Barbiturates impair cerebral metabolism during hypothermic circulatory arrest

Michael G. Siegman, Richard V. Anderson, Robert S. Balaban, Toni L. Ceckler, Richard E. Clark, Julie A. Swain

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Barbiturates have been used as a method of cerebral protection in patients undergoing open heart operations. Phosphorus 31 nuclear magnetic resonance spectroscopy was used to assess barbiturate-induced alterations in the cerebral tissue energy state during cardiopulmonary bypass, hypothermic circulatory arrest, and subsequent reperfusion. Sheep were positioned in a 4.7-T magnet with a radiofrequency coil over the skull. Nuclear magnetic resonance spectra were obtained at 37 °C, during cardiopulmonary bypass before and after drug administration at 37 °C and 15 °C, throughout a 1-hour period of hypothermic circulatory arrest, and during a 2-hour reperfusion period. A group of animals (n = 8) was administered a bolus of sodium thiopental (40 mg/kg) during bypass at 37 °C followed by an infusion of 3.3 mg · kg-1 · min-1 until hypothermic arrest. A control group of animals (n = 8) received no barbiturate. The phosphocreatine/adenosine triphosphate ratio, reflecting tissue energy state, was lower during cardiopulmonary bypass at 15 °C in the treated animals compared with controls (1.06 ± 0.08 versus 1.36 ± 0.17; p < 0.001). Lower phosphocreatine/adenosine triphosphate ratios were observed throughout all periods of arrest and reperfusion in the barbiturate-treated animals compared with controls (p ≤ 0.01). Thiopental prevented the increase in cerebral energy state normally observed with hypothermia and resulted in a decrease in the energy state of the brain during hypothermic circulatory arrest and subsequent reperfusion. These results suggest that thiopental administration before a period of hypothermic circulatory arrest may prove detrimental to the preservation of the energy state of the brain.

Original languageEnglish
Pages (from-to)1131-1136
Number of pages6
JournalAnnals of Thoracic Surgery
Issue number6
StatePublished - Dec 1992
Externally publishedYes


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