Selasa, 25 September 2007

BlOOD CLOTS ON A PLANE: WHAT DO A FORMER GOVERNOR OF MINNESOTA, OLYMPIC ICE SKATER AND 1 in 5000 AIRLINE PASSENGERS HAVE IN COMMON

BlOOD CLOTS ON A PLANE: WHAT DO A FORMER GOVERNOR OF MINNESOTA, OLYMPIC ICE SKATER AND 1 in 5000 AIRLINE PASSENGERS HAVE IN COMMON


ECONOMY CLASS SYNDROME Long Airplane Flights and the Reports of Blood Clots









Economy Class Syndrome and the Blitz of London



What do former wrestler a.k.a Governor of Minnesota Jesse Ventura, Olympic ice skater Tara Lipinski and one in 5000 airline passengers have in common? The answer? They have already had or will get a blood clot. Not only do people have a fear of flying they also have a fear of flying and developing a blood clot. The phenomenon of developing a blood clot while flying has been labeled "Economy Class Syndrome". It has been associated with sitting in one position for a long time. Remember TV Correspondent David Bloom who was said to have succumbed to a blood clot while covering the Iraq War? Even the people huddled in the Underground during the Blitz of London suffered from increased blood clots.



The Internet medical journal PLOS Medicine has a new study of Economy Class Syndrome. They calculated that for the under 40 group that they studied the risk of a blood clot was 1 in 5000. But they suspected it would be higher in the general population.

They figured that

  • 1.Long haul flights tripled the risk of developing VT (blood clot) and
  • 2.The absolute risk (the probability of something occurring in a certain time period) of a blood clot occurring shortly after such travel was one event per 4,656 flights.
  • 3.The risk of blood clot was increased by exposure to more flights during a short period and to longer flights
  • 4.Was greatest in the first two weeks after a flight
  • 5.The risk of a blood clot was particularly high in young employees, women taking oral contraceptives, and people who were short, tall or overweight.



  • The Absolute Risk of Venous Thrombosis after Air Travel: A Cohort Study of 8,755 Employees of International Organisations

    Probably one of the most important things you can do is to walk around during the flight. Not to sit in one position for long periods of time. Prolonged immobilization is one of the risk factors for a blood clot.






    There have been many stories in the press about blood clots while flying in an airplane. For example Dangerous In-Flight Blood Clots and Cramped Flights Fatal Blood Clots and also the story of a woman who had a blood clot after a transatlantic airplane flight and a rugby player who says he got a blood clot after a long flight from Australia.






    What is Deep Vein Thrombosis


    Tara Lipinski, the Olympic figure ice skater, was shocked she said, when she developed a blood clot after surgery Lipinski Glides Past Surgery Complications . But there are many things besides prolonged immobilization that can possibly predispose to the formation of a blood clot. They are called deep vein thrombosis because they tend to occur in the deep veins that run deep inside the legs (although DVT also comes from elsewhere such as the pelvis) versus the more superficial veins that you can see on the outside of your legs, called logically the superficial veins. A clot in the superficial veins is called phlebitis. Here is a diagram of the deep veins of the leg












    Symptoms of a DVT



    Symptoms of a DVT can include:
  • swelling of the leg
  • warmth and redness of the leg
  • pain that is noticeable, or worse when standing or walking or possible tenderness on touching the calf area





    What are Causes of Blood Clots: Tests for Pulmonary Embolism




    But it's more than just immobilization that increases risk for blood clots. Take for example the case of a twenty something woman who came to see the doctor because of a hard to describe discomfort or pain in her side. It had bothered her for the previous two days and when she had gone to see her regular physician the nurse had done a urine test and sent the woman home. But the woman had felt so bad that she and her husband went to see another physician



    Closer questioning revealed that the woman had been on birth control pills and had injured her leg earlier in the week.
    Now the doctor was suspicious of a blood clot.Birth control pills and trauma to the extremities are both risk factors for blood clots.The doctor sent her to the hospital where a test called a spiral CT scan demonstrated a blood clot in her lung. This woman had two things that increases chances of a blood clot.



