General

Can a Normal CT Scan Alone Clear the Cervical Spine in Obtunded Trauma Patients?

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This is the first in a series of articles on interesting abstracts presented at the 23rd Annual Scientific Assembly of the Eastern Association for the Surgery of Trauma in Phoenix, Arizona.

C-spine clearance in obtunded trauma patients has been problematic for some time. The options have been:

  • CT plus MRI. This is probably only valid for the first 72 hours after injury, and entails some risk in placing a critically ill patient inside the MRI for 30 minutes or more.
  • CT plus flexion/extension images under fluoroscopy. These are generally only performed by a few brave souls.
  • Leave the collar on until a clinical exam can be performed. This frequently leads to significant skin breakdown problems.

The authors have been reviewing their experience with using CT scan alone. In this paper, they used this technique in patients who met the following criteria:

  • Obtunded
  • Blunt trauma
  • CT normal, as read by a neuroradiologist
  • Moving all extremities

They studied 197 patients, and found no injuries in all surviving patients (11% were lost to followup). One deceased patient had a stable ligamentous injury without spine fracture seen at autopsy. Using this technique resulted in a decrease in the average number of days to spine clearance from 7.5 to 3.3 days, a decrease in skin breakdown from 5% to 0.5%. A decreased length of stay from 23.4 to 13.8 days was also seen, but this could not be attributed to the collar.

Very intriguing! However, the fear of SCIWORA is high in all who clear c-spines. The rarity of this catastrophic problem means that no existing study has the statistical power to show that this type of clearance is safe.

Bottom line: We all need to decide “How many missed injuries is okay?” We will never be able to absolutely clear 100.000% of c-spines by xray alone, or even by adding a clinical exam. This study provides support for one technique, but eventually a catastrophic injury will occur. Who will decide what constitutes an acceptable complication and with what frequency they will occur?

Reference: A Normal CT Alone May Clear the Cervical Spine in Obtunded Blunt Trauma Patients with Gross Extremity Movement – A Prospective Evaluation of a Revised Protocol. Leukhardt, Como, Anderson, Wilczewski, Samia, Claridge. MetroHealth Medical Center, Cleveland, OH.

General

Trauma Twenty Years Ago: January 1990

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It’s always interesting to review the trauma literature of days gone by to see where we’ve been and how it impacts where we are today in trauma care. Here are a few articles from the Jan 1990 Journal of Trauma (Volume 30 Number 1) worth commenting on:

Efficacy of Liver Wound Healing by Secondary Intent. Dulchavsky et al, page 44-48. This paper compared wound healing using tensile strength in pigs and dogs. The authors compared primary operative closure, closure with an omental buttress, and healing by secondary intention. They found that the strength of secondary healing equaled or exceeded that in both types of operative repair by 6 weeks post-injury. This paper and several similar ones laid the groundwork for our understanding of solid organ healing and lend weight to the somewhat arbitrary guidelines of resuming full physical activity after 6 weeks.

Intestinal Injuries Missed by Computed Tomography. Sherck et al, page 1-7. The authors retrospectively looked at 10 CT scans done over a 9 year period that were done in patients who eventually were found to have an intestinal injury. The injury became apparent in 2 hours to 3 days after the traumatic event. Even when the authors knew that a bowel injury was present, they could definitively diagnose the problem on the initial CT in only 2. The authors concluded that CT could not reliably detect these injuries. Little has changed since this paper was published, even though the scan technology has improved greatly (1 or 2 slice scanners in 1990, 16-64 slices now). We have gotten better at detecting bowel injury with better resolutions, but the diagnosis still remains a clinical one.

Techniques of Splenic Preservation Using Fibrin Glue. Shoemaker et al, page 97-101. The senior author first described the use of fibrin glue in splenic injury in 1983, and continued to investigate it over the next 7 years. This paper was the largest human series at the time. The authors found that it limited blood loss and transfusions, although there was no actual control group. They found that it increased splenic salvage rates to 86% in operative cases, and repeat CT did not show rebleeding or abscess formation. This study added a new technique to the trauma surgeon’s armamentarium in dealing with solid organ injury. Although later studies did find a modest increase in abscess formation, the technique remains a viable alternative when operatively managing solid organ injury. Overall, it is not used as much now because nonoperative management has become quite refined, with a success rate of about 93%.

General

Pulmonary Embolism and DVT in Trauma

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We have long assumed that pulmonary emboli start as clots in the deep veins of the legs (or pelvis), then break off and float into the branches of the pulmonary artery in the lungs. A huge industry has developed around how best to deal with or prevent this problem, including mechanical devices (sequential compression devices), chemical prophylaxis (heparin products), and physical devices (IVC filters).

The really interesting thing is that less than half of patients who are diagnosed with a pulmonary embolism have identifiable clots in their leg veins. In one study, 26 of 200 patients developed DVT and 4 had a PE. However, none of the DVT patients developed an embolism, and none of the embolism patients had a DVT! How can this kind of disparity be explained?

Researchers at the Massachusetts General Hospital retrospectively looked at the correlation between DVT and PE in trauma patients over a 3 year period. DVT was screened for on a weekly basis by duplex venous ultrsonagraphy. PE was diagnoses exclusively using CT scan of the chest, but also included the pelvic and leg veins to look for a source. A total of 247 patients underwent the CT study for PE and were included in the study.

Forty six patients had PE (39% central, 61% peripheral pulmonary arterial branches) and 18 had DVT (16 seen on the PE CT and 2 found by duplex). Of the 46 patients with PE, only 15% had DVT. All patient groups were similar with respect to injuries, injury severity, sex, anticoagulation and lengths of stay. Interestingly, 71% of PE patients with DVT had a central PE, but only 33% of patients without DVT had a central PE.

The authors propose 4 possible explanations for their findings:

  1. The diagnostics tools for detecting DVT are not very good. FALSE: CT evaluation is probably the “gold standard”, since venography has long since been abandoned
  2. Many clots originate in the upper extremities. FALSE: most centers do not detect many DVTs in the arms
  3. Leg clots do not break off to throw a PE, they dislodge cleanly and completely. FALSE: cadaver studies have not show this to be true
  4. Some clots may form on their own in the pulmonary artery due to endothelial inflammation or other unknown mechanisms. POSSIBLE

An invited critique scrutinizes the study’s use of diagnostics and the lack of hard evidence of clot formation in the lungs.

The bottom line: this is a very intriguing study that questions our assumptions about deep venous thrombosis and pulmonary embolism. More work will be done on this question, and I think the result will be a radical change in our use of anticoagulation and IVC filters over the next 3-5 years.

Velmahos, Spaniolas, Tabbara et al. Arch Surg. 2009; 144(10):928-932.

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