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VTE During Air Travel: Is It the Reduced Oxygen?

Hypobaric hypoxia was not prothrombotic in healthy people at low risk for venous thromboembolism.

Given the known risk for venous thromboembolism (VTE) from long-haul air travel, researchers hypothesized that hypoxia resulting from reduced cabin pressure might activate hemostasis. They conducted a crossover trial in which 73 healthy volunteers (mean age, 29; 58% women) sat in a hypobaric hypoxic environment (simulating air travel) and in a normobaric normoxic environment for single 8-hour sessions at least 1 week apart.

Arterial oxygen saturation, measured hourly, was significantly lower during hypobaric than during normobaric exposure, regardless of age, oral contraceptive use, or order of exposure. Although changes in some hemostatic markers occurred during the normobaric exposure (attributable to prolonged sitting and circadian variation), the normobaric and hypobaric exposures did not yield significant differences in coagulation activation, fibrinolysis, platelet activation, endothelial activation, blood-cell count, or hematocrit.

Comment: Hypobaric hypoxia during prolonged sitting did not induce prothrombotic changes in healthy people at low risk for venous thromboembolism. The study did not address potential effects on people with VTE risk factors.

— Joel M. Gore, MD

Published in Journal Watch Cardiology June 15, 2006

Citation(s):

Toff WD et al. Effect of hypobaric hypoxia, simulating conditions during long-haul air travel, on coagulation, fibrinolysis, platelet function, and endothelial activation. JAMA 2006 May 17; 295:2251-61.

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Bärtsch P. How thrombogenic is hypoxia? JAMA 2006 May 17; 295:2297-9.

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• Medline abstract (Free)