Acute canine model for drug-induced Torsades de Pointes in drug safety evaluation-influences of anesthesia and validation with quinidine and astemizole.

An acute in vivo model for drug-induced torsades de pointes (TdP) for use in safety evaluation of drugs was developed using dogs with acute complete atrioventricular (AV) block. In order to study the effects of anesthetic agents on the inducibility of TdP, arrhythmias were induced by programmed electrical stimulation (PES) before and after cumulative intravenous administration of quinidine under anesthesia with sodium pentobarbital, halothane, or isoflurane. Both prolongation of the QTc and the incidence of TdP were greatest in dogs anesthetized with halothane and were smallest in those given pentobarbital, suggesting that halothane is the most suitable anesthetic for this TdP model. To further validate this model, astemizole was administered intravenously to other dogs under halothane anesthesia. Astemizole at 0.3 mg/kg caused slight prolongation of the QT interval but did not induce any arrhythmias. At 1 mg/kg, however, TdP were induced in 5 of 10 animals and in an additional 2 animals at 3 mg/kg. Single and multiple ectopic beats preceded the induction of TdP, and the ectopic beats were observed in a dose-dependent manner. The plasma concentrations of quinidine in dogs with TdP were equivalent to or less than quinidine levels in humans with TdP, while those of astemizole were higher in dogs. In conclusion, this acute canine model of TdP with halothane anesthesia, complete AV block, PES, and simultaneous measurements of plasma drug concentration would be valuable for assessing the risk of drugs, especially I(Kr) blockers, to induce TdP in humans.     

Murine pulmonary inflammation model: a comparative study of anesthesia and instillation methods

Various techniques have been utilized historically to generate acute pulmonary inflammation in the murine system. Crystalline silica exposure results in acute inflammation followed by pulmonary fibrosis. Methods of exposure are varied in their techniques, as well as types of anesthesia. Therefore, the current study sought to compare the effects of two major anesthesia (isoflurane and ketamine) and three routes of instillation, intranasal (IN), intratracheal (IT), and trans-oral (TO), on markers of inflammation. Mice were anesthetized with isoflurane or ketamine and instilled IN with silica or phosphate-buffered saline (PBS). Mice were sacrificed and lavaged after 3 days. To assess inflammation, alveolar cells were assessed by cytospin and lavage fluid was analyzed for inflammatory cytokines and total protein. While all parameters were increased in silica-exposed groups, regardless of anesthesia type, there were significant increases in neutrophils and total protein in mice anesthetized with ketamine, compared to isoflurane. In comparing instillation techniques, mice were anesthetized with isoflurane and instilled IN, IT, or TO with silica. Increases were observed in all parameters, except tumor necrosis factor-α, following IT silica instillation as compared to the IN and TO instillation groups. In addition, fluorescent microsphere uptake by alveolar macrophages supported the notion that all methods of instillation were uniform, but IT had significantly greater dispersion. Taken together, these data show that each method of exposure tested generated significant inflammation among the silica groups, and any differences in parameters or techniques should be taken into consideration when developing an animal model to study pulmonary diseases.     

Possible hemodynamic basis to urethane anesthesia-induced reductions in renal clearance

