OBJECTIVE: To determine the maximum dose of continuously infused mivacurium for intraoperative neuromonitoring and observe its adverse effects in thyroid surgery. METHODS: Twenty-eight patients undergoing thyroid surgery with intraoperative neuromonitoring received continuous infusion of mivacurium at the initial rate of 5.43 μg?kg?min, and the infusion rate for the next patient was adjusted based on the response of the previous patient according to the results of neurological monitoring. The depth of anesthesia was maintained with sevoflurane and remifentanil during the surgery. The LD50 and 95% of mivacurium were calculated using Brownlee's up-and-down sequential method. RESULTS: The LD50 of continuously infused mivacurium was 8.94 μg?kg?min (95% : 8.89- 8.99 μg?kg?min) during thyroid surgery, which did not affect neurological function monitoring. Transient chest skin redness occurred after induction in 9 patients (32.1%). None of the patients experienced intubation difficulties or showed intraoperative body motions during the surgery. CONCLUSIONS In patients undergoing thyroid surgery under anesthesia maintained by inhalation and intravenous infusion, the LD50 of mivacurium was 8.94 μg?kg?min (95% : 8.89-8.99 μg?kg?min) for continuous infusion, which does not cause serious adverse effects during the operation.
Anesthesia ; Anesthetics, Inhalation ; Anesthetics, Intravenous ; Humans ; Intraoperative Neurophysiological Monitoring ; methods ; Lethal Dose 50 ; Mivacurium ; administration & dosage ; adverse effects ; Neuromuscular Nondepolarizing Agents ; administration & dosage ; adverse effects ; Remifentanil ; Sevoflurane ; Thyroid Gland ; surgery

Objective To observe the effects of two different intranasal dexmedetomidine doses as premedication on the ECof sevoflurane for successful laryngeal mask airway placement in children. Methods Children aged 3-6 years, of American Society of Anesthesiologists physical status 1, and scheduled for plastic surgery were enrolled in this study. Children were assigned to receive either spray administration of intranasal dexmedetomidine 1 μg/kg (group D1, n=21) or 2 μg/kg (group D2, n=20) approximately 30 minutes before anesthesia. Anesthesia was induced with sevoflurane up to 8% in 100% O, with fresh gas flow set to 6 L/min. After the pupil fixed to the middle position, sevoflurane dial setting was reduced to 5% and fresh gas flow reduced to 3 L/min. The endtidal sevofluran (ET) concentration for laryngeal mask airway insertion sustained for 10 minutes after vein intubation, which was determined according to the Dixon's up and down method. The initial endtidal sevoflurane concentration in each group was set at 2%. ETwas increased/decreased (1:1.2) in the next patient according to the response to laryngeal mask airway insertion. Bispectral index, mask acceptance, all response to laryngeal mask airway insertion, and ETof laryngeal mask airway insertion of children were recorded. Results The bispectral index value was 77.4±3.6 in group D2, which was significantly lower than that (87.4±1.9) in group D1 when children entered operation room (P<0.05). Mask acceptance was 76.2% in group D1 and 90.0% in group D2. The ECof sevoflurane for laryngeal mask airway insertion was 1.09% (95% CI=0.89%-1.28%) in group D2, which was lower than 1.59% (95% CI=1.41%-1.78%) in group D1 (P<0.05). Conclusion Compared with the dose of 1 μg/kg, spray administration of intranasal dexmedetomidine 2 μg/kg as premedication can reduce the sevoflurane ECfor successful laryngeal mask airway placement in children.
Administration, Intranasal ; Anesthesia ; Anesthetics, Inhalation ; administration & dosage ; Child ; Child, Preschool ; Dexmedetomidine ; administration & dosage ; Humans ; Laryngeal Masks ; Methyl Ethers ; administration & dosage

BACKGROUNDThe optimal ventilated status under total intravenous or inhalation anesthesia in neurosurgical patients with a supratentorial tumor has not been ascertained. The purpose of this study was to intraoperatively compare the effects of moderate hyperventilation on the jugular bulb oxygen saturation (SjO 2 ), cerebral oxygen extraction ratio (O 2 ER), mean arterial blood pressure (MAP), and heart rate (HR) in patients with a supratentorial tumor under different anesthetic regimens.

METHODSTwenty adult patients suffered from supratentorial tumors were randomly assigned to receive a propofol infusion followed by isoflurane anesthesia after a 30-min stabilization period or isoflurane followed by propofol. The patients were randomized to one of the following two treatment sequences: hyperventilation followed by normoventilation or normoventilation followed by hyperventilation during isoflurane or propofol anesthesia, respectively. The ventilation and end-tidal CO 2 tension were maintained at a constant level for 20 min. Radial arterial and jugular bulb catheters were inserted for the blood gas sampling. At the end of each study period, we measured the change in the arterial and jugular bulb blood gases.

