to look for large consolidation, air bronchograms, small subpleural consolidations, increased tissue density (B lines), pleural effusion, or normal lung.

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Finding 1:
Ultrasound: consolidation with air bronchograms 

Image from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

CXR: right sided consolidation 

Diagnosis: bacterial pneumonia 

From the Literature:  Tsung et al showed that ultrasound findings of lung consolidation with sonographic air bronchograms correlated 100% with the chest xray findings of bacterial pneumonia in their study. All of these patients were confirmed to have pneumonia based on the clinical course at 2 week follow up. 

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Finding 2:

Ultrasound:  subpleural lung consolidation with scattered adjacent B lines  

Image from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

Image from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

Image from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

CXR: peribronchial cuffing

Diagnosis: bronchiolitis / viral pneumonia

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Finding 3
Ultrasound:  normal A line pattern

CXR: normal

Diagnosis: asthma  

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Discussion:  

When a child presents with complaint of cough, it is up to the clinician to decide if the patient has pneumonia requiring antibiotic therapy, or if the child requires only supportive care. Lung ultrasound can be a useful tool to evaluate for consolidation or signs of interstitial lung disease.

Recent studies (Tsung et al) have defined bacterial pneumonia on ultrasound as the presence of lung consolidation with air bronchograms and viral pneumonia or bronchiolitis as the presence of small subpleural consolidations (usually <0.5cm) and/or individual or confluent B lines.

Take-home Point: Lung ultrasound may be used to help differentiate between normal lung, consolidation consistent with bacterial pneumonia and interstitial syndrome consistent with bronchiolitis or other viral upper respiratory infection.

Fictional case and images taken from Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16. 

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Case 2:  An 8 yo M presented to ED after being struck by a slow moving vehicle while crossing the street on a bicycle. He complains of severe, pleuritic chest pain localized to the right lateral chest.

Vitals: 100/60   110  20   95% RA   37.0C oral.

Physical Exam: appears uncomfortable due to pain, no respiratory distress.  Equal breath sounds bilaterally with no chest wall crepitus.  TTP along right midaxillary line in ICS 4-9.

Does this represent serious traumatic pulmonary pathology or simple musculoskeletal pain? 

Use ultrasound to look for pneumothorax, pulmonary contusion, pleural effusion / hemothorax, or normal lung.

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Finding 1:

FAST: Normal lung sliding on the left.  No lung sliding identified in the anterior Right lung field with a lung point identified one rib space down.

CXR: Small right sided pneumothorax.

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Finding 2:
Ultrasound: Normal lung sliding observed bilaterally with a focal area of B lines over the area of chest wall tenderness.

CT: pulmonary contusion

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Discussion:

As seen earlier, B lines and dynamic air bronchograms indicate lung tissue with higher-than-normal density. This increased density is caused by alveolar consolidation which inhibits air filling. The interpretation of these findings is heavily dependent on clinical context - in this case, a traumatic pulmonary contusion and not a pneumonia.

Take-home Point: Lung ultrasound may be used to help rapidly identify serious traumatic pathology in children.

Fictional case based on actual case report from Stone, MB and Secko MA. Bedside Ultrasound Diagnosis of Pulmonary Contusion. Pediatr Emer Care 2009;25:854-855. 20016357. 

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Further Reading

Basile V, Di Mauro A, Scalini E, et al. Lung ultrasound: a useful tool in diagnosis and management of bronchiolitis. BMC Pediatrics. 2015. 15:63

Guerra M, Crichiutti G, Pecile P, et al. Ultrasound detection of pneumonia in febrile children with respiratory distress: a prospective study. Euro J Pediatr. 2015. Published online prior to print. Accessible at doi:10.1007/s00431-015-2611-8.

Shah VP, Tunik MG, and Tsung JW. Prospective Evaluation of Point-of-Care Ultrasonography for the Diagnosis of Pneumonia in Children and Young Adults. JAMA Pediatr. 2013;167(2):119-125.

Tsung JW, Kessler DO, and Shah VP. Prospective application of clinician-performed lung ultrasonography during the 2009 H1N1 influenza A pandemic: distinguishing viral from bacterial pneumonia. Critical Ultrasound Journal. 2012. 4:16.

Urbankowska E, Krenke K, Drobczynski L, et al. Lung ultrasound in the diagnosis and monitoring of community acquired pneumonia in children. Respr Med. 2015. 109:1207-1212.