Near infrared determined cerebral transit time and oxy- and deoxyhemoglobin relationships during hemorrhagic hypotension in the dog.
The goal of the present study was to investigate the relationships among CBF, CMRO2, MTT and tissue/superior sagittal sinus hemoglobin saturations over a wide range of CPP using a canine model of hypotension. Microsphere-determined CBF was autoregulated in all tested cerebral regions over the 40-130 mmHg CPP range, but it decreased 50% around 30 mmHg. MTT, calculated by an indicator-dilution technique, progressively and proportionately increased over the 40-130 mmHg CPP range. The HbO2 content, measured in the same area by an optical method, parallely decreased. Around 30 mmHg CPP, MTT disproportionately lengthened (700% of control). CMRO2 maintenance was accompanied by a progressive decrease of tissue HbO2 and sagittal sinus hemoglobin saturation. In this framework, MTT measurement and tissue HbO2 monitoring by NIRS might give a sensitive evaluation of the hemodynamic reserve than CBF measurement in anesthesia and intensive care.
Department of Biomedical Sciences and Technology, University of L'Aquila, Italy.
M
M
Ferrari
D A
DA
Wilson
D F
DF
Hanley
R J
RJ
Traystman
D000818:Animals; D001921:Brain / Q000378:metabolism; D002560:Cerebrovascular Circulation; D004285:Dogs; D006454:Hemoglobins / Q000378:metabolism*; D006470:Hemorrhage / Q000097:blood* / Q000150:complications; D007022:Hypotension / Q000097:blood* / Q000209:etiology; D007208:Indocyanine Green; D007700:Kinetics; D010108:Oxyhemoglobins / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods
D006454:Hemoglobins; D010108:Oxyhemoglobins; D007208:Indocyanine Green