Clot risk: Long hours in front of the computer can cause DVT.
Computer users at risk of 'e-thrombosis'
Sitting for long hours at a computer terminal can cause fatal blood clots in the same way as taking a long flight in cramped seating, doctors say.
In the latest issue of the European Respiratory Journal, New Zealand researchers report the case of a 32-year-old man who suffered a swollen calf, with the pain subsiding 10 days later.
In the ensuing weeks, however, he became increasingly breathless when he exerted himself and then one day lost consciousness.
The cause was a massive blood clot that had formed in his leg veins, broken off and travelled to his lungs - a potentially fatal "deep vein thrombosis" (DVT) identical to that sometimes suffered by travellers on long flights.
The patient used to sit immobile at his computer screen, at work and at home, for 12 hours a day, and on occasions for up to 18 hours.
The authors, led by Richard Beasley of the Medical Research Institute of New Zealand, based in Wellington, said: "He would typically sit for one to two hours, and not infrequently as many as six, without standing up from his work station.
"This is the first reported case of an association between repeated prolonged immobility sitting at a computer and life-threatening (lung embolism)," they write.
They suggest the condition be called "e-thrombosis".
DVT as a result of prolonged sitting was first recognised during the Blitz in World War II, when cases of fatal embolisms emerged among Londoners who sat for long periods in deckchairs in air-raid shelters.
More recently, DVT has emerged as a potential, though remote, risk for travellers on long flights.
It has been dubbed "economy-class syndrome" because the phenomenon occurs more frequently among passengers in cramped seating, although researchers say it can occur in any seating where passengers are immobile.
The British High Court last month blocked a bid by 55 DVT victims who had filed suit against 27 airlines, alleging that the carriers had breached their duty of care because of their cramped seating.
It ruled that the plaintiffs had no case under the 1929 Warsaw Convention on air travel as DVT was unexpected and could not be considered an accident in the normal operating of an aircraft.
DVT occurs when the flow of blood is restricted in a vein and a clot forms.
It can also be caused by poor circulation because of problems such as heart disease, a recent heart attack or stroke, varicose veins, or from inactivity or prolonged bed rest.
Pregnant women, people who are overweight, the elderly, smokers and people with coronary heart disease and certain blood conditions are considered to be most at risk.
To prevent it, doctors suggest flexing one's toes and ankles, drinking water and avoiding alcohol, as well as getting up to stretch one's legs at least once an hour.
An aspirin, which helps to thin the blood, can also help.