Symptoms
Deep vein thrombosis develops as a result of a blood clot in the deep veins. Typical symptoms are:
- Painful and swollen legs and calves, edema.
- Redness and discoloration of the skin
- Locally increased temperature
- Often asymptomatic
It poses a significant risk for the development of pulmonary embolism when part of the thrombus breaks loose and enters the arterial blood vessels of the lungs. The symptoms of a pulmonary embolism include chest pain, difficulty breathing, coughing, palpitations, a rapid heartbeat and rapid breathing. Symptoms may also develop up to 4 to 8 weeks after travel. “Economy class syndrome” (Symington, Stack, 1977) can also occur in business class. To date, there is no evidence that thrombosis is less common in business class. Thrombosis can also occur in other modes of transportation where people sit immobile for long periods, such as on a bus or train.
Causes
Caused by air travel:
- Immobilization in a tight seat with little leg room, congestion of blood and compression of the popliteal vein.
- Fluid loss (dehydration) due to dry air, insufficient intake of fluids and additional loss due to stimulants such as alcohol and caffeine.
- Hypoxia
The decisive factors are the duration of the flight and individual risk factors!
Risk factors
- Long flight duration > 4-8 hours, e.g., transatlantic flights or multiple flights within short duration
- Seat at the window (not at the center aisle)
- Prolonged bed rest
- Age
- Pregnancy
- Postpartum (puerperium, 6-8 weeks after birth).
- Minimally invasive procedures such as laparoscopy, arthroscopy of the knee.
- Immobilization, for example, a fixed leg.
- Excess weight
- Varicose veins
- Heart failure
- Cancers
- Medications: Hormone replacement therapy, hormonal contraceptives, chemotherapy.
- Inherited disorders of blood clotting, e.g. factor V Leiden mutation, antithrombin III deficiency.
- Previous thrombosis / embolism
- Recent surgery, major trauma, femoral neck fracture, spinal cord injury, joint replacement
Not all factors carry equal weight. Individual risk can be determined by experts.
Non-drug prevention
Behavioral recommendations for all air travelers during long flights:
- Consume sufficient non-alcoholic beverages.
- Avoid stimulants such as coffee and alcohol. They promote fluid loss.
- While sitting, regularly move the calf muscles: For example, every 1-2 hours for 5-10 minutes lift and lower the tips of the feet or move them in circles. Streching.
- Regularly get up, move and walk through the center aisle.
- Do not take strong-acting sleeping pills such as benzodiazepines and similar substances, as they make movement and fluid intake impossible.
In case of medium to high increased risk (individual risk factors + long flight duration):
- Compression stockings (calf stockings, to below the knee, 15-30 mmHg at the ankle). Compression stockings have been shown to significantly reduce the risk of asymptomatic deep vein thrombosis. So-called travel compression stockings are commercially available.
Medication prevention
Antithrombotics should only be used if there is a high individual risk and a long flight duration on medical recommendation. One concern is potential adverse effects such as bleeding. They are usually used off-label. Low-molecular-weight heparins:
- E.g., dalteparin, enoxaparin, nadroparin, administered subcutaneously.
Factor Xa inhibitors:
- E.g. rivaroxaban
Vitamin K antagonists (coumarins) are a possible alternative but are poorly adjustable:
- Phenprocoumon
- Warfarin (not commercially available in many countries).
Platelet aggregation inhibitors:
- Acetylsalicylic acid (eg, aspirin) is less effective than heparins and is largely considered unsuitable and ineffective in the literature. However, aspirin is widely used in folk medicine and also recommended by some specialists, presumably because it is well known, readily available, and easy to take.
