VOTW: Hepatization of Lung

Here is this week's VOTW:

A 69-year old male with a history of COPD presented to the ED for 1 month of cough and 1 week of hemoptysis. A chest x-ray showed a left lower lobe consolidation vs atelectasis vs effusion. A POCUS was performed to better characterize the area which showed…

Clip 1 and Clip 2 shows "hepatized lung", a large isoechoic area of lung tissue just under the pleura that has a similar echogenecity to the liver which is suggestive of a consolidation. The echogenic jagged line in the far field is the interface between consolidated and aerated lung. Within the consolidation, air bronchograms (scattered echogenic dots and lines) can be seen. 

Findings of pneumonia on lung ultrasound

Hepatization of the lung - Normal lung tissue is not visible on ultrasound as it is filled with air. As pneumonia develops, inflammatory material (fluid, pus) fill the alveoli of the lung, and the affected lung tissue becomes more solid and visible on ultrasound. A large consolidation takes on the appearance of a solid organ like liver and is referred to as “hepatization of the lung”. Atelectasis can also have this appearance.

B-lines are not specific to pulmonary edema and can be see with pneumonia due to the fluid within the alveoli. This may be the only finding in early pneumonia. Focal B-lines are more suggestive of infectious process while diffuse B-lines are more suggestive of pulmonary edema.

Shred sign refers to small hypoechoic lesions abutting the pleura which gives the appearance of a jagged pleural line. This is highly specific for a small subpleural consolidation. The jagged line is the interface between consolidated and aerated lung and not actually the pleural interface.

Air bronchograms (image below) are small pockets of air that are present within the small bronchi within the consolidation seen in both atelectasis and consolidation. Dynamic air bronchograms move in and out along the bronchi with each breath and is more specific for a true consolidation. Static air bronchograms are more suggestive of atelectasis as with complete collapse of the lung air won’t move in or out but can also be seen with consolidation.

Image 1. Air bronchograms

Pleural effusions frequently accompany a pneumonia. Echogenic debris or septations within the effusion can suggest an empyema.

Tips and tricks on Lung Ultrasound

• Use the curvilinear probe using the Lung settings

• Orient your probe with the probe marker towards the head, find two ribs which are hyperechoic with posterior shadowing and identify the shiny shimmering pleura in between

• If looking for B-lines, increase the depth so you can see the b-lines which extend all the way down the screen. This lets you differentiate B-lines from comet tail artifacts which do not extend all the way down the screen and are not pathologic.

• If looking for a pneumothorax, decrease the depth so you can focus at the pleura and more easily look for lung sliding. You can also switch to a linear probe for higher resolution

• When looking for a pleural effusion at the lung bases, bring the vertebral bodies in view so that you can look for a “spine sign” (extension of the spine above the diaphragm which would indicate the presence of a pleural effusion)

Case conclusion

A CTA Chest showed a dense left lower lobe consolidation. The patient was given IV antibiotics and admitted for the management of pneumonia and hemoptysis.

Here is a great review of lung ultrasound for pneumonia: https://litfl.com/lung-ultrasound-pneumonia/

Happy Scanning,

Your Sono Team

VOTW: Lung Point

Hi all, this week's VOTW is presented by Drs Forrest, Yang and Schiller!

A 71 year old male w/ hx of COPD presented to the ED for altered mental status. He was found to be obtunded due to hypercapnia and was intubated in the ED. Several hours after admission to the MICU the patient suddenly desaturated to 64%. 

A POCUS was rapidly performed which showed…

Clip 1 shows a POCUS of the R anterior chest. On the left side of the screen, the pleural line has absent lung sliding. From the right of the screen, normal pleura with lung sliding is seen coming into the image with every breath. This is a “lung point” which is the exact point at which the pneumothorax starts. A chest x-ray confirmed a large R sided pneumothorax with mediastinal shift. A chest tube was placed by the ED team for a tension pneumothorax with improvement in vitals.

