Category Archives: Device

Should I Apply Compression Devices To Patients With DVT?

Everyone knows that venous thromboembolism (VTE) is a potential problem in hospitalized patients, and especially so in trauma patients. Several groups of them are at higher risk by virtue of the particular injuries they have sustained and the activity restriction caused.

Nearly every trauma program uses some form of screening and prophylaxis in an attempt to reduce the occurrence of this problem, which can result in deep venous thrombosis (DVT) and/or pulmonary embolism (PE). Screening looks at patient factors such as age, obesity, previous VTE as well as injury risk factors like spine and pelvic fractures, and decreased mobility.

Based on the screening protocol, prophylaxis may be prescribed depending upon level of VTE risk, which is then balanced with bleeding risk from brain, solid organ, or other injuries. The choices we have are primarily mechanical vs chemical and consist of compression devices (sequential or not) and various heparins.

An age old question surfaced on my own patient rounds recently. If a patient breaks through their prophylaxis and develops DVT, is it safe to apply compression devices to the extremity?

There has always been the fear that doing things that increase flow in the affected extremity may cause clots to dislodge and ultimately cause a PE. Seems logical right? But we know that often, our common sense about things is completely wrong.  Couldn’t just moving around cause pieces to break off? A meta-analysis of 13 studies published in 2015 showed that early ambulation was not associated with a higher incidence of new PE. Furthermore, patients who suffered from pain in the affected extremity noted significant improvements with early ambulation.

If ambulation makes the pain better, could the veins be recanalizing more quickly? Another study examined a small group of 72 people with DVT receiving anticoagulants, half of whom were prescribed exercise and compression stockings and the other half stockings only. There was a huge amount of variability in the rates of recanalization, but ultimately there were no significant differences with or without exercise.

So just lying in bed is not good, and exercise/ambulation may actually make people feel better. But interestingly, bedrest alone does not appear to increase the likelihood of PE! It does decrease the risk of developing problems other than the VTE, like pulmonary complications.

But what about compression devices? Common sense would say that you are intermittently  increasing pressures in the leg veins, which could dislodge any loose clots and send them flying to the lungs, right?

Unfortunately, I couldn’t find a paper from anyone who had the courage to try this. Or perhaps no institutional review board (IRB) would approve it. But the key fact is that every compression device manufacturer includes existing DVT as a contraindication in their product documentation. They don’t have any literature either, so I assume it’s an attempt to limit litigation, just in case.

Bottom line: Walking provides at least as much muscle compression as compression devices. But the simple truth is that we have no solid research that either supports or condemns the use of active compression devices in patients with known DVT. And we probably won’t, ever.

Compression stockings seem to be safe, but they really don’t do much. They are white, but don’t do much more than contribute to hospital clothing fashion. Since the manufacturers define existing DVT as a contraindication, application of their product would be considered an off-label use. So it looks like we cannot in good faith use these devices in patients with diagnosed DVT.

References:

  • Bed Rest versus Early Ambulation with Standard Anticoagulation in The Management of Deep Vein Thrombosis: A Meta-Analysis. PLOS One , April 10, 2015, https://doi.org/10.1371/journal.pone.0121388
  • Bed Rest or Ambulation in the Initial Treatment of Patients With Acute Deep Vein Thrombosis or Pulmonary Embolism: Findings From the RIETE Registry. Chest 127(5):1631-1636, 2005.
  • Does supervised exercise after deep venous thrombosis improve recanalization of occluded vein segments? A randomized study. J Thrombosis Thrombolysis 23:25-30, 2006.
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The “Double-Barrel” IO: Can It Work?

Intraosseous lines (IO) make life easy. They are quicker to insert, have a higher success rate, and require less experience than a standard IV. And they can be used for pretty much any solution or drug that can be given through an IV.

But there are some limitations. They can’t be inserted into a fractured bone. The manufacturer cautions against multiple insertions into the same bone. A second insertion should not be performed in the same bone within 48 hours.

But, as with so many things in medicine, there is little in the way of proof for these assertions. They seem like good ideas for precautions, but that does not mean they are correct. No real research has been done in this area. Until now.

The concept of using two IO needles in one bone was explored in an animal model by researchers in Canada. They used a swine model (using the foreleg/humerus, to be exact), and tested several infusion setups.

