Ask Ken, a Manitoba-based, long-haul trucker who has been driving since 1986, about how blood clots almost killed him and you'll hear the story of many truckers.
Ken (he asked that his real name not be used) said he missed the warning signs, and attributes his being alive to luck. "I missed the signals for DVT (Deep Vein Thrombosis, the medical term for blood clots formed most commonly in the legs). I knew that my legs hurt, but I just walked it off and figured, 'Well, I just needed to stretch my legs.'"
Ken recalls that he gradually got out of breath and couldn't figure out why. He made another trip and his breathing problems got worse, but he gritted his teeth and even took on another run. Finally, his breathing became so difficult that he called his dispatcher and said that he had to get home and see his doctor.
When he arrived home, "She kept asking is if had chest pains and I said 'no,' but she and the other doctors kept focusing on that." Finally, when they tested his lungs they found a blood clot, which had formed in his leg, and had now traveled to his lungs forming a pulmonary embolism which can be fatal.
Ken's doctor told him to stay off the road for four weeks and perhaps forever, but after a month of rest and blood thinning medicine, he was allowed back to work. "Okay, I'm going to let you drive," the doctor said, "but you have to wear compression socks and you have to take a blood thinner."
He adds, laughing, "I'm not what you think of as a typical truck driver. I'm not obese or use a CPAP. I'm five-foot ten and 170 pounds. I am very healthy. My blood pressure is 110 over 70 with a heart rate of about 70."
Ken says that he now gets out of his truck every few hundred miles and walks around even though he likes driving his truck so much that he doesn't want to stop. The 52 year-old says he considers himself lucky to be alive and repeats, "I had no idea what was wrong when I couldn't breathe."
Ken's experience highlights what may be a blind spot among drivers and their doctors. While blood clots are well studied and understood in air travelers and pilots who sit for hours in a plane, there is almost no clinical literature on truck drivers despite them being in similar conditions.
For Dr. Jack Ansell, professor of medicine at Hofstra-NorthShore/LIJ School of Medicine, this is surprising. "I think most people are familiar with the increased risk of having a blood clot if they fly very long distances, don’t move around and often maybe have some other risk factors associated with it," he says. "That's been well documented."
For drivers, however, he says that because they represent a smaller universe of patients than flyers, it has not been studied. Their cases are also not as dramatic, and thus may be overlooked by researchers. "In air flights you have people getting off planes and passing out from a pulmonary embolism. These are dramatic events, [in areas with many onlookers] as opposed to a truck driver who eventually develops a blood clot in his leg and goes home and sees his doctor. It just doesn't become noticeable by the medical profession."
Ansell, a hematologist who focuses on clinical problems of blood clots, says that despite not being able to find any significant studies in medical literature, he expects many drivers suffer from blood clots. "There is absolutely no reason to not expect the risk of having a blood clot in the leg to be higher in truck drivers, although I can't cite any evidence or study of that. I would expect that their risk is clearly increased over the average person because they're immobile and have other risk factors.
"When you go on the internet and raise the issue [of blood clots] you can see that there are many responses from truck drivers: 'Oh yes I had a blood clot in my leg,' 'I had this, I had that,' meaning that it's out there, it's just not cataloged well … In the medical literature it's so well documented that immobility and keeping still over long hours is a risk factor and that's an accepted aspect of this disease. You can easily relate that to the long-haul driver's life."
In the United States, there are an estimated one million blood clots diagnosed each year, according to Randy Fenninger, CEO of the National Blood Clot Alliance, a patient advocacy group. (Ansell is a member of the group's Medical & Scientific Advisory Board.) Of these, about 300,000 become pulmonary embolisms. About 100,000 deaths occur from clots, mostly from these embolisms, says Fenninger. Moreover, about 70% of clots originate in hospitals, due mainly to prolonged immobility and disruption of blood vessels caused by surgeries, leaving about 30% of clots, or 300,000 annually caused by other factors including occupational environments.
How can truckers prevent DVT?
Ansell says: "Try to get up and walk around, get out of your truck for five minutes if you can every hour, every two hours. If you can't, then every three hours. I realize that people don't tend to follow that type of guidance. At a minimum, I think individuals who are driving should exercise their legs at the wheel."
He recommends flexing the foot at the ankle, a movement called 'dorsiflexing.' "Dorsiflexing means going up and down with the foot and that tends to pump the muscle such that it moves blood around. Squeezing the calf muscle – not squeezing with your hand – but contracting the calf muscles or bending the leg at the knee back-and-forth while you're driving is beneficial. Sitting still, particularly in a cramped position is the worst. Move your legs around, get the muscle pumped."
Ansell says that although it has not been clinically studied in drivers, wearing graduated compression stockings – which can be bought in drugstores – may be helpful as they compress the muscles. "They have been shown to reduce blood clots in those who fly long distances."
He concludes: "This is a field that probably should be looked at with some type of survey to really understand it better."