title: Coagulation changes during lower body negative pressure and blood loss in humans.
abstract: We tested the hypothesis that markers of coagulation activation are greater during lower body negative pressure (LBNP) than those obtained during blood loss (BL). We assessed coagulation using both standard clinical tests and thrombelastography (TEG) in 12 men who performed a LBNP and BL protocol in a randomized order. LBNP consisted of 5-min stages at 0, -15, -30, and -45 mmHg of suction. BL included 5 min at baseline and following three stages of 333 ml of blood removal (up to 1,000 ml total). Arterial blood draws were performed at baseline and after the last stage of each protocol. We found that LBNP to -45 mmHg is a greater central hypovolemic stimulus versus BL; therefore, the coagulation markers were plotted against central venous pressure (CVP) to obtain stimulus-response relationships using the linear regression line slopes for both protocols. Paired t-tests were used to determine whether the slopes of these regression lines fell on similar trajectories for each protocol. Mean regression line slopes for coagulation markers versus CVP fell on similar trajectories during both protocols, except for TEG α° angle (-0.42 ± 0.96 during LBNP vs. -2.41 ± 1.13°/mmHg during BL; P < 0.05). During both LBNP and BL, coagulation was accelerated as evidenced by shortened R-times (LBNP, 9.9 ± 2.4 to 6.2 ± 1.1; BL, 8.7 ± 1.3 to 6.4 ± 0.4 min; both P < 0.05). Our results indicate that LBNP models the general changes in coagulation markers observed during BL.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands;
authors.forename: Noud
authors.initials: N
authors.lastname: van Helmond
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York; and blairjoh@buffalo.edu.
authors.forename: Blair D
authors.initials: BD
authors.lastname: Johnson
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota;
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Curry
authors.affiliation: U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Cap
authors.affiliation: U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Convertino
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota;
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
mesh_terms: D000328:Adult; D001777:Blood Coagulation / Q000502:physiology*; D001780:Blood Coagulation Tests; D002496:Central Venous Pressure; D004837:Epinephrine / Q000097:blood*; D006339:Heart Rate; D006470:Hemorrhage; D006801:Humans; D020896:Hypovolemia / Q000097:blood*; D008150:Lower Body Negative Pressure; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D010314:Partial Thromboplastin Time; D018962:Phlebotomy; D011517:Prothrombin Time; D013916:Thrombelastography
chemical_list: D009638:Norepinephrine; D004837:Epinephrine
keywords: blood coagulation; blood coagulation tests; central hypovolemia; hemorrhage; humans; lower body negative pressure