Effects of different general anesthetics on peripheral microcirculation.

Human keep body temperature in a narrow range by a variety of regulatory mechanism. Peripheral thermal receptors send signals to central nervous system which regulate body temperature via peripheral effectors, such as vasoconstriction, vasodilatation, shivering, sweating and etc. In patients undergoing general anesthesia, the regulatory mechanism is altered. General anesthesia changes blood distribution in the body, the metabolic rate of muscle, threshold of thermal regulation in the brain and etc, so that heat distribution and microcirculation condition will also change. In this study, near-infrared spectroscopy (NIRS) is used to measure the microcirculatory condition. NIRS is a non-invasive continuous measurement to detect tissue saturation with the method of different wavelength of near-infrared. General anesthesia with inhalational sevoflurane and intravenous propofol is separated into 2 groups. Because of different mechanism of general anesthesia of these 2 anesthetics, different physiologic response may occur. Body temperature and somatic saturation are compared in each group.

Inclusion Criteria:

1. Breast surgeries under general anesthesia
2. BMI 18.5~30

Exclusion Criteria:

1. Cardiac disease
2. Lung disease
3. Renal disease
4. Neurological disease
5. Autonomic nervous system dysfunction