Coagulation changes induced by lower-body negative pressure in men and women

Abstract

We investigated whether lower-body negative pressure (LBNP) application leads to coagulation activation in whole blood (WB) samples in healthy men and women. Twenty-four women and 21 men, all healthy young participants, with no histories of thrombotic disorders and not on medications, were included. LBNP was commenced at −10 mmHg and increased by −10 mmHg every 5 min until a maximum of −40 mmHg. Recovery up to 10 min was also monitored. Blood samples were collected at baseline, at end of LBNP, and end of recovery. Hemostatic profiling included comparing the effects of LBNP on coagulation values in both men and women using standard coagulation tests, calibrated automated thrombogram, thrombelastometry, impedance aggregometry, and markers of thrombin formation. LBNP led to coagulation activation determined in both plasma and WB samples. At baseline, women were hypercoagulable compared with men, as evidenced by their shorter “lag times” and higher thrombin peaks and by shorter “coagulation times” and “clot formation times.” Moreover, men were more susceptible to LBNP, as reflected in their elevated factor VIII levels and decreased lag times following LBNP. LBNP-induced coagulation activation was not accompanied by endothelial activation. Women appear to be relatively hypercoagulable compared with men, but men are more susceptible to coagulation changes during LBNP. The application of LBNP might be a useful future tool to identify individuals with an elevated risk for thrombosis, in subjects with or without history of thrombosis.NEW & NOTEWORTHY LBNP led to coagulation activation determined in both plasma and whole blood samples. At baseline, women were hypercoagulable compared with men. Men were, however, more susceptible to coagulation changes during LBNP. LBNP-induced coagulation activation was not accompanied by endothelial activation. The application of LBNP might be a useful future tool to identify individuals with an elevated risk for thrombosis, in subjects with or without history of thrombosis.

Menstrual Phase Affects Coagulation and Hematological Parameters during Central Hypovolemia

“…We recently reported that sex differences exist in coagulation in both resting conditions and during LBNP application [ 4 ]. Specifically, women are relatively hypercoagulable compared to men during resting baseline conditions, but men show a more pronounced LBNP-induced shift towards hypercoagulability [ 4 ].…”

“…We recently reported that sex differences exist in coagulation in both resting conditions and during LBNP application [ 4 ]. Specifically, women are relatively hypercoagulable compared to men during resting baseline conditions, but men show a more pronounced LBNP-induced shift towards hypercoagulability [ 4 ]. The current study extends the above literature with the finding that respective baseline levels of FII, FVII, FVIII, PC, and PS are the same in the two phases, thus implying that the phase of the menstrual cycle does not affect coagulability during resting conditions.…”

“…The number of participants required to show statistical significance were based on previously published studies, in which coagulation parameters were assessed during central hypovolemia [ 4 , 12 , 13 ]. The sample size calculation utilized the effects of LBNP on coagulation tests and markers of thrombin formation.…”

“…LBNP-induced hemoconcentration elevates plasma protein concentration and blood viscosity. Overall, the increased interactions between coagulation factors and procoagulant factors released from vascular endothelial cells, together with platelet activation, create a procoagulant milieu, which is seen in both sexes [ 2 , 4 ].…”

“…For example, women, as compared to men, have lower median levels of the anticoagulant protein S (PS), and thrombelastometry (TEM) measurements show an earlier onset and an elevated coagulation velocity [ 9 , 10 ]. We have recently also reported differences in baseline coagulation parameters between men and women and reported how central hypovolemia, induced by LBNP, affects coagulation responses [ 4 ]. We observed that, at baseline, women were hypercoagulable compared to men, as evidenced by their shorter ‘Lag times’ and higher thrombin peaks and by shorter “Coagulation times” and ‘Clot formation times’.…”