不同麻醉方法对大鼠血气电解质及能量代谢的影响

目的探讨不同麻醉方法和不同麻醉药物对大鼠血气、电解质及能量代谢的影响。方法采用异氟烷、乙醚吸入麻醉,戊巴比妥钠、水合氯醛腹腔注射麻醉,经腹主静脉取血,经血气一电解质分析仪全自动分析测定,观察不同麻醉方法和麻醉药物对大鼠血气、电解质及能量代谢的影响。结果异氟烷吸人麻醉组Na’离子浓度略低于戊巴比妥钠腹腔注射组（P〈0．05）;戊巴比妥钠腹腔注射组Ca2离子浓度显著低于其他三组（P〈0．01）;吸入麻醉组的Mg2离子浓度显著高于药物腹腔注射麻醉组（P〈O．05,P〈0．01）;水合氯醛腹腔注射组Lac含量显著高于乙醚和戊巴比妥钠麻醉组（P〈0．01）;吸人类麻醉药能较好的维持较高的PO2、SO2、O2Ct和A（肺泡气中氧分压）,而BE-ECF、BE-B、PCO2、HC03-和TCO2降低,表明不同麻醉药均有不能程度的引起大鼠静脉血血气、电解质及能量代谢产物的改变。结论不同麻醉药物均有不同程度的引起大鼠静脉血血气、电解质及能量代谢产物的改变,异氟烷和乙醚对动物机体心血管、神经系统具有一定的保护作用,机体损害较少,而戊巴比妥钠腹腔注射对动物机体心血管、神经系统具有一定的抑制作用,机体损害较大。因此,在使用麻醉药时应合理选用和控制,避免由于麻醉引起实验误差。     

不同层流净化级别室内微量麻醉气体对医护人员的影响

目的:研究净化级别不同室内麻醉药物残留浓度对医护人员健康的影响,为制定麻醉操作规范提供参考依据。方法:通过Tedlar采样袋采集麻醉医生及麻醉恢复室人员呼出气20 mL,双盲法送30 min内相关人员应用气相色谱法进行分析。结果:不同层流净化级别室内医务人员呼出微量麻醉气体的浓度不同。十万级恢复室内医护人员呼出气体的浓度高于百级和万级手术间。结论:麻醉废气污染对手术室工作人员的心理行为及操作能力产生影响,医护人员应增强自我防护意识,定期监测手术室环境污染的程度,制定预防和减少麻醉废气污染的有效措施。     

NARCOBIT: a newly developed inhalational anesthesia system for mice.

NARCOBIT is the first anesthetic system for mice and rats to incorporate a ventilator. Therefore, it is expected to improve the reliability of mice and rat experiments by accurately controlling and maintaining the depth of anesthesia. In this study, we used NARCOBIT for inducing inhalational anesthesia in mice and evaluated the changes in their hemodynamic parameters. ICR mice were anesthetized with 5% isoflurane and room air, followed by endotracheal intubation. Subsequently, they were mechanically ventilated, and anesthesia was maintained by 2% isoflurane for a 60-min period (maintenance state) using NARCOBIT. In study 1, the heart rate (HR) and mean arterial blood pressure (MAP) were measured. The skin blood flow (SBF) from the hind legs was continuously measured during the maintenance state. Subsequently, the concentration-dependent effects of isoflurane on MAP were examined. In study 2, blood samples were obtained from the abdominal aorta for blood gas analysis. The HR and MAP decreased after anesthesia but were stable during the maintenance state. Decreased MAP and concentration-dependent effects of isoflurane were observed. The SBF increased slightly during the maintenance state but this increase was insignificant. The blood gas analysis showed neither hypoxia nor hypercapnia. Since the use of NARCOBIT enables the anesthetic concentration of isoflurane to be easily changed, a suitable anesthesia depth can be obtained for experimental purposes. Therefore, we conclude that NARCOBIT can be used for providing inhalational anesthesia to mice.     

Anesthetic inhibition of firefly luciferase, a protein model for general anesthesia, does not exhibit pressure reversal.

The surprising observation that pressures of the order of 150 atmospheres can restore consciousness to an anesthetized animal has long been central to theories of the molecular mechanisms underlying general anesthesia. We have constructed a high-pressure gas chamber to test for "pressure reversal" of the best available protein model of general anesthetic target sites: the pure enzyme firefly luciferase, which accounts extremely well for animal potencies (over a 100,000-fold range). We found no significant pressure reversal for a variety of anesthetics of differing size and polarity. It thus appears that either firefly luciferase is not an adequate model for general anesthetic target sites or that pressure and anesthetics act at different molecular sites in the central nervous system.     

