Fluid-percussion brain injury adversely affects control of vascular tone during hemorrhagic shock.
To test the hypothesis that brain injury impairs control of vascular tone during compensation from hemorrhagic shock, Sprague-Dawley rats underwent fluid-percussion brain injury (or sham injury control) followed by a stepwise hemorrhage period to 1/2 baseline mean arterial pressure (1/2 MAP), a shock period holding at 1/2 MAP for 30 min, and a resuscitation period. Aortic blood flow (ABF) was measured and vascular conductance (ABF/MAP) was calculated. No differences occurred between groups during the stepwise hemorrhage period. During the 30 min shock period, controls decreased conductance from .2 +/- .07 to .16 +/- .04 and required repeated additional hemorrhage (3.4 +/- 1.3 cc) to maintain 1/2 MAP. In contrast, brain-injured animals increased conductance from .21 +/- .07 to .24 +/- .06 (p < .05) during the shock period and required repeated fluid replacements (3.0 +/- 1.3 cc lactated Ringer's (LR), p < .05) to maintain 1/2 MAP. Following resuscitation, conductance appropriately increased to .31 +/- .05 in controls but did not change (.25 +/- .04, p < .05) in brain-injured animals. We conclude that brain injury adversely affects control of vascular tone during shock and resuscitation in this model.
Law
M M
MM
Department of Surgery, UCLA School of Medicine 90024, USA.
Hovda
D A
DA
Cryer
H G
HG
D000818:Animals; D001794:Blood Pressure; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology*; D003326:Coronary Circulation; D006439:Hemodynamics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012151:Resuscitation; D012771:Shock, Hemorrhagic / Q000150:complications / Q000503:physiopathology*; D013997:Time Factors; D014664:Vasodilation