Katsuji Hirai

Effects of sevoflurane on the middle latency auditory evoked response and the electroencephalographic power spectrum

We investigated the effects of sevoflurane on the middle latency auditory evoked response (MLR) and the power spectrum of the electroencephalogram (EEG) in 10 elective surgical patients.The MLR and the EEG power spectrum were recorded with a surface electrode placed at the central (Cz) scalp location. End-tidal sevoflurane concentrations of 0%, 0.25%, 0.5%, 0.75%, 1.0%, and 1.5% in 50% nitrous oxide and oxygen were studied. The Na, Pa, and Nb components of the MLR increased in latency and decreased in amplitude in a dose-dependent manner at increasing concentrations of sevoflurane. The latencies for Na, Pa, and Nb increased in a linear fashion (correlation coefficients: r = 0.81, r = 0.81, and r = 0.89, respectively). The EEG delta power was dominant with increasing sevoflurane concentration, and was significantly increased at sevoflurane concentrations of 1.0%-1.5%. The beta power, median power frequency (MPF), and 95% spectral edge frequency (SEF) decreased significantly according to the increases by 0.5% sevoflurane. Regarding the changes evoked by 0.25% sevoflurane, the Nb latency of the MLR responded significantly under 0.75% of sevoflurane. At these low concentrations of sevoflurane, the MLR seemed to be more sensitive to changes in anesthetic concentration than the various EEG variables. (Anesth Analg 1995;80:940-3)

The Effects of β-adrenoceptor Antagonists on Proinflammatory Cytokine Concentrations After Subarachnoid Hemorrhage in Rats

BACKGROUND: Proinflammatory cytokines increase in cerebrospinal fluid (CSF) after subarachnoid hemorrhage (SAH). Recent evidence suggested that &bgr;-adrenoceptor antagonist could reduce proinflammatory cytokines. We conducted the present study to examine whether &bgr;-adrenoceptor antagonists would reduce proinflammatory cytokine concentrations after SAH in rats. METHODS: In Experiment 1, to investigate the time course of interleukin-6 (IL-6) and tumor necrosis factor-&agr; (TNF-&agr;), rats were randomized into groups: 1, 3, 6, and 12 h after SAH or sham operation. CSF and blood samples were obtained at each time point. In Experiment 2, to investigate the effects of &bgr;-adrenoceptor antagonists on the IL-6 and TNF-&agr; concentrations, rats were randomized into groups: 1) control group: SAH + normal saline, 2) propranolol group: SAH + propranolol, 3) metoprolol group: SAH + metoprolol, and 4) butoxamine group: SAH + butoxamine (&bgr;2-adrenoceptor antagonist). CSF and blood samples were obtained 6 h after SAH. IL-6 and TNF-&agr; concentrations in samples were measured. RESULTS: In Experiment 1, CSF IL-6 concentrations in the SAH groups increased markedly and peaked at 6 h after SAH, whereas CSF TNF-&agr; concentrations in the SAH groups were consistently low. In Experiment 2, CSF IL-6 concentrations in the propranolol and butoxamine groups were significantly lower compared with those in the control group (P < 0.01 and P < 0.05 for each group). Plasma IL-6, CSF TNF-&agr;, and plasma TNF-&agr; concentrations were comparable in all four groups. CONCLUSIONS: CSF IL-6 concentrations increased in the acute stage of SAH and &bgr;-adrenoceptor antagonists with a &bgr;2-adrenoceptor blocking action suppressed this elevation of IL-6 concentrations after SAH in rats.

Normothermic treatment in acute clinical encephalitis: a case report

IntroductionEncephalitis is a common infection of the brain, associated with a high risk of mortality and morbidity despite intensive supportive therapy. This report describes a patient with acute clinical meningoencephalitis who responded dramatically when her body temperature was decreased to normothermia (36 to 37°C) in combination with barbiturate therapy.Case presentationA 15-year-old, previously healthy girl presented with a 2-day history of headache and meningeal stiffness and pyrexia. Cranial magnetic resonance imaging showed high-intensity signals in the splenium of the corpus callosum on T2-weighted and diffusion-weighted images. On day 4 of admission, the level of consciousness decreased and ataxic respiration and apnea appeared. After that, fever (body temperature >40°C) developed with remarkable tachycardia. The body temperature was decreased with the use of a forced-air-cooling blanket and head cooling. The core temperature, measured in the bladder, was maintained at between 36 and 37°C for 5 days. During the period of normothermia, thiopental sodium was given continuously for 3 days. After normothermia, the level of consciousness increased without the development of fever, and ventilatory support was withdrawn.ConclusionOur experience suggests that normothermic treatment in combination with barbiturate therapy may be an effective option for the management of brain swelling associated with acute meningoencephalitis, particularly when accompanied by a persistent high fever.