The hemodynamic basis of reported urethane anesthesia-induced reductions in the clearance of some renally eliminated compounds has been investigated in the laboratory rat. The use of urethane as an anesthetic in pharmacokinetic studies still persists, particularly in experiments of long duration. Using a microsphere technique, the per cent distribution of cardiac output to the kidneys, in both ip urethane- and ip Hypnorm/Hypnovel-anesthetized animals was significantly (p less than 0.01) lower than that observed in ip pentobarbital-anesthetized animals. However, the cardiac index in the Hypnorm/Hypnovel-anesthetized animals was 42% greater (p less than 0.01) than in the pentobarbital-treated animals and 86% greater (p less than 0.01) than in the urethane-treated group. Additionally, the cardiac index in the pentobarbital-anesthetized animals was significantly greater (p less than 0.01) than in the urethane-anesthetized animals. The lower cardiac index and reduced cardiac distribution to the kidneys in the urethane-treated group resulted in significant (p less than 0.01) reductions of approximately 40% in renal blood flow and glomerular filtration rate compared with the animals anesthetized with pentobarbital or Hypnorm/Hypnovel. The transport capacity of the basolateral organic anion secretory mechanism was not compromised by an ip injection of urethane, as demonstrated by p-aminohippuric acid transport studies conducted in isolated renal tubule fragments prepared from anesthetized animals. In conclusion, urethane anesthesia results in significant alterations of renal hemodynamics compared with pentobarbital and Hypnorm/Hypnovel anesthesia in the rat. For primarily renally eliminated compounds, such alterations are likely to influence pharmacokinetic data generated using this anesthetic agent.     

苦碟子注射液对犬心脏功能和血流动力学的影响

目的考察苦碟子注射液对麻醉开胸犬心脏功能和血流动力学的影响。方法采用麻醉开胸犬模型,测量其心率、心输出量、冠脉流量、心肌耗氧量以及血流动力学各参数。结果苦碟子注射液以2.0、4.0 g.kg-1静脉注射给药可显著增加戊巴比妥钠麻醉犬的心输出量和冠脉流量,降低平均动脉压、左心室内压和左心室舒张末期压力,减少左室内压力变化速度和心肌耗氧量(P<0.05,P<0.01)。结论苦碟子注射液能显著改善麻醉开胸犬血流动力学。     

Differential effects of anesthetic agents on regional blood flow and central hemodynamic parameters in rats

Three commonly used anesthetic agents (pentobarbital, chloralose-urethane, and inactin) were studied in a rat model. The radiolabeled microsphere technique was used to evaluate rats anesthetized (no reaction to pain stimulus) with the three drugs as compared to awake unanesthetized animals. Of the three anesthetic agents studied, pentobarbital caused the smallest alteration in central hemodynamic parameters. Chloralose-urethane significantly lowered cardiac output (56%), stroke volume (35%), and minute work (51%). Chloralose-urethane also significantly increased total peripheral resistance (59%). Inactin at the concentration used in the present study had very little effect on cardiac index, heart rate, stroke volume, and minute work but significantly increased total peripheral resistance and mean arterial pressure. All three anesthetic agents reduced cerebral and skeletal muscle blood flows equally. While pentobarbital and chloralose-urethane significantly decreased renal blood flow (33%), inactin did not change flow to the kidney. It is concluded that anesthetic agents used in small animal experiments should be chosen carefully so that they do not influence blood flow to the organ being studied.     

Effects of two benzodiazepine inverse agonists, RO 15-4513 and FG 7142, on recovery from pentobarbital and halothane anesthesia in the rat

A new class of drugs, the benzodiazepine inverse agonists, have recently been shown to antagonize some of the behavioral and sedative effects of benzodiazepines, barbiturates, and alcohol. Preliminary studies suggested that at least one of these drugs, RO 15-4513, may also be able to reverse the general anesthetic properties of volatile halogenated agents. Another inverse agonist, FG 7142, exhibits a similar ability to antagonize alcohol or benzodiazepines. However, FG 7142 is less potent than RO 15-4513 and has less affinity for the benzodiazepine receptor (BZR). The present studies were therefore undertaken to compare the analeptic effects and relative potencies of RO 15-4513 and FG 7142 on the anesthetic properties of pentobarbital compared with the general anesthetic agent halothane as measured by the time for recovery of the righting reflex in the rat. Three basic experimental paradigms were employed. Drug (FG or RO) or carrier was administered 5 minutes prior to the induction of pentobarbital anesthesia. Drug or carrier was administered to anesthetized animals 60 minutes after pentobarbital injection. Lastly, drug or carrier was administered 5 minutes prior to 15 minutes of halothane anesthesia. In addition, the selective benzodiazepine antagonist, flumazenil (RO 15-1788), was used to determine if the effects of the benzodiazepine inverse agonists on recovery from barbiturate or halothane anesthesia were due to activity at the BZR. The results revealed that RO was both more potent and more effective than FG at speeding recovery from barbiturate anesthesia in the rat. RO's effects appeared to be primarily due to BZR inverse agonist activity since it could be reversed by the BZR antagonist, flumazenil.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同剂量右旋美托咪啶对七氟醚吸入麻醉诱导的影响

