BACKGROUND: The purpose of this study was to evaluate the safety and efficacy of low-flow anesthesia with a semi-closed circle anesthesia system in infants. METHODS: Twenty, ASA physical status 1 or 2, infants were randomly assigned into two groups: high-flow anesthesia (HFA) or low-flow anesthesia (LFA). An identical semi-closed Dr ger circle anesthesia system (Cato) was used to all patients. Initial fresh gas flow (FGF) was N2O 1.5 L/min and O2 1.5 L/min in both groups. This FGF of 3 L/min was maintained in the HFA group. After 10 min of HFA, the FGF was reduced to 500 ml/min (N2O 250 ml/min and O2 250 ml/min) in the LFA group. RESULTS: Hypoxic or hypercarbic gas concentrations were not observed in all patients. Enflurane consumption during LFA was about 1/3 of that during HFA (6.8 +/- 1.3 ml vs. 19.5 +/- 5.8 ml). The mean highest esophageal temperature was similar in both groups. The mean highest inspiratory gas and soda lime temperatures were significantly higher in the LFA group than in the HFA group. CONCLUSIONS: Low-flow anesthesia in a circle system with a fresh gas flow of N2O 250 ml/min and O2 250 ml/min could be performed safely and economically for infants.
Anesthesia* ; Enflurane* ; Humans ; Infant*

Enflurane* ; Metabolism* ; Methoxyflurane* ; Panax*

We chose enflurane as the primary anesthetic agent for the surgical removal of a pheochromocytoma (23 year old male) with the satisfactory results. A review of the literature on the anesthetic management of pheochromocytoma discloses no general agreement regarding choice of an anesthetic agent. Almost all agents have at some time been both praised and rejected. It would suggest that selection of an anesthetic agent is not as important as the adequate management of that agent.
Anesthesia* ; Enflurane* ; Pheochromocytoma*

Plasma inorganic fluoride concentrations were measured in adult patients without hepatic or renal disease following sevoflurane-N2O anesthesia (n=7) or enflurane-N2O anesthesia (n=6). The anesthetic dosage of sevoflurane and enflurane was 6.48+/-2,15%-hour and 6.57+/-2.05%-hour, respectively. The mean peak plasma inorganic fluoride concentration in the sevoflurane group was 19.5+/-13.4 umol/L 1hour after anesthesia, which decreased to preanesthetic levels 24 hours after anesthesia. In the enflurane group the values were 13.2+/-5.8 umol/L at the end of anesthesia and decreased, but remained, still twice as high as the preanesthetic level 24 hours after anesthesia. The relationship of plasma inorganic fluoride concentration and anesthetic dosage was more pronounced in the sevoflurane group (r=0.68, slope=4.2) than in the enflurane group (r=0.39, slope=1.2). In conclusian, sevoflurane-N2O anesthesia results in similar subnephrotoxic levels of plasma inorganic fluoride as enflurane-N2O. anesthesia, and although the fluoride concentration had a better correlation to anesthetic dosage in the sevoflurane group than in the enflurane group, its excretion was faster in the sevoflurane group than in the enflurane group.
Adult ; Anesthesia* ; Enflurane ; Fluorides* ; Humans ; Plasma*

