七氟醚对单肺通气期间血气和循环的影响

目的观察七氟醚吸入麻醉在胸外科非肺部手术行单肺通气期间对病人血气和循环的影响。方法20例ASAⅠ-Ⅱ级的病人，用芬太尼2μg／kg，咪唑安定0．05mg／kg，异丙酚（2—3）mg／kg，司可林1．5mg／kg作静脉快速诱导，插入右侧双腔气管导管。用吸入1．3—2．0MAC的七氟醚，间断静注维库溴铵和芬太尼维持麻醉。于双肺通气（TLV）30min，右侧单肺通气（OLV）15min，30min，60min测定血气及血流动力学指标。结果右侧OLV期间，动脉血氧分压（PaO2）和氧饱和度（SaO2）较TLV30min时明显下降（P〈0．05），但绝对值仍在正常范围内，而其他参数基本保持不变。结论在右侧OLV期间七氟醚吸入麻醉对肺内分流有影响，对机体HPV有一定的抑制作用，但不影响临床安全使用。     

Sevoflurane low-flow anaesthesia: best strategy to reduce Compound A concentration

BACKGROUND: To define the best strategy to reduce Compound A production in Sevoflurane low-flow anaesthesia by experiments in vitro and in vivo of different absorbers and different anaesthesia machines. METHODS: In vitro Compound A has been measured at 45 degrees C in vitro following Sevoflurane interactions with potassium hydroxide, sodium hydroxide, soda lime, Dragersorb 800 Plus and Amsorb, a new absorber that does not contain sodium or potassium hydroxide. In vivo Compound A concentration in the anaesthesia circuit (inspiratory branch) has been measured using an indirect sampling method through absorber vials (SKC) with active coal granules, during low flows (500 ml/min) general anaesthesia using soda lime, Dragersorb 800 Plus or Amsorb as absorber. Compound A was also measured during low flows (500 ml/min) general anaesthesia using as carbon dioxide absorber soda lime with different anaesthesia machines. RESULTS: In vitro at 45 degrees C Compound A concentration with soda lime and Dragersorb 800 Plus was about 10 times higher than with Amsorb. In vivo the Compound A concentrations in the inspiratory branch of the circuit were lower in the group with Amsorb. CONCLUSION: The Compound A production is minimal with Amsorb as carbon dioxide absorber.     

Effects of sevoflurane anesthesia combined with epidural block on renal function in the elderly: comparison with isoflurane

Purpose. Renal function declines with age, but little is known about the renal effects of the inhaled anesthetic sevoflurane in the elderly. We therefore compared the renal effects of sevoflurane and isoflurane anesthesia in elderly patients. Methods. Thirteen patients aged ≥70 years undergoing gastrectomy with epidural anesthesia combined with general anesthesia were randomly assigned to receive either sevoflurane (n = 7) or isoflurane (n = 6). Dopamine (3–5 μg·kg⁻¹·min⁻¹) was administered to all patients. Blood and urine samples were collected before, during, and after anesthesia. Serum and urinary inorganic fluoride was measured, and renal function tests were performed. Results. Serum inorganic fluoride was significantly elevated in both groups. The production of inorganic fluoride was significantly greater in the sevoflurane group, but the level did not exceed 50 μmol·l⁻¹ in any patient. No abnormalities were observed in blood urea nitrogen (BUN), serum creatinine, or urine volume in either group. The albumin excretion index increased during anesthesia and decreased after anesthesia in both groups. Creatinine clearance was unchanged in the sevoflurane group but fluctuated during and after anesthesia in the isoflurane group. α₁-Microglobulin (MG), β₂-MG, and urinary N-acetyl-β-d-glucosaminidase (NAG) excretion increased up to 3 h after anesthesia, and α₁-MG and β₂-MG excretion increased on postanesthesia day 3. Conclusion. In both groups, glomerular and tubular function were transiently affected, but no abnormalities were found in routine laboratory tests, suggesting that neither isoflurane nor sevoflurane in combination with dopamine and epidural anesthesia seriously affects renal function in the elderly. Received for publication on October 23, 1998; accepted on October 27, 1999     

