Thromboembolic phenomena include:
(1) deep vein thrombosis (DVT)
(2) pulmonary embolism
(3) stroke (as paradoxical embolus)
(4) peripheral arterial thrombosis
(5) myocardial infarction
Risk factors include:
(1) cramped seating
(2) immobilization
(3) reduced oxygen in the cabin atmosphere
(4) dehydration
(5) tight-fitting or constrictive clothes
(6) hereditary hypercoagulable state
(7) obesity
(8) history of recent surgery, pregnancy or early postpartum
(9) medications (hormone replacement therapy, oral contraceptives, etc)
(10) cancer
(11) smoking
(12) autoimmune disease (antiphospholipid syndrome, vasculitis)
(13) infection
(14) lack of precautions (elastic compression stockings, exercise, hydration, etc)
(15) history of previous thromboembolic event
(16) varicose veins
(17) length of the flight (12 hours > 8 hours > 4 hours > 2 hours)
