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The WRIGHT project is an international
research program under auspices of the World Health
Organization (WHO) on the possible link between long
distance air travel and venous thrombosis. This program aims
to determine the frequency and causes of venous thrombosis
after air travel in order to identify who is at greatest
risk and would benefit most from preventive strategies.
The risk of venous thromboembolism is known
to be multifactorial – with factors such as age, prolonged
immobilization, malignancy, pregnancy, oral contraception (OC)
and HRT.
Prolonged immobilization has been well known
since the 1930’s and 1940’ as a cause of thrombosis. Car
related travel in the 1930’s and in the 1940’s in WW11 a six
fold increase in pulmonary embolism in people sheltering the
underground resting on deckchairs rather than beds.
Latterly, it has been the number of high
profile events related to air travel that has lead to the
WRIGHT study in 2001,
The study has found that certain people seem
to be have a higher risk - ‘hyper responders’ which is
related to a combination of air travel with thrombophilic
Factor V Leiden and/or the OC.
This study has concluded that the overall
relative risk of thrombosis following air travel increases
by a factor of three, with an absolute risk of 1:6000
passenger flights.
The longer the flight the greater the risk
including multiple trips immobility is an important factor
‘hyper responders’ seem to react to something airplanes
people who are short, tall or overweight are at a slightly
higher risk.
Very high predisposing risk factors are
a previous VTE and
some major thrombophilic abnormalities.
Other factors are
1st degree relative with VTE,
age >50 years,
recent surgery,
active cancer,
oestrogens, and
BMI>30.
Finally, in terms of thromboprophylaxis
recommendations for:
Low Risk Passengers (i.e. most passengers)
Exercise legs and calves
Keep legs straight
Consider avoiding dehydration and not
drinking alcohol (it dehydrates)
Consider support stockings (Grade 1 fitted)
Medium Risk Passengers (more than one risk
factor)
Support stockings
Consider aspirin 75mg one day prior to travel
unless prone to asthma or indigestion.
High Risk (with very high risk factors)
passengers
As above plus
Low-molecular-weight-heparin – single
subcutaneous at standard venous dose, 2-4 hours before
travel
Patients on warfarin do not need LMWH before
flying
Avoid sleeping tablets |
