A comprehensive review of epinephrine in the finger: to do or not to do.

The prohibition against the use of local anesthetics with epinephrine for digital blocks or infiltration is an established surgical tradition. The present article provides a comprehensive review of all reported digital necrotic and ischemic complications with epinephrine in the digits in an effort to understand whether the current prohibition is based on documented reports. A comprehensive review of articles showing the successful use of local anesthetic with epinephrine in the digits is presented.A review of Index Medicus from 1880 to 1966 and a computer review of the National Library of Medicine database from 1966 to 2000 were performed using multiple keywords. Selected major textbooks from 1900 to 2000 were also reviewed.A total of 48 cases of digital gangrene after anesthetic blocks (mostly using cocaine or procaine) have been reported in the world literature. Only 21 cases involved the use of epinephrine; 17 involved an unknown concentration based on manual dilution. Multiple other concurrent conditions (hot soaks, tight tourniquets, and infection) existed in these case reports, making it difficult to determine the exact cause of the tissue insult. There have been no case reports of digital gangrene using commercial lidocaine with epinephrine (introduced in 1948). Multiple studies involving thousands of patients support the premise that the use of lidocaine with epinephrine is safe in the digits.An extensive literature review failed to provide consistent evidence that our current preparations of local anesthesia with epinephrine cause digital necrosis, although not all complications are necessarily reported. However, as with all techniques, caution is necessary to balance the risks of this technique with the dangers of mechanical tourniquets and upper extremity block anesthesia.     

The effects of ketamine, phencyclidine and lidocaine on catecholamine secretion from cultured bovine adrenal chromaffin cells

The ability of ketamine, phencyclidine and analogues to alter catecholamine secretion from cultured bovine adrenal chromaffin cells was investigated. Both ketamine and phencyclidine specifically inhibited nicotinic agonist-induced secretion at concentrations which did not alter secretion induced by elevated K+ depolarization. The inhibition of nicotinic agonist-induced secretion was not overcome by increasing concentrations of nicotinic agonist. The effects of stereoisomer pairs of phencyclidine-like drugs - dexoxadrol, levoxadrol and (+)PCMP, (-)PCMP - did not reveal stereospecificity for the inhibition, in contrast to the stereospecific behavioral effects of the drugs. The local anesthetic lidocaine (0.3 mM) also noncompetitively inhibited nicotinic agonist-induced secretion without inhibiting elevated K+-induced secretion. The data indicate that ketamine and phencyclidine at clinically relevant concentrations specifically inhibit the adrenal chromaffin cell nicotinic receptor at a site similar to or identical with the site of action of local anesthetic. Although the nicotinic receptor inhibition is probably not related to the anesthetic and behavioral effects of ketamine and phencyclidine, it is likely that the centrally mediated increase in sympathetic nervous system activity which is characteristic of these drugs is moderated by the peripheral blocking effects on catecholamine secretion from the adrenal medulla.     

Study,by use of coarse-grained models,of the functionally crucial residues and allosteric pathway of anesthetic regulation of the Gloeobacter violaceus ligand-gated ion channel

Although pentameric ligand-gated ion channels (pLGICs) have been found to be the targets of general anesthetics, the mechanism of the effects of anesthetics on pLGICs remains elusive. pLGICs from Gloeobacter violaceus (GLIC) can be inhibited by the anesthetic ketamine. X-ray crystallography has shown that the ketamine binding site is distant from the channel gate of the GLIC. It is still not clear how ketamine controls the function of the GLIC by long-range allosteric regulation. In this work, the functionally crucial residues and allosteric pathway of anesthetic regulation of the GLIC were identified by use of a coarse-grained thermodynamic method developed by our group. In our method, the functionally crucial sites were identified as the residues thermodynamically coupled with binding of ketamine. The results from calculation were highly consistent with experimental data. Our study aids understanding of the mechanism of the anesthetic action of ketamine on the GLIC by long-range allosteric modulation.     

