Effect of hypobaric hypoxia, simulating conditions during long-haul air travel, on coagulation, fibrinolysis, platelet function, and endothelial activation

Abstract

ENOUS THROMBOEMBOLISM after long-haul air travel was first reported more than 50 years ago. 1 Subsequent case reports and epidemiological studies have provided further evidence of an association but it remains unclear whether this is due to the effects of prolonged sitting, as in other modes of travel, or whether there is a causal relationship to some other specific factor in the airplane environment. 2 One putative factor, which has attracted attention, is hypoxia associated with the decreased cabin pressure. At cruising altitude during a long-haul flight, cabin pressure is typically equivalent to that at an altitude of 1524 to 2134 m, although international regulations permit a maximum For editorial comment see p 2297.

Travel and venous thrombosis: a systematic review

“…In a much larger study, Toff and colleagues exposed 73 volunteers alternately to hypobaric hypoxia and normobaric normoxia. They found no difference between the changes in markers of thrombin generation during hypobaric or normobaric exposures [64]. These findings were confirmed by Schobersberger and colleagues [63].…”

“…Several studies investigated the effect of prolonged immobilization on thrombin generation, but conflicting results were shown [54–67] (Table 4). Stricker et al.…”

“…Markers of fibrinolysis mainly remained unchanged during hypoxia in most studies [59, 61, 62, 64], although Schobersberger found a decrease in t‐PA after 10 h of hypoxia [63].…”

“…Secondly, when only pre‐ and postexposure data are compared, effects of circadian rhythm are not accounted for. Only four studies compared changes in coagulation parameters during air travel or hypobaric hypoxia to a control situation and may be considered to have yielded valid data [61, 62, 64, 67].…”

The effect of flight‐related behaviour on the risk of venous thrombosis after air travel

“…Potential risk factors for air travel‐related thrombosis can be divided into factors that either relate to the passenger or to the environment in the cabin of the aircraft. Environmental factors in the cabin are the cramped position that passengers are exposed to, in particular for passengers who are short, tall or obese, as well as hypobaric hypoxia and possibly also mild dehydration (Bendz et al , 2000; Crosby et al , 2003; Schreijer et al , 2006, 2008; Toff et al , 2006). Passenger‐related factors are sex, oral contraceptive use, and coagulation defects, such as the factor V Leiden ( F5 R506Q) mutation and high levels of prothrombin (factor II), clotting factors VIII and IX (Cannegieter et al , 2006; Martinelli et al , 2003; Kuipers et al , 2007a,c).…”