Quantification of the degradation products of sevoflurane using four brands of CO2 absorbent in a standard anesthetic circuit

Purpose. CO₂ absorbents convert sevoflurane to fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), whose toxicity in rats raises concern regarding the safety of sevoflurane in a low-flow system. The type of CO₂ absorbent is one of factors that affect compound A concentration in the anesthetic circuit. The aim of the present study was to investigate the concentration of compound A in an anesthetic model circuit following the use of different brands of soda lime and Baralyme. Methods. We measured the concentrations of compound A in four different brands of CO₂ absorbent using a low-flow (1 l·min⁻¹ fresh gas) model circuit in which 2% sevoflurane was circulated. Sodasorb II, Baralyme, Sofnolime and Wakolime-A were used as CO₂ absorbents. The concentration of compound A was measured hourly, and the temperature of the CO₂ absorbent was monitored. Results. The maximum concentration of compound A in the circuit was highest for Baralyme (25.5 ± 0.6 ppm) (mean ± SD), followed by Sodasorb II (18.9 ± 1.6 ppm), Wakolime-A (16.1 ± 0.7 ppm), and Sofnolime (15.8 ± 1.4 ppm). The maximum temperature was 50.8 ± 1.3°C for Baralyme, 48.8 ± 1.3°C for Wakolime-A, 47.0 ± 1.4°C for Sodasorb II, and 43.5 ± 3.9°C for Sofnolime. Conclusion. The relative concentrations of compound A in the low-flow circuit were Baralyme > Sodasorb II > Wakolime-A = Sofnolime. Received: August 27, 1999 / Accepted: January 13, 2000     

Effects of two volatile anesthetics (sevoflurane and halothane) on the hypothalamic noradrenaline release in rat brain

There are marked increases in noradrenaline (NA) release during emergence from general anesthesia induced with volatile anesthetics. These changes in NA in the posterior hypothalamus of the rat were assessed by intracranial microdialysis. Sevoflurane and halothane in equipotent concentrations were used to obtain the same depth of anesthesia. NA release increased similarly with the two agents during recovery. However, NA release remained elevated longer with halothane, from which recovery was also slower.     

Effect of flumazenil on recovery from sevoflurane anesthesia in children premedicated with oral midazolam before undergoing herniorrhaphy with or without caudal analgesia

Purpose Oral midazolam is frequently used to treat children, but its effect on recovery from anesthesia is controversial. This study was designed to evaluate the effect of flumazenil on reversal of midazolam during recovery from sevoflurane-induced anesthesia in children who underwent caudal analgesia compared to those who did not.Methods A series of 60 children 1–8 years of age, with an American Society of Anesthesiologists (ASA) physical status of 1 or 2, who were scheduled to undergo herniorrhaphy were randomly assigned to one of four groups: group 1, control/placebo; group 2, control/flumazenil; group 3, caudal/placebo; group 4, caudal/flumazenil. After oral administration of midazolam 0.5 mg · kg⁻¹, anesthesia was induced and maintained with sevoflurane and nitrous oxide in oxygen via a face mask with spontaneous ventilation. The time from the discontinuation of anesthetics to emergence was recorded, and at the time of discharge from the operating room each patient’s recovery characteristics were assessed using a three-point scale.Results Emergence from anesthesia was significantly less agitated in the group of children who underwent caudal analgesia without flumazenil compared to the other three groups. Flumazenil shortened the time to emergence regardless of the application of caudal analgesia, and caudal analgesia delayed the time to emergence regardless of flumazenil administration.Conclusion Caudal analgesia and avoiding the use of flumazenil synergistically resulted in the emergence from anesthesia in a less agitated state for children who underwent herniorrhaphy after oral midazolam premedication.This study was presented in part at the International Anesthesia Research Society’s 77th Clinical and Scientific Congress, New Orleans, March 22, 2003     