Image 1 shows an M-mode image obtained expertly by the team at the lung point which shows both "seashore sign" indicative of normal lung as well as "barcode sign" indicative of pneumothorax in one clip. You'll see this only if you use M-mode at the lung point.

M-mode showing areas of “sandy beach” alternating with “barcode sign” at the lung point

Lung sliding

In normal lung, the pleural line will appear to shimmer due to the movement of the visceral and parietal pleura sliding against each other. With a pneumothorax the contact between the two pleura are lost and the pleural line will appear still. 

*The presence of lung sliding rules out a pneumothorax at the location of the chest you are scanning. 

*Image the least dependent site (where air is most likely accumalate) to maximize sensitivity of the test (anterior chest in a supine patient).

*Reduce your image depth all the way! This way you don't have to squint while looking for lung sliding

Lung point

This is the point at which normal lung sliding and absent lung sliding are seen next to eachother simultaneosuly and is the exact point where the viseral pleural is peeling away from the parietal pleura. If found, this finding is highly specific for pneumothorax. It won't be seen with a large pneumothorax that envelops the entire lung.

Does absence of lung sliding always indicate pneumothorax?

No. Absence of lung sliding can be seen with many conditions including a bleb from COPD, right mainstem intubation (no left-sided lung sliding), patients w/ previous thoracic surgery (such as pleurodesis or VATS), pleural adhesions, ARDS, pulmonary fibrosis, atelectasis, and phrenic nerve paralysis. If the patient is stable, confirm the diagnosis with a chest x-ray or CT prior to placing a chest tube.

Which lung ultrasound artifacts rule out pneumothorax?

A-lines are reverberation artifacts that can be generated by air in normal lung tissue or air in the pleura so cannot be used to rule out pneumothorax.

B-lines indicate the presence of interstitial edema which can only be seen if the lung tissue is abutting the pleura. Even seeing one B-line is enough to rule out pneumothorax.
Happy sliding,

Your Sono Team

Intubating Asthmatic Patients

Asthma is Greek for panting, which is a fitting translation for a patient that presents with a severe asthma exacerbation. We try to avoid intubating these patients because they are prone to compilations such as pneumothorax, mucus plugging, and increased morbidity and mortality. 

However, there are specific situations when you may consider intubating an asthmatic patient. One reason is that your patient may not be improving despite maximal medical therapy, such as BIPAP, albuterol, ipratropium, magnesium, epinephrine/terbutaline, ketamine, etc. Another reason is that your patient may now be altered, and have worsening work of breathing, and vital sign abnormalities. Remember that a “silent chest” is a poor prognostic indicator; you may not hear wheezing because they are not moving any air. 

If you choose to intubate, there are tricks to maximize your success and optimize your management of your patient on the vent. 

• Use a large ETT (8-9) because it reduces airflow resistance and can facilitate procedures later (such as bronchoscopy). 

• Ketamine is a useful induction agent because of its bronchodilatory effects. It may also be useful if you choose delayed sequence intubation. 

• High airway pressures can cause hypotension after intubation, so consider giving volume if there is a current or prior history of hypotension. 

• If hemodynamics are compromised consider giving an epinephrine drip. It is considered a systemic bronchodilator that can provide hemodynamic support as well as bronchodilation. 

• Keep a low respiratory rate when bagging or on the vent (6-8 breaths/min). Giving them time to exhale will decrease the chances of air trapping and pneumothorax. Another way to do this is to increase the I:E time (1:4 or 1:5). 

• If the vent is alarming, troubleshoot (DOPES mnemonic) but be suspicious for mucus plugs, pneumothorax, or breath stacking. If they are breath stacking, disconnect them from the vent and push on their chest to help them fully exhale.  

A quick note about auto-PEEP and breath stacking: Auto-PEEP refers to trapping gas in the lungs during respiration. This occurs when one breath can’t be fully exhaled before the next inhalation. This trapped gas causes additional positive pressure, known as “auto-PEEP” in the chest which is typically higher than the PEEP set on the ventilator. This process predisposes patients to develop a pneumothorox. 

Thanks for reading!

Ariella