Here are the factoids:

  • Infusing crystalloid using an infusion pump set to 999ml/hr took 30 minutes with a single IO, and 15 minutes with a “double-barrel” setup
  • Giving crystalloid using a pressure bag set at 300 mm/Hg took 24 minutes with a single IO, and 23 minutes with double the fun
  • The double-barrel setup also worked for a blood/drug combo. 250cc of blood and 1 gm of TXA in 100ml of saline infused via pump in 13 minutes.
  • Simultaneous anesthesia drugs (ketamine infusion in IO #1, fentanyl and rocuronium bolus in IO #2) without problems
  • Multiple fluid + drug infusion combinations were tested without incident
  • There were no needle dislodgements, soft tissue injuries, fractures, or macrohistologic damage to the bone or periosteum

Bottom line: Remember, these are pigs. Don’t do this in humans yet. However, this is pretty compelling evidence that the double-barrel IO concept will work in people. And it appears that infusion pumps must be used for effective, fast infusions. I recommend that prehospital agencies with inquiring minds set up a study in people to prove that this works in us, too.

Reference: Double-barrelled resuscitation: A feasibility and simulation study of dual-intraosseous needles into a single humerus. Injury 46(11):2239-42, 2015.

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Air Embolism From an Intraosseous (IO) Line

Intraosseous (IO) lines are a godsend when we are faced with a patient who desperately needs access but has no veins. The tibia is generally easy to locate and the landmarks for insertion are straightforward. They are so easy to insert and use, we sometimes “set it and forget it”, in the words of infomercial guru Ron Popeil.

But complications are possible. The most common is an insertion “miss”, where the fluid then infuses into the knee joint or soft tissues of the leg. Problems can also arise when the tibia is fractured, leading to leakage into the soft tissues. Infection is extremely rare.

This photo shows the inferior vena cava of a patient with bilateral IO line insertions (black bubble at the top of the round IVC).

During transport, one line was inadvertently disconnected and probably entrained some air. There was no adverse clinical effect, but if the problem is not recognized and the line is not closed properly, there could be.

Bottom line: Treat an IO line as carefully as you would a regular IV. You can give anything through it that can be given via a regular IV: crystalloid, blood, drugs. And even air, so be careful!

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4 Good Lab Values From Intraosseous Blood – And Some Not So Good Ones Too

The intraosseous access device (IO) has been a lifesaver by providing vascular access in patients who are difficult IV sticks. In some cases, it is even difficult to draw blood in these patients by a direct venipuncture. So is it okay to send IO blood to the lab for analysis during a trauma resuscitation?

A study using 10 volunteers was published last year (imagine volunteering to have an IO needle placed)! All IO devices were inserted in the proximal humerus. Here is a summary of the results comparing IO and IV blood:

  • Hemoglobin / hematocrit – good correlation
  • White blood cell count – no correlation
  • Platelet count – no correlation
  • Sodium – no correlation but within 5% of IV value
  • Potassium – no correlation
  • Choloride – good correlation
  • Serum CO2 – no correlation
  • Calcium – no correlation but within 10% of IV value
  • Glucose – good correlation
  • BUN / Creatinine – good correlation

Bottom line: Intraosseous blood can be used if blood from arterial or venous puncture is not available. Discarding the first 2cc of marrow aspirated improves the accuracy of the lab results obtained. The important tests (hemoglobin/hematocrit, glucose) are reasonably accurate, as are Na, Cl, BUN, and creatinine. The use of IO blood for type and cross is not yet widely accepted by blood banks, but can be used until other blood is available. NOTE: your lab may try to refuse the specimen due to “other stuff” (marrow) in the specimen. Have them run it anyway!

Reference: A new study of intraosseous blood for laboratory analysis. Arch Path Lab Med 134(9):1253-1260, 2010.

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Finding Tough-To-See Veins – Revisited

I’m always interested in technology that makes what we do easier, and this item seems to be in the news again. It’s not new technology any more; I first wrote about this way back in 2011. 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).

One of the first published papers was from Providence, Rhode Island.  It evaluated 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.

The Children’s Hospital of Colorado repeated this study and reported their results earlier this year. And unfortunately they had similar findings. There were no significant differences in success rates using the VeinViewer. Also, nurses did not note any difference in their perceived insertion skills or confidence.

Bottom line: Once again, it seemed like a good idea. But that doesn’t necessarily mean that it is. And we always automatically reach for the new shiny toy. 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 or pediatric nurse can already accomplish.

 

References: 

  1. VeinViewer-assisted intravenous catheter placement in a pediatric emergency department. Acad Emerg Med, 18(9):966-971, 2011.
  2. Utilization of a biomedical device (VeinViewer® ) to assist with peripheral intravenous catheter (PIV) insertion for pediatric nurses. J Spec Pediatr Nurs. 23(2):e12208, 2018.

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

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