Vickers, Blood Clots and Sitting Down

Sometimes, life isn’t content with just kicking you.  It insists on running you over a couple of times and then spitting on you for good measure.  Just in case you had an inkling of getting up again.

The last twelve months have been very rough for me.  Lots of broken dreams, lots of challenges to my deeply held belief that, when given a choice, most people will do the right thing, and than a lot more time spent on medical issues that are probably a by-product of the stress.  So I have great empathy for Brian Vickers just wanting some answers.  I am betting that Brian is also finding, as I did, that you learn a lot about other people during times of challenge like this.  Sometimes it’s information you really rather would have not known, but sometimes you find out that there are some amazing people in the world that teach you things about yourself you wouldn’t have known otherwise.

Brian Vickers is out for the remainder of the season due blood clots in his lungs and legs.  See Marty Smith’s excellent article for details.  Hopefully one of the things Brian has learned is that you should always listen to what your body is telling you — especially when it is shouting.  A recent study showed that married men live longer than single or divorced men, with one of the hypotheses being that married men are nagged more by their wives to do routine medical checkups and to see a doctor when they start to hurt.  So guys, don’t take our nagging lightly!  We nag because we care.

In general, clotting is good and one of the most important things blood does.  The particulars of when and where are the issue.  You’d like your blood to flow freely when everything is normal; however, a ruptured blood vessel should stimulate the formation of a clot to cover the hole and keep the rest of the blood inside.

Blood, it turns out, is pretty complicated.  If you think there’s just red blood cells running around, you’re not giving blood its due.  Blood is blood cells suspended in blood plasma.  Blood plasma is 90% water – the other 10% are dissolved proteins, sugars, mineral ions, hormones, oxygen on its way into the body, carbon dioxide on it’s way out of the body, etc.  Then there are red blood cells and white blood cells, which include leukocytes and platelets.  In the scaning electron microscope picture below, the thing on the left is the red blood cell, the middle object is a platelet and the right-most object is a white blood cell.  (Yes, the same type of cell that tried to extravasate Raquel Welch in Fantanstic Voyage .) A red blood cell is about 6-8 micrometers, where a micrometer is one millionth of a meter.  A single strand of your hair is about 70 micrometers, so ten blood cells would just about fit across the diameter of your hair.

Platelets (the smaller, middle cell in the picture) are tiny cells from the bone marrow.  They normally wander about the blood freely; however, any type of rupture in a blood vessel signals the platelets to start a series of chemical reactions that make the platelet surfaces near the breach very sticky. The sticky platelets start to adhere to the blood vessel wall at the place where bleeding is occuring.

Among the many proteins dissolved in your blood is a protein called fibrin, which is shown below.  Proteins are very complicated molecules – so complicated that biologist don’t even draw every molecule.  There are a couple hundred thousand of them there.  Fibrin is made from a protein made in the liver called fibrogen.  Lots of little fibrin pieces start to join together to form long protein strands.  These long strands bind to the platelets and form a mesh that acts like a bandage.  In the process of linking, the fibrin usually catches up red blood cells and that is why scabs are red.  (There are two phases to clotting – the platelets gathering in the area form a whitish cover.  You know that the fibrin has gotten into the act when the red color appears.

Clotting becomes a problem when it hapens in places it is not supposed to happen.  When clots form in the deep veins of the leg (fermoral vein, for example), it blocks blood flow, creating pain in the leg.  Of more concern is what can happen when the blood clot loosens – if it travels to the lungs, it can cause a pulmonary embolism, which is blockage of an artery in the lung.  This can lead to complications like not being able to breathe and death.  Clots that work their way loose and travel to the lungs (or brain) can cause death in a matter of minutes.  Brian is extremely lucky that, despite his ignoring the warning signs for a couple of days (!), the clots didn’t do major damage.

The question remains as to why a very healthy 26-year old would have blood clots.  One theory floated around that the blood clots may be due to increased carbon monoxide levels in the blood.  Carbon monoxide (CO) is produced by incomplete combustion of gasoline. About 2 percent of the average car exhaust is CO, but the figure is higher for racecars, as they have no catalytic converter.  Damange to the racecar can also open a hole in the cockpit that allows CO into the cockpit.

One of the things the blood does is provide taxi service for other molecules.  Hemoglobin moves oxygen from the lungs to places like the heart, brain, and muscles. When the hemoglobin reaches its destination, the oxygen hops off and the hemoglobin goes back to the lungs for more oxygen. Carbon monoxide also likes the hemoglobin taxi, but once it gets in, the CO doesn’t want to get out again. CO binds to hemoglobin 240 times more strongly than does oxygen, which leaves fewer opportunities for oxygen to get to other parts of your body.  You have less oxygen in your blood and that leads to nausea, weakness and other impairments.

CO, like most poisons, can affect you acutely or chronically. Acute exposure is exposure to a high level over a short time while chronic exposure is small doses over long periods of time. Neither is good, but chronic CO exposure is more of a problem for drivers. Each successive exposure further impairs their body’s ability to distribute oxygen throughout their body. Driver Rick Mast ended his career in 2002 because of chronic carbon monoxide exposure. He became so sensitive to CO that he couldn’t even bear to be around lawnmowers.