Response of wild subantarctic fur seal (Arctocephalus tropicalis) females to ketamine and tiletamine-zolazepam anesthesia

This study is the first to compare the anesthetic effects of two cyclohexamines on free-ranging subantarctic fur seal (Arctocephalus tropicalis) females. From April to July 1999, 107 females were immobilized for tooth extraction and blood sampling, using either ketamine (Ketalar, n = 58) alone or tiletamine-zolazepam (Zoletil 100, n = 49) mixture. Animals were injected intramuscularly at mean doses of 2.1 mg/kg for ketamine and 1.1 mg/kg for tiletamine-zolazepam mixture. Individual response to both drugs was highly variable. The dosage required to achieve a satisfactory level of anesthesia was smaller for subantarctic fur seals than for most other species of seals and was less for animals in better body condition. Few side effects were observed during the trials, aside from mild tremors caused by ketamine, and respiratory depression or prolonged apnea caused by tiletamine-zolazepam. We recommend use of ketamine, especially by those with little experience in anesthesia of fur seals. However, precautionary measures should be taken, such as using low doses for animals in good body condition and being prepared for anesthetic emergencies to avoid any casualties.     

Effects of Anesthetic Ketamine on Anxiety-Like Behaviour in Rats

There is scarce information regarding the effects of anesthetic doses of the non-competitive N-methyl-d-aspartate receptor antagonist ketamine on anxiety. The current study evaluated the acute effects of intraperitoneally (i.p.) administered anesthetic ketamine (100 mg/kg) i.p. on anxiety in rats. For this purpose, the light/dark and the open field tests were utilized. The effects of anesthetic ketamine on motility were also examined using a motility cage. In the light/dark test, anesthetic ketamine, administered 24 h before testing reduced the number of transitions between the light and dark compartments and the time spent in the light compartment in the rats compared with their control cohorts. In addition, ketamine was found to exert a depressive effect on rats’ motility. In the open field test, animals treated with anesthetic ketamine 24 h before testing spent essentially no time in the central area of the apparatus, decreased horizontal ambulatory activity, and preserved to a certain extent their exploratory behaviour compared to their control counterparts. The results suggest that, in spite of its hypokinetic effect, a single anesthetic ketamine administration apparently induces an anxiety-like state, while largely preserving exploratory behaviour in the rat. These effects were time-dependent they since they were extinguished when testing was carried out 48 h after anesthetic ketamine administration.

     

The tumescent technique: the effect of high tissue pressure and dilute epinephrine on absorption of lidocaine

Injection of lidocaine into the subcutaneous tissues by the tumescent technique results in a delayed absorption of the local anesthetic and has allowed clinicians to exceed the maximum recommended dose of lidocaine without reported complications. However, little knowledge exists about the mechanisms that permit such high doses of lidocaine to be used safely with this technique. The presence of low concentration epinephrine and the increased tissue pressure resulting from the tumescent injection have both been implicated as important factors, but neither has been studied in patients whose results were not altered by the variability of the suction procedure. The purpose of this work was to determine the effect of tissue pressure during tumescent injection and presence of low concentration epinephrine on the absorption of lidocaine from subcutaneous tissues in human volunteers. Twenty healthy female human volunteers were randomized into four study groups. After body fat measurements, all subjects received an injection of 7 mg/kg of lidocaine into the subcutaneous tissues of both lateral thighs. The injected solution consisted of 0.1% lidocaine and 12.5 meq/liter sodium bicarbonate in normal saline with or without 1:1,000,000 epinephrine. Tissue pressure was recorded during injection using a specially designed double-barreled needle. The time required for injection was also recorded. Subjects in group 1 received lidocaine with epinephrine injected by a high-pressure technique. Group 2 subjects received lidocaine with epinephrine injected by a low-pressure technique. Group 3 subjects received lidocaine without epinephrine injected under high pressure. Group 4 subjects received lidocaine without epinephrine injected under low pressure. Following injection, sequential blood samples were drawn over a 14-hour period, and plasma lidocaine concentrations were determined by gas chromatography. No suction lipectomy was performed. Maximum tissue pressure during injection was 339 +/- 63 mmHg and 27 +/- 9 mmHg using high- and low-pressure techniques, respectively. Addition of 1:1,000,000 epinephrine, regardless of the pressure of injected fluid, significantly delayed the time to peak plasma concentration by over 7 hours. There was no significant difference in the peak plasma concentration of lidocaine among the four groups. Peak plasma concentrations greater than 1 mcg/ml were seen in 11 subjects. Epinephrine (1:1,000,000) significantly delays the absorption of lidocaine administered by the tumescent technique. High pressure generated in the subcutaneous tissues during injection of the solution does not affect lidocaine absorption. The delay in absorption may allow time for some lidocaine to be removed from the tissues by suction lipectomy. In addition, the slow rise to peak lidocaine concentration in the epinephrine groups may allow the development of systemic tolerance to high lidocaine plasma levels.     

