Posted in Med Surg

What is a deep vein thrombosis (DVT)?

A deep vein thrombosis is a blood clot that forms in the deep veins of the body, most often in the legs, but they can occur in the upper extremities as well. These blood clots can become dislodged leading to a pulmonary embolism. Notice that the “thrombus” caused the “embolism.” A thrombus is the blood clot as it exists in the vessel; once it dislodges and starts to travel throughout the blood stream, it is then called an embolus. Think of an embolus as a thrombus on the move! Actually, an embolus can be ANYTHING that is traveling through the blood stream (there are air emboli, fat emboli and even foreign body emboli), but for this discussion we’re talking about blood clots. These emboli travel along in the blood stream until they get to a vessel too small for them to continue and that’s where the embolism occurs…leading to all sorts of problems for your patient. But, with the right DVT nursing interventions, you can help protect your patients (plus, it will help you rock your nursing school care plans!)

Who is at risk for a DVT? 

When we look at DVT risk factors, we refer to something called VIrchow’s Triad. This is a collection of three factors that place the patient at risk for development of a DVT. The more risk factors they have, the greater the chance your patient could have a DVT.  The three components of VIrchow’s Triad are: 

1) altered vascular integrity
2) immobility or venous stasis
3) conditions of hypercoagulability

Altered vascular integrity can come about for a variety of reasons. These include inflammation (those vessel walls get leaky!), vascular injury (think surgery!) and mechanical devices such as vascular grafts, PICC lines, and mechanical valves. Orthopedic surgeries (especially of the pelvis and lower extremities) can typically place patients at higher risk, but note that any surgical patient can be at risk for a variety of reasons.

Venous stasis/immobility occurs usually because patient’s aren’t as active as usual when hospitalized. Some are on bedrest, and some feel too weak or sick to get out of bed. Hypoperfusion, shock and heart failure can all contribute to venous stasis, so have a high index of suspicion with these patients!

Hypercoagulability also puts the patient at risk for DVT. This would be any patient with coagulaopathies such as tissue factor abnormalities, thrombocytosis or even someone who was administered an anticoagulant reversal agent. Some conditions of cancer can predispose the patient to hypercoagulable states, as can hormone replacement therapy. Smoking also affects blood clotting (yet another reason not to smoke!)

Obesity, though not technically part of the triad, can predispose a patient to having a higher risk for DVT. A study conducted in 2012 states that obese patients have more than twice the risk of developing a thrombosis…that’s huge! The association between obesity and the factors that contribute to DVT is complex, but if you’re into that sort of thing, you can read it here.

So…let’s think about this triad in action. Let’s say you have an obese female patient on hormone replacement therapy, current smoker, had hip replacement surgery three days ago. She now has an active infection and refuses to get out of bed. If  you’re thinking this patient is at very high risk for a DVT, you are correct, my friend!

What are the signs & symptoms of a DVT?

  • Pain in the leg, especially the calf; if in the arm, then pain in the affected arm. Note that PICC lines are a huge risk factor for upper extremity DVT, so be watchful!
  • Swelling in the affected extremity.
  • The affected extremity may be red, warm to the touch.
  • Veins may be swollen, hard and/or tender to the touch.
  • Positive Homan’s Sign. This is somewhat of a controversial way to assess for DVT. Some studies suggest it has low sensitivity and specificity for DVT , while some practitioners suggest it may actually dislodge the DVT leading to pulmonary embolism. However, it may be on your nursing school exams, so just know that Homan’s Sign is tested by dorsiflexion of the foot while bending the knee…if the patient has pain, it’s considered a positive Homan’s. 

How is a DVT diagnosed?

  • D-Dimer blood test: This test measures the byproducts that occur when clots degrade. If it’s elevated, this could be positive for the presence of a clot. Note that other conditions can cause an elevated D-Dimer, so your physician team will look at the entire patient presentation before diagnosing the DVT.
  • Ultrasound: This is a pretty common way to diagnose DVT and how we typically do it where I work You may see it ordered as a “venous duplex ultrasound”…when you see that, you’ll know what it means.
  • Venography: In this test, contrast dye is injected into the vein and it is viewed on X-ray…the clot shows up at the location where the flow of dye is impaired.
  • CT or MRI: These tests may be used to diagnose a clot, but I’ve never seen it. We typically use less intensive tests first, but these may be used in some situations.

How is a DVT treated?

DVTs are treated with anticoagulants to prevent them from growing larger, though they don’t break up the clot itself (read all about anticoagulants here). In my experience, patients with a DVT will be on heparin or enoxaparin in the hospital and then transitioned to an oral anticoagulant such as warfarin, Eliquis or Pradaxa for long-term therapy. Some patients go home on long-term enoxaparin, so treatment regimens can definitely vary.

