Pulsatile vs. mean component of baroreflex compensation for posthemorrhage hypotension.
We studied the influence of pulsatile pressure and mean arterial pressure signals on the restoration of arterial pressure after 10% hemorrhage in seven anesthetized dogs. After transection of the aortic nerve, a quick 10% hemorrhage was repeated under four different sinus conditions: condition 1, carotid sinus pressure depulsated and fixed at a level equal to the prehemorrhage level (no feedback); condition 2, pulsatile component of aortic pressure fed back to the carotid sinus with a fixed mean pressure (pulsatile feedback); condition 3, depulsated mean aortic pressure fed back (mean pressure feedback); condition 4, both pulsatile and mean pressure fed back (pulsatile plus mean component feedback). The restoration of arterial pressure in condition 2 was not significantly different from that in condition 1, but there was greater restoration in conditions 3 and 4. At 1.5 min posthemorrhage, the open-loop gains calculated from the restoration values were nearly zero for the pulsatile feedback only, 2.8 +/- 0.8 for mean arterial pressure feedback, and 1.5 +/- 0.3 for pulsatile and mean pressure feedback. These results indicate that the pulsatile component of the carotid baroreflex contributes minimally to the restoration of arterial pressure after 10% hemorrhage in the anesthetized dog.
Yamazaki
T
T
Department of Biomedical Engineering, Johns Hopkins Medical School, Baltimore, Maryland 21205.
Brunner
M J
MJ
Sagawa
K
K
D000818:Animals; D001794:Blood Pressure; D001803:Blood Transfusion; D004285:Dogs; D006339:Heart Rate; D006470:Hemorrhage / Q000503:physiopathology*; D007022:Hypotension / Q000209:etiology / Q000503:physiopathology*; D008954:Models, Biological; D011311:Pressoreceptors / Q000502:physiology*; D012016:Reference Values; D013997:Time Factors