Take a Deep Breath and Scan

Lung POCUS in the clinic.

Background:

Finally! The last patient of the day has arrived in your community pediatric emergency clinic and is quickly rushed to triage for vitals. Your medical assistant reminds you that the patient’s mother called the ED earlier after being seen by her primary medical doctor (PMD) yesterday. Their PMD’s follow-up was initially scheduled for tomorrow, but the mother requested more urgent evaluation due to persistent coughing and intermittent fever.

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Your patient is an eight-year-old male with a known history of asthma taking inhaled beclomethasone and as needed albuterol. Per your records, he is poorly controlled on these medications and frequently visits the ED for asthma exacerbations.

As part of his primary clinic’s evaluation, he received corticosteroids and albuterol nebulizer treatment for suspected underlying exacerbation in the presence of upper respiratory infection now at Day 6.  As you review his record, you note that he received a formal chest radiograph to assess for pneumonia. Findings from this evaluation was indeterminate and suggestive of viral etiology. He was sent home with instructions for supportive care and close follow up the following day.

On exam your patient is well appearing and mildly labored in his breathing. He is afebrile, but tachycardic and lung sounds reveal scattered crackles on right lung field greater than left without discernable wheezing. He has intermittent cough paroxysms during your evaluation but able to speak in full sentences. The patient’s mother expresses concern about his symptoms worsening at home with coughing and fever, the latter of which is treated with alternating ibuprofen and Tylenol. His last albuterol treatment was just two hours ago.

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Treatment

Based on your initial assessment, you order another albuterol-ipratropium combination treatment.  However, given your focal findings on auscultation you consider ordering a chest radiograph, but it’s late in the day and that would certainly prolong the visit.

The easier alternative is to send the patient to the county hospital ED and close up shop, but your clinical suspicion leads you to perform a bedside lung ultrasound with your hand-held portable ultrasound device to augment your bedside clinical evaluation. The device has a curvilinear transducer, which easily plugs into your mobile phone. Your approach to the evaluation is to scan eight zones of the torso as described by Volpicelli (Figure 1).¹

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Figure 1: Illustration of the eight zones as described by Volpicelli et al. Areas 1 and 2 represent the upper anterior and lower anterior torso, whereas areas 3 and 4 represent the upper and basal lateral of the torso respectively.

With the patient sitting upright on the exam bed and transducer in the sagittal orientation, you begin scanning the right lung and note the hyperechoic sliding pleura on zone 1 (Figure 1) with horizontal reverberating artifacts indicating normal lung (Figure 2).  The depth of the lung preset on the hand-held device is set to 16 centimeters so you appropriately adjust it to 10 cm. The movement of the pleura allows you to appreciate the A-lines on the subsequent zones 1 and 2 (Figure 2).

Figure 2- Reverberating horizontal artifact commonly seen on normal lung or lungs without subpleural pathology(i.e. Asthma, COPD).

However, you begin to notice some B-lines, which are long multiple coalescing hyperechoic artifacts originating from the pleural line that moves with respiration and extends to the bottom of the screen in zone 3 (Figure 3).

Figure 3: Subpleural vertical artifact also known as B-lines indicating interstitial edema. Note that the artifact may coalesce depending on the pathology as they originate from the pleura and traverse the entire lung window.

Making certain the artifacts are originating from the pleural line you slide the probe inferiorly to obtain images of zone 4 (Figure 4). You note that the B-lines are even more pronounced with an area of thickened, irregular pleural line just above the diaphragm. This leads you to see an area of consolidation with static and dynamic air bronchograms. This is further made evident as you rotate the transducer to the transverse plane. The remaining zones on the left lung reveal scattered B-lines in zones 3 and 4.

Figure 4: B-lines with consolidation suggestive of subpleural pathology. Note that the hypoechoic pleural defect with an inferior hyperechoic consolidation depicted by the red arrow.