A Conserved Behavioral State Barrier Impedes Transitions between Anesthetic-Induced Unconsciousness and Wakefulness: Evidence for Neural Inertia

One major unanswered question in neuroscience is how the brain transitions between conscious and unconscious states. General anesthetics offer a controllable means to study these transitions. Induction of anesthesia is commonly attributed to drug-induced global modulation of neuronal function, while emergence from anesthesia has been thought to occur passively, paralleling elimination of the anesthetic from its sites in the central nervous system (CNS). If this were true, then CNS anesthetic concentrations on induction and emergence would be indistinguishable. By generating anesthetic dose-response data in both insects and mammals, we demonstrate that the forward and reverse paths through which anesthetic-induced unconsciousness arises and dissipates are not identical. Instead they exhibit hysteresis that is not fully explained by pharmacokinetics as previously thought. Single gene mutations that affect sleep-wake states are shown to collapse or widen anesthetic hysteresis without obvious confounding effects on volatile anesthetic uptake, distribution, or metabolism. We propose a fundamental and biologically conserved concept of neural inertia, a tendency of the CNS to resist behavioral state transitions between conscious and unconscious states. We demonstrate that such a barrier separates wakeful and anesthetized states for multiple anesthetics in both flies and mice, and argue that it contributes to the hysteresis observed when the brain transitions between conscious and unconscious states.     

Anesthetic Gases and Water Structure : The effect of xenon on tritiated water flux across the gut

Pauling and Miller have independently proposed that the presence of an anesthetic gas in tissue induces a cage-like arrangement of hydrogen-bonded water molecules. The theories recognize that most gas-hydrate crystals would not form at the temperature and pressure that exist during anesthesia and propose that other components of tissue such as protein should have a stabilizing effect. Measurements of the behavior of water, rather than the anesthetic agent, would provide alternative information about the likelihood of hydrate crystal formation and this information could be such as to be applicable to body temperature and to pressures used for anesthesia. If the number of hydrogen-bonded water molecules in tissue is increased, then the movement of an average water molecule should be hindered. Movement of water through the tissue may be measured by tagging it with tritium and the anesthetic gas should then slow the movement of tritiated water through the tissue. The flux of tritiated water through rat cecum is indeed slowed when the cecum is exposed to the anesthetic gas, xenon, which can participate biochemically only by virtue of its van der Waals interaction. The decrement in water flux is in reasonable agreement with what could be expected theoretically from calculations based on the activation energy for the self-diffusion of water and the degree of hypothermia necessary to produce narcosis.     

麻醉药物在肝细胞凋亡中的作用

围术期最常用,最重要的药物是全身麻醉药(包括吸入麻醉药和静脉麻醉药),麻醉药是适应手术的需要而出现的,经过长时间的发展,它的药理作用也越来越完善。在过去几年里很多研究报道的麻醉药的药理作用与介导的细胞凋亡之间的关系主要集中在神经系统。然而,麻醉实践中大部分麻醉药物都在肝脏代谢,已有证据表明麻醉药对肝细胞也有影响。麻醉药介导的细胞凋亡作用可能与caspase通路,Bcl-2家族,TRADD,FADD等多种因素有关。但不是所有麻醉药都对肝细胞有凋亡作用,部分还具有保护作用。因此本文就现有的麻醉药对肝细胞凋亡中的作用进行了综述。     

Reversal of ketamine/xylazine anesthesia in the rabbit with yohimbine

Ketamine and xylazine used in combination have been shown to be effective, easily administered, cost efficient agents for surgical anesthesia in the rabbit. The effect of xylazine on the central nervous system has been shown to be mediated through alpha-2 adrenergic receptors. Yohimbine, an alpha-2 adrenergic antagonist has been shown to reverse xylazine induced depression and partially antagonize ketamine in other species. We evaluated the antagonistic effect of yohimbine on ketamine/xylazine anesthesia in the rabbit. Six New Zealand White rabbits were anesthetized with intramuscular ketamine (50 mg/kg) and xylazine (10 mg/kg) to establish baseline parameters including respiratory rate, heart rate, and palpebral, pedal and postural reflex activity. Fourteen days later each rabbit was subjected to the same anesthetic regimen followed 30 minutes later by the intravenous administration of yohimbine (0.2 mg/kg). The duration of anesthesia estimated by the time elapsed between the loss and return of the palpebral reflex was reduced in the yohimbine treated trial (means = 29.7 +/- 1.9 minutes) compared to the control trial (means = 67.0 +/- 13.5 minutes). The palpebral reflex returned within 5 minutes following yohimbine treatment. Our results indicated that yohimbine is an effective antagonist of ketamine/xylazine anesthesia in the rabbit. Yohimbine decreases anesthetic duration after intravenous administration and also may aid in the control of undesirable anesthetic effects and overdosage.     

