Woman lands in hospital with Deep Vein Thrombosis after a one-hour flight; Top doctor reveals why this happens

A woman recently took to her IG handle to reveal that she got severe leg cramps following a short 1 hour flight, and soon she was in the hospital with clots in her legs and lungs. While this might be the rarest of rare cases, even short flights can slightly raise the risk of deep vein thrombosis (DVT), a blood clot in a deep leg vein that may travel to the lungs as a pulmonary embolism. The absolute risk of deep vein thrombosis remains low, occurring in less than 1 case per 4,500 to 4,600 flights. Travelers who want to stay safe during their trips should learn essential information to help them prevent common problems. Dr Kunal Sood, MD, tells us more...



What is Deep Vein Thrombosis

Deep vein thrombosis (DVT) happens when a blood clot forms in a deep vein, most often in the legs. The condition causes calf or thigh pain, along with swelling, redness and warmth, but some patients remain symptom-free. A pulmonary embolism develops when a blood clot fragment separates from its original location to block lung arteries, resulting in breathing difficulties, chest discomfort, coughing up blood, and potentially fatal outcomes when the condition becomes severe.

The risk of developing DVT increases with age, but the condition occurs in people of all ages including those who are under thirty. The blood circulation system functions properly until DVT triggers abnormal clotting factor activation, which leads to blood vessel blockage. The use of heparin blood thinners during early treatment helps stop the condition from progressing, while it decreases the chances of developing PE. The diagnosis process includes ultrasound imaging to detect blood clots, while D-dimer blood tests assist in excluding the condition for patients with low risk factors.




Why flights trigger DVT

The combination of blood flow problems, vessel damage and clotting factor changes in airplane cabins, creates an environment which leads to clot formation according to Virchow's triad. The decrease in cabin pressure causes passengers to experience mild dehydration, while their blood becomes thicker because of the lower air pressure. The reduced oxygen levels in the air could lead to increased levels of clotting factors.

The restricted seating space prevents people from moving their legs, which results in slower calf muscle operations, that fight against gravity to move blood upward through veins. Research indicates that blood flow through the popliteal vein decreases by 40%, when patients remain seated without movement, but increases by two times when their feet remain above the floor level. Short people experience pressure on their popliteal veins when they sit because of the seat edge, but tall people develop leg cramps. The combination of dry cabin air and restricted water availability, leads to dehydration progression which makes blood more viscous.

The risk of developing VTE conditions increases by two times for all flights which last less than 8 hours. The risk reaches its highest point during the second week after the flight, before it disappears completely at week eight.

Risk from short flights

Short flights which last less than 4-8 hours, were previously believed to be risk-free, yet research indicates that passengers face a small danger beginning at the 4-hour mark. A large cohort of 8,755 frequent flyers found 3.2 cases per 1,000 person-years within 8 weeks of flights over 4 hours, versus 1.0 without—1 per 4,656 flights.

They found out that risk rises 26% per 2 extra air travel hours after 4 hours. Short-haul pilots do not form new blood clots which remain undetected, but repeated air travel by passengers leads to the development of these clots. The research based on 14 studies, demonstrated that any trip lasting more than three hours, would result in a two-fold increase of VTE risk. Air travel multiple times exposes business travelers to increasing dangers, because their repeated flights create more opportunities for danger at each subsequent flight.

The risk of developing a severe PE during short flights remains extremely low, because it occurs only once per million passengers but the total number of flights each year makes this risk significant. "The "Healthy traveler effect" might conceal the true risk levels which affect people who make regular travel trips.

Who faces higher risk

The use of oral contraceptives together with hormone therapy, results in blood clot formation which occurs at three times the normal risk rate.

The risk of obesity (BMI over 25) increases to 2-10 times after spaceflight.

The risk factor of previous DVT together with cancer, recent surgery, pregnancy and smoking will significantly increase the chances of developing the condition.

The risk of exposure increases by 1.4 times for each additional flight when someone needs to take multiple flights.

The presence of varicose veins or family history of blood clots will increase your risk of developing the condition by two times.

Young travelers who are under 30 years old, show unexpected high infection rates because their population includes people who have not developed immunity yet ("attrition of susceptibles"). Women achieve higher numbers than men do.

Prevention for short flights

People who fly at low risk should follow standard procedures to reduce their flight risks instead of taking any medication.

Drink plenty of water; skip alcohol and caffeine to avoid dehydration.

Get up and walk the aisle every hour, while doing calf raises, ankle circles and knee lifts during each 30-minute interval.

Choose aisle seats for easy movement over windows.

Wear loose clothing; avoid crossing legs tightly.

The implementation of graduated compression stockings (15-30 mmHg below-knee) has shown to decrease the occurrence of asymptomatic DVT by 90% based on research findings. The research shows that Aspirin provides no therapeutic value yet low-molecular-weight heparin shows promising results, although its effectiveness for standard treatment remains unknown.

Treatment for high-risk flyers includes wearing stockings, and their doctor should provide guidance on blood thinner usage, though little evidence is available on it. Guidelines from the American Society of Hematology and others recommend stockings over medication for most people. The best results will emerge when pre-flight calf exercises and hydration start at least one day before the flight departure.




Get the latest lifestyle updates on Times of India, along with Happy New Year wishes, messages and quotes !