Pneumothorax

A pneumothorax occurs when air collects in the interpleural space. It can be caused by blunt or penetrating thoracic trauma. The most common cause is lung laceration from a rib fracture with air leak.

 

Clinical signs

Patients with massive or tension pneumothoraces are generally unstable – this should be detected clinically (as part of the primary survey)

Smaller simple pneumothoraces may have subtle clinical findings

• Decreased air entry of affected side
• Hyper-resonant percussion note
• Subcutaneous emphysema

 

Investigations

Chest x-ray is a usual first line modality for the detection of pneumothorax.

In studies, the sensitivity and specificity of CXR for detecting pneumothorax is 46 and 100% respectively¹. Small or occult pneumothoraces might not be apparent. In supine CXRs – look for the “deep sulcus sign”

 

Above: Left hemithorax deep sulcus sign on a supine CXR (note patient also has multiple left sided rib #s)

 

Ultrasound is more sensitive than CXR for detecting pneumothoraces with sensitivity of 91% and specificity of 99%¹.

 

CT is almost 100% sensitive for detecting pneumothoraces. Occult pneumothoraces are clinically insignificant and are frequently detected on imaging, especially of other body areas that capture some imaging of the thorax (eg: cervical spine or abdomen).

 

A – CXR shows no pneumothorax, B – CT performed immediately after CXR shows occult right pneumothorax

 

Treatment

Patients with moderate to large traumatic pneumothoraces will require drainage, usually with insertion of a tube thoracostomy via a blunt dissection technique.

 

Size of intercostal catheter

 

Controversy exists is terms of what size catheter to place in patients with traumatic pneumothorax.

 

Very large drains (36-40F) drains were traditionally advocated for trauma patients, but research has shown that smaller drains (28-32F) are just as effective.²

 

Patients with pneumothoraces associated with haemothorax or significant thoracic injuries (multiple rib fractures, flail chest, pulmonary contusions) should have a 28-32F tube thoracostomy placed by the blunt dissection method.

 

In patients with a simple isolated traumatic pneumothorax (without haemothorax), a small pigtail catheter (12-14F) is probably acceptable – discuss with the admitting trauma team.

 

There are different kits available for small bore chest drain insertion – here is a video link for the insertion via the seldinger technique

 

Treatment of small/occult pneumothoracs

Traditionally it was taught that all patients with traumatic pneumothoraces, regardless of size, should be treated with tube thoracostomy.

 

However, there is evidence that asymptomatic, haemodynamically stable patients with occult (pneumothorax detected on CT but not seen on CXR) can be observed without chest drain insertion.^3,4 Small pneumothoraces that are visible on CXR might also be amenable to observation⁵, however there is no universally accepted radiological measurement of what a “small” pneumothorax is. Clinically stable patients with asymptomatic small pneumothoraces can be observed safely, if being admitted to hospital. Note “small” is difficult to define – <2cm has previously been favoured but a study in 2022 demonstrated that up to 35mm can be safely managed without intervention)⁶

 

There is some controversy surrounding the treatment of occult pneumothoraces in patients that are to have positive pressure ventilation. The concern is that PPV may lead to a tension pneumothorax – the literature is conflicting^3,4,7

 

The decision whether to place a thoracostomy tube in these patients should be made in conjunction the treating intensivist or anaesthetist.

 

 

 

Disposition – interhospital transfer guidelines

Most patients with a simple traumatic pneumothorax will require admission either for observation (occult or small) or for ongoing management of the inserted chest drain.

Simple pthx

 

 

References

 

1. 1. Kenneth K Chan et al. Chest ultrasonography versus supine chest radiography for diagnosis of pneumothorax in trauma patients in the emergency department. Cochrane Database Stst Rev. 2020 Jul 23;7(7)
   2. Inaba K, Lustenberger T, Recinos G, Georgiou C, Velmahos GC, Brown C, Salim A, Demetriades D, Rhee P. Does size matter? A prospective analysis of 28–32 versus 36–40 French chest tube size in trauma. Journal of Trauma and Acute Care Surgery. 2012 Feb 1;72(2):422-7.
   3. Ball CG, Kirkpatrick AW, Feliciano DV. The occult pneumothorax: What have we learned? Can J Surg. Vol 52, No 5, October 2009.
   4. Dennis BM, Bellister SA, Guillamondegui OD. Thoracic Trauma. Surgical Clinics of North America, The, 2017-10-01, Volume 97, Issue 5, Pages 1047-1064
   5. MacDuff, Andrew; Arnold, Anthony; Harvey, John; et al. (BTS Pleural Disease Guideline Group) (December 2010). “Management of spontaneous pneumothorax: British Thoracic Societypleural disease guideline 2010″. Thorax. 65 (8): ii18–ii31
   6. Figueroa, J.F., Karam, B.S., Gomez, J., Milia, D., Morris, R.S., Dodgion, C., Carver, T., Murphy, P., Elegbede, A., Schroeder, M. and de Moya, M.A., 2022. The 35-mm rule to guide pneumothorax management: Increases appropriate observation and decreases unnecessary chest tubes. Journal of Trauma and Acute Care Surgery, 92(6), pp.951-957
   7. Brasel KJ, Stafford RE, Weigelt JA, Tenquist JE, Borgstrom DC. Treatment of occult pneumothoraces from blunt trauma. Journal of Trauma and Acute Care Surgery. 1999 Jun 1;46(6):987-91.