Flushing induction chambers used for rodent anesthesia to reduce waste anesthetic gas

Anesthetic induction chambers used for medical research are a substantial source of waste anesthetic gas (WAG). Ideally, any generated waste gas should be actively vented away from personnel operating the chamber by either a ventilated hood or snorkel. Unfortunately, the ideal environment for anesthetizing rodents is not always available. In an effort to create a safer environment, the authors designed a system to reduce WAG. This system is portable, can be adapted to different precision vaporizing anesthetic systems and fits in a variety of physical locations. The system flushes anesthetic gas out of an induction chamber before operators open the chamber. To ensure that the system was adequately flushing the anesthetic gas, the authors measured WAG concentration in the environment above the induction chamber and directly behind the vent of an activated charcoal filter. They also compared the efficiency of the filters in vertical and horizontal positions. Finally, they measured the recovery time for mice and rats after flushing the anesthetic gas from an induction chamber. The results show that flushing the induction chamber was an inexpensive and effective method for reducing WAG accumulation in the air surrounding the chamber.     

麻醉蒸发器输出浓度的影响因素与蒸发器校准研究进展

麻醉蒸发器是麻醉呼吸机的核心部件。它能够体现麻醉呼吸机的品质水平,直接影响吸入麻醉的临床效果,并进而关乎接受麻醉的患者的安全。随着现今临床患者周转率提高、手术量增大,应用到全麻手术中的吸入麻醉技术也占了更大比重,蒸发器临床使用频率也因此不断提高,蒸发器本身使用年限也在逐年增大--这些因素皆可能会引起蒸发器实际输出浓度的偏差,继而或对临床麻醉的实施和患者麻醉效果造成影响。本文立足于对麻醉蒸发器结构及相关原理的综述,着眼于不同条件对挥发效率的影响和输出浓度的检测校准的最新标准与进展;为指导临床麻醉过程中蒸发器更为科学精准的应用提供科学理论依据。     

Comparison of isoflurane and sevoflurane for anesthesia in beaver

We compared the hemodynamic and respiratory effects, recovery time, and cost of two gas inhalants (isoflurane and sevoflurane) for anesthetic induction and maintenance of beaver (Castor canadensis) during surgery to implant radio transmitters in the peritoneal cavity. Heart rate, respiratory rate, relative hemoglobin saturation with oxygen (SpO2), and body temperature were measured every 5 min for the first 45 min, and arterial blood gas was measured once, 25 min into the anesthetic procedure. Induction for either agent was smooth and rapid. Heart rate and respiratory rate both decreased during the procedure though neither was lower than baseline values reported in the literature for beaver. Relative hemoglobin saturation with oxygen, body temperature, and blood gas variables did not differ between each anesthetic regime. Both inhalants caused slight respiratory acidosis. Recovery time from anesthesia was highly variable (1-178 min) but did not differ statistically between drugs. Sevoflurane costs ($22.30/60 min) were much higher than isoflurane costs ($3.50/60 min). We recommend isoflurane or sevoflurane for anesthetic induction and maintenance of beaver because of the lack of physiologic differences.     

The compression-ordering and solubility-disordering effects of high pressure gases on phospholipid bilayers.

Inert gases at high pressure may compress and dissolve in tissue of intact organism to result in narcosis, reversal of the effects of anesthetic agents or hyperexcitability. The effects of 51 and 102 atm of helium, hydrogen, nitrogen, argon, xenon and nitrous oxide on the molecular motion of nitroxide spin-labeled phospholipid-cholesterol bilayers were measured by electron paramagnetic resonance (EPR) techniques. Immediately, application of high pressures of all gases decreased the molecular motion of the fatty acid chains of the membrane phospholipids; the magnitude of ordering was linearly related to the amount of pressure applied. The second effect was an increase in molecular motion of the fatty acid chains which appeared more slowly due to the slow gas diffusion through the column of lipid dispersion. The magnitude of disorder of the phospholipid membrane at equilibrium correlated with the known lipid solubilities of the gases in olive oil as well as with the anesthetic potency of all the gases except xenon. The environment of the spin label became less polar as the gases diffused into the bilayer. The present studies in the phospholipid model membrane show that the net effects of high pressure gases in the lipid phase consist of an initial ordering of the membrane by compression opposed by the ability of the gas molecules to diffuse and dissolve in the lipid bilayers and disorder them. It is thus suggested that the resultant perturbations of the membrane lipid fluidity by high pressure gases may subsequently be transmitted to membrane-bound protein to result in changes that may be associated, in part, with the diverse effects of anesthesia and of the high pressure nervous syndrome (HPNS) observed in deep-sea divers. The model system may be useful in developing gas mixtures which minimize HPNS.     

