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.

Bedside Lung Ultrasound in Emergency - the BLUE Protocol

Acute respiratory failure requires immediate action on the part of the healthcare provider. Timely, appropriate treatment is important to change the course of the disease and improve morbidity and mortality. Thus, bedside ultrasound is an ideal tool for the evaluation of changes in lung aeration present in many life-threatening conditions.

Each disease process has its own unique ultrasound profile. The BLUE protocol is a stepwise binary analysis of three lung signs which are evaluated at six standardized points, including venous analysis as required, to then generate disease profiles. It was proposed by D. Lichtenstein in 2008 as a tool to help the clinician rapidly reach a diagnosis in patients who present with acute respiratory failure. 

How do you perform the BLUE protocol?

What probes do you need for the BLUE protocol?

• Microconvex probe (3.5-5MHz) OR
• Phased-array probe (3.5-5MHz)

What are the six standardized BLUE points?

Four anterior BLUE points follow the anatomy of the lung while avoiding the heart as much as possible. To find these points, place two hands (approximately the patient's size) on the patient's chest with the little finger just below the clavicle and with thumbs overlapping. 

BLUE Points. Image from Lichtenstein Lung Ultrasound in the Critically Ill.  Curr Opin Crit Care 2014. 

The Upper BLUE Point is located at the middle of the upper hand and the Lower BLUE Point is located at the middle of the lower palm. The PLAPS (posterolateral alveolar and/or pleural syndrome) Point is located at the intersection between a horizontal line drawn from the Lower BLUE Point and the posterior axillary line on each side. 

What are the three lung signs used in the BLUE protocol?

1) Lung Sliding - Present or Absent 

2) Artifact Analysis - A lines or B lines 

3) Alveolar Consolidation and/or Pleural Effusion - Present or Absent

What are the lung profiles? 

1) A-profile: normal lung sliding plus predominant A lines (horizontal hyperechoic lines that are static and appear at regular intervals). 

2) B-profile: normal lung sliding plus B lines (vertical hyperechoic lines that flicker in sync with respirations). 

3) C-profile: hyperechoic areas that take on the appearance of tissue structure, consistent with consolidation.  

Lung Profiles. Images from Neto et al. Diagnostic Accuracy of the BLUE Protocol for the Diagnosis of Acute Respiratory Failure in spontaneously breathing patients. J Bras Pneumol 2015.

The six BLUE points are then evaluated, generating the following combinations:

• A profile with normal lung sliding and without a DVT = obstructive lung disease (COPD or asthma) 
• A profile with normal lung sliding and with a DVT = pulmonary embolism 
• A profile with no lung sliding or a lung point = pneumothorax 
• A profile with PLAPS = pneumonia 

• B profile with normal lung sliding = pulmonary edema
• B profile without normal lung sliding = pneumonia 

• C profile = pneumonia 

• A profile on one side with B profile on the other side = pneumonia 

From D. Lichtenstein Lung Ultrasound in the Critically Ill. Curr Opin Crit Care 2014. 

How good is the science?

Lichtenstein and Meziere. Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure: The BLUE Protocol. Chest 2008; 134:117-125. 

Observational study, n=301. Bedside ultrasound was performed within 20 minutes of ICU admission. Healthcare providers managing the patients were blinded to ultrasound results. Official diagnoses were established by standard diagnostic practice including history, physical, and standard practice lab or imaging studies, excluding ultrasound. 

Bedside ultrasound provides a correct diagnosis in <5 minutes in 90.5% of cases.  

From Lichtenstein and Meziere. Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure: The BLUE Protocol. Chest 2008

Silva et al. Usefulness of Cardiothoracic Chest Ultrasound in the Management of Acute Respiratory Failure in Critical Care Practice. Chest 2013; 144(3):859-865. 

Prospective randomized study, n=78. Again, bedside ultrasound was performed within 20 minutes of ICU admission and treating providers were blinded. Official diagnosis was established by chart review, excluding ultrasound.  

Bedside ultrasound showed improved diagnostic accuracy compared to standard approach (83% vs 63%, p<0.02). 

Neto et al. Diagnostic accuracy of the Bedside Lung Ultrasound in Emergency protocol for the diagnosis of acute respiratory failure in spontaneously breathing patients. J Bras Pneumol. 2015;41(1):58-64. 

Prospective randomized study, n=42. In contrast to the previous two studies, the examiners performing the BLUE protocol were non-experts (5 hours of theoretical training and 10 supervised LUS exams). The examiners did not participate in patient management and treating providers were blinded. Official diagnosis was the ICU discharge diagnosis. 

Non-experts can use bedside lung ultrasound to reach a correct diagnosis 84% of the time (k=0.81) with bedside ultrasound significantly more accurate than chest xray (84% vs 43%, p=0.01). 

Take Home Point: BLUE Protocol can be used to establish correct diagnosis in acute respiratory failure with a 90% accuracy in <5 minutes.