Sevoflurane can induce prolongation of the cardiac QT interval by inhibiting the repolarization phase of the action potential. This may occur as a result of inhibition of the human ether-a-go-go related gene (HERG) channel. To clarify the mechanisms of anesthetics on HERG channels, we monitored the electrocardiogram and measured QT intervals in the guinea pig in the presence of sevoflurane and propofol. Sevoflurane (1%-4%) prolonged QTc dose-dependently (7.5%-21.2%), but propofol did not affect it. Furthermore, HERG channels were expressed in Xenopus oocytes and outward HERG currents were obtained on step depolarization from a holding potential of -70 mV. Repolarization to -70 mV from positive test potentials resulted in large outward tail currents. Sevoflurane (1%-4%), in a dose-dependent manner, inhibited the HERG outward tail currents (9.7%-26.6%), whereas steady-state currents were inhibited only at large concentrations. The time constant of the converging current was decreased in the presence of sevoflurane, but the inactivation and activation curves were not shifted. Propofol did not affect these currents within the clinically relevant concentration. In conclusion, compared with steady-state currents, sevoflurane was more potent in inhibiting the outward tail currents, suggesting that sevoflurane may modulate the HERG channel kinetics in its inactivated state.
Ropivacaine has an inhibitory effect on I(Ca) in the guinea-pig single ventricular myocyte. It is concluded that the mild negative inotropic effect induced by ropivacaine can be attributed in part to shortening of the duration of the action potential, which is caused by inhibition of I(Ca).
We retrospectively compared the peri-operative respiratory functions of the complete thoracoscopic esophagectomy in the prone position (group P, n=15) and video-assisted thoracoscopic esophagectomy with mini-thoracotomy in the left lateral position (group L, n=10) . Intra-operative arterial blood gas analysis indicated no significant difference in PaO 2 /FIO 2 during one lung ventilation between the two groups (220.2 卤 82.8 vs 192.7 卤 111 Torr, p=0.513) . The duration from the end of surgery to extubation in group P was significantly shorter than that in group L (P<0.01) . In conclusion, thoracoscopic esophagectomy in the prone position contributed to maintenance of pulmonary oxygenation, and reduced the duration of mechanical ventilation in the post-operative period.
Comparison of the calculation formula, reproducibility, correlation and variation of bicarbonate ion concentration (HCO(3) (-)), and base excess value (BE) among four blood-gas analyzers was performed. No HCO(3) (-) and BE values calculated from the formulas showed any clinically significant difference, and all analyzers showed good correlation on their measurements. On the actual measurement of a specific sample, however, BE values from the same sample ranged between -6.3 and -15.7, which might affect therapeutic strategy. Caution should be taken for the assessment of data if different types of blood-gas analysis devices are used in the same facility.
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