Finding pneumomediastinum on a chest xray or CT scan always gets one’s attention. However, seeing this condition after a simple fall from standing is very simple to evaluate and manage.
There are 3 potential sources of gas in the mediastinum after trauma:
Smaller airways / lung parenchyma
Blunt injury to the esophagus is extremely rare, and probably nonexistent after just falling down. Likewise, a tracheal injury from falling over is unheard of. Both of these injuries are far more common with penetrating trauma.
This leaves the lung and smaller airways within it to consider. They are, by far, the most common sources of pneumomediastinum. The most common pattern is that this injury causes a small pneumothorax, which dissects into the mediastinum over time. On occasion, the leak tracks along the visceral pleura and moves directly to the mediastinum.
Management is simple: a repeat chest xray after 6 hours is needed to show non-progression of any pneumothorax, occult or obvious. This image will usually show that the mediastinal air is diminishing as well. There is no need for the patient to be kept NPO or in bed. Monitor any subjective complaints and if all progresses as expected, they can be discharged after a very brief stay.
This injury is likely to occur in patients who have a full bladder and sustain anterior pelvic trauma that typically leads to fractures. They generally present with gross hematuria upon placement of the bladder catheter. This should prompt an abdominal CT scan with cystogram technique.
CT cystogram involves pressurizing the bladder with contrast prior to the study. This differs from the usual method of clamping the catheter and allowing the bladder to passively fill. The literature here is clear: failure to use cysto technique will miss 50% of these injuries.
The majority of extraperitoneal bladder injuries can be treated nonoperatively, and probably do not need Urology involvement. The bladder catheter is left in place 10-14 days (we do 10 days), and a repeat cystogram is obtained. If there is no leak, the catheter can be removed. If there is still some leakage, Urology consultation should then be obtained.
There are a few cases where operative management is required:
There is some intraperitoneal component of bladder injury
Fixation of the pubic rami is required (bathing the orthopedic hardware with urine is frowned upon)
Failure of conservative management
Arrows in the photo show extraperitoneal extravasation of cystogram contrast.
A few days ago, I wrote about using a therapy tank for immersion to rapidly rewarm patients (click here to read it). Since this type of management usually means moving out of the ED to a separate patient care are, it is important to have a policy that spells out responsibilities for all personnel involved.
Click here or click the image above to download a copy of the Regions Hospital Trauma Program policy.
CT scan is now the standard screening test for injury to the thoracic aorta. But 20 years ago, we were still gnashing our teeth about how to detect this injury.
An interesting paper was published in the Journal of Trauma 20 years ago this month on this topic. Over a 2 year period, the Medical College of Wisconsin at Milwaukee looked at all patients who underwent imaging for aortic injury. At the time the gold standard was aortogram. They looked at patients who underwent this study and CT, which was not very common at the time.
They had 50 patients who underwent aortography alone and 17 who underwent both tests. Of the 17, 5 had the injury, but only three were seen on CT. There were also two false positives. Sensitivity was 83%, specificity was 23%, with 53% accuracy. The authors concluded that any patients with strong clinical suspicion of aortic injury should proceed directly to aortogram.
Why the difference today? Scan technology and resolution has increased immensely. Also, the timing of IV contrast administration has been refined so that even subtle intimal injuries can be detected. CT scan is now so good that we have progressed from the CV surgeon requiring an aortogram before they would even consider going to the OR, to the vascular surgeon / interventional radiologist proceeding directly to the interventional suite for endograft insertion.
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