Hemodynamic response to anesthesia in pregnant and nonpregnant ICR mice

Mean arterial blood pressure (BP) and heart rate (HR) during and after recovery from anesthesia in pregnant and nonpregnant ICR mice were evaluated. Mice were evaluated during mechanical ventilation, from 15 to 60 min after induction of anesthesia. The anesthetic protocols were pentobarbital (80 mg/kg, given intraperitoneally [i.p.]); two low doses of ketamine and xylazine (90 mg/kg, 7.5 mg/kg, respectively, i.p., with a second dose given 20 min after the initial dose); and a single high dose of ketamine and xylazine (150 mg/kg, 12.5 mg/kg, respectively, i.p.). The BP was measured in the right carotid artery, using a fluid-filled catheter connected to a chamber containing a solid-state pressure transducer. Mechanical ventilation was performed via tracheotomy, using a normalized minute ventilation of 3.5 ml*min-1*g-1 for nonpregnant mice and 3.0 ml*min-1*g-1 for pregnant mice. Mean BP was lower and HR was higher in pregnant than in nonpregnant mice for each anesthetic protocol. Pentobarbital induced significantly greater tachycardia and hypotension than did the other protocols. The average BP and HR were similar between two low doses and a single high dose of ketamine and xylazine. During spontaneous breathing from 30 to 180 min after recovery from anesthesia by use of a single low dose, ketamine and xylazine induced similar HR profiles, but mean BP in pregnant mice recovered earlier than did that in nonpregnant mice. These results suggest that ketamine and xylazine induced adequate anesthesia for superficial surgical procedures in pregnant and nonpregnant mice while inducing small changes in HR and BP, and pregnancy resulted in a different hemodynamic reaction in response to ketamine and xylazine. These data will be useful for the design and interpretation of physiologic protocols using pregnant and nonpregnant genetically targeted mice.     

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.     

Menstrual cycles in rhesus monkeys (Macaca mulatta) are unaffected by a single dose of the anesthetics ketamine and xylazine administered during the midfollicular phase at laparoscopy

To identify an anesthetic regimen that produces more complete relaxation and analgesia than ketamine hydrochloride (Ketaset®) alone, a combination of ketamine (15 mg/kg body weight) and the hypnotic xylazine (Rompun®, 0.33 mg/kg) was evaluated. Since the desired experimental application required that the anesthetic not interfere with normal hormonal events during the menstrual cycle, this combination administered on day 6 of the cycle was tested to determine whether hormonal surges, incidence of ovulation, or cycle length would be altered relative to the use of ketamine alone. In five of six animals, ketamine plus xylazine had no effect on the occurrence of timely surges of estrogen, luteinizing hormone (LH), or follicle-stimulating hormone (FSH), or on ovulation as determined by the presence of a corpus luteum at laparoscopy and normal serum concentrations of progesterone. There were no significant differences between the cycle during treatment and previous cycles in the same animal for length of the menstrual cycle (26.0 ± 2.3 [5] days; X? ± S.D. [n] or luteal phase (13.4 ± 2.4 [5] days). Likewise, these values did not differ from those of ten control monkeys treated with ketumine only on day 5 or 6 of the cycle (incidence of ovulation, 10/10; cycle length, 27.9 ± 1.8 [10]; luteal phase length, 15.1 ± 1.4 [10], P > 0.05). Patterns of circulating progesterone were not altered by the addition of xylazine anesthesia. These findings indicate that xylazine, given in the midfollicular phase, did not alter ovulatory events or menstrual cycle characteristics in rhesus monkeys. Ketamine plus xylazine apparently provides anesthesia appropriate for laparoscopy.     