Do inhalation general anesthetic drugs induce the neuronal release of endogenous opioid peptides?

The antagonism of some effects of inhalation general anesthetic agents by naloxone suggests that there may be an opioid component to anesthetic action. There is evidence that this opioid action component is due to neuronal release of endogenous opioid peptides. The strongest evidence is provided by studies that monitor changes in the concentration of opioid peptides in the perfused brain following inhalation of the anesthetic. Indirect or circumstantial evidence also comes from studies of anesthetic effects on regional brain levels of opioid peptides, antagonism of selected anesthetic effects by antisera to opioid peptides and anesthetic-induced changes radioligand binding to opioid receptors. It is likely that some inhalation general anesthetics (e.g., nitrous oxide) can induce neuronal release of opioid peptides and that this may contribute to certain components of general anesthesia (e.g., analgesia). More definitive studies utilizing in vivo microdialysis or autoradiography in selected areas of the brain during induction and successive states of general anesthesia have yet to be conducted.     

Renal effects of general anesthesia from old to recent studies

Various types of anesthesia are being utilized to maintain physiologically secured surgical conditions. Nearly all categories of general anesthesia are characterized by various perioperative and postoperative complications. These shortcomings are important aspects that need to be considered by the anesthesiologist and surgeon before administration of these compounds. The renal effects of anesthesia play an important role in understanding possible systemic changes due to the fact that the kidney has a direct or indirect impact on nearly all the systems of the body. Various studies have been conducted to find out changes in renal parameters and its systemic effects upon administration of the anesthesia and its postoperative repercussions. Besides that, the impaired renal function might have an impact on the excretion of anesthetic metabolites, which can lead to long-term dysfunction. Patients with a previous history of disease ought to be brought under consideration because these chemicals can ameliorate pre-existent symptoms. This review is intended to discuss the early and latest studies based on the effects of general anesthesia on the renal system.     

Biological effects of noble gases

Noble gases are known for their inertness. They do not react chemically with any element at normal temperature and pressure. Through that, some of them are known to be biologically active by their sedative, hypnotic and analgesic properties. Common inhalation anesthetics are characterized by some disadvantages (toxicity, decreased cardiac output, etc). Inhalation of xenon introduces anesthesia and has none of the above disadvantages, hence xenon seems to be the anesthetic gas of the future (with just one disadvantage - its cost). It is known that argon has similar anesthetic properties (under hyperbaric conditions), which is much cheaper and easily accessible. The question is if this could be used in clinical practice, in anesthesia of patients who undergo treatment in the hyperbaric chamber. Xenon was found to be organ-protective. Recent animal experiments indicated that xenon decreases infarction size after ischemic attack on brain or heart. The goal of our study is to check if hyperbaric argon has properties similar to those of xenon.     

The effect of propofol and fentanyl as compared with sevoflurane on postoperative vomiting in children after adenotonsillectomy

Postoperative vomiting (PV) after adenotonsillectomy in children is a common problem with an incidence as high as 40-80%. Only few studies in the recent literature compared the effect of different anesthetic techniques concerning PV in children. The aim of this study was to compare the incidence of PV in two groups of children who underwent two different general anesthesia techniques in order to determine what type of anesthetic technique is more related to less PV. The clinical trial included 50 children (physical status ASA I, 3-12 years old) divided into 2 groups and monitored for PV 24 hours following the surgery. Group one (G1) consisted of 25 children who underwent general anesthesia with gas mixture 60% nitrous oxide and 40% oxygen and anesthetic propofol, opioid fentanyl and muscle relaxant vecuronium intravenously and group two (G2) included 25 children to whom volatile anesthesia with sevoflurane in the same gas mixture was given. Demographic characteristics (gender, age, weight, history of motion sickness and earlier PV) as well as surgical data (length of surgery and anesthesia, intraoperative blood loss) were recorded. There were no significant differences considering demographic characteristics and surgical data between the investigated groups. The incidence of PV was relatively low 3 children (12%) in G1 group and 5 children (20%) in G2 group. Statistically there was no significant difference between the groups regarding the incidence of PV and both anesthetic techniques can be used equally safe regarded to PV.     