BACKGROUND: The bispectral index (BIS) has been designed to objectively measure the degree of sedation and hypnosis for anesthesia. Although it has been well-known that BIS correlates highly with the concentration of inhalation anesthetics, it is not clear whether analgesic potency expressed as MAC is comparable to hypnotic potency described as BIS50 in inhaled anesthetics. This study was conducted to examine the degree of correspondence by correlating the changes of BIS according to the different MAC of commonly used inhalation anesthetics. METHODS: One hundred ASA class 1 or 2 patients, scheduled for laparoscopic knee surgery were included. Patients were equally divided into 4 groups (n = 25 each) according to the inhalational agent enflurane, isoflurane, desflurane, or sevoflurane. Anesthetic depth for each individual agent was controlled to 2.0, 1.75, 1.5, 1.25, 1.0, 0.75 and 0.5 MAC, respectively. After equilibration for each concentration, BIS values were measured three times at 30 second intervals and an average was obtained. In addition, MAC values for each agent were measured when the bispectral index showed 50. RESULTS: The concentrations of inhaled agents vs. BIS showed high negative correlations (enflurane; -0.91, isoflurane; -0.94, desflurane; -0.84, and sevoflurane; -0.86). BIS50 for each agent was enflurane, 0.93 (1.6 vol%); isoflurane, 0.71 (0.9 vol%); desflurane, 0.95 (5.7 vol%); and sevoflurane, 0.84 MAC (1.7 vol%). Isoflurane-BIS50 showed a significant difference to the others (P<0.05). CONCLUSIONS: We concluded that the MAC of inhalation anesthetics showed poor correlation with BIS, suggesting a difference between the hypnotic and analgesic potency of individual inhaled anesthetic agents.
Anesthesia ; Anesthetics ; Anesthetics, Inhalation* ; Enflurane ; Humans ; Hypnosis ; Inhalation* ; Isoflurane ; Knee

BACKGROUND: We examined the use of DFA-Detrended fluctuation analysis-of heart rate variability during general anesthesia in order to assess the depth of anesthesia. METHODS: In this study, we observed changes in alpha1, the short range scaling exponent, in alpha2, the long range scaling exponent, and in the alpha2/alpha 1 ratio during enflurane anesthesia. We monitored 7 stages during general anesthesia, i.e., 1) preoperation (awake state), 2) during induction, 3) after induction, 4) during maintenance, 5) before extubation, 6) after extubation, and 7) postoperation (Next day). RESULTS: The alpha 2/alpha 1 ratio increased during the induction and extubation state compared to preoperation (awake state). This may be related to increased sympathetic activity due to stimulation of the autonomic nervous system. In the postoperation (awakened state), the ratio returned to the preoperation value (awake state). These results are similar to low frequency (LF), high frequency (HF) and LF/HF ratio values which reflect activity of autonomic nervous system. CONCLUSIONS: Detrended fluctuation analysis parameters, especially the alpha 2/alpha 1 ratio, would be used for monitoring the depth of anesthesia. Also these parameters are useful indexes with the LF/HF ratio for the evaluation of sympathetic activity during general anesthesia.
Anesthesia* ; Anesthesia, General ; Autonomic Nervous System ; Enflurane ; Heart Rate

BACKGROUND: This study was performed to evaluate whether the degree of hypotension influences blood loss during spinal surgery. METHOD: Fifty patients undergoing only one level spinal fusion were assigned to one of three groups. In group 1 (n = 14), the systolic blood pressure (SBP) was maintained at 100 120 mmHg with enflurane. In groups 2 (n = 18) and 3 (n = 18), the SBP were maintained at 80 100 and 60 80 mmHg, respectively. Hydralazine and esmolol were used in the hypotensive groups. RESULTS: Blood losses during operation in groups 2 (554 +/- 287 ml) and 3 (456 +/- 162 ml) were significantly lower than in group 1 (1141 +/- 690 ml) (P < 0.05), although there was no significant difference between groups 2 and 3. The percentage of patients receiving transfusions during the operation in groups 1 and 2 were 57.1 and 5.6%, respectively. CONCLUSIONS: The results show that a moderate reduction in SBP (80 - 100 mmHg) reduces blood loss by more than half in comparison to a mild reduction in SBP (100 - 120 mmHg). However, a severe reduction in SBP (60 - 80 mmHg) does not increase the reduction in blood loss in comparison to moderate hypotension.
Blood Pressure ; Enflurane ; Humans ; Hydralazine ; Hypotension* ; Spinal Fusion

