Cerebral effects of anaesthesia and hypothermia.
Cerebral blood flow, cerebral oxygen and glucose consumption, and cerebral lactate and pyruvate release were measured; spectral analysis of the EEG was recorded in 10 male patients who had coronary artery bypass surgery. The measurements were taken to evaluate the effects of fentanyl-midazolam anaesthesia during normothermia and during hypothermic nonpulsatile cardiopulmonary bypass at 26 degrees C venous blood temperature, when a temperature-corrected PaCO2-value of 5.3 kPa was maintained. Anaesthesia with fentanyl 7 micrograms/kg and midazolam 200 micrograms/kg as induction doses, followed by infusions of fentanyl 0.15 micrograms/kg/minute and midazolam 3 micrograms/kg/minute, was characterised by a decrease in fast-wave activity and an increase in high-amplitude, slow-wave activity in the EEG. There was also a decrease in cerebral blood flow (38%), oxygen consumption (22%) and glucose consumption (25%), while lactate and pyruvate production remained unchanged. Hypothermia of 26 degrees C venous blood temperature suppressed EEG almost completely and decreased oxygen and glucose consumption by a further 61% and 54%, respectively, with no changes in lactate and pyruvate production while cerebral blood flow increased by 145%. These results show that the effects of fentanyl-midazolam anaesthesia on cerebral metabolism are enhanced during hypothermic cardiopulmonary bypass while the influence of anaesthesia on cerebral blood flow is overshadowed by the practice of a temperature-corrected acid-base management.
Stephan
H
H
Department of Anaesthetics, University of Göttingen, Germany.
Sonntag
H
H
Lange
H
H
Rieke
H
H
D000328:Adult; D000758:Anesthesia / Q000009:adverse effects*; D001921:Brain / Q000378:metabolism*; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation; D001026:Coronary Artery Bypass; D005283:Fentanyl / Q000009:adverse effects*; D005947:Glucose / Q000378:metabolism; D006439:Hemodynamics; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D008874:Midazolam / Q000009:adverse effects*; D008875:Middle Aged; D010101:Oxygen Consumption; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid
D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose; D008874:Midazolam; D005283:Fentanyl