Dupuytren's fasciectomies in 60 consecutive digits using lidocaine with epinephrine and no tourniquet

Dupuytren's contracture is a common hand problem. Its treatment, other than percutaneous fasciectomy, is an outpatient operation performed with the patient under regional or general anesthesia. If local anesthetics are used, they are used without epinephrine, and an arm or forearm tourniquet is essential. Multiple reviews have described the safety of local anesthetics with epinephrine in the digits. This study is a retrospective review of operations performed by the same surgeon in the hospital (43 digits) versus the office using local anesthetics with epinephrine and no tourniquet (60 digits). Results and complications were compared and tabulated. The hospital and epinephrine groups were comparable regarding preoperative measurements. Postoperative improvement in extension at the metacarpophalangeal and proximal interphalangeal joints was similar in both the hospital and epinephrine groups. Complications, including digital nerve and artery injuries, infections, and hematomas, were similar between the groups. There were no cases of digital necrosis or gangrene in the epinephrine group, even though one patient sustained a transection of a digital artery at the proximal interphalangeal joint. Because of the similarities in results and complications, there does not seem to be an advantage to performing Dupuytren's excisions with full arm tourniquet and outpatient admission in many cases. Local anesthetics with epinephrine are safe in the treatment of Dupuytren's contracture, although both the use of digital epinephrine and the use of mechanical tourniquets carry the potential for complications. Visibility is similar to that for facial or head and neck surgery and is aided by the use of loupe magnification. The old dogma against its use in the fingers is refuted, as seen by the results in these 60 consecutive Dupuytren's fasciectomies and the results of other authors.     

Effect of the general anesthetic ketamine on the potassium permeability of plasma membranes of brain synaptosomes

General anesthetic ketamine (1 mM) decreases relative sodium permeability (PNa+/PK+) of synaptosomes measured by transmembrane potential--external potassium concentration curves. Since tetrodotoxin (10(-7) M) does not affect the value PNa+/PK+ it is concluded that potassium permeability of the membrane increases in the presence of ketamine.     

山羊单纯与复合全身麻醉效果的比较

目的对比山羊单纯麻醉与复合麻醉的效果,探讨一种安全高效便捷的山羊麻醉方法。方法选取山羊30只,随机分为A、B、C三组,A组给予单纯戊巴比妥钠麻醉,B组给予单纯氯胺酮麻醉,C组给予地西泮、戊巴比妥钠和氯胺酮复合麻醉,记录三种麻醉方法的起效时间、麻醉维持时间、麻醉药物用量及麻醉死亡率。结果地西泮、戊巴比妥钠和氯胺酮复合麻醉,起效快、麻醉维持时间长、动物死亡率低、麻醉效果好。结论安定、戊巴比妥钠和氯胺酮复合麻醉优于单纯麻醉,是一种高效、便捷、安全山羊全身麻醉方法。     

Ketamine inhibits fetal ACTH responses to cerebral hypoperfusion

The present study tested the effect of ketamine on the fetal reflex responses of late-gestation sheep to brachiocephalic occlusion (BCO), a stimulus that mimics the reduction in cerebral blood flow that results from severe fetal hypotension. Ketamine, a dissociative anesthetic and known noncompetitive antagonist of N-methyl D-aspartate (NMDA) receptors, has previously been shown to impair chemoreceptor responsiveness. Studies from this laboratory suggest that fetal reflex ACTH responses to hypotension are largely mediated by chemoreceptors; therefore, we hypothesized that ketamine would inhibit the reflex hormonal response to BCO. Chronically catheterized fetal sheep were subjected to acute cerebral hypoperfusion through occlusion of the brachiocephalic artery. Fetal blood pressure and heart rate were continuously recorded, and fetal blood samples drawn during the experiment were analyzed with specific hormone assays. Our results demonstrate that ketamine attenuates hemodynamic responses to cerebral hypoperfusion and is a potent inhibitor of ACTH and proopiomelanocortin (POMC)/pro-ACTH release. These data support the hypothesis that fetal reflex responses hypotension are chemoreceptor mediated. Given the potency with which ketamine inhibits ACTH response to fetal hypotension, we suggest that the use of ketamine or other anesthetic or analgesic drugs that block or otherwise interact with the NMDA-glutamate pathways, in late pregnancy or in preterm newborns be reconsidered.     

