Thermoregulatory responses of sevoflurane, desflurane, and isoflurane during gynecologic laparoscopic surgery / 대한마취과학회지

BACKGROUND: Core temperature decreases rapidly after the induction of general anesthesia, because the heat is redistributed to peripheral tissues. Thermoregulatory responses of volatile anesthetics have been tested, but their effects have not been directly compared. Therefore, we evaluated the thermoregulatory responses to sevoflurane, desflurane, and isoflurane. METHODS: Sixty healthy patients scheduled for laparoscopic myomectomy or radical hysterectomy were allocated into three groups; Group S (sevoflurane, n = 20), Group D (desflurane, n = 20), and Group I (isoflurane, n = 20). Anesthesia was maintained with 1 minimum alveolar concentration (MAC) of sevoflurane, desflurane, and isoflurane in a 50/50 mixture of N2O/O2. Patients were maintained in a normovolemic and normocapnic state. The core temperature and forearm minus fingertip skin-temperature gradient (an index of peripheral vasoconstriction) were monitored after the induction of general anesthesia. RESULTS: Each of the seven patients given sevoflurane, desflurane, and isoflurane vasoconstricted at a core temperature of 35.3 +/- 0.5degrees C, 33.6 +/- 0.4degrees C, and 35.2 +/- 0.4degrees C, respectively. The vasoconstriction threshold was the lowest in patients anesthetized with desflurane. The core temperature gradient (Ti-Tf) was significantly higher in patients that were anesthetized with desflurane than in those that were anesthetized with sevoflurane or isoflurane. The core temperature of desflurane was significantly lower than that of sevoflurane or isoflurane 15 minutes after the induction of anesthesia until 180 minutes of anesthesia. CONCLUSIONS: These results indicate that the core temperature is maintained at a higher level in patients that have been anesthetized with sevoflurane or isoflurane than in those that have been anesthetized with desflurane.

Influence of warm-up on thermoregulatory responses during exercise / 体力科学

To examine the influence of warm-up on thermoregulatory responses during exercise, heat balance was measured in 5 healthy male students during lhr of exercise at 600 kpm/min work intensity in a climatic room of WBGT (Wet-Bulb Globe Temperature) at 30°C with or without pre-exercise warm-up at the minimum phase (6: 00-7: 00) of body temperature.<BR>There was no significant difference in heat production between exercise with and without warm-up. Evaporative heat loss during exercise with warm-up was 4-8% higher than that without warm-up.<BR>Warm-up did not influence dry heat loss. Body heat storage during exercise without warm-up was 36% higher than that with warm-up.<BR>The slope of the characteristic curve between the sweating response and elevation of rectal temperature during exercise with warm-up was higher than that without warm-up. These results indicate that the increased evaporative heat loss resulting from warm-up is brought about by changes in the sensitivity of the thermoregulatory response.

Circadian variation of thermoregulatory responses during rest in water / 体力科学

To observe possible influences of the biological clock on thermoregulatory responses, heat balance was measured 6 healthy students wearing only trunks during 30 min of immersion in water at a temperature of 21°C in both the rising phase (11: 00-13: 00) and the falling phase (23: 00-1: 00) of body temperature.<BR>Heat production was higher in the rising phase than in the falling phase. Duration of shivering was longer in the rising phase than in the falling phase. Dry heat loss was nearly constant, 163 to 166 W/m<SUP>2</SUP> in both phases. Body heat storage was negative in both phases, but higher in the falling phase than in the rising phase.<BR>The mean body temperature, however, changed to a similar extent in the rising phase and in the falling phase when the circadian temperature variation was balanced.<BR>Analysis of these results implies that the increased shivering in the rising phase is brought about by changes in the sensitivity of the thermoregulatory response.