Findings

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Your suspicion of an underlying lung pathology is confirmed with the identification of right lower lobe pneumonia based on your bedside lung evaluation. The patient’s respiratory distress improves after the nebulizer treatment. You provide strict return precautions to the ED after sending patient home on antibiotics and continued albuterol treatments every four hours for 24 hours. You appropriately schedule a close follow-up in clinic and the patient’s mother agrees with the plan.

Key Teaching Points:

1. It well known that point-of-care of ultrasound can out-perform the chest radiograph (CXR) for diagnosis of pneumonia.² While the gold standard is still the chest computed tomography, ultrasound is an alternative first-line imaging modality for the diagnosis of community acquired pneumonia (CAP) in pediatric patients.
2. The frequency of CXR for diagnosis of CAP is often non-adherent to Pediatric Infectious diseases Society and Infectious Diseases Society of America guidelines making ultrasound a strong alternative tool. This modality is not and should not be restricted to acute care in the emergency department alone. The use of POCUS in the outpatient setting continues to evolve and provides an opportunity for rapid, efficient and safe CAP diagnosis.
3. Historically, the method used for accurate and reliable diagnosis of pneumonia has been extrapolated from adult studies with evidence now showing technique and sonographic findings reproducible in pediatric patients as well.² However, it is important to note that in pediatric evaluation for pneumonia, there are distinct techniques that can augment for sonographic findings of pneumonia.
4. For the best results, the patient should be examined in the most comfortable position. Infants are commonly examined while on caretaker’s lap. Older children can be examined in the upright, supine or decubitus position. The uncooperative patient requires patience and timely distraction through child life experts, if available. The use of warm gel is strongly encouraged for pediatric patient comfort.
5. Transducer selection can be a key advantage to optimize image acquisition and interpretation. Virtually all types of transducers have been shown to be effective in pulmonary ultrasound.³ Most commonly used traducers are the convex and linear transducers especially because the pediatric anterior-posterior diameter does not require a significant depth adjustment to acquire images necessary for interpretation. The phased array or curvilinear transducers are also an alternative choice especially in adolescents who may require an increased depth.
6. A depth of 8-10 cm is often appropriate for all ages of pediatric patients. We recommend the linear of convex transducer for infants and young children and curvilinear transducer for adolescents who may require an increased depth for optimal evaluation.
7. A simplified scanning technique that should be utilized in the emergency setting is the eight-zone examination consisting of scanning four chest zones per side (Figure 1) as described by Volpicelli G et al.¹ These combined areas cover the anterior and lateral chest wall in a sagittal and coronal planes respectively.
8. Identifying the pleural line is paramount to evaluation for pneumonia. The hyperechoic pleura will be deep to the ribs. The pleura is only adjacent to rib shadows for a very short distance. The rib shadows extend all the way to the bottom of the sonographic window. Recognizing and interpreting lung sliding, pleural effusions, A-lines, B-lines and consolidations are all characteristics necessary for lung evaluation for pneumonia.

Pearls and Pitfalls

1. The ribs are a good reference point to identify the pleural line. Become familiar with the normal sliding pleura.
2. Beware of misinterpreting the cardiac movement (lung pulse) for motion that may be identical to pleural movement when performing ultrasound on the left lung fields.
3. Lung ultrasound is operator dependent and frequent evaluation and practice as with all applications improves skill and confidence for medical decision making.³

References

1. Volpicelli, G et al., International evidence-based recommendations for point-of-care lung ultrasound. 2012. Vol 38;4.pp577-591.
2. Balk D, Schafer J, Welwarth J, Hardin J, Novack V, Yarza S, Hoffmann B. 2018. Lung ultrasound compared to chest X-ray for diagnosis of pediatric pneumonia: A meta-analysis. Pediatr Pulmonol. 1130-1139
3. Doniger, Stephanie. Pediatric Emergency and Critical Care Ultrasound. 2013. Cambridge Medicine.
4. Gargani L, Volpicelli, G. How I do it: Lung Ultrasound. 2014. Cardiovasc Ultrasound. 12:25.