What you need to know about warfarin: 

  • It takes several days for blood levels to become therapeutic.
  • The patient will have their INR tested regularly. A normal INR is 1.0, but with warfarin we want it a bit higher…typically 2.0 to 3.0 or 2.5 to 3.0. When the INR is in this range we say “the INR is therapeutic” because even though it’s elevated, it’s on purpose…a result of the therapy. 
  • The patient will need to keep their consumption of leafy greens consistent. This is because warfarin is reversed with Vit K…leafy greens have a lot of Vitamin K! You may hear that patients taking warfarin can’t EVER have things like spinach salads…this is actually untrue. However, they do need to keep it consistent. If these patients have any greens, they should have the same amount basically every day.
  • The reversal agents for warfarin are Vitamin K (given IV) and clotting factors which are found in fresh frozen plasma (FFP), prothrombin complex concentrates (PCCs) and recombinant activated factor VII (rFVIIa).

What  you need to know about heparin:

  • Can be given as a subcutaneous injection of a continuous infusion.
  • Lab test to follow is the PTT.
  • Watch for signs of bleeding.
  • No heparin if the patient has had a lumbar puncture recently or has an epidural catheter in place…the heparin would put them at giant risk for an epidural hematoma, which can lead to paralysis. 
  • Watch your patient’s platelet levels…if they are low, it is probably a good idea to confirm with the MD whether or not the patient still needs the heparin. Never assume…always always always ask.
  • The reversal for heparin is protamine sulfate (given IV).

Fibrinolytics such as alteplase are used to dissolve the clot. These medications can be instilled via a peripheral IV or central line, or through a special catheter placed right at the site of the clot itself. 

What you need to know about alteplase:

  • Labs to follow are fibrinogen, aPTT, INR. You’ll also want to keep an eye on platelets…low platelets in combo with alteplase can be very bad news for your patient (think huge huge huge risk for bleeding). 
  • Monitor for signs of bleeding.
  • Bleeding can occur in the brain, so monitor for neuro changes. Instruct the patient to report any headaches, blurred vision or other neurological concerns immediately.
  • Listen to podcast episode 53 TPA Administration here!

What are the complications of a DVT?

The biggest problem we worry about with a DVT is that the clot will dislodge (go from being a thrombus to being an embolus) and block vessels in the lung, becoming a pulmonary embolism (also called a PE). IVC filters may be used to prevent a pulmonary embolism from occurring. These are filters placed in the inferior vena cava that “catch” an embolus before it gets to the lungs. 

Post-thrombotic syndrome is another complication of DVT. Thromboses damage the vessel wall and the valves, leading to chronic venous insufficiency. Recall that venous return (getting the blood back to the heart) relies on a variety of factors such as skeletal muscle movement, respiration, the action of the valves, and constriction of the smooth muscle in the vessel walls. If these valves and vessels aren’t functioning properly, chronic venous insufficiency results. The patient can develop a whole host of problems including swelling in the affected leg (edema), dark pigmentation of the skin, dilated veins, and venous ulcers that are very difficult to treat.

Also, DVTs are expensive!! A study conducted in 2015 estimates that a DVT can add approximately $5800 to $7000 to your patient’s hospital bill (and that’s WITHOUT any complications…a PE adds much, much more!). So, the main takeaway here is that we do not want our patient to have a DVT. The good news is, you can do a lot to help prevent it!

How is a DVT prevented? 

Finally…the good stuff! What are you going to do about it? As the nurse, you are going to do plenty! Below are the key components of DVT nursing interventions:

  • Early ambulation. One of the best things you can do to prevent DVT is get those patients up and walking. Patients often don’t want to walk because they’re in pain (raising my hand here…I was the WORST patient after my appendectomy!) so try to ensure their pain is manageable prior to ambulation. Also, you’ll be surprised how quickly patients lose strength while on bedrest, so they may be quite weak. Use walkers, gait belts, and any other assistive devices you need to get those patients moving safely!
  • If the patient can’t walk at this time, they can still mobilize in bed or in the chair…having them “step on the gas” by alternating dorsiflexion with plantarflexion helps improve venous return.
  • Sequential compression devices (SCDs). You’ll often hear these referred to as “scuds” which is what we say instead of S-C-Ds most of the time. They gently squeeze each leg in turn, promoting venous return when patients are in bed or immobile for any period of time.
  • Antiembolic stockings (often called Ted hose…I have no idea why). One thing to know about these stockings is they are pretty snug fitting, so they’re hard-as-heck to get on. Also, if they roll down, they can become so tight at the location of the roll that they have a tourniquet effect. Also, make sure there are no creases or folds in the fabric that could lead to skin breakdown. 
  • Administer anticoagulants as prescribed
  • Deep breathing (remember that respiratory action promotes venous return!)

So there you have it…pretty much the main points for preventing, spotting and treating a DVT. Good job, you!

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Get this on audio in Episode 59 on the Straight A Nursing Podcast.