Preventing blood clots

       The risk of life-threatening blood clots related to air travel spurred a marketing boom for flight socks and airlines recommending passengers to do seat exercises, especially on long-haul journeys. Cramped seating, long periods of inactivity and dehydration are major factors contributing to so-called economy-class syndrome or deep vein thrombosis (DVT).
       Besides frequent flyers, those on a long drive may also have increased risk of DVT, said Assoc Professor Thanainit Chotanaphuti, MD of Phramongkutklao College of Medicine."If you're on a coach for nine hours from Chiang Mai to Bangkok and develop pain and swelling in one leg then you may have DVT," he said.
       In clinical practice, the orthopaedic surgeon has to deal with DVT as a complication of total knee and total hip replacement, especially among ageing Thais.Fifteen years ago, he was more busy fixing broken arms and legs of younger people from accidents whereas today Phramongkutklao Hospital's Orthopaedic Department is receiving more older patients for major operations.
       Venous blood clots, also known as venous thromboembolism (VTE), include DVT and pulmonary embolism (PE).
       DVT, a blood clot in a deep vein usually in the leg,can be caused by slowing or stopping blood flow.Blood in the leg veins travel to the heart and then to the lungs. A blood clot that breaks loose and blocks a vessel in the lung can lead to PE, damaging the lung and other vital organs and in some cases resulting in death.
       How does surgery put patients at a higher blood clot risk? Blood vessel damage during an operation can trigger a blood clot formation as the body naturally responds to the injury byproducing blood clots to act as a plug to prevent bleeding. Afterwards, restricted mobility during hospitalisation doubles the trouble.Moreover, the risk of developing venous blood clots continues for at least two months after surgery, and most symptomatic cases develop after discharge from the hospital.
       "Blood clot prevention for patients undergoing major orthopaedic surgery includes using anticoagulants. After the operation, instead of bed rest for two or three days, we advise patients to get moving and walk as soon as they can to reduce the risk," said Dr Thanainit."Not many people recognise that it can cause sudden death. Out of four cases, it is likely that two are due to heart disease, one from stroke, and the fourth from a venous blood clot."
       Killing around 300,000 people in the US and 500,000 in Europe each year, venous blood clots are estimated to be the third most common cardiovascular disease after heart disease and stroke. What was once thought to be a rare phenomenon among Asian populations has become a worrying trend and studies have shown that Asians do get clots. According to the Assessment of the Incidence of DVT in Asia study conducted among 407 patients who had undergone major orthopaedic surgery,41 percent of Asian patients were at risk of the disease.
       Despite the well-recognised risks, there remains a low rate of appropriate preventative treatment for blood clotting. The recent multinational ENDORSE study in 32 countries revealed that fewer than 60 percent of surgical patients at risk received standard venous blood clot prophylaxis.
       Anticoagulants in current use for the prevention of blood clots have several disadvantages. Low molecular weight heparin injections make long-term and home use inconvenient and impractical for the patient. Vitamin K antagonists, while taken orally,may require frequent monitoring.
       "The need for drugs that are convenient for both the patient and the physician has led to the development of Factor Xa inhibitors, which target specific points in the blood coagulation cascade, as a new treatment option," said Dr Frank Misselwitz, head of Bayer Schering Pharma's Cardiovascular Therapeutic Area in Wuppertal, Germany. Last September,the German pharmaceutical giant introduced a Factor Xa inhibitor taken as a once-daily tablet, to provide uncomplicated blood clot prevention.
       The new drug has been extensively studied in the RECORD clinical program, the largest of its kind ever conducted on an oral anticoagulant in the prevention of venous blood clots after total knee or hip surgery. Comprising four trials, it involved more than 12,500 participants, of which 1,300 were from the Asia Pacific region.
       "With its favourable benefit-risk profile, rivaroxaban could transform treatment approaches for the prevention of potentially life-threatening blood clots following hip or knee replacement surgery," said Dr Misselwitz.