The effect of exercise at high altitude on thrombin generation in whole blood and ATP release from platelets

Hypoxia is known to be associated with thrombosis and plays an important role
in many pathologies, e.g. Chronic Obstructive Pulmonary Disease and obstructive
sleep apnea syndrome, in which oxygen desaturation seems to be one of the
mediators in the connection with hypercoagulability. In order to study the
influence of hypoxia on haemostasis, several studies have been done in healthy
individuals being exposed to lower oxygen pressure by either going to high
altitude or by inducing hypobaric hypoxia. Our group also investigated the
effect of hypoxia on haemostasis and from these studies, we could conclude that
hypoxia caused an increase in thrombin generation when performed in whole
blood, but not in plasma, as well as an increase in coagulation factor VIII and
von Willebrand factor due to exercise. As we did not observe an increase in
platelet activation, we hypothesize that the hypercoagulability caused by
hypoxic conditions (either due to high altitude or due to hypobaric hypoxia),
is balanced by the human body by decreasing platelet activation.

The objective of our study is to investigate the effect of exercise on thrombin
generation in WB and on ATP release from platelets under hypoxic conditions at
high altitude.

It is an unblinded cross-over interventional study. In total blood will be
taken 4 times: 1. Maastricht (50m); 2. Furi (1832m); 3. Klein Matterhorn after
going up passively (3883m); 4. Klein Mattherhorn after going up actively
(3883m). Every participant is its own control.

The volunteers in our study will experience oxygen deprivation by up the
mountain. This will be done passively and actively by walking up the mountain.
Blood samples will be taken via venipuncture.

All volunteers will undergo medical test prior to the start of the study, to
ensure that all participants are physically healthy. Four blood samples of 27
ml each will be drawn, which poses a risk of developing a local bruise or
hematoma. Mountaineering poses a risk of developing acute mountain sickness
(AMS), a clinical syndrome ranging from dizziness, nausea and lethargy to
ataxia, vomiting and unconsciousness. All participants will be screened daily
for symptoms of AMS by using the Lake Louise AMS questionnaire. Participants
will be accompanied by the principal investigator at high altitude and
emergency care will be delivered if necessary. An experienced mountain guide
will be present. Participants will be escorted back to 1000m if AMS symptoms
are present.