Medizinische Universität Graz - Research portal
Selected Publication:
Waha, J.
Pro- and anti-coagulatory effects of bed rest
Humanmedizin; [ Diplomarbeit ] Medical University of Graz; 2014. pp. 91
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- Authors Med Uni Graz:
- Advisor:
- Goswami Nandu
- Hinghofer-Szalkay Helmut
- Altmetrics:
- Abstract:
- Background: 6 degrees head-down bed rest (HDBR) is routinely used in laboratories worldwide to simulate spaceflight deconditioning. Coagulatory changes have been associated with bed rest immobilization in addition to cephalad fluid shifts, muscle atrophy, osteoporotic changes. The exact mechanisms of bed rest induced coagulatory changes are, however, not clearly elucidated. For example, while pro-coagulatory changes in bed rested and immobilized patients are commonly known and treated with anti-coagulants to prevent hyper-clotting, it is still unclear which exact endothelial and hemostatic effects occur during bed rest over time. We examined whether medium-term bed rest of 21 days leads to anti-/pro-coagulatory effects. Methods: The blood samples were collected under simulated microgravity conditions (HDBR) from 12 male subjects over a period of 21 days at the Institute for Space Medicine and Physiology (MEDES), Toulouse, France. None of the participants suffered from any pathological condition or were under treatment. Blood collection was done in the morning between 7 a.m. and 8 a.m., 5 days before bed rest (baseline data collection) and during bed rest on the 2nd (HDT+2), 7th (HDT+7), 14th (HDT+14), 21st (HDT+21) and just before standing up (R 0) on the first day of recovery. Post-bed rest samples were taken on the second day of recovery (R+2). Data from thrombelastometry (coagulation time (CT), clot formation time, a-angle and maximum clot firmness (MCF)) and other coagulation parameters determined in platelet poor plasma (endogenous thrombin potential (ETP), thrombin peak (TP), time to peak (ttPeak), slope, lag time, start tail, factor II, factor VII, factor VIII activity, thrombin-antithrombin complex (TAT), prothrombin fragment 1+2 (F1+2) and tissue-type plasminogen activator (t-PA)) were collected. Results: CT was significantly prolonged throughout the whole time course. The a-angle was significantly reduced. ETP was decreased from HDT+7 onwards. TP and slope were significantly elevated on HDT+21 together with a decrease in start tail and ttPeak values. Lag time was prolonged on HDT+2, but showed no changes on other sampling points. Prothrombin showed no change during the bed rest, but a decrease on R+2. F1+2 showed no change except for a reduction on HDT+7 and HDT+21. Factor VIII was slightly elevated on R 0. TAT, t-PA, factor VII and MCF showed no significant change. No parameter showed pathological signs. Discussion: According to the results of this study there is no pro-coagulant effect in healthy subjects undergoing 21 days of strict 6 degree head-down bed rest. These results are in contrast to the broad belief that bed rest and immobilization induces pro-coagulatory effects. As our subjects were healthy volunteers it is perhaps in those who have an imbalance in the anti- and pro-coagulatory system that tip towards increased clotting during immobilization. The question arises whether all patients unexceptionally need treatment to prevent thromboembolic events during immobilization.