• Kenichi Ogawa, Takeshi Uema, Nobutaka Motohashi, Masami Nishikawa, Harumasa Takano, Masahiko Hiroki, Etsuko Imabayashi, Takashi Ohnishi, Tomio Inoue, Yutaka Takayama, Masatoshi Takeda, Hiroshi Matsuda, Tomio Andoh, and Yoshitsugu Yamada.
• National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. k-ogawa@pd5.so-net.ne.jp
• Anesthesiology. 2003 May 1;98(5):1101-11.

BackgroundThe precise neural mechanisms of propofol anesthesia in humans are still unknown. The authors examined the acute effects of propofol on regional cerebral blood flow (rCBF) using positron emission tomography in patients with severe depression.MethodsIn six severely depressed patients (mean age, 55.0 yr) scheduled for electroconvulsive therapy, anesthetic levels were monitored by electroencephalography, and rCBF was serially quantified in the awake, sedated, and anesthetized states. The authors used high-resolution positron emission tomography with 15O-labeled water and statistical parametric mapping 99 for imaging and analysis of the data.ResultsGlobal cerebral blood flow showed sharp decreases from the awake level during the administration of propofol, decreasing 26.8% in the sedated state and 54.4% in the anesthetized state. Moreover, a dose effect was seen in both parietal cortices and the left lateral prefrontal region with larger regions of relative decrease in rCBF at higher propofol doses. At the higher dose, the values of rCBF in the pulvinar nucleus of the thalamus, the pontine tegmentum, and the cerebellar cortex were also affected. Meanwhile, there were few changes of relative rCBF in the basal frontal lobes during both sedated and anesthetized states.ConclusionsAs in earlier studies using normal subjects, pronounced suppression in rCBF in the brain stem reticular formation, the thalamus, and the parietal association cortex occurred even in severely depressed patients. However, previously reported decreases in rCBF in the basal frontal lobe were absent in depressed patients.

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