Impact of ether anesthesia on the hypophyseal content of oxytocin neurophysin I and II: a comparative study with ketamine in the rat

The effect of anesthetic stress on the major hormones of the posterior pituitary (PP), such as oxytocin (OT), oxytocin-neurophysin (OTNP-I) and its metabolic product, OTNP-II, was studied. Rats were treated with either a combination of atropine (0.87 mg/kg) and diphenylhydantoin (85 mg/kg) and then anesthetized with ketamine (42 mg/kg) or were directly anesthetized with diethyl-ether, and then killed. Controls were killed with a laboratory guillotine. Our study revealed that 1.) animals killed with a guillotine or being medicated with our drug combination prior to sacrifice had similar concentrations of OT, OTNP-I and OTNP-II per PP and ml of blood; 2.) animals anesthetized with either prior to sacrifice had a decreased concentration of neuropeptides per PP; the blood concentration of OT was 1.6 times higher than in animals treated with the drug combination or killed directly with a guillotine. In addition plasma concentrations of OTNP-I and OTNP-II were above the baseline. We conclude that ether is not an adequate anesthetic for studying the neurophysins from the PP in vivo. Treatment of animals with atropine and diphenylhydantoin in combination with ketamine does not alter the profile of the major hormones from the PP during anesthetic stress.     

Late bleeding after rhytidectomy from injury to the superficial temporal vessels

Five healthy, normotensive women, whose mean age was 49.8 years, developed expanding hematomas between 8 and 10 days (average 9 days) after rhytidectomy. In each patient, the bleeding vessel could be identified: In two, it was the parietal branch of the superficial temporal artery; in two, it was the parietal branch of the superficial temporal vein; and in one, it was the superficial temporal artery immediately before its branching. Contributing factors may have been sudden physical exertion in four of the five patients and in another salicylate ingestion. Several measures can help avoid late bleeding from the superficial temporal vessels or their branches; not using a too potent vasoconstrictive agent (epinephrine) in the local anesthetic so that the vessels will be easier to visualize; not injecting the local anesthetic too deeply or incising to deeply; dividing and ligating the superficial temporal vessel and its major branches if injured; using bipolar coagulation on small branches; and instructing patients repeatedly not to engage in strenuous activity or to ingest salicylates for at least 2 weeks after operation.     

Ketamine antagonizes toxic action of anticholinesterase agents

Ketamine is an anaesthetic interacting with several neurotransmitters. Among others, ketamine exerts some cholinergic actions (ACh). This paper presents the results of studying the interaction of ketamine with ACh in two animal species. Atropine slightly increased the time of immobility produced by ketamine injections in rats. Meanwhile, neostigmine slightly decreased such immobility. Ketamine resulted similar in behavioral actions and shared some electroencephalographic (EEG) actions of scopolamine in cats. The most striking interaction consisted on an antagonism of ketamine on the action of anticholinesterase agents. In both species, ketamine blocked the EEG and the behavioral toxic effects of neostigmine and physostigmine. Notwithstanding, the anticholinesterase agents were unable in reducing the actions of ketamine. This partial cholinergic agonist action of ketamine support certain but limited use of the anesthetic against insecticidal anticholinesterase poisoning.     

Technique,Safety, and Efficacy of Intra-Abdominal Transmitters in Nine-Banded Armadillos

