Category Archives: General

Brain Injury and DVT Prophylaxis Part II

I previously wrote about a new review that looked at using chemical prophylaxis for deep venous thrombosis (DVT) in patients with traumatic brain injury (TBI). The authors showed that it was safe to give subcutaneous heparin products within 24 to 48 hours after a stable 24 hour followup CT.

A just-published article now helps to refine the selection of the heparin product. A retrospective review looked at 386 ICU patients with a head Abbreviated Injury Score (AIS) > 2. A total of 57 received mechanical prophylaxis, the remainder received heparin products. Chemical prophylaxis consisted of subcutaneous enoxaparin 30mg bid or unfractionated heparin 5000u tid, at the whim of the attending neurosurgeon.

The heparin group had a slightly but significantly higher Head AIS (4.1 vs 3.8). The drugs were started at the same time post-injury, about 48 hours from admission. Unfractionated heparin was found to be inferior to enoxaparin. The unfractionated heparin patients had both a higher rate of pulmonary embolism, and were more likely to have progression of any intracranial hemorrhage (12% vs 5%). The authors claim a significantly lower DVT rate, but information in their data tables do not support this. Additionally, their overall DVT rate is very low, most likely because they did not routinely screen for it.

Bottom line: The head injury / DVT prophylaxis literature is expanding rapidly. It’s time to start working with your neurosurgeons to initiate chemoprophylaxis early (within 48 to 72 hours from injury once any intracranial bleeding is stable). And it looks like the drug of choice is enoxaparin, not unfractionated heparin.

Reference: Safety and efficacy of heparin or enoxaparin prophylaxis in blunt trauma patients with a head abbriviated injury severity score >2. J Trauma 71(2):396-400, 2011.

Related post: Brain injury and chemical prophylaxis for DVT

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Technology: The VeinViewer

I’m always interested in technology that makes what we do easier. Here’s an objective look at an interesting machine that’s been around for a while. It uses near-infrared light to detect skin temperature changes to allow it to map out veins. It then projects an image of the map in real time onto the skin. In theory, this should make IV starts easier (as long as you can keep your head out of the way of the projector).

A paper just published from Providence, Rhode Island looked at this device to see if it could simplify IV starts in a tertiary pediatric ED. It was a prospective, randomized sample of 323 children from age 0 to 17 looking at time to IV placement, number of attempts, and pain scores.

Unfortunately, the authors did not find any differences. They found that nearly 80% of IVs were started on the first attempt with or without the VeinViewer, which is less than the literature reported 2-3 attempts. This is most likely due to the level of experience of the nurses in this pediatric ED. 

The authors did a planned subgroup analysis of the youngest patients (age 0-2) and found a modest decrease in IV start time (46 seconds) and the nurse’s perception of the child’s pain. Interestingly, the parents did not appreciate a difference in pain between the two groups. This may be due to the VeinViewer’s pretty green display acting as distraction therapy for the child.

Bottom line: This paper points out the importance of carefully reviewing all new (read: expensive at about $20,000 each) technology before blindly implementing it. In this case, an expensive peice of equipment can’t improve upon what an experienced ED nurse can already accomplish.

Reference: VeinViewer-assisted intravenous catheter placement in a pediatric emergency department. Acad Emerg Med, published online, doi: 10.1111/j.1553-2712.2011.01155.x, 2011.

I have no financial interest in Christie Digital Systems, distributor of the VeinViewer Vision®.

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What To Do About Upper Extremity DVT

Deep vein thrombosis (DVT) is a potential problem for all trauma patients, primarily due to the small but real possibility of a resultant pulmonary embolism (PE). Many trauma programs have protocolized their evaluation and management of DVT, but this usually only involves clot in the lower extremities and pelvis. Unfortunately, up to 10% of DVT occurs in the upper extremities, and they are not usually addressed in the same fashion as lower extremity clot.

The American College of Chest Physicians has issued a number of recommendations for managing upper extremity DVT. This includes the use of anticoagulants in a similar manner as for lower extremities. These recommendations have varying literature support behind them, and it is not clear how well they apply to trauma patients.

Cedars Sinai Medical Center in Los Angeles has just published a paper that prospectively looks at the problem of upper extremity DVT in critically ill trauma and surgery patients. They used an existing protocol to screen and treat lower extremity DVT, but had no such algorithm for the upper extremity. A total of 1269 patients were treated in 2.5 years, and 862 patients were screened for DVT at least once. 

