Long-term car rides can really lead to sudden death! This group of people should be especially careful →

Last month, the media reported that a woman suffered from "economy class syndrome" while riding a train and nearly died. In February this year, three migrant workers died from "economy class syndrome" after taking a long bus ride on their way back to work during the Spring Festival.

What exactly is “Economy Class Syndrome”? How can riding a car or plane be life-threatening?

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What is Economy Class Syndrome?

1. What is Economy Class Syndrome?

There is a clinical disease called "venous thromboembolism (VTE)", which most commonly manifests as deep vein thrombosis (DVT) in the lower limbs and pulmonary embolism (PE). In severe cases, it can lead to shock or sudden death.

Because one of the risk factors is sitting for a long time, and long-distance travel, riding in long-distance buses or hard seats on trains, and especially flying in economy class on airplanes will increase the risk of VTE, this phenomenon is also called "economy class syndrome" in medicine.

2. What causes economy class syndrome?

The seats in long-distance buses, economy class airplanes and other means of transportation are narrow and crowded, and it is inconvenient to move around, especially in window seats. Most people's lower limbs basically remain motionless or move less.

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If the lower limbs are inactive for a long time, the venous blood flow will slow down and the level of coagulation factors will increase or become activated. If there are other factors for thrombosis, such as vascular endothelial damage and hypercoagulable state of blood components, venous thrombosis will easily form.

3. What are the risks of economy class syndrome?

If venous thrombosis is formed, the thrombus may fall off after the person resumes normal activities, leading to vascular embolism, which develops into deep vein thrombosis (DVT) in the lower limbs. Leg swelling, pain, increased skin temperature and erythema may occur; if the thrombus enters the pulmonary artery through blood circulation, it can cause difficulty breathing, chest pain, coughing, and in severe cases, hemoptysis, fainting, and even sudden death.

Current studies suggest that there is a dose-response relationship between venous thromboembolism (VTE) and travel time, that is, starting from 4 hours of flight, the risk of VTE increases by 18% to 26% for every additional 2 hours of flight.

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Studies have shown that long-distance car, bus and boat travel can also increase the risk of blood clots caused by sitting for long periods of time.

Overall, the incidence of symptomatic VTE after travel was less than 0.05%, and the pooled risk of VTE in travelers was 2.8 times that in non-travelers.

How to prevent economy class syndrome?

The current medical view is that healthy passengers without underlying diseases or high-risk factors for VTE do not need to prevent economy class syndrome.

Although it may lead to serious consequences, the incidence of VTE after travel is not high, and venous thrombosis usually requires three elements: changes in blood flow (i.e. blood stasis), vascular endothelial damage, and changes in blood composition (inherited or acquired hypercoagulable state).

Long-distance travel appears to increase only pre-existing VTE risk and does not cause economy class syndrome in a person without a prior risk of VTE.

So who needs to prevent economy class syndrome? The following summarizes the risk factors associated with VTE:

Recent major surgery (usually within 12 weeks), especially orthopedic surgery (including hip or knee replacement within 6 weeks), major blood vessel surgery, neurosurgery, and cancer surgery;

Suffering from major or minor trauma (i.e., vascular endothelial injury factors);

Have had VTE;

Have active malignant tumors;

During pregnancy or postpartum period;

Advanced age (> 65 years, the risk of first VTE increases with age);

Taking medication (contraceptive pills, other hormone preparations, antidepressants, etc.);

obesity;

Suffering from inherited thrombophilia or family history of VTE;

Suffering from underlying diseases (liver disease, kidney disease, cardiovascular disease).

For passengers with risk factors for VTE, the following preventive interventions are generally recommended if travel time exceeds 4 hours:

1. Use compression stockings, namely medical graduated compression stockings (GEC), also known as graduated compression stockings (GCS), with a pressure between 15 and 30 mmHg.

2. Walk around as often as possible, at least once every 1 to 2 hours.

3. Maintain frequent calf activities, including ankle flexion and extension (calf muscle stretching) and knee flexion and extension (thigh muscle stretching).

4. However, if the traveler's risk of VTE is particularly high, he or she may be given medication for prevention after evaluation by a doctor.

What are the signs of economy class syndrome?

Many patients with deep vein thrombosis (DVT) in the lower limbs have no warning symptoms, but if the following symptoms occur during or after travel, especially if you are a high-risk group, you need to be vigilant and seek medical attention in time.

1. Leg symptoms: Leg swelling, pain, increased skin temperature and skin erythema (usually affecting one side, but can also affect both sides). DVT should be suspected at this time and it is recommended to seek medical attention immediately.

2. Pulmonary symptoms: If DVT develops into pulmonary embolism (PE), with or without the above-mentioned leg symptoms, there will be progressively more and more severe lung symptoms, even shock (syncope). Sometimes the process is very fast, only a few hours or minutes.

Progressive changes in lung symptoms may include:

Dyspnea that progresses from dyspnea during activity to dyspnea at rest

Chest pain, characterized by localized, stabbing pain that worsens with deep breathing or coughing

Coughing, even coughing up blood

Orthopnea, sitting or semi-recumbent position to relieve breathing difficulties

Wheezing, shortness of breath, and a whistling sound in the throat

If the above situation occurs, please seek medical attention immediately.

References

[1] Wang

[2] Kenneth A Bauer. Overview of the causes of venous thrombosis. UpToDate Clinical Advisor. https://www.uptodate.com/contents/zh-Hans/overview-of-the-causes-of-venous-thrombosis. Accessed on Oct 02, 2023.

[3] Kenneth A Bauer, Menno V Huisman. Clinical presentation and diagnosis of the nonpregnant adult with suspected deep vein thrombosis of the lower extremity. UpToDate Clinical Advisor. https://www.uptodate.com/contents/en/clinical-presentation-and-diagnosis-of-the-nonpregnant-adult-with-suspected-deep-vein-thrombosis-of-the-lower-extremity. Accessed on Oct 25, 2022.

[4] DynaMed. Pulmonary Embolism (PE). EBSCO Information Services. Accessed March 4, 2024. https://www.dynamed.com/condition/pulmonary-embolism-pe

[5] B Taylor Thompson, Christopher Kabrhel, Constantino Pena. Clinical presentation, evaluation, and diagnosis of the nonpregnant adult with suspected acute pulmonary embolism. UpToDate Clinical Advisor. https://www.uptodate.com/contents/en/clinical-presentation-evaluation-and-diagnosis-of-the-nonpregnant-adult-with-suspected-acute-pulmonary-embolism. Accessed on Jan 19, 2024.

[6] James D Douketis, Siraj Mithoowani. Prevention of venous thromboembolism in adult travelers. UpToDate Clinical Advisor. https://www.uptodate.com/contents/en/prevention-of-venous-thromboembolism-in-adult-travelers. Accessed on Jun 01, 2023.

Author: Fan Yunzhu, Chief Physician of Jiahui Medical

Reviewer: Tang Qin, Director and Researcher of the Science Popularization Department of the Chinese Medical Association