jeffp
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I thought this was interesting, so I posted the article abstract as the site is access controlled to members:
March 14, 2006 ? Coagulation factors are activated more during prolonged air travel than in other immobilizing situations, according to the results of a crossover study reported in the March 11 issue of The Lancet. The editorialist recommends appropriate prophylaxis for deep vein thrombosis.
"Activation of coagulation occurs in some individuals after an 8-hour flight, indicating an additional mechanism to immobilization underlying air travel related thrombosis," senior author Frits Rosendaal, MD, from Leiden University Medical Centre in the Netherlands, said in a news release.
To separate the effect of air travel on the coagulation system from those of immobilization and circadian rhythm, the investigators measured markers of activation of coagulation and fibrinolysis in 71 healthy volunteers (15 men, 56 women) before, during, and after an 8-hour flight, and in 2 control exposure situations (8-hour movie marathon and daily life). Of the 71 participants, 30 had no specific risk factors, 11 had the factor V Leiden mutation, 15 took oral contraceptives but did not have the Leiden mutation, and 15 took oral contraceptives and had the Leiden mutation.
Median concentrations of thrombin-antithrombin (TAT) complex increased by 30.1% after the flight (95% confidence interval [CI], 11.2 ? 63.2), but decreased by 2.1% (95% CI, -11.2 to 14) after the movie and by 7.9% (95% CI, -16.2 to -1.2) after the daily life situation. Increase in TAT levels was especially marked in 11 (17%) of 66 participants after air travel, in 2 (3%) of 68 during the movie marathon, and in 1 (1%) of 70 in daily life. These increases were most apparent in participants with the factor V Leiden mutation who used oral contraceptives. After the flight, 4 (6.3%) of 63 volunteers had a high response in all variables (prothrombin fragment 1 and 2, TAT, and D-dimer), but none of the participants had this response after either of the control situations.
"Our findings indicate that flight-associated factors ? e.g., hypobaric hypoxia ? lead to increased thrombin generation after air travel, especially in individuals with the factor V Leiden mutation who also took oral contraceptives," the authors write.
Study limitations include lack of randomization of the order of the 3 exposure situations, lack of blinding of the volunteers, blood drawing more difficult than during a routine blood draw in the clinic, and possible artifacts due to preanalytic activation of coagulation.
The UK Government and the European Commission sponsored this study. The authors have disclosed no relevant financial relationships.
In an accompanying editorial, Hans Stricker, MD, from Ospedale La Carità in Locarno, Switzerland, discusses measures to help prevent potentially fatal thromboembolism during flights. These include intermittent calf contraction and avoiding excessive sedation due to alcohol or sedative drugs.
"We do not favor an indiscriminate use of prophylactic heparin because the incidence of mostly asymptomatic and distal deep vein thrombosis is estimated to be less than 4% after long-haul flights and fatal pulmonary embolism is rare, with an estimated death rate of 1 per 2 million passengers of international flights terminating in Australia," Dr. Stricker writes. "Thus medical prevention should be limited to persons at risk, such as those with a history of VTE [venous thromboembolism], active cancer, or recent major surgery or minor surgery of the lower extremities. The study by Schreijer and colleagues shows us that women on oral contraception and individuals with a mutation of factor V should be offered the possibility of extended prophylactic measures, such as low-molecular-weight heparin or compressive stockings."
Dr. Stricker has disclosed no relevant financial relationships.
Lancet. 2006;367:792-794, 832-838
March 14, 2006 ? Coagulation factors are activated more during prolonged air travel than in other immobilizing situations, according to the results of a crossover study reported in the March 11 issue of The Lancet. The editorialist recommends appropriate prophylaxis for deep vein thrombosis.
"Activation of coagulation occurs in some individuals after an 8-hour flight, indicating an additional mechanism to immobilization underlying air travel related thrombosis," senior author Frits Rosendaal, MD, from Leiden University Medical Centre in the Netherlands, said in a news release.
To separate the effect of air travel on the coagulation system from those of immobilization and circadian rhythm, the investigators measured markers of activation of coagulation and fibrinolysis in 71 healthy volunteers (15 men, 56 women) before, during, and after an 8-hour flight, and in 2 control exposure situations (8-hour movie marathon and daily life). Of the 71 participants, 30 had no specific risk factors, 11 had the factor V Leiden mutation, 15 took oral contraceptives but did not have the Leiden mutation, and 15 took oral contraceptives and had the Leiden mutation.
Median concentrations of thrombin-antithrombin (TAT) complex increased by 30.1% after the flight (95% confidence interval [CI], 11.2 ? 63.2), but decreased by 2.1% (95% CI, -11.2 to 14) after the movie and by 7.9% (95% CI, -16.2 to -1.2) after the daily life situation. Increase in TAT levels was especially marked in 11 (17%) of 66 participants after air travel, in 2 (3%) of 68 during the movie marathon, and in 1 (1%) of 70 in daily life. These increases were most apparent in participants with the factor V Leiden mutation who used oral contraceptives. After the flight, 4 (6.3%) of 63 volunteers had a high response in all variables (prothrombin fragment 1 and 2, TAT, and D-dimer), but none of the participants had this response after either of the control situations.
"Our findings indicate that flight-associated factors ? e.g., hypobaric hypoxia ? lead to increased thrombin generation after air travel, especially in individuals with the factor V Leiden mutation who also took oral contraceptives," the authors write.
Study limitations include lack of randomization of the order of the 3 exposure situations, lack of blinding of the volunteers, blood drawing more difficult than during a routine blood draw in the clinic, and possible artifacts due to preanalytic activation of coagulation.
The UK Government and the European Commission sponsored this study. The authors have disclosed no relevant financial relationships.
In an accompanying editorial, Hans Stricker, MD, from Ospedale La Carità in Locarno, Switzerland, discusses measures to help prevent potentially fatal thromboembolism during flights. These include intermittent calf contraction and avoiding excessive sedation due to alcohol or sedative drugs.
"We do not favor an indiscriminate use of prophylactic heparin because the incidence of mostly asymptomatic and distal deep vein thrombosis is estimated to be less than 4% after long-haul flights and fatal pulmonary embolism is rare, with an estimated death rate of 1 per 2 million passengers of international flights terminating in Australia," Dr. Stricker writes. "Thus medical prevention should be limited to persons at risk, such as those with a history of VTE [venous thromboembolism], active cancer, or recent major surgery or minor surgery of the lower extremities. The study by Schreijer and colleagues shows us that women on oral contraception and individuals with a mutation of factor V should be offered the possibility of extended prophylactic measures, such as low-molecular-weight heparin or compressive stockings."
Dr. Stricker has disclosed no relevant financial relationships.
Lancet. 2006;367:792-794, 832-838