目的:观察不同剂量右旋美托咪啶对七氟醚吸入麻醉诱导和气管插管过程中血流动力学和脑电双频指数(BIS)的影响。方法:选择择期妇科腹腔镜手术全麻患者45例,随机分为3组,每组15例,A组为单纯吸入七氟醚麻醉诱导组,B组和C组为吸入七氟醚麻醉诱导前分别静脉泵注右旋美托咪啶0.5μg/kg和1.0μg/kg组,观察3组患者的血流动力学和BIS的变化,并记录患者入睡时间、BIS值达到60时间、可以实施气管插管时间、手术和麻醉时间、入睡前实施肺活量次数和整个过程发生的不良反应事件。结果:与麻醉诱导前(T0)相比,麻醉后插管前(T1)血压、心率和BIS明显下降(P<0.05),围插管期(T2)A组血压较诱导前插管前增高(P<0.05);与A组相比,围诱导期(T1和T2)B组和C组血压、心率和BIS值较低(P<0.05),围拔管期(T3)B组和C组血压和心率较诱导前增加较低(P<0.05);与A组相比,B组和C组患者的意识消失时间、BIS值小于或等于60时间、气管插管时间较短(P<0.05),以C组缩短明显;B组和C组吸入过程中N次肺活量较A组少。结论:右旋美托咪啶0.5、1.0μg/kg均可产生明显镇静效应,缩短诱导时间;抑制七氟醚吸入诱导气管插管时的应激反应,以右旋美托咪啶1.0μg/kg的作用更理想,但要注意防止围麻醉期出现的严重心动过缓和低血压。     

Calcium ethylenediaminetetraacetate (CaEDTA) toxicity: studies on the mechanism of CaEDTA potentiation of pentobarbital anesthesia in the rat.

Rats which received an iv infusion of CaEDTA (6 mmol/kg/24 hr for 36 and 48 hr) were more susceptible to the anesthetic effect of pentobarbital Na than rats similarly infused with 0.9% NaCl solution. Less mg/kg pentobarbital Na, administered iv, were required to induce a state of surgical anesthesia. The data indicated that the potentiative action of CaEDTA probably was due to an effect on central neurones rather than enhanced distribution of the anesthetic to the brain. This contention was based upon the following findings in CaEDTA-treated rats relative to controls: lower pentobarbital concentrations in the brain at the onset of anesthesia, no difference in brain/plasma concentration ratios of anesthetic when appropriate corrections were made for binding to plasma proteins and pH-pK_A relationships in blood, and no difference in brain/plasma concentration ratios of a normally nonpermeating solute. Moreover, when standard doses of pentobarbital Na were given ip, CaEDTA-treated rats slept significantly longer and concentrations of pentobarbital in plasma and brain were significantly less than controls on arousal. Dexamethasone antagonized the potentiative effect of CaEDTA on pentobarbital anesthesia. The occurrence of higher concentrations of pentobarbital in brain and a lower brain/plasma concentration ratio at the onset of anesthesia suggested the steroid acted to stabilize cerebral neurones to the effect of the anesthetic as well as impede the distribution of pentobarbital to the brain. Serotonin concentrations were found to be significantly decreased in brain, duodenum, and kidney, but not the liver, consequent to CaEDTA administration. The iv infusion of calcium acetate, equimolar to CaEDTA, also potentiated barbiturate anesthesia.     

