记忆与麻醉深度相关性的研究现状

记忆通常存在的形式有：外显记忆、内隐记忆和无意识-控制记忆。随着麻醉深度逐渐加深，记忆形成逐渐减弱。BIS值逐渐下降，MLAEP、SEF、MF等也呈剂量相关性抑制。记忆的消失与BIS、MLAEP、SEF、MF存在一定的相关性，其中MLAEP能更好的反应麻醉深度，预示记忆是否形成。     

记忆与麻醉深度相关性的研究现状

记忆通常存在的形式有:外显记忆、内隐记忆和无意识-控制记忆。随着麻醉深度逐渐加深,记忆形成逐渐减弱,BIS 值逐渐下降,MLAEP、SEF、MF等也呈剂量相关性抑制。记忆的消失与BIS、MLAEP、SEF、MF存在一定的相关性,其中MLAEP能更好 的反应麻醉深度,预示记忆是否形成。     

硬膜外麻醉下异丙酚联合咪达唑仑镇静对内隐记忆的影响

目的探讨术中异丙酚联合咪达唑仑镇静对内隐记忆的影响,分析内隐记忆消失的中潜伏期听觉诱发电位(MLAEP)参数界值,为临床镇静深度监测提供一项新的客观指标。方法 硬膜外麻醉下择期手术病人45例(ASA Ⅰ～Ⅱ级),随机分为异丙酚组(P)、联合用药一组(PM1)、联合用药二组(PM2)3组,每组15例。P组:异丙酚2 mg·kg-1·h-1;PM1组:异丙酚1.5 mg·kg-1·h 咪达唑仑0.03 mg·kg-1·h-1;PM2组:异丙酚1.5 mg·kg-1·h-1 咪达唑仑0.06 mg·kg-1·h-1。所有病人经异丙酚或异丙酚联合咪达唑仑镇静15 min后,让病人听录音带即内隐记忆刺激。记录入室时(T1)、行硬膜外麻醉后(T2)、静脉给药后15min(T1)、切皮后2min(T4)、内隐记忆刺激完成即刻(T5)等时点的心率(HR)、平均动脉压(MAP)、MLAEP。术后6 h进行记忆调查,测定病人的模糊辨听率。结果 异丙酚镇静Pa、Nb波潜伏期延长、波幅降低(P<0.05),但联合用药组潜伏期延长更明显、波幅降得更低(P<0.05)。所有病人外显记忆均消失;P组均存在内隐记忆,两联合用药组内隐记忆均消失。结论异丙酚和咪达唑仑联合镇静可以消除外显记忆和内隐记忆。MLAEP参数Pa、Nb波潜伏期、波幅可以作为评价术中镇静深度的客观监测指标。     

麻醉诱导期脑电双频指数和听觉诱发电位指数监测的观察比较

全身麻醉是一种特殊而复杂的状态,包括催眠、记忆和意识消失、痛觉消失、应激抑制和肌肉松弛等因素.而麻醉诱导又是病人由清醒状态进入麻醉状态的关键过程,此过程中置人喉镜与插入气管导管又是较强烈的伤害性刺激,常引起剧烈的血流动力学变化,需要一定的麻醉深度才能抑制应激反应的发生.以往对于麻醉深度的判断有多种方法[1～3].近年来随着微机的应用和发展,国内外学者普遍认为中潜伏期听觉诱发电位（MLAEP）和脑电双频指数（BIS）更有价值,更具可靠性.本研究旨在观察BIS和听觉诱发电位指数（AEPindex）两项指标在麻醉诱导期间对于麻醉深度监测的指导作用,同时针对以往镇痛药物对此两项指标的影响报道不多的情况,观察了不同诱导剂量的芬太尼对它们各自的影响.     

听觉诱发电位与双频谱指数监测地氟醚麻醉后苏醒的比较

目的：比较中潜伏期听觉诱发电位（MLAEP）与双频谱指数（BIS）在预计地氟醚麻醉后苏醒的作用。方法：30例择期全麻腹部手术病人，诱导后地氟醚维持麻醉，麻醉停药前3min记录MLAEP和BIS，观察麻醉停药后命令反应时间，拔管时间及达到修正Aldrete计分（MAS）≥时间。结果：MLAEP的Nbi潜伏期和BIS与苏醒各指标相关，但Nb潜伏期能更确切反映地氟醚麻醉后苏醒。结论：NbI潜伏期是反映地氟醚麻醉后苏醒的可靠指标。     

中潜伏期听觉诱发电位在麻醉深度监测中的应用

术中知晓在全麻手术中日益受到重视,研究发现中潜伏期听觉诱发电位(MLAEP)的潜伏期和波幅与麻醉药呈剂量依赖性抑制。本文综述了MLAEP在麻醉深度监测中的应用。     

BIS、AAI麻醉深度监测在七氟烷麻醉中的应用评价

目的：观察并分析围术期应用脑电双频谱指数（BIS）及听觉诱发电位指数（AAI）监测对七氟烷用量及对术毕苏醒时间和拔管时间的影响,并与传统以血流动力学指标来判断麻醉深度组相比较。方法：择期七氟烷全麻下行腹腔镜胆囊切除手术患者45例,ASAⅠ～Ⅱ级．随机分为三组：控制组（根据患者的血压来调节ETsevo。保持血压和心率波动在基础值的±15％）、AAI组（保持术中AAI值维持在15～20）、BIS组（保持术中BIS值维持在45～55）,每组15例。氧流量2L／min。于麻醉诱导前（基础值）．T1．T2、T3,T4、T5和苏醒即刻（T6）记录MAP．HR．SPO2、AAI、BIS和ETsevo,并记录苏醒时间和拔管时间。术毕1小时内取3个时点行OAA／S评分。结果：与AAI组和BIS组相比较,控制组麻醉维持期ETsevo大于其它两组（P〈0．05）。AAI组与BIS组的苏醒时间和拔管时间均较控制组短（p〈0．05）。但是术后1小时内各时点的OAA／S评分三组之间无明显差异。同时．AAI和BIS两组之间无差异。结论：将脑电监测运用于吸入麻醉能在很大程度上减少七氟烷用量,缩短患者麻醉苏醒时间和拔管时间．更有预见性的使用吸入麻醉。     