RESULTSThe mean value of the jugular bulb oxygen saturation (SjO 2 ) significantly decreased, and the oxygen extraction ratio (O 2 ER) significantly increased under isoflurane or propofol anesthesia during hyperventilation compared with those during normoventilation (SjO 2 : t = -2.728, P = 0.011 or t = -3.504, P = 0.001; O 2 ER: t = 2.484, P = 0.020 or t = 2.892, P = 0.009). The SjO 2 significantly decreased, and the O 2 ER significantly increased under propofol anesthesia compared with those values under isoflurane anesthesia during moderate hyperventilation (SjO 2 : t = -2.769, P = 0.012; O 2 ER: t = 2.719, P = 0.013). In the study, no significant changes in the SjO 2 and the O 2 ER were observed under propofol compared with those values under isoflurane during normoventilation.

CONCLUSIONSOur results suggest that the optimal ventilated status under propofol or isoflurane anesthesia in neurosurgical patients varies. Hyperventilation under propofol anesthesia should be cautiously performed in neurosurgery to maintain an improved balance between the cerebral oxygen supply and demand.

Adolescent ; Adult ; Aged ; Anesthetics, Inhalation ; Anesthetics, Intravenous ; Arterial Pressure ; physiology ; Blood Gas Analysis ; Craniotomy ; methods ; Female ; Heart Rate ; physiology ; Humans ; Hyperventilation ; chemically induced ; physiopathology ; Isoflurane ; administration & dosage ; therapeutic use ; Male ; Middle Aged ; Propofol ; administration & dosage ; therapeutic use ; Young Adult

PURPOSE: The purpose of this study was to determine the effect-site concentration (Ce) of remifentanil in 50% of patients (EC50) and 95% of patients (EC95) for smooth laryngeal mask airway (LMA) removal in adults under propofol and remifentanil anesthesia. MATERIALS AND METHODS: Twenty-five patients of ASA physical status I-II and ages 18-60 years who were to undergo minor gynecological or orthopedic surgery were assessed in this study. Anesthesia was induced and maintained with propofol and remifentanil target-controlled infusion (TCI). Remifentanil was maintained at a predetermined Ce during the emergence period. The modified Dixon's up-and-down method was used to determine the remifentanil concentration, starting from 1.0 ng/mL (step size of 0.2 ng/mL). Successful removal of the LMA was regarded as absence of coughing/gagging, clenched teeth, gross purposeful movements, breath holding, laryngospasm, or desaturation to SpO2<90%. RESULTS: The mean+/-SD Ce of remifentanil for smooth LMA removal after propofol anesthesia was 0.83+/-0.16 ng/mL. Using isotonic regression with a bootstrapping approach, the estimated EC50 and EC95 of remifentanil Ce were 0.91 ng/mL [95% confidence interval (CI), 0.77-1.07 ng/mL] and 1.35 ng/mL (95% CI, 1.16-1.38 ng/mL), respectively. CONCLUSION: Our results showed that remifentanil TCI at an established Ce is a reliable technique for achieving safe and smooth emergence without coughing, laryngospasm, or other airway reflexes.
Adolescent ; Adult ; Analgesics, Opioid/*administration & dosage ; Anesthetics, Inhalation/*administration & dosage ; Cough/prevention & control ; Device Removal ; Dose-Response Relationship, Drug ; Female ; Gynecologic Surgical Procedures ; Humans ; *Laryngeal Masks ; Male ; Middle Aged ; Orthopedic Procedures ; Piperidines/*administration & dosage ; Propofol/*administration & dosage ; Treatment Outcome ; Young Adult

INTRODUCTIONDraw-over anaesthesia remains an attractive option for conduct of anaesthesia in austere conditions. The Diamedica Draw-over Vaporiser (DDV) is a modern draw-over vaporiser and has separate models for isoflurane/halothane and sevoflurane.

MATERIALS AND METHODSA laboratory study was done to measure sevoflurane output in an isoflurane/ halothane DDV. We did 3 series of experiments with the isoflurane/halothane DDV. We measured anaesthetic agent output in both push-over and draw-over setups, and at minute ventilation of 6 L/min and 3 L/min. Series 1 experiment was done with isoflurane in the DDV at ambient temperature of 20°C. Series 2 experiment was done with sevoflurane in the DDV at ambient temperature of 20°C. Series 3 experiment was done with sevoflurane in the DDV and with the DDV placed in a water bath of 40°C.