Carbon monoxide is tasteless, odorless and invisible, so how do you know when your driver is being exposed? Ray Evernham, when he was crew chiefing for Jeff Gordon, said that he could tell immediately,

 

“by the way Jeff answers me on the radio, when the carbon monoxide is getting to him. He becomes a smart-ass. When I started working with him, I thought he was a smart-ass. But the more I got to know him, and the more I learned about carbon monoxide, the more I realized what was happening.”

 

Other crew chiefs have said that drivers start to delaying answering questions, ignore instructions or make irrational decisions.  Of course, a number of crew chiefs also noted that their drivers were that way most of the time and this was not a good metric for establishing exposure.

Breathing pure oxygen, which increases the number of oxygen molecules in the lungs, is the primary treatment for CO exposure. More severe cases sometimes use hyperbaric oxygen therapy. The driver is placed in a sealed pressure chamber, similar to those used for treating decompression sickness in divers, and exposed to high-pressure oxygen. Advocates claim greater penetration of oxygen at tissue level, and that oxygen displaces the carbon monoxide-laden hemoglobin from red blood cells more quickly; however, there is disagreement in the medical community about the efficacy of this treatment.  It may be that repeated exposure permanently elevates your CO levels, or CO levels may be reversible over time.  It’s sort of an important thing to know if you want to make intelligent decicison about hanging around the track.

We do know that different people react very differently to CO exposure.  It’s easy to measure the amount of CO exposure:  you can track how much CO a driver exhales, or measure the ratio of carbon to hemoglobin molecules in the blood. A 2001 study reported blood levels of carboxyhemoglobin (carbon monoxide bound with hemoglobin) between 15 percent and 18 percent immediately after short-track races and 8-10 percent on superspeedways. A 5 percent concentration is enough to decrease motor skills. CO also exacerbates heat stress and decreases driving accuracy.  NASCAR drivers have the option of implementing a filter that filters the air before it reaches the driver to remove much of the CO.

Aside:  if Brendan Gaughan had to get out of his car at Charlotte due to carbon monoxide fumes, how bright do you have to be to volunteer to step in for him?  If you were a car owner and you knew CO was getting into the cabin, don’t you have a moral obligation to pull the car and fix it before you ask someone else to get in?  I know, there were only 50 laps to go, but you still have to wonder if Mrs. Green was asking Mark what the heck he was thinking doing that when he got home.  I don’t understand why the drivers don’t insist on CO sensors in their helmets so that at least have some idea of the CO levels of CO to which they are exposed.

What does CO have to do with blod clots?  There are three primary factors in blod clots:  how fast the blood flows, the thickness of the blood and the nature of the blood vessels.  These factors are affected by a number of other factors:  sitting for long periods of time slows down blood flow (bad).  Carbon monoxide depletes the blood of oxygen and slows down blood flow.  Usually, the people who are most at risk for blood clots are the elderly and the infirm, people suffering from cancer, or having had recent surgery, and people with genetic predisposition to developing blood clots.  Interestingly enough, there are some researchers who think that endurance athletes may actually have a higher risk of certain types of blood clots because they have slower blood flows.

Most NASCAR drivers have been exposed to plenty of CO in their careers.  If that’s the important factor, why don’t more drivers have blood clots?  As with most things in medicine, everything is so interrelated that you can’t point to a single factor.  Brian may just have exceptionally slow moving blood that is prone to clotting.  Thrombophilia is a genetic predisposition to blood clotting that is inherited. Factor V Leiden is a syndrome in which the clotting process is enhanced (the blood is “hypercoagulant”).  About 5% of Caucasians in North America have Factor V Leiden, with less prevalence (1-2%) in Hispanics and African-Americans and very rare cases in people of Asian descent.  Women with Factor V Leiden have a much higher chance of miscarrying and having blood clots form during pregnancy.  You can be tested for Factor V Leiden and I’m sure Brian is looking into all of these options.  If the clotting is a genetic predisposition, it is a very different problem than if the clots he experienced last month were due to circumstances that are unlikely to be repeated.

The standard treatment for blod clots is blood thinner, which makes the blood thinner (duh) and can incrtease the rate of flow.  Another treatment is wearing anti-embolism compression stockings.  Not the old-lady hose your grandmother used to wear for her varicose veins.  They actually make compression stockings specifically for preventing embolisms and they exert significantly more pressure on your legs than the ones you can buy at the drugstore.  The stockings don’t do much for people who are immobile and stuck in bed, but there is some evidence that they are effective for airline flyers.

I wonder if they make Nomex nylons?

Kidding aside, the blood thinner treatments are generally aggressive in the first week and then taper down, depending on whether the origin is situational or genetic.  People with a strong pre-disposition to blood clots can be stuck taking blood thinners their entire life.  Obvious, Brian’s personal life is just that and we have no business asking him about the details of his condition (although I would like to see one of the ever-so-serious NASCAR press members ask him if he’s taken to wearing nylons!).

For Brian, all I can say is that I’ve found in my life that disruptions that initially seem to tear apart my world almost always end up with new revelations.  Even if there is no change in your situation, you learn important things about yourself and the people around you.  Sometimes you find out that it is possible for you to do things you didn’t even know you were interested in doing.  I hope for you that this episode is short and resolved quickly, but even if it isn’t, I hope that you find as many answers as you can.  Take care of yourself and, as I’m sure you already know, there are lots and lots of people out here cheering for you to have the best possible outcome.