Lung Septations

Ultrasound images and text Genevieve Carbonatto.

A 62 year old man with known metastatic non small cell carcinoma presents to the Emergency Department SOB (short of breath). His excercise tolerance has been decreasing over a period of a week. He has been seen by his oncologist as an outpatient and an outpatient Xray shows a large pleural effusion. He has been referred for a CT and drainage of the pleural fluid.

On examination he is SOB at rest. Saturations 91% on RA (room air). HR 101/min sinus rythm     BP 110/60    Temperature 37.3   There is dullness throughout the right chest posteriorly, and reduced AE on auscultation. He is seen by the admitting team and a CT is organised.

The following is his chest Xray done as an outpatient: 

There is a white out of the right hemithorax consitent with a large pleural effusion with mediastinal shift to the right compared to his previous Xrays.

The following is his CT scan:

There is collapse of the right lung with a large pleural effusion

A chest drain is inserted without ultrasound guidance. 120 mls of blood stained fluid is drained and the drain is complicated by a  moderate sized  post thoracostomy tube insertion pneumothorax.

This is his Xray post chest tube insertion.

Again there is complete whiteout of the right lung with a new moderate right pleural effusion

An ultrasound of his chest is then performed by the Emergency Physician and this is what is visible through his chest both anteriorly and posteriorly.

 

Discussion

This case highlights that Ultrasound should be a part of the evaluation of pleural effusions. This case also highlights that septa may not be visible on CT and that ultrasound is a better imaging  modality to identify the presence of septa. The presence of septa does not always imply loculations as fluid may still be free flowing within the hemithorax (1)

The Royal College of Radiologists strongly recommends the use of ultrasound guidance when inserting a chest drain especially if the operator is inexperienced (1) The commonest complications from pleural asiration are pneumothorax, procedure failure, pain, haemorrhage and visceral injury.  A table from” Pleural procedures and thoracic ultrasound: British Society pleural disease guidelines 2010″  shows the complication rates of pleural procedures when performed by radiologists , radiologists in training, senior physicians and physicians in training  with and without ultrasound guidance.

It is clear from this table that physicians in training, and no doubt this is a similar cohort to Emergency Physicians in training, have a much higher rate of post procedure pneumothorax when they are not  using ultrasound guidance. The recommendation from the Royal college of Radiologists regarding image guidance is

Thoracic ultrasound is strongly recommended for all pleural procedures for pleural fluid. (B)

Essentially all pleural taps and thoracostomy tubes should be done under some sort of ultrasound guidance in the Emergency Department in order to identify the best site for needle insertion.

The technique is simple. An Xray of the patient is on hand. With the patient in the seated position or seated position, an ultrasound of the chest is performed both anteriorly, laterally and posteriorly. Using either a 3.5 – 5 MHz sector probe or abdominal probe, the probe is placed in the longitudinal position on the chest wall.  In this way the pleura, the fluid and the ribs can be identified.

  

The diaphragm needs to be identified to avoid intraabdominal tube insertion. Once the intercostal space where fluid has been identified is localised, the probe can then be rotated so that it lies between the ribs (transverse plane). At least 10mm of pleural fluid should be present for aspiration. The measurement is taken  from the visceral pleura to the pariental pleura in inspiration.

There are 2 methods of aspiration. One is by marking the spot  where the needle insertion should occur and doing it without using direct ultrasound visualisation , the second by leaving the probe on the skin and inserting the needle using direct visualisation.

The recommendation from the BTS guidelines however states that:

The marking of a site using thoracic ultrasound for subsequent remote aspiration or chest drain insertion is not recommended except for large pleural effusions. (C)

Clearly ultrasound guided needle insertion is going to be essential in drainage of complex pleural effusions especially loculated effusions.

Teaching point: Ultrasound is a powerful imaging modality in the patient with a pleural effusion. It not only identifies the effusion but is better than CT for identifying septations. It has been strongly recommended for a long time for all pleural procedures for pleural fluid because it reduces  the complication rate of  pleural procedures.

References

  1. Thorax 2010;65:i61-i76 doi:10.1136/thx.2010.137026 BTS guidelines
    Pleural procedures and thoracic ultrasound: British Thoracic Society pleural disease guideline 2010
    Tom Havelock1, Richard Teoh2, Diane Laws3, Fergus Gleeson4 on behalf of the BTS Pleural Disease Guideline Group
  2. Am J case report 2013; 14: 63–66 Multiloculated pleural effusion detected by ultrasound only in a critically-ill patient
    Mohammad Esmadi,1,A,B,D,E Nazir Lone,2,B,D Dina S. Ahmad,1,A,B,E John Onofrio,2,E,F and Ruth Govier Brush3,A,B,E,F
  3. J Bras Pneumol 2014 Jan-Feb; 40(1): 1–5.Lung ultrasound in the evaluation of pleural effusion   Elena Prina,* Antoni Torres, Full Professor of Pulmonology, and Carlos Roberto Ribeiro Carvalho, Full Professor of Pulmonology

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