Blood Clot Worries When Traveling

Over the past 25 years we have witnessed an explosion in travel, especially longer haul (> 4 hours) airline travel.  Airlines admit that they are providing passengers with far less seat/leg space than ever before.  Just last month, I flew overnight from Portland to Newark in the smallest confines I have ever experienced.  I did not leave my seat for nearly 5 hours.

Given that the US population continues to increase in average weight, airline seat area reduction creates the perfect storm as confined space travel in the overweight passenger will likely increase the incidence of leg blood clots, or “deep vein thrombosis”.

Past research has shown there is nothing environmentally unique to long haul airline travel compared to confined space travel in a car or train with respect to blood clot risk.  However, currently there is less space to move in your airline seat and for a variety of reasons, less opportunity to move about the cabin.  Train travel does allow quite a bit of movement and it is infrequent for a car or bus not to stop for a break during 4 hours of travel.  So it’s primarily the airline traveler who should be considered for blood clot prevention, especially on flights over 4 hours.

In addition to obesity, a history of DVT (blood clots in veins) congestive heart failure, active or recently treated malignancy, abdominal, pelvic or leg surgery in the past 30-45 days, post-pregnancy states within 30 days of delivery, and known genetic or acquired states that predispose to blood clots are all “highest risk” situations where the chance of getting a blood clot during or after travel approaches 1 in 20 (5%). Recent leg trauma with immobilization also fits this risk category.

Self-administered injections of blood thinner drugs have traditionally been prescribed for traveling patients at highest risk for blood clots:  usually one or two injections.  Aside from this practice being inconvenient, it is also concerning since the risk of blood clots has been shown to extend days beyond the actual transit period, similar to that seen in the total hip/knee joint replacement patient where the blood clot risk can extend out to 21 days after the surgery.

Compression hose or socks do reduce blood clot risk in the traveler and should be universally used in these patients.  However, compression is not effective when not worn, and ideally should be used days after a transit, which is also inconvenient.

We now have oral blood thinner drugs (pills) with rapid onset of action that only have to be taken once daily.  The medication safety profiles of these drugs seem good especially if the lower doses are used.  For travelers at highest blood clot risk, I would recommend use of one of these newer drugs or the older injected drugs.   Depending on risk factors, itinerary, other medication use as well as kidney function and fall risk, the length of time taking these blood thinners should extend at least 24 hours beyond arrival.  Aspirin or other anti-platelet  drugs are ineffective for blood clot prevention in this setting and would not be expected to protect the high risk traveler.