To evaluate the depth of enflurane anesthesia, spectrum analysis of rat EEG was used. Bipolar EEG was recorded through one lead form rat scalp during inhalation with 1,2,3 and 4% of enflurane, and analysed to produce the spectrum from which the density of each band(delta 1-3.25Hz, theta 3.5-7.75Hz, alpha 8-12.75Hz, beta2 18-20.75Hz, and beta3 21-31.75Hz)and total density, and medican power frequency were calculated. Differences among the EEG patterns, which were represented by F values through discriminant analysis of those 8 variables, in each level of anesthesia were significant among all concentrations except between 1% and 2% enflurane administration. The results suggest that the discriminat anlysis for the EEG parameters derived from power spectrum analysis can apply to determine the level of enflurane anesthesia.
Anesthesia ; Anesthetics* ; Animals ; Electroencephalography* ; Enflurane* ; Inhalation ; Rats* ; Scalp ; Spectrum Analysis*

BACKGROUND: Various aspects of immunological homeostasis are affected by anesthesia and surgery, including the function of immunocompetent cells and the modulation of stress responses. To evaluate immunologic changes that occurred following propofol and enflurane anesthesia, we evaluated the proliferative responsiveness of peripheral blood mononuclear cells (PBMC) in patients undergoing laparoscopic gynecologic surgery. METHODS: PBMC were isolated from patients prior to anesthesia and on the first postoperative day (n = 10). The proliferative response was then evaluated based on the level of 5-bromo-2-deoxyunridine (BrdU) incorporation that occurred during DNA synthesisafter the induction of mitogenic stimulation by treatment with 1 microgram/ml lipopolysaccharides (LPS). To accomplish this, cell proliferation was assayed by enzyme-linked immuno-sorbent assay (ELISA), after which a stimulation index was calculated. RESULTS: Although the calculated stimulation index decreased in response to both propofol and enflurane anesthesia, the stimulation index did not differ significantly between groups. However, following stimulation with LPS, the stimulation index was significantly higher in the enflurane group than in the propofol group (P < 0.05). CONCLUSIONS: Propofol and enflurane anesthesia inhibit the PBMC proliferation. However, the decrease in proliferation that occurred in response to enflurane was attenuated by LPS.
Anesthesia ; Bromodeoxyuridine ; Cell Proliferation ; DNA ; Enflurane ; Homeostasis ; Humans ; Lipopolysaccharides ; Propofol

To evaluate the second gas effect and the effect of solubility of volatile anesthetics on the alveolar concentration, the ratio of the end-tidal to the inspired concentration(FET/F1) of enflurane and isoflurane with or without N2O were measured in 40 adult patients in ASA class I or Il. The patients were devided into four groups ; group 1 received 100% O2-1 vol% enflurane, group 2 received 50% O2-50% N2O-1 vol % enflurane, group 3 received 100 % O2-1 vo1% isoflurane and group 4 received 50% 0 50% N2O-1 vo1% isoflurane. The ratio of FET/F1 were measured at 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 30 minute after administration of inhalation anesthetics in each group. The results were as follows. 1) The increase in FET/F1, compared with previous value in each group was significant at 2 minute in group 1 and 2(p<0.05), and at 2 minute and 3 minute in group 3 and 4(p< 0.05), respectively. 2) To compare between group 1 and 2, the significant differance of FET/F1 was noticed during entire observation period and between group 3 and 4, too(p<0.05). This is the result of the second gas effect. 3) The FET/F1 ratio of isoflurane which has lower blood solubility rised more rapidly than the FET/F1 ratio of enflurane. When given without NO, the FET/F1 ratio of group 3 rised significantly more rapidly than the FET/F1 ratio of group 1(p<0.05). But, when given with N2O, changes of the FET/F1 ratio were not significantly different between group 2 and 4. In this study, the alveolar concentration of enflurane and isoflurane rised more rapidly when given with 50% N2O than when given without N2O, it might be the second gas effect by the uptake of NO. And, to the exclusion of the second gas effect, the FET/F1 ratio of less soluble isoflurane rised more rapidly than the more soluble enflurane. But, under the presence of the second gas effect, the difference of the alveolar concentration which depends on the anesthetic solubility between enflurane and isoflurane was not significant.
Adult ; Anesthetics* ; Anesthetics, Inhalation ; Enflurane ; Humans ; Isoflurane ; Solubility*