Cerebral blood flow during experimental endotoxemia in volunteers.
OBJECTIVE
To measure cerebral blood flow, cerebral metabolic rate for oxygen, cerebral oxygen delivery, and cerebral vascular resistance during experimental endotoxemia in volunteers.


METHODS
Experimental, prospective study.


METHODS
University general clinical research center.


METHODS
Healthy volunteers (six male, four female, 30.1 +/- 1.9 yrs of age).


METHODS
Volunteers had radial, pulmonary arterial, and jugular venous bulb catheters inserted. All volunteers received a bolus of Escherichia coli endotoxin (4 ng/kg). Cerebral blood flow was measured, using the Kety-Schmidt technique.


RESULTS
Cerebral and systemic hemodynamics and oxygenation variables were measured at baseline and hourly for 5 hrs after endotoxin administration. A systemic hyperdynamic response characterized by an increase in body temperature (97.9 +/- 0.02, 100.2 +/- 0.02, and 99.7 +/- 0.02 degrees F [36.6 +/- 0.01, 37.9 +/- 0.1, and 37.6 +/- 0.1 degrees C] at baseline, 3, and 5 hrs, respectively), cardiac index (3.7 +/- 0.2, 6.2 +/- 0.2, and 5.7 +/- 0.2 L/min/m2 at baseline, 3, and 5 hrs), and heart rate (70 +/- 2.6, 96 +/- 2.6, and 93 +/- 2.9 beats/min at baseline, 3, and 5 hrs), and a decrease in mean arterial pressure (99.3 +/- 2.2, 84.4 +/- 2.8, and 84 +/- 3.4 mm Hg at baseline, 3, and 5 hrs) and systemic vascular resistance (1498 +/- 53, 788 +/- 37, 849 +/- 36 dyne.sec/cm5.m2 at baseline, 3, and 5 hrs) followed the endotoxin bolus. Cerebral blood flow (65.4 +/- 4.3, 57.7 +/- 3.1, and 58.6 +/- 3.0 mL/100 g/min at baseline, 3, and 5 hrs), cerebral oxygen delivery (11.6 +/- 0.7, 9.8 +/- 0.6, and 9.5 +/- 0.6 mL/100 g/min at baseline, 3, and 5 hrs), cerebral metabolic rate for oxygen (3.8 +/- 0.4, 3.3 +/- 0.3, and 3.0 +/- 0.3 mL/100 g/min at baseline, 3, and 5 hrs), and cerebral vascular resistance (1.4 +/- 0.2, 1.4 +/- 0.2, and 1.3 +/- 0.2 mm Hg/mL/100 g/min at baseline, 3, and 5 hrs) were unchanged throughout the 5-hr study period. Signs of cerebral dysfunction were not apparent, although the volunteers appeared drowsy during the latter part of the study.


CONCLUSIONS
A dose of endotoxin sufficient to induce systemic vasodilation in healthy subjects does not influence cerebral blood flow or the cerebral metabolic rate for oxygen.
Pollard
V
V
Department of Anesthesiology, University of Texas Medical Branch, Galveston 77555-0591, USA.
Prough
D S
DS
Deyo
D J
DJ
Conroy
B
B
Uchida
T
T
Daye
A
A
Traber
L D
LD
Traber
D L
DL
D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D019446:Endotoxemia / Q000378:metabolism / Q000503:physiopathology*; D004731:Endotoxins / Q000008:administration & dosage / Q000494:pharmacology*; D004926:Escherichia coli; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D011446:Prospective Studies; D013997:Time Factors
D004731:Endotoxins