RESULTSThe sevoflurane output was found to be two-thirds of the isoflurane/ halothane DDV dial setting at ambient temperature of 20°C. With the DDV in a 40°C water bath, the sevoflurane output was found to be about the isoflurane/ halothane DDV dial settings.

CONCLUSIONIn our experiment, we show that it is possible to use sevoflurane in an isoflurane/halothane DDV.

Anesthesia, Inhalation ; instrumentation ; methods ; Anesthetics, Inhalation ; administration & dosage ; Halothane ; Humans ; Isoflurane ; Methyl Ethers ; administration & dosage ; Nebulizers and Vaporizers ; Temperature

OBJECTIVE: To assess the efficacy of different methods of anesthesia on children underwent hypospadias surgery.
 METHODS: A total of 90 children (2-6 years old, 11.5-21.0 kg weight) with I or II grade of hypospadias based on ASA standard, who scheduled for hypospadias angioplasty, were randomly divided into 3 groups: Group I, general anesthesia combined epidural anesthesia; Group II, laryngeal mask airway under general anesthesia; Group III, laryngeal mask airway under general anesthesia combined epidural block. All children were inhaled sevoflurane to keep bispectral index value in a range from 45 and 60. The Group I adopted epidural anesthesia after intravenous induction of anesthesia; the Group II was inserted laryngeal mask after induction; the Group III was inserted laryngeal mask after induction and adopted epidural block. The anesthesia efficacy, hemodynamic changes, adverse reaction and the postoperative complications were observed in the 3 groups.
 RESULTS: Compared with the Group I or the Group II, the blood pressure and heart rate ran more smoothly in the Group III, and the postoperative agitation and incidence of adverse events were also significantly reduced (all P<0.05).
 CONCLUSION The laryngeal mask airway under general anesthesia combined epidural block is a better choice for children scheduled for hypospadias angioplasty.
Anesthesia ; methods ; Anesthesia, Epidural ; Anesthesia, General ; Anesthetics, Inhalation ; Blood Pressure ; Child ; Hemodynamics ; Humans ; Hypospadias ; surgery ; Laryngeal Masks ; Male ; Methyl Ethers ; administration & dosage ; Postoperative Complications ; Sevoflurane

PURPOSE: Mentally disabled patients show different recovery profiles compared to normal patients after general anesthesia. However, the relationship of dose-recovery profiles of mentally disabled patients has never been compared to that of normal patients. MATERIALS AND METHODS: Twenty patients (10 mentally disabled patients and 10 mentally intact patients) scheduled to dental surgery under general anesthesia was recruited. Sevoflurane was administered to maintain anesthesia during dental treatment. At the end of the surgery, sevoflurane was discontinued. End-tidal sevoflurane and recovery of consciousness (ROC) were recorded after sevoflurane discontinuation. The pharmacodynamic relation between the probability of ROC and end-tidal sevoflurane concentration was analyzed using NONMEM software (version VII). RESULTS: End-tidal sevoflurane concentration associated with 50% probability of ROC (C50) and gamma value were lower in the mentally disabled patients (C50=0.37 vol %, gamma=16.5 in mentally intact patients, C50=0.19 vol %, gamma=4.58 in mentally disabled patients). Mentality was a significant covariate of C50 for ROC and gamma value to pharmacodynamic model. CONCLUSION: A sigmoid Emanx model explains the pharmacodynamic relationship between end-tidal sevoflurane concentration and ROC. Mentally disabled patients may recover slower from anesthesia at lower sevoflurane concentration at ROC an compared to normal patients.
*Anesthesia Recovery Period ; Anesthesia, Dental/*methods ; Anesthesia, General/*methods ; Anesthetics, Inhalation/*administration & dosage/pharmacology ; Case-Control Studies ; Child ; Child, Preschool ; Consciousness/drug effects ; Dental Care for Disabled/*methods ; Dose-Response Relationship, Drug ; Female ; Humans ; Male ; Mentally Disabled Persons ; Methyl Ethers/*administration & dosage/pharmacology

