Haemostasis at high altitude.
Haemostasis has been studied by several authors during exposure to altitude hypoxia. On acute induction to hypoxia, platelet count, platelet aggregability and bleeding time are normal; an increase of thromboxane released from platelets and of prostacyclin, released from endothelial cells is observed; coagulation factors are unchanged except of F. VIII which is increased; modified antithrombin III (ATm) are normal; fibrinopeptide A is increased in subjects with pulmonary edema and fibrinolytic activity after venous occlusion is normal. In chronic hypoxia, during a stay at 6542 m (Mt. Sajama), we found in 7 subjects an important increase in D. Dimer (p < 0.001) that seems to correspond to an activation of coagulation and a decrease of F. VIII R. Cof/F. VIII R. Ag ratio which suggests an endothelial cell damage.
Le Roux
G
G
ARPE, UFR Médecine, Bobigny, France.
Larmignat
P
P
Marchal
M
M
Richalet
J P
JP
D000532:Altitude Sickness / Q000097:blood* / Q000503:physiopathology; D001779:Blood Coagulation Factors / Q000037:antagonists & inhibitors / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism; D005342:Fibrinolysis / Q000502:physiology; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D009051:Mountaineering / Q000502:physiology; D010976:Platelet Count; D013927:Thrombosis / Q000209:etiology
D001779:Blood Coagulation Factors