Increase of thiopental concentration in rat tissues due to anesthesia with isoflurane.

Thiopental distribution was studied in rats (30 mg/kg i.v.) anesthetized simultaneously with 1.25 "rat"-MAC isoflurane. The thiopental concentration in serum and several tissues was determined UV-photometrically at 305 nm after extraction and TLC. In the serum of rats anesthetized with isoflurane the thiopental concentration was significantly increased to +39----+74% in comparison to controls during 30 min following the barbiturate injection. Also in liver, brain, heart, kidney, lung and spleen of rats anesthetized with isoflurane the thiopental concentration was significantly increased at 3 and 10 min; at 30 min the difference vs. control had vanished in brain, heart, lung and spleen. Obviously, thiopental was transiently "trapped" during the early distribution phase to a considerable amount in these vessel-rich tissues when anesthesia with isoflurane was simultaneously performed; this pharmacokinetic interaction might be explained at least to some extent hemodynamically; in many tissues regional blood flow is reduced during anesthesia with isoflurane; thereby the "washout" of thiopental from the tissues and the redistribution are delayed.     

Preferable anesthetic conditions for echocardiographic determination of murine cardiac function

Ketamine and xylazine are routinely used for measurement of hemodynamics of mice and rats by echocardiography. The anesthetic agents produce low heart rate (HR) in the animals, which may result in misleading data in the hemodynamic profiles of the small animals. The purpose of the present study was to select an appropriate anesthetic condition in the evaluation of mouse and rat cardiac function by echocardiography. Echocardiographic measurement was performed in male C57BL6 mice anesthetized with an intraperitoneal injection of 30 or 40 mg/kg pentobarbital (P30 or P40) or a combination of 60 mg/kg ketamine and 6 mg/kg xylazine (KX) and in male Wistar rats with an intraperitoneal injection of 40 or 50 mg/kg pentobarbital (P40 or P50) or a combination of 100 mg/kg ketamine and 10 mg/kg xylazine (KX). Basal HR of P30-anesthetized mice and P40-anesthetized were comparable to those in the conscious state, whereas KX-anesthetized mice and rats were 38% and 74% of those of the conscious animals, respectively. Fractional shortening (FS) and cardiac output index (COI) of the P30-anesthetized mice or the P40-anesthetized rats were greater than those of KX-anesthetized animals. Intraperitoneal injection of dobutamine at 0.3 and 1 mg/kg increased HR, FS, and COI of the P30-anesthetized mice and the P40-anesthetized rats, respectively, whereas the percent responses of these parameters in KX animals were greater than those in pentobarbital-anesthetized ones due to the lower basal values for the cardiac functional parameters. Anesthesia with P30 for the mouse and P40 for the rat rather than ketamine/xylazine may be relevant to the evaluation of cardiac function using echocardiography.     

The general anesthesia induced by various drugs differentially affects analgesia and its variability

Responses to noxious stimuli in awake animals are not totally consensual but are influenced by environmental factors. We considered the possibility that the influence of the environment could be reduced by induction of general anesthesia. We, therefore, compared responses to nociceptive thermal stimuli by measuring tail flick latency, a spinal reflex, in anesthetized and awake mice. All anesthetics tested decreased the intraindividual variability in the measurement of response, suggesting that environmental factors may account for much of this variability in the awake mouse. Mice treated with pentobarbital showed a graded response to increasing levels of heat but were unresponsive to either morphine or naloxone. In mice anesthetized with pentobarbital, increases in latencies occurred only at very deep levels of anesthesia, while urethane nociceptive effect of ketamine was reversed by morphine. Thus, the various anesthetics could show differential effects towards opiate action. The decrease in statistical variability, the differential effects of general anesthetics on tail flick latency, and the distinctive effects of the different anesthetics on opiate action suggest that the anesthetized animal may be a useful tool in the study of nociception.     