Although empirically well understood in their clinical administration, volatile anesthetics are not yet well comprehended in their mechanism studies. A major conundrum emerging from these studies is that there is no validated model to assess the presumed candidate sites of the anesthetics. We undertook this study to test the hypothesis that the single-celled Paramecium could be anesthetized and served as a model organism in the study of anesthetics. We assessed the motion of Paramecium cells with Expert Vision system and the chemoresponse of Paramecium cells with T-maze assays in the presence of four different volatile anesthetics, including isoflurane, sevoflurane, enflurane and ether. Each of those volatiles was dissolved in buffers to give drug concentrations equal to 0.8, 1.0, and 1.2 EC50, respectively, in clinical practice. We could see that after application of volatile anesthetics, the swimming of the Paramecium cells was accelerated and then suppressed, or even stopped eventually, and the index of the chemoresponse of the Paramecium cells (denoted as I ( che )) was decreased. All of the above impacts were found in a concentration-dependent fashion. The biphasic effects of the clinical concentrations of volatile anesthetics on Paramecium simulated the situation of high species in anesthesia, and the inhibition of the chemoresponse also indicated anesthetized. In conclusion, the findings in our studies suggested that the single-celled Paramecium could be anesthetized with clinical concentrations of volatile anesthetics and therefore be utilized as a model organism to study the mechanisms of volatile anesthetics.
Anesthetics, Inhalation ; administration & dosage ; Biological Assay ; methods ; Cell Movement ; drug effects ; physiology ; Chemotaxis ; drug effects ; physiology ; Dose-Response Relationship, Drug ; Drug Evaluation, Preclinical ; methods ; Paramecium tetraurelia ; drug effects ; physiology ; Volatile Organic Compounds ; administration & dosage

BACKGROUND: The chemical reaction of carbon dioxide absorbent and sevoflurane is known to produce compound A. However, carbon dioxide absorbents are not controlled by the Food and Drug Administration, but are treated as industrial products in some nations. Moreover, carbon dioxide absorbents differ in their capacities to produce compound A, because their chemical compositions differ. In this study, we compared the renal safety between carbon dioxide absorbent products in patients under sevoflurane anesthesia. METHODS: Eighty patients with no preexisting renal disease undergoing elective gynecologic surgery were randomly assigned to receive sevoflurane or isoflurane anesthesia with one of four carbon dioxide absorbent products (Sodasorblime(R), Sodalyme(R), Sodasorb(R), Spherasorb(R)) at the same fresh gas flow of 2 L/min. The renal safety was evaluated by changes of blood urea nitrogen (BUN), creatinine and urine N-acetyl-b-glucoseaminidase (NAG)-creatinine ratio at 24 hours and 72 hours after surgery from preoperative level. RESULTS: There was no significant difference in the renal safety indicators between carbon dioxide absorbents during sevoflurane anesthesia (P > 0.05). However, the BUN and urine NAG-creatinine ratios at 72 hours after surgery were higher in isoflurane anesthesia in some carbon dioxide absorbent groups (P = 0.03 and 0.04, respectively). CONCLUSIONS: We could not find significant differences of renal safety indicators with carbon dioxide absorbents. Although the adverse effect of carbon dioxide absorbents on renal function was not proved, consideration should be given to their contol by the regulation on their efficacy and safety because carbon dioxide absorbents can produce compound A.
Anesthesia ; Anesthetics ; Blood Urea Nitrogen ; Carbon ; Carbon Dioxide ; Creatinine ; Female ; Gynecologic Surgical Procedures ; Humans ; Inhalation ; Isoflurane ; Kidney ; Methyl Ethers ; Pilot Projects ; United States Food and Drug Administration

PURPOSE: Anesthesia and surgery commonly cause hypothermia, and this caused by a combination of anesthetic-induced impairment of thermoregulatory control, a cold operation room environment and other factors that promote heat loss. All the general anesthetics markedly impair normal autonomic thermoregulatory control. The aim of this study is to evaluate the effect of two different types of propofol versus inhalation anesthetic on the body temperature. MATERIALS AND METHODS: In this randomized controlled study, 36 patients scheduled for elective laparoscopic gastrectomy were allocated into three groups; group S (sevoflurane, n=12), group L (lipid-emulsion propofol, n=12) and group M (micro-emulsion propofol, n=12). Anesthesia was maintained with typical doses of the study drugs and all the groups received continuous remifentanil infusion. The body temperature was continuously monitored after the induction of general anesthesia until the end of surgery. RESULTS: The body temperature was decreased in all the groups. The temperature gradient of each group (group S, group L and group M) at 180 minutes from induction of anesthesia was 2.5+/-0.6degrees C, 1.6+/-0.5degrees C and 2.3+/-0.6degrees C, respectively. The body temperature of group L was significantly higher than that of group S and group M at 30 minutes and 75 minute after induction of anesthesia, respectively. There were no temperature differences between group S and group M. CONCLUSION: The body temperature is maintained at a higher level in elderly patients anesthetized with lipid-emulsion propofol.
Aged ; Aging ; Anesthesia, General/*methods ; Anesthetics, Combined/administration & dosage ; Anesthetics, Inhalation/*administration & dosage ; Anesthetics, Intravenous/*administration & dosage ; Body Temperature/*drug effects ; Body Temperature Regulation/drug effects ; Fat Emulsions, Intravenous ; Female ; Humans ; Male ; Methyl Ethers/*administration & dosage ; Middle Aged ; Propofol/*administration & dosage