The association between varicose veins and post-flight venous complications, in particular thromboembolim is unclear,. Air travel has been identified as a main contributor to deep vein thrombosis and although varicose veins have been assumed to exacerbate of this, there is a surprising lack of evidence to support this.
Is there a relationship between varicose veins and DVT?
Many are unsure as to whether there is a link between varicose veins and deep vein thrombosis even without the added element of air travel. The NHS has erred on the side of caution. On its website patients are warned of ‘other factors that increase your risk of DVT’ including previous DVTs and varicose veins.
Despite this, Donnelly and London claim there is no evidence of such an association in primary varicose veins but admit that there may be an increased risk when combined with orthopedic or abdominal surgery. They describe an increased risk of thrombophlebitis if patients also take the oral contraceptive pill or hormone replacement therapy, and suggest avoiding these therapies. Campbell supports this view, claiming that ‘warnings of high risk of thrombosis for people with varicose veins are based on limited evidence’. The author describes a tendency of other scientists to discuss thrombosis in varicose vein patients with confounding factors of abdominal surgery, Campbell makes the point that there is a big difference between patients with primary varicose veins due to various intrinsic factors, and patients with varicose veins secondary to deep vein thrombosis (and hence a confusion between cause and effect). Many large studies do not even mention varicose veins as a predisposing factor to DVT,.
Is there a relationship between air travel and DVT?
The increased risk of thrombus formation associated with air travel is well established During the second world war blitz Simpson noticed the high incidence of pulmonary embolism in people hiding and remaining static,. More recent and reliable studies, have shown that there is a considerably higher incidence of thrombosis in those having traveled more than 5000km (1.5 cases per million compare to 0.01 cases per million in those traveling less than 5000km).
While there have been many studies that have found a relationship between air travel and thrombosis, some studies still report no higher incidence in those recently traveling long-distance. One study found that the control group had a higher percentage having traveled long-distance in the past 4 weeks than the DVT group.
Most attribute this increased incidence to the fact that conditions on an air craft match the three components of Virchow’s theory of coaguability. These are met due to the individuals inability to move freely (stasis), the compression of the veins by the seat (vessel trauma) and the hyperbaric conditions of the craft (hypercoagulability). Having said this, recent surgery does occur as a risk factor in many studies, so patients who have recently undergone surgical intervention for their varicose veins may be prudent to take precautions, as any post-op potential flyer should. Certainly the criteria of ‘recent surgery’ is the most common risk factor of DVT most frequently discussed and advertised by airlines.
Is there a relationship between varicose veins air travel and DVT?
It is difficult in studies which support the argument that varicose veins predispose to DVT when flying to distinguish the causative factor. It has been argued that the intrinsic characteristics of the aeroplane, such as the hyperbaric conditions, high altitude, low humidity and relative hypoxia could be responsible for the DVT, to which people with varicose veins may be more susceptible to. It may, however, simply be due to the lack of mobility afforded by long periods spent squashed into a small seat with limited leg room, again something which may affect varicose vein patients more considering conservative treatment of varicose veins involves mobilisation, as does advice to a post-op patient. Post-op patients may also be restricted in movement and discouraged subconsciously from movement by any pain they may feel in there legs or any constrictive bandages. It therefore seems sensible that they should wait a few weeks after their surgery, until the pain has subsided and bandages have been removed before embarking on a flight. Regardless of this, the patient should be advised to mobilise regularly during the flight.
Given, the benefits of compression stockings and low-molecular-weight heparin in preventing thrombosis, it is prudent to consider prophylactic treatment. Whether these precautions are adhered to depends on the belief of the individual and which evidence or opinion is taken to be true. The LONFLI1, 2 and 3 studies have shown a considerable decrease in incidence of DVT in high-risk patients if using compression stockings (18.75 times decreased incidence), aspirin (1.22% decrease) or low-molecular weight heparin (4.82% decrease). Despite this, the term ‘high risk’ is also not clear. These studies included ‘large varicose veins’ as a criteria for high risk, but with seemingly little evidence. The perceived benefit of taking these precautions is therefore not specific to varicose veins, as the increased risk for each “high-risk group” is not explored individually but lumped together . Indeed, 94.7% of DVTs occurred in “high risk passengers” who were sitting in non-aisle seats. This prompts the question as to whether medical prophylaxis can be justified where a simple commitment to a regime of movement may be all that is required. Compression stockings are also a cheap and apparently effective way to help reduce DVTs if added protection is desired.
Varicose veins, air travel and venous complications remain a cloudy issue, with surprisingly little convincing and specific literature dedicated to the matter. From the sparse data that is available, it seems that there is little justification at the moment to suggest that patients should be prevented from flying or that medical prophylaxis should be taken. Due to confusion on the matter and perhaps to relieve anxious patients, those with primary varicose veins should probably be educated about staying active during a flight, but again there is not solid evidence to prove that this is necessary or sufficient to prevent thromboembolism. There is also an argument for compression stockings in varicose vein patients. Due to the probable benefits of mobilization during flights, it is also wise to postpone flying until the leg is back to full function following varicose vein surgery.
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