SD大鼠使用舒泰®50和盐酸塞拉嗪麻醉比较研究

目的：比较SD大鼠经肌肉注射和腹腔注射舒泰^® 50或盐酸塞拉嗪后的麻醉效果,并比较腹腔注射后对血液学、血清生化指标及主要脏器的病理学影响。方法：以腹腔注射给予戊巴比妥钠作为对照,设置低、中、高3个剂量的舒泰^® 50或盐酸塞拉嗪肌肉注射和腹腔注射麻醉SD大鼠,观察其麻醉诱导时间、 维持时间和苏醒时间。大鼠腹腔注射舒泰^® 50(50 mg·kg^-1)和盐酸塞拉嗪(25 mg·kg^-1)麻醉后约 20 min采血并分离主要脏器,比较血液学、血清生化指标及组织病理学检查结果。结果：舒泰^® 50的2种给予方式的麻醉效果无明显差异,且诱导时间较盐酸塞拉嗪短而维持时间更长;腹腔注射舒泰^® 50或盐酸塞拉嗪对血液学、血清生化指标及组织病理学均无明显影响。结论：与盐酸塞拉嗪相比,舒泰^® 50对SD 大鼠的麻醉效果更好,可应用于大鼠的毒理学评价研究。     

Asynchronism of the recovery of baroreflex sensitivity, blood pressure, and consciousness from anesthesia in rats

Anesthesia inhibits arterial baroreflex functions such as baroreflex sensitivity (BRS). The main objective of the present study was to determine the time course of BRS recovery from anesthesia and to determine whether BRS recovery is synchronous with the recovery of consciousness and blood pressure (BP). Experiments were performed in male Sprague-Dawley rats using different commonly used anesthetics at routine doses through intraperitoneal administration: (1) diazepam/ketamine, a mixture of diazepam (5 mg/kg) and ketamine (50 mg/kg); (2) chloral hydrate (0.3 g/kg); (3) sodium pentobarbital (30 mg/kg); and (4) urethane (1.0 g/kg). The anesthetic state, evaluated by algesthesia and cornea reflex, was maintained for 1-2.5 hours. The BRS, assessed by intravenous injection of phenylephrine, was inhibited rapidly and dramatically, with maximum depressions of 51%-80%. The BRS recovery time was approximately 5 hours for diazepam/ketamine, chloral hydrate, and pentobarbital, but more than 24 hours for urethane. Compared with BRS inhibition, BP reduction was less pronounced by 8% (not significant) for diazepam/ketamine and by 12%-30% for the others. The BP recovery time was approximately 2 hours, with the exception of chloral hydrate (>6 hours). In conclusion, after anesthesia, BRS inhibition is more obvious than BP reduction, and the recovery of BRS lags behind the recovery of consciousness or BP.     

Influence of different anesthetics on skin oxygenation studied by electron paramagnetic resonance in vivo

The effects of two general anesthetics on skin oxygenation in mice are evaluated by electron paramagnetic resonance oximetry. Up to now no data on the effects of different anesthetics on skin oxygenation could be found. In this study animals were anesthetized with ketamine/xylazine or isoflurane, and partial pressure of oxygen (pO(2)) in the skin, heart rate and hemoglobin oxygen saturation were followed as a function of time and inhaled oxygen concentration. The skin pO(2) significantly increased continuously for about 60 min in mice anesthetized with isoflurane and remained constant after that. During ketamine/xylazine anesthesia, the pO(2) in the skin only slightly decreased. The skin pO(2) increased with higher inspired oxygen concentrations for both anesthetics groups. When breathing 21% oxygen, mice anesthetized with isoflurane had two-fold higher pO(2) in the skin compared to mice anesthetized with ketamine/xylazine. The heart rate was significantly lower in animals anesthetized with ketamine/xylazine, while hemoglobin saturation was almost the same in both groups at all inhaled oxygen concentrations. These results show that the type of anesthesia is an important parameter that needs to be considered in experiments where skin pO(2) is followed.     