Insulin secretion and glucose utilization are impaired under general anesthesia with sevoflurane as well as isoflurane in a concentration-independent manner

Purpose The dose-dependent effects of sevoflurane and isoflurane anesthesia on glucose tolerance were compared in humans. Methods A prospective, randomized clinical study was conducted in 30 patients. The 30 patients were divided randomly into three sevoflurane anesthesia groups (0.5, 1.0, and 1.5 minimum alveolar concentration [MAC]) and three isoflurane anesthesia groups (0.5, 1.0, and 1.5 MAC). Induction of anesthesia was accomplished by inhalation of the volatile agent and nitrous oxide. After induction, anesthesia was maintained at the designated MAC for 15 min without surgical stimulation. The intravenous glucose tolerance test (IVGTT) was performed in these 30 patients while they were under general anesthesia and again several days after surgery in 5 of these patients while they were awake, as a control. Results The insulinogenic index (change in concentration of immunoreactive insulin/change in glucose concentration), the acute insulin response, and rates of glucose disappearance were significantly lower in all anesthesia groups than in the control group. However, the insulinogenic index, acute insulin response, and the glucose disappearance rate did not differ significantly among the six anesthesia groups. Conclusion Sevoflurane anesthesia impairs glucose tolerance to the same degree as does isoflurane anesthesia. Glucose intolerance during sevoflurane or isoflurane anesthesia is independent of agent and dosage up to 1.5 MAC.     

Isoflurane increases,but sevoflurane decreases blood concentrations of melatonin in women

The blood concentrations of melatonin are elevated by stress-induced sympathetic nerve excitation and are affected by some anesthetics. Isoflurane has an effect to increase sympathetic nerve activity when compared with sevoflurane. This study was performed to investigate the effects of these two anesthetics on the blood concentrations of melatonin. Female patients were anesthetized with either isoflurane or sevoflurane. We obtained blood samples before and 5min after 5% isoflurane (ISO group) or 7% sevoflurane (SEV group) anesthesia. The blood melatonin concentrations during anesthesia in the ISO group increased significantly, from 65 ± 60 to 170 ± 90pg·ml^–l; mean ± SD (P < 0.05), whereas those in the SEV group decreased, from 60 ± 50 to 30 ± 30pg·ml^–l (P < 0.05). In conclusion, isoflurane increases, but sevoflurane decreases blood melatonin concentrations.     

Propofol or sevoflurane anesthesia without muscle relaxants for thymectomy in myasthenia gravis

Background Myasthenia gravis is a challenging clinical condition due to its neuromuscular involvement. We sought to compare two non-muscle relaxant anesthetic techniques in patients undergoing trans-sternal thymectomy, evaluating the intra and postoperative conditions including extubation in the operating room. Methods Eight consecutive myasthenic patients undergoing trans-sternal thymectomy were prospectively randomized into two groups: propofol and sevoflurane. In both groups anesthesia was induced with propofol (2mg. Kg⁻¹) and intubation performed after topical anesthesia of the airway with lignocaine. Anesthesia was maintained in the propofol group (4 patients) with continuous propofol infusion (3–10 mg. Kg⁻¹., hr⁻¹) with oxygen and nitrous oxide and in the sevoflurane group (4 patients), with sevoflurane (end tidal 1–1.5%) in oxygen and nitrous oxide. Fentanyl was used for analgesia in both the groups. Intubating conditions, haemodynamic changes, neuromuscular transmission along with postoperative intensive care unit stay were evaluated. Data were evaluated using ANOVA, Chi-square test and Student'st test. Results Intubating conditions were good in all patients. There were no significant haemodynamic changes. All patients were extubated in the operating room and none had to be re-intubated for postoperative respiratory depression. Neuromuscular transmission showed minimal changes and at the end of the procedure the recovery was complete in all the patients. There were no other significant differences between the two groups studied. Conclusion These two anesthetic techniques allow early extubation of myasthenic patients in the operating room.