    Virchow's Triad for blood clots


    Over one hundred years ago a physician name Virchow elucidated Virchow's Triad: three circumstances associated with an increased chance of a blood clot:



  • increased coagulability of the blood
  • damage to the walls of the blood vessel
  • things slowing down the blood flow




    In light of this it's easier to understand this list of some of the things associated with an increased chance of blood clots:


  • long time periods of immobility such as sitting for hours and hours in one position (long flight?) see Incidence of Air Travel–Related Pulmonary Embolism at the Madrid-Barajas Airport
  • certain genetic problems such as a genetic defect that may alter the normal formation of a chemical called factor V Leidin that helps the body to form clots so that blood clots are more likely to form. The FDA has approved a DNA test for factor V Leidin and factor II 2 (prothrombin) genetic abnormality as you can read at FDA Approves Lab Tests for Genetic Clotting Risk.

  • certain kinds of birth control pills
  • recent surgery
  • trauma to the body
  • chronic atrial fibrillation. Atrial fibrillation is a heart condition where the atria (upper chambers of the heart) pump into the lower chambers (the ventricles) in a less coordinated fashion so that the blood may be standing in place longer and thus increase the chance of clotting



  • NASA Occupational Health Web Site: Flight-related Deep Vein Thrombosis (DVT) -Economy Class Syndrome



    So What's a Pulmonary Embolism?


    Pulmonary Embolism and Deep Vein Thombosis DVT are Related as Blood Clot in Leg Can Travel thru Heart Into Lung





    Former Governor of Minnesota and wrestler Jesse Ventura had a pulmonary embolism the night he was scheduled to wrestle Hulk Hogan as you can read in this account of Jesse Ventura's pulmonary embolisms. And David Bloom, the television correspondent who was said to have had a blood clot as a result of prolonged time traveling in an armored vehicle. A pulmonary embolism is a blockage in an artery in the lungs caused by an embolus, a blood clot that has traveled from another place in the circulatory system such as a vein in a leg or in the pelvic area to the lungs to become a blood clot in the lung. Here you can see a diagram of the mechanism of a pulmonary blood clot embolism



    The Symptoms of a Pulmonary Embolism Blood Clot in the Lung


    Symptoms can include:


  • shortness of breath
  • chest pain
  • fever
  • cough
  • coughing up blood





    How do They Test for Pulmonary Embolism and for a DVT Blood Clot




    The Ventilation Perfusion Test (The VQ Scan) and the Spiral CT Scan


    The two most prominent tests for a pulmonary embolism are the VQ Scan and Spiral CT. Oxygen is exchanged between the air and the blood in the lungs. Thus there is ventilation of the lungs and also perfusion in the lungs by the blood. If there is a blood clot blocking some part of the lung one would expect to see a mismatch where there is not an approptiate blood flow to an area of the lung because of the clot blocking the area.



    The perfusion scan is performed by injecting a radioactive substance with a short half life into a vein. The patient´s lungs are scanned to detect the location of the radioactive material as blood flows through the lungs. The ventilation scan is performed by scanning the lungs while having the person inhale radioactive gas with a short half life.



    The Spiral CT Scan


    The Spiral CT Scan is a newer and more sophisticated relation of the old CT scanner. It has detectors that rotate rapidly in a spiral and can image an area much faster than the older CT, so fast that it can get the whole image while a person holds their breath. Original CT scanners would spin 360° in one direction and make an image , then spin 360° in the other direction to make another cross section. Between each image, the machine would stop completely and reverse directions while the patient table was moved forward incrementally. The spiral CT scanner rotates continuously and can scan entire anatomic regions in less than a minute.




    Ultrasound and D Dimer


    DVTs are most commonly detected by the use of an ultrasound scan of the legs or affected area.
    Blood tests can also give a good indication that there is a thrombosis which is a fancy word for blood clot. A blood test for something called D Dimer measures the levels of a by-product of clotting material that can be used to help rule out a blood clot. Since other things besides a dvt can give a positive D Dimer test it can't be used alone to diagnose a dvt. A positive D-dimer indicates the presence of an abnormally high level of fibrin degradation products in the body and indicates that there has been significant clot (thrombus) formation and breakdown in the body, but it does not tell the location or cause. An elevated D-dimer may be due to a a number of other conditions besides a dvt. But a neagtive D Dimer is useful in ruling out a blood clot.








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