Taking the sting out of darting: Risks,restraint drugs and procedures for the chemical restraint of Southern Hemisphere otariids

The need to manage otariid populations has necessitated the development of a wide range of capture methods. Chemical restraint by remote drug delivery (i.e., darting) is a highly selective method that can be used to facilitate otariid capture in a range of scenarios, when other methods may be impracticable. However, the risks associated with darting otariids are not widely known and guidelines necessary to promote and refine best practice do not exist. We review the risks associated with darting and in light of our findings, develop darting guidelines to help practitioners assess and minimize risks during capture, anesthesia and recovery. Published studies reveal that mortalities associated with darting predominantly result from complications during anesthetic maintenance (e.g., prolonged respiratory depression, apnea, or hyperthermia), rather than from complications during capture or recovery. In addition to monitoring vital signs and proper intervention, the risk of irreversible complications during anesthesia can be reduced by administering drug doses that are sufficient to enable the capture and masking of animals, after which anesthetic depth can be regulated using gas anesthesia.     

Action of a dental anesthetic on cell respiration

It is often required to employ local anesthetics in practising dentistry, particularly when children have to be treated. Our researches on neurotropic drugs in the last years follow our hypothesis that the strong effects on nervous system have always hidden more widespread effects on all tissues and cells. In vitro essays carried out on rat liver mitochondria show that a dental anesthetic, lidocaine, depress respiration coupled to phosphorylation in mitochondria having a good respiratory control; so respiratory control too is depressed, but P/O ratio is unaffected; also respiration uncoupled by 2,4-dinitrophenol is depressed. Depressing respiration cooperates with anesthesia; unchanging P/O is good for the health of the cells and tissues treated by the lidocaine.     

A Pharmacokinetics-Neural Mass Model (PK-NMM) for the Simulation of EEG Activity during Propofol Anesthesia

Modeling the effects of anesthetic drugs on brain activity is very helpful in understanding anesthesia mechanisms. The aim of this study was to set up a combined model to relate actual drug levels to EEG dynamics and behavioral states during propofol-induced anesthesia. We proposed a new combined theoretical model based on a pharmacokinetics (PK) model and a neural mass model (NMM), which we termed PK-NMM—with the aim of simulating electroencephalogram (EEG) activity during propofol-induced general anesthesia. The PK model was used to derive propofol effect-site drug concentrations (C _eff) based on the actual drug infusion regimen. The NMM model took C _eff as the control parameter to produce simulated EEG-like (sEEG) data. For comparison, we used real prefrontal EEG (rEEG) data of nine volunteers undergoing propofol anesthesia from a previous experiment. To see how well the sEEG could describe the dynamic changes of neural activity during anesthesia, the rEEG data and the sEEG data were compared with respect to: power-frequency plots; nonlinear exponent (permutation entropy (PE)); and bispectral SynchFastSlow (SFS) parameters. We found that the PK-NMM model was able to reproduce anesthesia EEG-like signals based on the estimated drug concentration and patients’ condition. The frequency spectrum indicated that the frequency power peak of the sEEG moved towards the low frequency band as anesthesia deepened. Different anesthetic states could be differentiated by the PE index. The correlation coefficient of PE was 0.80±0.13 (mean±standard deviation) between rEEG and sEEG for all subjects. Additionally, SFS could track the depth of anesthesia and the SFS of rEEG and sEEG were highly correlated with a correlation coefficient of 0.77±0.13. The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity.     

Mass-spectrometry analysis of disflurane,propofol, and fentanyl in plasma and cerebrospinal fluid

Concentrations of anesthetic agents were measured in blood plasma and cerebrospinal fluid using mass spectrometry with a membrane interface. Sampling of biological fluids was performed during balanced inhalational (disflurane and fentanyl) anesthesia and total intravenous (propofol and fentanyl) anesthesia. A rapid test method for the concentration measurement of organic molecules in biological fluids is described. This method does not require long-term sample processing before injecting the sample into the mass spectrometer interface. The pervaporation properties (uptake, diffusion, and evaporation) of anesthetic agents from biological fluids in a silicone membrane were used in the mass spectrometry interface. We report on the possibility of using a mass spectrometer with a membrane interface for the measurement of the absolute concentration of anesthetic agents in blood plasma for study of the properties of the blood–brain barrier.