TY - JOUR
T1 - The impact of acute central hypovolemia on cerebral hemodynamics
T2 - does sex matter?
AU - Rosenberg, Alexander J.
AU - Kay, Victoria L.
AU - Anderson, Garen K.
AU - Luu, My Loan
AU - Barnes, Haley J.
AU - Sprick, Justin D.
AU - Rickards, Caroline A.
N1 - Funding Information:
Funding for this study was provided, in part, by the U.S. Army Medical Research and Materiel Command Combat Casualty Care Research Program (Grant W81XWH-11-2-0137; C.A.R.), the William and Ella Owens Medical Research Foundation (C.A.R.), a contract with Pendar Medical LLC (C.A.R.), and training fellowships awarded to G.K.A. through a National Institutes of Health-supported Neurobiology of Aging Training Grant (T32 AG020494, Principal Investigator: N. Sumien), and an American Heart Association Predoctoral Fellowship (20PRE35210249), to A.J.R. through a Ruth L. Kirchstein National Research Service Award (NRSA) F32 Postdoctoral Fellowship (1F32 HL144082-01A1), and to J.D.S. through a National Institutes of Health-supported Neurobiology of Aging Training Grant (T32 AG020494, Principal Investigator: S. Singh) and a Ruth L. Kirchstein NRSA F31 Predoctoral Fellowship (1 F31 HL134242-01A1).
Publisher Copyright:
© 2021 American Physiological Society. All rights reserved.
PY - 2021/6
Y1 - 2021/6
N2 - Trauma-induced hemorrhage is a leading cause of disability and death due, in part, to impaired perfusion and oxygenation of the brain. It is unknown if cerebrovascular responses to blood loss are differentiated based on sex. We hypothesized that compared to males, females would have reduced tolerance to simulated hemorrhage induced by maximal lower body negative pressure (LBNP), and this would be associated with an earlier reduction in cerebral blood flow and cerebral oxygenation. Healthy young males (n = 29, 26 ± 4 yr) and females (n = 23, 27 ± 5 yr) completed a step-wise LBNP protocol to presyncope. Mean arterial pressure (MAP), stroke volume (SV), middle cerebral artery velocity (MCAv), end-tidal CO2 (etCO2), and cerebral oxygen saturation (ScO2) were measured continuously. Unexpectedly, tolerance to LBNP was similar between the sexes (males, 1,604 ± 68 s vs. females, 1,453 ± 78 s; P = 0.15). Accordingly, decreases (%D) in MAP, SV, MCAv, and ScO2 were similar between males and females throughout LBNP and at presyncope (P ≥ 0.20). Interestingly, although decreases in etCO2 were similar between the sexes throughout LBNP (P = 0.16), at presyncope, the %D etCO2 from baseline was greater in males compared to females (-30.8 ± 2.6% vs. -21.3 ± 3.0%; P = 0.02). Contrary to our hypothesis, sex does not influence tolerance, or the central or cerebral hemodynamic responses to simulated hemorrhage. However, the etCO2 responses at presyncope do suggest potential sex differences in cerebral vascular sensitivity to CO2 during central hypovolemia. NEW & NOTEWORTHY Tolerance and cerebral blood velocity responses to simulated hemorrhage (elicited by lower body negative pressure) were similar between male and female subjects. Interestingly, the change in etCO2 from baseline was greater in males compared to females at presyncope, suggesting potential sex differences in cerebral vascular sensitivity to CO2 during simulated hemorrhage. These findings may facilitate development of individualized therapeutic interventions to improve survival from hemorrhagic injuries in both men and women.
AB - Trauma-induced hemorrhage is a leading cause of disability and death due, in part, to impaired perfusion and oxygenation of the brain. It is unknown if cerebrovascular responses to blood loss are differentiated based on sex. We hypothesized that compared to males, females would have reduced tolerance to simulated hemorrhage induced by maximal lower body negative pressure (LBNP), and this would be associated with an earlier reduction in cerebral blood flow and cerebral oxygenation. Healthy young males (n = 29, 26 ± 4 yr) and females (n = 23, 27 ± 5 yr) completed a step-wise LBNP protocol to presyncope. Mean arterial pressure (MAP), stroke volume (SV), middle cerebral artery velocity (MCAv), end-tidal CO2 (etCO2), and cerebral oxygen saturation (ScO2) were measured continuously. Unexpectedly, tolerance to LBNP was similar between the sexes (males, 1,604 ± 68 s vs. females, 1,453 ± 78 s; P = 0.15). Accordingly, decreases (%D) in MAP, SV, MCAv, and ScO2 were similar between males and females throughout LBNP and at presyncope (P ≥ 0.20). Interestingly, although decreases in etCO2 were similar between the sexes throughout LBNP (P = 0.16), at presyncope, the %D etCO2 from baseline was greater in males compared to females (-30.8 ± 2.6% vs. -21.3 ± 3.0%; P = 0.02). Contrary to our hypothesis, sex does not influence tolerance, or the central or cerebral hemodynamic responses to simulated hemorrhage. However, the etCO2 responses at presyncope do suggest potential sex differences in cerebral vascular sensitivity to CO2 during central hypovolemia. NEW & NOTEWORTHY Tolerance and cerebral blood velocity responses to simulated hemorrhage (elicited by lower body negative pressure) were similar between male and female subjects. Interestingly, the change in etCO2 from baseline was greater in males compared to females at presyncope, suggesting potential sex differences in cerebral vascular sensitivity to CO2 during simulated hemorrhage. These findings may facilitate development of individualized therapeutic interventions to improve survival from hemorrhagic injuries in both men and women.
KW - Cerebral blood velocity
KW - Lower body negative pressure
KW - Sex differences
UR - http://www.scopus.com/inward/record.url?scp=85108302941&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.00499.2020
DO - 10.1152/japplphysiol.00499.2020
M3 - Article
C2 - 33914663
AN - SCOPUS:85108302941
SN - 8750-7587
VL - 130
SP - 1786
EP - 1797
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 6
ER -