Effects of sevoflurane general anesthesia: immunological studies in mice.

Based on the immunomodulatory effects of anesthesia and surgery, a study was undertaken to assess the effect of sevoflurane anesthesia on the immune system in a murine model without surgery. Adult male mice were anesthetized with 3% sevoflurane (1.2 minimal alveolar concentration, MAC) in oxygen for 40 min, whereas nontreated animals served as controls. After sevoflurane anesthesia, peripheral blood leukocyte counts, the splenic composition and in vitro macrophage phagocytic activity and lymphoproliferative response were assessed. The in vivo specific immune response to sheep red blood cells (SRBC), a conventional T-dependent antigen was determined. In addition, liver, spleen, thymus and kidney histopathology and also hepatic and renal functions after anesthesia were studied. Sevoflurane diminished the number of peripheral blood lymphocytes and splenic B-cell counts, enhancing CD4+ lymphocytes in spleen. The in vitro functionality of macrophages and the mitogen-induced lymphoproliferative response were preserved, while the in vivo immune response to SRBC was enhanced in treated animals. Microscopic studies revealed conserved architecture of the spleen, thymus, lymph node, liver and kidney, and there were no differences in serum parameters of hepatic and renal functions between treated and control groups. Our results suggest that 3 days after the anesthetic exposure, animals treated with sevoflurane modulated their peripheral blood leukocyte counts, splenic lymphoid composition and the characteristics of the specific response to SRBC, while there was no evidence of hepatic or renal toxicity.     

盐酸右美托咪定用于老年患者膝关节镜手术腰麻联合硬膜外麻醉的临床观察

目的 探讨盐酸右美托咪定在膝关节镜手术腰硬联合麻醉中的应用效果及安全性。方法 80例膝关节镜手术患者按随机双盲对照法分为对照组和观察组,每组40例。两组均采取腰硬联合麻醉。对照组在术中静脉泵注生理盐水,观察组术中静脉泵注盐酸右美托咪定。结果 观察组手术开始前5 min(T1)、手术开始时(T2)、手术开始后5 min(T3)、手术开始后30 min(T4)、手术结束时(T5)的收缩压(SBP)、舒张压(DBP)、平均动脉压(MBP)、心率(HR)均显著低于对照组(P<0.05)。观察组术后的皮质醇、去甲肾上腺素(NE)、肾上腺素(E)水平,VAS(疼痛视觉模拟评分法)评分、麻醉不良反应发生率均显著低于对照组,Ramsay评分显著高于对照组,神经阻滞时间及术后恢复时间明显比对照组更长(P<0.05)。结论 在膝关节镜手术腰硬联合麻醉中应用盐酸右美托咪定能有效增强局麻药的镇痛、镇静作用,维持血流动力学稳定,减少麻醉相关并发症的发生。     

The anesthesia record

The standard format of preoperative, perioperative, and postoperative patient anesthesia records, the categories of information included, and pharmacists use of this information are described. On the preoperative evaluation form, the anesthesiologist or anesthetist records information on the physical status of the patient and an overall impression of the anesthetic risk. The perioperative record is used for notation of the administration of anesthetic agents, fluids, blood products, and other medications and for recording vital signs, anesthetic and surgical interventions, and airway maintenance; this record shows a dynamic account of the patient's responses throughout the operation. Finally, the anesthesiologist notes postoperative problems related to anesthesia on the postoperative section of the record. The anesthesia record can be used by pharmacists for medication scheduling and therapeutic drug monitoring, assessment of fluid status, evaluation of hemodynamic response to drug and fluid interventions, quality assurance, and drug-use reviews.     

Effects of GABAergic agents on anesthesia induced by halothane, isoflurane, and thiamylal in mice

The effects of gamma-aminobutyric acid (GABA) receptor modulators and GABA uptake inhibitors on volatile and intravenous anesthetic-induced anesthesia were examined in male ICR mice, as assessed by the loss of righting reflex (LORR). The GABA uptake inhibitors, NO-711 and SKF89976A, which are permeable to the blood-brain barrier (BBB), but not nipecotic acid or guvacine, which poorly permeate BBB, shortened the onset of LORR but did not affect the duration of LORR induced by 1.5% halothane and 2% isoflurane. NO-711 and SKF89976A shortened the onset of and prolonged the duration of LORR induced by thiamylal (45 mg/kg i.p.). The GABA mimetics, muscimol and diazepam, shortened the onset of and prolonged the duration of LORR induced by halothane, isoflurane, and thiamylal. On the other hand, picrotoxin, a GABAA receptor antagonist, prolonged the onset of LORR induced by all anesthetics tested. Another GABAA receptor antagonist, bicuculline, prolonged the onset of LORR induced by halothane, but not by isoflurane or thiamylal. Both antagonists failed to affect the duration of LORR induced by halothane, isoflurane, or thiamylal. Baclofen, a GABAB receptor agonist, enhanced both volatile anesthetics- and thiamylal-induced anesthesia. These results suggest that anesthesia induced by volatile and intravenous anesthetics might be correlated with the modification of the pre- and/or postsynaptic GABAergic activities.     

Tricaine (MS-222) is a safe anesthetic compound compared to benzocaine and pentobarbital to induce anesthesia in leopard frogs (Rana pipiens)

Tricaine (MS-222) is used commonly for sedation, immobilization, and anesthesia of poikilothermic animals. The anesthetic efficacy of different concentrations of MS-222 was compared to benzocaine and pentobarbital on the physiological changes, heart rate and ECG (electrocardiogram) parameters in the leopard frog, Rana pipiens. Loss of righting reflex (RR), loss of pain response (NR = nociceptor response) and recovery time were measured. Heart rate and ECG parameters were also tested before and during anesthesia. The time to loss of RR and NR decreased while recovery time markedly increased with the increasing concentration of MS-222. Benzocaine at 200 mg/l induced a rapid anesthesia, but all frogs needed resuscitation. Pentobarbital at 300 mg/l induced a slow anesthesia, however, all of the frogs also needed resuscitation. All anesthetics at the mentioned concentrations decreased heart rate significantly as well as altered the ECG parameters. All anesthetics prolonged the Q-T interval, and MS-222 at 800 mg/l and benzocaine at 200 mg/l were the most effective anesthetic concentrations in increasing the Q-T interval. Frogs anesthetized by benzocaine and pentobarbital and high concentrations of MS-222 required resuscitation due to hypoxia. Pentobarbital and benzocaine seem to be very effective compounds, but their safety margins are narrow because of ventilatory failure. Therefore, MS-222 at a concentration of 200 mg/l or less is highly recommended for leopard frogs because prolonged recovery, high mortality rate and significant ECG changes are observed with higher concentrations of MS-222.     

丙泊酚复合瑞芬太尼麻醉对腹部手术患者的麻醉效果观察

目的:探讨丙泊酚复合瑞芬太尼麻醉对腹部手术患者的麻醉效果。方法:选择我院腹部手术患者共233例,并随机分为观察组和对照组。两组患者均实施全身麻醉,采用相同麻醉诱导,对照组采用异氟醚和芬太尼麻醉维持,观察组患者给予丙泊酚和瑞芬太尼麻醉维持。观察两组患者麻醉效果。结果:观察组插管5分钟时的血压和心率及插管10分钟的血压和心率分别与对照组的同时间的血压和心率比较,差异有统计学意义(P<0.05)。观察组患者自主呼吸恢复时间早于对照组,且差异有统计学意义(P<0.05);观察组苏醒时间早于对照组,且差异有统计学意义(P<0.05)。结论:丙泊酚复合瑞芬太尼麻醉用于腹部手术患者的麻醉时血流动力学稳定、患者术后苏醒时间及麻醉效果显著。