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.
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
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
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 (<2cm on CXR) can be observed safely, if being admitted to hospital.
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 conflicting3,4,6
The decision whether to place a thoracostomy tube in these patients should be made in conjunction the treating intensivist or anaesthetist.
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
Blunt abdominal trauma
First published: February 2018 (Author: Emma Batistich)
Updated April 2021 (Sue Johnson)
Approved by: Northern Region Trauma Network, ADHB, WDHB, CMDHB, NDHB, NRHL, St John
Review due: 2 years