ABSTRACT The future management of nine-banded armadillos (Dasypus novemcinctus) requires solid space-use and activity data, which are currently lacking and which radiotelemetry can provide. External radiotransmitters have not been successful applied with this species. To make recommendations for intra-abdominal radiotransmitter placement in nine-banded armadillos, we 1) evaluated 4 different anesthetic protocols for safety, efficiency, and cost-effectiveness; 2) evaluated a surgical technique for the intra-abdominal placement of radiotransmitters that addresses problems described in previous studies; and 3) evaluated the physiologic and behavioral effects of such a technique. We captured and surgically implanted 37 nine-banded armadillos using either butorphanol and isoflurane, ketamine alone, ketamine and xylazine, or a combination of butorphanol, ketamine, and medetomidine for anesthesia. We recovered and necropsied armadillos after the completion of the study. The objective and subjective assessment of butorphanol, ketamine, and medetomidine combination protocol, followed by reversal of the anesthesia with atipamezole, showed that it was the best overall anesthetic protocol for field use, providing both a smooth induction and fast recovery. We evaluated the fate and effects of radiotransmitters on 13 recovered animals at the end of the study and found no adverse effects. We recommend the implantation of radiotransmitters that are allowed to free-float within the abdominal cavity and specifically emphasize the need for strict aseptic technique. Wildlife managers and wildlife veterinarians aiming to implant nine-banded armadillos with radiotransmitters will benefit from using the recommended anesthetic protocol and surgical technique in future studies.     

A comparison of ketamine/xylazine and ketamine/xylazine/acepromazine anesthesia in the rabbit

Parenteral anesthetic combinations such as ketamine and xylazine have become the agents of choice for anesthesia in the rabbit, because they are effective, easily administered and inexpensive. A number of recent reports have recommended including acepromazine in this combination, but a critical evaluation of this combination in the rabbit has not been reported. Five adult New Zealand white rabbits were anesthetized intramuscularly with ketamine (35 mg/kg) and xylazine (5 mg/kg) with or without acepromazine (0.75 mg/kg). The study was conducted in a double blind fashion, where each rabbit was administered both combinations at a minimum of 7 day intervals. Physiologic parameters were evaluated including heart rate, respiratory rate, central arterial blood pressure, pedal, palpebral and postural reflex activity. The duration of general anesthesia, estimated by the time elapsed between the loss and return of the palpebral reflex, was greater (means = 99 +/- 20 minutes) when acepromazine was employed in the combination compared to (means = 77 +/- 5 minutes) when ketamine/xylazine were used alone. Mean central arterial blood pressure reached a lower level when acepromazine was utilized (means = 46 +/- 8 mm/Hg) than when it was not (means = 57 +/- 12 mm/Hg.). The addition of acepromazine in a ketamine/xylazine combination resulted in a 28% longer period of anesthesia, a 19% lower mean central arterial blood pressure and a 32% longer recovery of postural reflexes. The ketamine/xylazine/acepromazine combination is a useful regimen for normovolemic animals when anesthetic duration greater than that produced by ketamine/xylazine alone is required.     

外科教学中犬的复合麻醉效果观察

目的比较氯胺酮、地西泮和丙泊酚复合麻醉在外科教学中对犬的麻醉效果。方法成年健康杂种犬42条,诱导麻醉相同,均肌注氯胺酮（10 mg/kg）和氟哌利多（0.5 mg/kg）混合液。静脉维持采用不用的方法,分为三组,分别是静脉滴注氯胺酮地西泮混合液（n=12）、静脉推注氯胺酮地西泮混合液（n=12）和静脉滴注丙泊酚利多卡因混合液（n=18）。结果三组麻醉效果显示,静脉滴注丙泊酚利多卡因混合液效果最好,优83.3%,良16.7%,死亡率0%。结论在外科教学中,对犬采用丙泊酚复合麻醉是一种较为理想的麻醉方法。     

The effects of local anesthetics on lipid multilayers. A spin probe study

The effects of a series of local anesthetics on multilayers formed from ox brain white matter lipids were investigated using an intercalated spin-labeled analog of cholestane as a monitor of molecular organization. Local anesthetics could disorder or disrupt these films at pH values approaching or above the pK of the anesthetic. At a constant concentration of a local anesthetic this effect increased with increasing pH. In films formed from lipids with a reduced cholesterol content, local anesthetics promoted the formation of ordered multilamellar arrays and increased their thermal stability. This effect required a lower concentration of local anesthetic than did the disordering effect, and each local anesthetic exhibited an optimal pH range. Depending upon the lipid, the concentration of anesthetic, and the pH of the bathing solution, local anesthetics can either stabilize or disrupt lipid bilayers.