All posts by TheTraumaPro

DVT: Does spinal cord level make a difference?

Deep venous thrombosis (DVT) is always a concern in trauma patients. Patients with spine and spinal cord injury have been shown to be at higher risk for DVT than many other trauma patients, with a reported incidence ranging from 5% to 70%. However, a few studies have suggested that paraplegics are actually at higher risk than quadriplegics. This just doesn’t seem to make sense.

A NTDB study was done to look at this issue. A total of 18,000+ patients were reviewed, and correlations with spinal cord injury level, demographics, comorbidities and associated injuries were determined.

High cervical (C1-4) and lumbar cord injuries had the lowest DVT rates at about 3%. Lower cervical (C5-7) and high thoracic (T1-6) had the highest rates at 5% and 6.3%, respectively. The lower thoracic spine was about 4.5%. These differences were statistically significant, and the authors also confirmed the usual DVT suspects as being significant (increasing age, increasing injury severity, TBI, chest trauma, and male gender).

Bottom line: Yes, this study does confirm the suspicion that paraplegics are at higher risk for DVT than quadriplegics. Why? We don’t know. And although it is statistically significant, is it clinically significant? I’m not so sure. We’re talking another 1-2 spinal cord injured patients with DVT for every 100 quadriplegics treated. How many do you admit per year? At my institution, this means that there will be 1 additional DVT in this patient group every three to four years. It’s hard to justify making any changes to existing protocols based on these new facts. Always look at the practical side of what you read!

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Reference: Risk of venous thromboembolism after spinal cord injury: not all levels are the same. J Trauma 71(5):1241-1245, 2011.

Needle Thoracostomy: Where To Put It?

This is another one of those “everything you know is wrong” posts. Since forever, we’ve been taught that an emergent needle thoracostomy should be placed in the second intercostal space, mid-clavicular line. But how do we know?

Once again, the crew at USC+LAC has taken a new look at something we take for granted. They studied thoracostomy insertion in 20 cadavers, using both the classic insertion site as well as a fifth intercostal space, mid-axillary line position.

They found that only 58% of classically placed needles entered the chest cavity, while 100% of the 5th intercostal space catheters were successful. The success rate in the classic position in males was 75%, but in females was only 17%. The authors speculate that the perfect success rate with the lateral approach was due to the absence of extra tissue over the second intercostal space (pectoralis muscle, breast tissue).

Bottom line: Always question dogma. Granted, there are some limitations with this study (using dead people, age and weight not available). Nevertheless, this correlates with my experience, especially when shorter (5cm long) catheters are used. Although I will not necessarily change my practice immediately until there’s a little more literature, I will keep this in mind for obese patients or in those where traditional placement doesn’t seem to be having the desired effect.

Related post:

Reference: Optimal positioning for emergent needle thoracostomy: a cadaver-based study. J Trauma 71(5):1099-1103, 2011.

Using A 3D Printer To Plan Orthopaedic Surgery

I’ve previously written about new printing technology applications in trauma. A recent article details a new way to use 3D printing technology for planning complex orthopaedic procedures.

An orthopedic registrar in Monklands Hospital (North Lanarkshire, Scotland) found a way to combine new printing technology and orthopaedics. CT scans are routinely taken of complex fractures. Scanners now have powerful software that enables us to create 3D reconstructions from the helical or axial images. However, these are just a series of 2D images viewed on a computer monitor.

Mr. Mark Frame found a way to convert the CT information into a format that can be used as input for a 3D printer. Using two open source (free) software packages for the Mac, OsiriX and MeshLab, he was able to create a medical quality 3D image file. The file was sent to a company that printed it using a 3D printer.

The cost? About $235 US plus a little time for a complete model of the pelvis. The advantage? The actual size 3D model can be used to select hardware and practice the repair technique. And the cost to own a 3D printer keeps coming down!

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What’s The INR of Fresh Frozen Plasma?

So what’s the INR of FFP? Or stated another way, what’s the lowest you can correct a patient’s INR using infusions of fresh frozen plasma?

One of the mainstays of correcting coagulopathy, either from hemorrhage or due to medication like warfarin, is transfusion of FFP. Frequently, clinicians will write orders to administer FFP until a certain INR is achieved. What is a reaonable INR?

A “normal” INR is 1.0, plus or minus about 0.2, depending on your laboratory. However, two separate studies have shown that transfusion of FFP will not reliably decrease the INR below about 1.7. 

Bottom line: The answer to the question is about 1.6. If any clinician orders FFP transfusions with a goal INR below this, it probably won’t happen. And since transfusions of any product have risks, my “juice to squeeze” ratio of risk vs benefit begins to fail at an INR of 1.6. Below that point, the patient needs a normal temperature and good perfusion to drop their INR further.

References:

  • Toward rational fresh frozen plasma transfusion: the effect of plasma transfusion on coagulation test results. Am J Clin Pathol 126(1):133-139, 2006.
  • Effect of fresh frozen plasma transfusion on prothrombin time and bleeding in patients with mild coagulation abnormalities. Transfusion 46(8):1279-1285, 2006.