They found 316 DVTs in 198 patients (115 lower extremity, 201 upper extremity). A total of 77 patients with upper extremity DVT met inclusion criteria by have at least one followup duplex ultrasound. Since no protocol existed, management was at the discretion of the individual attending physician. Important findings regarding upper extremity DVT were:

  • Most were nonocclusive (72%) and occurred in the internal jugular vein (52%)
  • The average diagnosis was made on hospital day 19
  • 64% were associated with a central venous catheter, usually double or triple lumen. Removal of the catheter was predictive of improvement by the next duplex exam.
  • Pulmonary embolism occurred in 2.6%
  • Two thirds were treated with prophylactic or therapeutic anticoagulation
  • Anticoagulation did not lead to significant resolution by the final duplex exam

Bottom line: Trauma centers should develop a protocol for screening and treating upper extremity DVT. Anticoagulation may not be necessary, and specific criterial should be developed for its use. The patency and necessity for any central venous catheter associated with upper extremity DVT should be assessed, and preference given to moving or removing it.

Reference: The natural history of upper extremity deep venous thromboses in critically ill surgical and trauma patients: what is the role of anticoagulation? J Trauma 71(2):316-322, 2011.

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Pelvic Trauma Radiographs Demystified

Although we are becoming increasingly reliant on CT scans for diagnosis, plain old radiographs still have their place. This is especially true in pelvic imaging after trauma. 

The most common pelvic radiograph obtained is the supine A-P view taken during trauma resuscitation. This image gives a quick and dirty look at the entire pelvis, from iliac crest to ischial tuberosity. The main areas of interest are the pubic symphysis and the SI joints, so if some of the periphery is cut off a repeat is not necessary prior to CT scan. This image helps predict the need for blood and pelvic compression devices.

If fractures are present, the orthopedic surgeons will generally request additional views in addition to the CT scan. The scan gives excellent detail, but the axial image slices are still not as good as a plain old radiograph in many cases.

Inlet and outlet views are used to get a better look at the pelvic ring. The inlet view opens the ring up into a big circle (or oval) and allows identification of fractures of the sacrum or displacement of the SI joints, as well as changes in the pubic symphysis. The outlet view shows any vertical displacements through the sacrum or SI joints well, and gives a better appreciation of some pubic fractures.

Judet views help demonstrate acetabular fractures by lining up the iliac wing with the xray tube. They can give additional information that the orthopedists use for determining operative or nonoperative management.

Rule of thumb: For major trauma patients, obtain an A-P pelvis radiograph if indicated by mechanism of injury or physical exam. Perform CT scan of the abdomen and pelvis if indicated. If a pelvic ring fracture is identified, obtain inlet and outlet radiographs before calling your orthopedic surgeon. If an acetabular fracture is seen, obtain Judet views before calling.

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Compression Of The Fractured Pelvis With A Sheet

Fractures of the posterior pelvis are notorious for their potential to bleed. Here are some tips to use if you encounter a trauma patient with an unstable pelvis and want to slow down the bleeding in the ED.

First, figure out what type of pelvic fracture it is. You will probably be able to do this using physical exam and a simple A-P radiograph. Push down hard on the anterior superior iliac spines to see if the pelvis moves. If so, the patient has an anterior-posterior compression type fracture, and you will likely see diastasis of the pubic bones on the xray. These are amenable to compression maneuvers discussed here.

If the pelvis collapses with lateral compression of the iliac wings, then the patient has a lateral compression fracture and compression maneuvers should not be used. Similarly, if a vertical shear is seen on the xray, do not use compression maneuvers.

There are several pieces of equipment available to help compress the pelvis:

  • Commercial pelvic compression product (e.g. T-Pod). These are convenient but pricey.
  • MAST trousers – just inflate the abdominal compartment, not the legs. But who has these laying around any more?
  • Sheet – cheap and quick. Very effective if used properly.

To apply a sheet, it needs to be folded into a narrow band no more than 12 inches high. It should be passed under the patient’s legs and moved upwards. It must be centered over the greater trochanters. This will apply proper pressure, but will not cover the lower abdomen (think laparotomy) or the genitalia (think urinary catheter). Cross the ends of the sheet over as shown above, with one person holding the cinch point while the sheet is secured. This can be carried out with a knot or plastic clamps. Metal clamps will degrade CT or angiographic imaging and should not be used. The sheet should be left in place for the shortest period of time possible, as skin breakdown can occur.

The picture above on the left shows a sheet that is folded too wide (difficult to get enough tension, and covers the good stuff) and uses metal towel clips. The picture on the right shows the proper technique.

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