**6.3 Air travel, pulmonary embolism, and thrombosis**

Air travel can cause clots of the deep veins of the thigh and feet [49–52].

This thrombosis can in turn cause a pulmonary embolism which is a very serious condition which can cause death.

Thrombosis in the lower limbs (thighs, ankles, legs) is due to thickening phenomena that occur in the deep long veins due to the many hours that passengers remain seated.

Lack of physical movement, dehydration observed in passengers, and alcohol consumption in flight are considered to be among the factors contributing to the occurrence of dangerous thrombotic conditions and pulmonary embolism.

In addition, some people may have inherited diseases with an increased risk of thrombosis and thus be at greater risk than air travel.

To date, 100 cases of pulmonary embolism due to venous thrombosis of the lower limbs have been described. A significant number of cases have died due to this condition. A case of lower limb amputation due to thrombosis has recently been described.

Research shows that clotting problems occur in the lower limbs and in up to 10% of long-haul passengers.

In fact, this syndrome is called by some people the "financial position" syndrome because passengers in these places do not have enough space in front of them to move their legs and remain motionless for many hours.

Researchers believe the incidence of pulmonary embolism after a long plane trip is higher.

The reason they are not detected is because the passengers are not immediately aware of what is happening or because the clinical signs are manifesting themselves severely a few hours after disembarkation. Even sudden deaths on flights or on landings may be due to a pulmonary embolism.

Some even argue that the problem is even greater and that the incidents detected constitute a very small percentage of those occurring.

## **6.4 Precaution that must be taken into account during traveling**

Passengers should drink plenty of water to eliminate the risk of dehydration. Avoid drinking alcohol and excessive caffeine intake.

Passengers should be able to get up, walk, do small exercises, or even stretch or move their lower limbs. It is also not good to cross legs.

Patients with a personal or family history of thrombosis should consult their physicians prior to an air trip [5, 52–54].

Some researchers recommend that passengers wear special high-pressure socks to improve blood circulation to the lower limbs. This is especially true for people at increased risk for thrombosis.

For some passengers, taking low doses of aspirin before a long flight can be beneficial. The World Health Organization recommends [5, 52–55] the following:


The mechanisms that have been implicated to date for this phenomenon are venous posture due to prolonged sitting posture, pressure exerted on the large vein behind the knee, blood buildup due to reduced intake and increased fluid loss, abnormalities in the system, and blood coagulation created in the subarctic and hypoxic environment.

Air travel or road trips, for many hours, run the risk of vein thrombosis in the legs and even more severe, pulmonary embolism. Posttraumatic thrombosis accounts for about 10% of all thromboses that occur.

According to the American College of Chest Physicians (ACCP) (2012) British Committee for Standards in Hematology (BCSH) (2011), British Thoracic Society (BTS) (2011) Traveler's thrombosis: International Consensus Statement (Wien 2008) [21, 57–59], low-risk, medium-risk, and high-risk factors for VTE after air travel are as follows:
