Regional hemodynamic responses to nicotine in conscious and anesthetized dogs: comparative effects of pentobarbital and chloralose

This study was conducted in 12 dogs to evaluate regional hemodynamic responses during intravenous infusion of nicotine (36 micrograms/kg/min) in the conscious state and compare them with those in the same dogs following either pentobarbital (n = 6) or chloralose anesthesia (n = 6). Values for regional blood flow were obtained with 15-microns radioactive microspheres and used to calculate regional vascular conductance. In the conscious state, nicotine increased aortic pressure (+70%) and caused hyperventilation that reduced arterial PCO2 (-44%). These systemic effects were associated with decreases in vascular conductance in the renal cortex (-48%), pancreas (-81%), duodenum (-58%), and cerebral cortex (-55%), whereas no significant change in vascular conductance was evident in spleen, liver, or myocardium. Pentobarbital anesthesia blunted the increases in aortic pressure and respiratory activity and the reductions in vascular conductance in the renal cortex, pancreas, duodenum, and cerebral cortex during nicotine infusion. In contrast, chloralose anesthesia accentuated the increase in aortic pressure and the decrease in vascular conductance in the renal cortex during nicotine infusion, while it converted no change in vascular conductance in the spleen into a decrease and no change in vascular conductance in the myocardium into an increase. Chloralose anesthesia blunted nicotine-induced hyperventilation. These findings demonstrate that general anesthetic agents may have markedly different effects on cardiovascular reflex pathways. They emphasize the importance of considering the particular characteristics of the anesthetic agent used in interpreting results from studies of cardiovascular pharmacology and physiology in anesthetized animals.     

三种麻醉方法在骨科动物实验中效果比较

目的比较3种麻醉方法在骨科动物实验中的效果,从而得出最佳方法。方法将80只实验动物随机分为3组,A组（速眠新II肌肉注射组）,B组（0.6%戊巴比妥钠静脉注射组）,C组（速眠新II肌肉注射＋0.6%戊巴比妥钠静脉注射联合用药组）,在骨科动物实验中分别进行麻醉、手术,比较3组的麻醉效果,观察其诱导期、麻醉期（麻醉维持时间）、苏醒期、麻醉效果、死亡率等。结果 A组麻醉的诱导期长,效果不好;B组麻醉的诱导期短,但麻醉效果不理想,死亡率高;C组麻醉的诱导期短,麻醉效果好,安全。结论 C组诱导期短,麻醉效果好,安全。无论在实验动物的伦理道德方面,还是在保证动物实验质量方面都是最佳选择。     

Oxygen metabolism and catecholamine secretion during chloralose anesthesia in lambs.

Anesthetic agents are required when restraining animals in most forms of animal research. In particular, alpha-chloralose is a widely used anesthetic for respiratory and cardiovascular research despite limited controlled studies investigating whether chloralose could represent a variable influencing cardiorespiratory reflexes in acute animal studies. We previously used a chronically-instrumented neonatal lamb model to determine that chloralose had important effects on oxygen delivery and on basal hemodynamics. To investigate the influence of chloralose on oxygen metabolism and catecholamine secretion in relation to these hemodynamic changes, we studied 12 lambs before and after infusion of chloralose (30 mg/kg, i.v.) or control saline vehicle. Chloralose caused no differences in arterial or mixed venous oxygen contents, arterio-venous oxygen difference, or oxygen delivery, consumption, or extraction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apgar score after induction of anesthesia for canine cesarean section with alfaxalone versus propofol

The effects of alfaxalone and propofol on neonatal vitality were studied in 22 bitches and 81 puppies after their use as anesthetic induction agents for emergency cesarean section. After assessment that surgery was indicated, bitches were randomly allocated to receive alfaxalone 1 to 2 mg/kg body weight or propofol 2 to 6 mg/kg body weight for anesthetic induction. Both drugs were administered intravenously to effect to allow endotracheal intubation, and anesthesia was maintained with isoflurane in oxygen. Neonatal vitality was assessed using a modified Apgar score that took into account heart rate, respiratory effort, reflex irritability, motility, and mucous membrane color (maximum score = 10); scores were assigned at 5, 15, and 60 minutes after delivery. Neither the number of puppies delivered nor the proportion of surviving puppies up to 3 months after delivery differed between groups. Anesthetic induction drug and time of scoring were associated with the Apgar score, but delivery time was not. Apgar scores in the alfaxalone group were greater than those in the propofol group at 5, 15, and 60 minutes after delivery; the overall estimated score difference between the groups was 3.3 (confidence interval 95%: 1.6–4.9; P < 0.001). In conclusion, both alfaxalone and propofol can be safely used for induction of anesthesia in bitches undergoing emergency cesarean section. Although puppy survival was similar after the use of these drugs, alfaxalone was associated with better neonatal vitality during the first 60 minutes after delivery.     

Susceptibility of rats to corneal lesions after injectable anesthesia

Corneal injury is not a commonly reported side effect after injectable or inhalation anesthesia in rats, but a number of surgery studies at our facility resulted in a high incidence of these injuries. To explore the potential association of various anesthetic protocols with the development of corneal lesions in rats, we retrospectively evaluated clinical records and sections of eyes from 215 male and 187 female Wistar rats used in eight intravenous infusion toxicology studies. None of the studied compounds was associated with eye toxicity. For placement of jugular vein vascular access ports, rats were anesthetized with enflurane, isoflurane, ketamine-xylazine, or Hypnorm-midazolam. Histologically, corneal changes were scored from 0 to 4 in light of degree of mineralization, leukocytic infiltrates, neovascularization, fibrosis, and ulceration. Prestudy (postsurgical) ophthalmic examination findings of corneal opacities were correlated with mineralization of the anterior limiting membrane and corneal ulceration. Corneal lesions were more severe in animals anesthetized with ketamine-xylazine, and minimal changes occurred after anesthesia with either enflurane or isoflurane. The results of further analysis suggest that corneal lesions can be observed within 24 h after injectable anesthetic administration and are not reversible. The severity of corneal changes was reduced when ketamine-xylazine anesthesia was reversed with yohimbine. Compared with Sprague-Dawley and Lewis rats, Wistar, Long-Evans, and Fischer 344 rats had increased incidence and severity of corneal lesions after anesthesia with ketamine-xylazine, suggesting that these three strains are at increased risk for developing postanesthetic corneal lesions with this regimen.     

Effect of anesthetic agents on lavage fluid parameters used as indicators of pulmonary injury

The effect of the anesthetic agent used in killing animals in an in vivo pulmonary toxicity screening test was examined in Fischer-344 rats and in Syrian hamsters. Using animals killed by cervical dislocation with no anesthesia as a baseline, two types of anesthetic agents (halothane, sodium pentobarbital) and carbon dioxide were tested. Carbon dioxide caused the greatest perturbance of baseline lavage fluid and tissue parameters normally used in the screening test. Halothane anesthesia caused the least perturbance in the screening test parameters and was selected as the anesthetic of choice for use in future pulmonary toxicity tests.     

Anesthetic effects of a three-drugs mixture —comparison of administrative routes and antagonistic effects of atipamezole in mice—

The anesthetic mixture of medetomidine (MED), midazolam (MID) and butorphanol (BUT) produced anesthetic duration of around 40 minutes (min) in ICR mice. We reported that this anesthetic mixture produced almost the same anesthetic effects in both male and female BALB/c and C57BL/6J strains. Intraperitoneal (IP) administration of drugs has been widely used in mice. However, various injectable routes of the anesthetic mixture may cause different anesthetic effects. First, we examined effects of the anesthetic mixture by subcutaneous (SC) and intravenous (IV) injection compared to IP injection. After injection of the anesthetic mixture, administration of atipamezole (ATI) induced mice recovery from anesthesia. Secondly, we examined how different dosage and optimum injection timing of ATI affected mice recovery from anesthesia. We used an anesthetic score to measure anesthetic duration and a pulse oximeter to monitor vital signs under anesthesia. Usually, drugs from SC injection work more weakly than IP or IV injection. However, we found no significant differences of anesthetic duration among the three different injection routes. Antagonistic effects of ATI (0.3 mg/kg and 1.5 mg/kg) worked equally when administered at 30 min after injection of the anesthetic mixture. Antagonistic effects of ATI (1.5 mg/kg) were stronger than ATI (0.3 mg/kg) at 10 min after injection of the anesthetic mixture. The anesthetic mixture is a useful drug to induce nearly the same anesthetic effects by different injection routes and has an antagonist of ATI which helps mice quickly recover from anesthesia. These results may contribute to the welfare of laboratory animals.     

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.     

Anesthesia for outpatient female sterilization

This issue of the Bulletin deals with the principles of anesthesia for outpatient female sterilization with emphasis on techniques for laparoscopy and minilaparotomy. General anesthesia techniques provide analgesia, amnesia, and muscle relaxation and are particularly useful for managing the anxious patient. Disadvantages include increased expense, need for specialized equipment, and highly trained personnel, and delayed recovery. Complications, though relatively rare, can be life-threatening and include aspiration of stomach contents, hypoxia, hypercarbia, hypotension, hypertension, cardiac arrhythmias, cardiorespiratory arrest, and death. There is no single preferred technique of general anesthesia, athough most anesthetists employ methods that allow rapid recovery of faculties, enabling the patient to be discharged soon after surgery. To accomplish this end, light anesthesia with sodium thiopental induction and nitrous oxide maintenance is often used. Short duration muscle relaxation with an agent such as succinylcholine supplements this technique. Other techniques include light anesthesia with inhalational anesthetic agents and the use of intravenous ketamine. Local anesthesia augmented by systemic and/or inhalational analgesia is supplanting general anesthesia techniques for laparoscopy in many locales. This approach is also particularly well-suited for minilaparotomy in developing countries, where it has achieved its greatest popularity. The local technique carries with it reduced morbidity and mortality but may not entirely relieve discomfort. The primary danger of local anesthesia is respiratory depression due to excessive narcosis and sedation. The operator must be alert to the action of the drugs and should always use the minimal effective dose. Although toxicity due to overdosage with local anesthetic drugs is occasionally experienced, allergic reactions to the amide-linkage drugs such as lidocaine or bupivacaine are exceedingly rare. For outpatient laparoscopy or minilaparotomy, local anesthesia with proper preoperative counselling and premedication should provide adequate relief of pain and is the method of choice, unless the patient cannot be examined awake or is totally uncooperative. The decision to utilize either general or local anesthesia should be made by the patient after thorough counselling by the surgical team. In many cases, the circumstances of the surgical environment will dictate the choice, but patient comfort and safety should always be the goal.     

General anesthesia in an office-based plastic surgical facility: a report on more than 23,000 consecutive office-based procedures under general anesthesia with no significant anesthetic complications

The popularity of elective office-based plastic surgery has increased significantly over the past two decades. The continuing demand for improved aesthetic results has stimulated the development of ever more complex plastic surgical techniques. These techniques may require extended periods of operative time spent under anesthesia. Patients have come to expect an almost perfect anesthetic and surgical experience, with safety and comfort being their foremost concerns. Because of increasingly complex and lengthy operations, the authors believe that intravenous sedation, used for many years in their plastic surgery practice, is now suboptimal for most longer and complex surgical procedures. In their experience, under most circumstances, general anesthesia provides the optimal anesthetic experience for the patient, anesthesiologist, and surgeon. The authors present a consecutive 18-year study of general anesthesia in more than 23,000 procedures in an accredited, office-based plastic surgical facility that offers a very safe and uniformly pleasant anesthesia experience for patients. There were no intraoperative or postoperative deaths and no significant complications. The authors' experience differs from the common perception that general anesthesia is too risky for aesthetic surgery procedures.     

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.     

Lactate levels in the brain are elevated upon exposure to volatile anesthetics: a microdialysis study

Anesthetic agents have well-defined pharmacological targets but their effects on energy metabolism in the brain are poorly understood. In this study, we examined the effects of different anesthetics on extracellular lactate and glucose levels in blood, CSF and brain of the mouse. In vivo-microdialysis was used to monitor extracellular energy metabolites in the brain of awake mice and during anesthesia with seven different anesthetic drugs. In separate groups, lactate and glucose concentrations in blood and CSF were measured for each anesthetic. We found that anesthesia with isoflurane caused a large increase of extracellular lactate levels in mouse striatum and hippocampus (300-400%). Pyruvate levels also increased while glucose and glutamate levels were unchanged. This effect was dose-dependent and was mimicked by other gaseous anesthetics such as halothane and sevoflurane but not by intravenous anesthetics. Ketamine/xylazine and chloral hydrate caused 2-fold increases of glucose levels in mouse blood and brain while lactate levels were only moderately increased. Propofol caused a minor increase of extracellular glucose levels while pentobarbital had no effect on either lactate or glucose. Volatile anesthetics also increased lactate levels in blood and CSF by 2-3-fold but had no effect on plasma glucose. Further experiments demonstrated that lactate formation by isoflurane in mouse brain was independent of neuronal impulse flow and did not involve ATP-dependent potassium channels. We conclude that volatile anesthetics, but not intravenous anesthetics, cause a specific, dose-dependent increase in extracellular lactate levels in mouse brain. This effect occurs in the absence of ischemia, is independent of peripheral actions and is reflected in strongly increased CSF lactate levels.     

Failure of yohimbine to reverse ketamine anesthesia in rhesus monkeys

Yohimbine hydrochloride has been used experimentally to reverse the anesthetic effects of ketamine and xylazine in dogs, cats, cattle and mule deer, but there are no reports of its use in nonhuman primates. Nine adult female rhesus monkeys were given an intravenous dose of either 0.5 mg/kg yohimbine hydrochloride or saline 10 minutes after intramuscular administration of 10 mg/kg ketamine hydrochloride. There was no difference in the duration of anesthesia between the yohimbine and saline treatments, suggesting yohimbine is not effective in the rhesus monkey.     

Lactate levels in the brain are elevated upon exposure to volatile anesthetics: A microdialysis study

Anesthetic agents have well-defined pharmacological targets but their effects on energy metabolism in the brain are poorly understood. In this study, we examined the effects of different anesthetics on extracellular lactate and glucose levels in blood, CSF and brain of the mouse. In vivo-microdialysis was used to monitor extracellular energy metabolites in the brain of awake mice and during anesthesia with seven different anesthetic drugs. In separate groups, lactate and glucose concentrations in blood and CSF were measured for each anesthetic. We found that anesthesia with isoflurane caused a large increase of extracellular lactate levels in mouse striatum and hippocampus (300–400%). Pyruvate levels also increased while glucose and glutamate levels were unchanged. This effect was dose-dependent and was mimicked by other gaseous anesthetics such as halothane and sevoflurane but not by intravenous anesthetics. Ketamine/xylazine and chloral hydrate caused 2-fold increases of glucose levels in mouse blood and brain while lactate levels were only moderately increased. Propofol caused a minor increase of extracellular glucose levels while pentobarbital had no effect on either lactate or glucose. Volatile anesthetics also increased lactate levels in blood and CSF by 2–3-fold but had no effect on plasma glucose. Further experiments demonstrated that lactate formation by isoflurane in mouse brain was independent of neuronal impulse flow and did not involve ATP-dependent potassium channels. We conclude that volatile anesthetics, but not intravenous anesthetics, cause a specific, dose-dependent increase in extracellular lactate levels in mouse brain. This effect occurs in the absence of ischemia, is independent of peripheral actions and is reflected in strongly increased CSF lactate levels.     

依托咪酯用于乳腺癌手术的麻醉效果及对患者应激水平和术后苏醒质量的影响

目的:探讨依托咪酯用于乳腺癌手术的麻醉效果及对患者应激水平和术后苏醒质量的影响。方法:选择我院2017年7月～2018年7月收治的93例乳腺癌患者,按随机数字表法分为对照组(43例)和研究组(50例),对照组予以丙泊酚静脉维持麻醉,研究组予以依托咪酯静脉维持麻醉,比较两组不同时点促肾上腺皮质激素(ACTH)、醛固酮、皮质醇水平、心率(HR)、舒张压(DBP)、收缩压(SBP)、Ramsay镇静评分,术后苏醒质量和不良反应的发生情况。结果:气管插管时,研究组ACTH浓度较麻醉诱导前上升,醛固酮、皮质醇浓度相应下降,对照组ACTH、醛固酮、皮质醇均较麻醉诱导前上升,组间差异有统计学意义(P0.05);术后24 h,两组ACTH、醛固酮、皮质醇较麻醉诱导前无统计学意义(P0.05);气管插管时,对照组HR、DBP、SBP均上升,研究组变化不明显,两组差异有统计学意义(P0.05);拔管后即刻,两组Ramsay评分较麻醉诱导前下降,组间比较差异无统计学意义(P0.05)。两组拔管时间、睁眼时间、定向力恢复时间比较差异无统计学意义(P0.05)。两组总不良反应发生率比较差异无统计学意义(P0.05)。结论:依托咪酯用于乳腺癌手术可获得良好的麻醉效果,能够抑制机体应激反应,维持血流动力学的稳定,术后苏醒质量满意,安全性高。     

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.     

Le bloc paracervical en obstétrique

Local anesthesia can be very useful in the first stage of labour when a general anesthetic cannot be given during this stage, and it is associated with reduced respiratory depression in the fetus. Paracervical block anesthesia is one such method of local anesthesia. Its successful use depends upon a proper technique, knowledge of the indications and contraindications, appropriate equipment and use of a long-acting anesthetic agent of low toxicity. A series of 90 cases of paracervical block are described in which the success rate was 90 to 95%.     

Ketaset-Rompun extends the effective interstimulus interval in long-trace taste-aversion conditioning in rats

The effect of anesthesia (Ketaset-Rompun) interpolated between the conditioned stimulus (CS) and unconditioned stimulus (US) during long-trace taste-aversion conditioning in rats was examined in three experiments. In Experiment 1, rats that were anesthetized immediately after experiencing a saccharin solution formed a taste aversion at a 3-h interval that typically does not support conditioning, a prolongation effect. Prior experience with the anesthetic eliminated the associability of the aversive consequences of the anesthetic but did not eliminate the anesthetic's prolongation effect. Some evidence was also obtained indicating that LiCl produced an aversion at the 3-h interval in unanesthetized rats if they had experience with the anesthetic prior to conditioning. In Experiment 1a, the interval between prior experience and conditioning was extended from 24 to 96 h. Results demonstrated that the evidence for conditioning at 3 h for unanesthetized subjects in Experiment 1 was not a robust finding. By reversing the role of Ketaset-Rompun (KR) and LiCl as prior experience manipulation and US treatment in Experiment 2, the prolongation effect was shown not to be due to the summation of the aversive properties of the anesthetic and the LiCl. Results were interpreted in terms of a hypothesized metabolic pacemaker.     

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.     

不同麻醉方式对老年肺肿瘤患者术后早期认知功能的影响

目的:探讨不同麻醉选择对老年肺肿瘤术后患者早期认知功能的影响。方法:分析我院2011年3月至2013年3月老年肺肿瘤患者,分别有62例用全凭静脉麻醉和61例用静吸复合麻醉的麻醉方法,记录手术时间和麻醉时间,用MMSE量表进行认知功能评分,分别评定手术前1天和手术后出麻醉室时及1、3、5天患者的认知功能,并判断患者的POCD。结果:两组患者在手术时间和麻醉时间方面无统计学差异。与术前1天比较,全凭静脉麻醉组、静吸复合麻醉组出麻醉恢复室时、术后1 d时MMSE评分降低(P0.05);与术前1 d比较,两组在术后3天和7天时MMSE评分恢复正常(P0.05),两组患者之间的MMSE认知功能评分在术前、术后均无统计学差异(P0.05),出麻醉恢复室时,全凭静脉麻醉组发生POCD24例(39.34%),全凭静脉麻醉组发生25例(40.32%),两组发生率比较无统计学差异(P0.05);术后1天、3天、7天两组分别POCD的发生率比较均无统计学意义(P0.05)。结论:老年患者用全凭静脉麻醉、静吸复合麻醉不同麻醉方法对老年患者术后早期发生认知功能障碍的影响无统计学差异。