MLAEP在临床麻醉深度监测中的价值评估

中潜伏期听觉诱发电位（middle latency auditory evoked potentials,MLAEP）是听觉诱发电位（auditory evoked potentials,AEP）的一部分,已作为判断麻醉深度和提示术中知晓的有效方法用于临床,而由MLAEP得出的AAI（A-line ARX Index）临床应用最为广泛.     

BIS和AEPI监测镇静深度的评价

目的比较脑电双频指数（BIS）和听觉诱发电位指数（AEPI）在丙酚靶控镇静深度的临床价值.方法45例腰-硬联合麻醉术中需丙泊酚镇静病人,ASA I级,腰麻平面确定后开始丙泊酚靶控输注镇静.结果（1）丙泊酚镇静期BIS、AEPI逐渐降低,苏醒期逐渐升高（P＜0.01）,而AEPI则在意识转换过程中变化更敏感（P＜0.01）.（2）在丙泊酚镇静期和苏醒期BIS、AEPI与丙泊酚EC密切相关.（3）在丙泊酚镇静期,联合监测当BIS≤63和AEPI≤30时敏感度即可达100%.结论BIS和AEPI是监测麻醉镇静深度的良好指标,BIS和AEPI联合监测提高了诊断的敏感度.     

双频指数和听觉诱发电位在监测麻醉深度中的价值

目的　评估脑电双频指数 (BIS)和中潜伏期听觉诱发电位 (MLAEP)在监测麻醉深度中的价值。方法　 2 1例择期手术患者随机分为Ⅰ组 (对照组 ,n =11)和Ⅱ组 (咪唑安定组 ,n =10 ) ,输入复方乳酸钠液 10ml/kg后 ,以 0 4mg·kg-1·min-1的速度静脉推注丙泊酚 2mg/kg ,在诱导第 4分钟注入维库溴铵 0 1mg/kg、芬太尼 2 μg/kg ,Ⅱ组同时注入咪唑安定 0 0 4mg/kg。记录OAA/S镇静评分、收缩压、舒张压、心率、BIS和反映MLAEP的ARX指数 (ARX Index ,AAI)的基础值 ,以及诱导插管时每分钟的数值。结果　 (1)AAI反应时间较BIS显著缩短 (P <0 0 5 ) ;(2 )OAA/S镇静评分与BIS、AAI显著相关 (r =0 86 0 2、0 85 5 0 ,P <0 0 1) ;(3)Ⅱ组注入咪唑安定后 1分钟 ,AAI较Ⅰ组显著下降 (P <0 0 5 ) ;2分钟后 ,BIS较Ⅰ组显著下降 (P =0 0 0 1) ;(4)Ⅰ组的插管反应大于Ⅱ组 ,插管即刻AAI差异显著 (P =0 0 1) ,插管后 1分钟BIS差异显著 (P <0 0 5 ) ;Ⅱ组在插管前后AAI和BIS均无显著差异。结论　 (1)AAI和BIS均能反映镇静程度和插管反应 ,但AAI反应更快 ,趋于实时监测 ;(2 )联合应用咪唑安定诱导可以抑制插管反应     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents

Abstract Immunoadsorption (1A) therapy with tryptophan (TR-350) or phenylalanine (PH-350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)-immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR-350, and 5 patients were treated with PH-350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR-350; p < 0.04 for PH-350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara-metric test (Wilcoxon's signed-rank test or the Mann-Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.     

Intravenous endotoxin does not increase tissue extravasation of albumin in rats

Background : It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.
Methods : Chloralose anaesthetised male Wistar rats received E. coli lipopolysacharide (LPS), 3 mg kg^-1 i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio-labelled albumin, during the last 2 h of each experiment, was determined by a double-isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.
Main Results : LPS initially decreased MAP and lastingly increased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5-h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).
Conclusion : After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.     

The multiply injured child

Blunt trauma is the principal cause of childhood death in many developed countries. This review outlines the differences between adults and children with respect to resuscitation and treatment of orthopaedic injuries in a child with polytrauma. Recent advances in techniques of fracture stabilization are reported.     

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery: A randomised, double-blind, cross-over study with and without adrenaline

Background: Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture. Methods: A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml · h^?1 of bupivacaine 1 mg · ml^?1, fentanyl 2 μg · ml^?1, and adrenaline 2 μg · ml^?1 were included. On the 1^st and 2^nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score. Results: The number of hypaesthetic dermatomal segments decreased (P <0.001) and pain intensity at rest and when coughing increased (P <0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15–20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng · ml^?1 (P <0.01), and there was more sedation during the period without adrenaline. Conclusions: Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.     

Utilisation des médicaments prokinétiques en réanimation : indications et limites ?

Enteral feeding is often limited by gastric and intestinal motility disturbances in critically ill patients, particularly in patients with shock. So, promotility agents are frequently used to improve tolerance to enteral nutrition. This review summaries the pathophysiology, presents the available pharmacological strategies, the clinical data, the counter-indications and the principal limits. The clinical data are poor. No study demonstrates a positive effect on clinical outcomes. Metoclopramide and erythromycin seems to be the more effective. Considering the risk of antibiotic resistance, the first line use of erythromycin should be avoided in favor of metoclopramide.