异丙酚靶控输注时瑞芬太尼抑制气管插管反应的半数有效血浆浓度

目的测定异丙酚靶控输注时瑞芬太尼抑制气管插管反应的半数有效血浆浓度。方法择期手术病人20例,瑞芬太尼靶控输注2 min后,输注血浆靶浓度为3 mg·L-1的异丙酚,病人意识消失后给予罗库溴铵行气管插管。瑞芬太尼血浆靶浓度按序贯法确定,相邻血浆靶浓度之间比率为 1．2。结果瑞芬太尼抑制气管插管反应的半数有效血浆浓度为2．6μg·L-1,95％可信区间为2．4- 2．8μg·L-1。结论在复合靶控输注3 mg·L-1异丙酚时,瑞芬太尼抑制气管插管反应的半数有效血浆靶控浓度为2．6μg·L-1。     

丙泊酚麻醉下舒芬太尼抑制气管插管反应的半数有效浓度

目的探讨丙泊酚靶控输注(TCI)时舒芬太尼抑制气管插管反应的半数有效浓度(Ce50)。方法择期全麻手术患者29例,以效应室浓度TCI舒芬太尼,3 min后给予血浆靶浓度为3μg/ml丙泊酚,意识消失后给予维库溴铵0.1 mg/kg。舒芬太尼效应室靶浓度按序贯法确定,舒芬太尼靶控浓度从0.4 ng/ml开始,相邻靶浓度之间比率为1.2。结果丙泊酚3μg/ml麻醉下,舒芬太尼抑制气管插管反应的Ce50为0.32 ng/ml,95%可信区间(CI)为0.3～0.36 ng/ml。结论在复合TCI丙泊酚3μg/ml时,舒芬太尼抑制气管插管反应的Ce50为0.32 ng/ml。     

雷米芬太尼呼吸抑制的半数有效血浆浓度的临床研究

目的测定靶控输注雷米芬太尼引起呼吸抑制的半数有效血浆浓度(Cp50)。方法20例择期手术病人行椎管内阻滞。按序贯法给予雷米芬太尼靶控输注20min,相邻血浆靶浓度之间比率为1·5。测定RR、SpO2、PETCO2及动脉血气。结果雷米芬太尼引起呼吸抑制的Cp50为1·8μg/L,95%可信区间为1·5~2·1μg/L。结论雷米芬太尼引起呼吸抑制的Cp50为1·8μg/L。     

瑞芬太尼引起全麻患者呼吸抑制的量效关系

目的 评价全麻患者靶控输注(TCI)或静脉注射瑞芬太尼引起呼吸抑制的量效关系.方法 择期全麻患者40例,ASA Ⅰ或Ⅱ级,年龄18～60岁,体重45～80 kg.随机分为TCI组和静脉注射组(V组)(n=20).按照序贯法进行试验,TCI组靶控输注瑞芬太尼7 min,相邻血浆靶浓度之间的梯度为70%,分别设为1.7、2.9、4.9和8.3 μg/L,初始靶浓度8.3 μg/L;V组静脉注射时间10 s,相邻靶剂量之间梯度为62%,分别设为0.8、1.3、2.1、3.3和5.3 μg/kg,初始靶剂量5.3 μg/kg.若上一例患者未发生呼吸抑制,则应用高一级的血浆靶浓度或剂量;若发生呼吸抑制,则应用低一级的血浆靶浓度或剂量.发生呼吸抑制的标准为脉搏血氧饱和度≤90%.结果 TCI瑞芬太尼引起呼吸抑制的半数血浆靶浓度为3.97 μg/L,95%可信区间为3.16～4.99 μ/L;静脉注射瑞芬太尼引起呼吸抑制的半数有效剂量为2.50 μg/kg,95%可信区间为1.93～3.24 μg/kg.结论 全麻患者TCI瑞芬太尼引起呼吸抑制的半数血浆靶浓度为3.97 μg/L;静脉注射瑞芬太尼引起呼吸抑制的半数有效剂量为2.50 μg/kg.     

七氟醚麻醉下瑞芬太尼抑制小儿气管插管心血管反应的半数有效血浆靶浓度

目的 确定七氟醚麻醉下瑞芬太尼抑制小儿气管插管心血管反应的半数有效血浆靶浓度(Cp<50).方法 择期全麻手术患儿,年龄2～5岁,ASA Ⅰ或Ⅱ级.初始七氟醚吸入浓度为8%,氧流量3 L/min,待患儿意识消失后调整七氟醚吸入浓度,使呼气末七氟醚浓度为2.5%(1 MAC),2 min后采用Minto药代动力学模型靶控输注瑞芬太尼,10 min后进行气管插管.瑞芬太尼血浆靶浓度按序贯法确定,瑞芬太尼血浆靶浓度从6μg/L开始,相邻浓度的比值为1.2,气管插管心血管反应的标准:插管后2 min内MAP和/或HR较插管前升高≥15%.结果 瑞芬太尼抑制气管插管心血管反应的Cp50为3.6μg/L,95%可信区间为3.1～4.0μg/L.结论 七氟醚1 MAC麻醉下瑞芬太尼抑制小儿气管插管心血管反应的Cp50为3.6 μg/L,95%可信区间为3.1～4.0μg/L.     

瑞芬太尼抑制气管内表面麻醉时呛咳反射的半数有效血浆浓度

目的 测定咪达唑仑镇静下瑞芬太尼抑制气管内表面麻醉时呛咳反射的半数有效血浆浓度(CP50).方法 择期经鼻气管插管手术患者24例,静注咪达唑仑60μg/kg5 min后,靶控输注瑞芬太尼,达目标靶浓度后行环甲膜穿刺表麻及经鼻气管插管.观察有无呛咳反射及插管反应发生.瑞芬太尼血浆靶浓度按序贯法确定,相邻血浆靶浓度之间的比率为1.2.结果 瑞芬太尼抑制经环甲膜穿刺注药时气管呛咳反射的Cp50为1.8 μg/L,95%可信区间(CI)为1.5～2.2μg/L.结论 复合咪达唑仑60μg/kg镇静时,瑞芬太尼抑制气管内表面麻醉时呛咳反射的Cp50为1.8μ/L(95%CI 1.5～2.2μg/L).     

重症肌无力患者无肌松药下靶控输注丙泊酚时舒芬太尼诱导气管插管的半数有效浓度

目的 研究靶控输注(TCI)丙泊酚时舒芬太尼复合气管内表面麻醉,在无肌松药下诱导重症肌无力(MG)患者气管插管所需的半数有效浓度.方法 拟行经胸骨正中劈开胸腺切除术的MG患者20例,AsA Ⅰ或Ⅱ级.麻醉诱导丙泊酚采用血浆浓度(Cp)TCI,维持3.5μg/ml不变;舒芬太尼采用效应室浓度(Ce)TCI,按序贯法确定浓度,依次为0.15、0.23、0.34、0.50 ng/ml等比递增,相邻效应室靶浓度之间比例为1.5.复合气管内表面麻醉后行气管插管.监测诱导、插管过程中的血压,心率和脑电双频指数(BIS).结果 50%患者完成插管时舒芬太尼的浓度为0.23 ng/ml,95%的可信区间为0.20～0.27 ng/ml.结论 MG患者在不使用肌松药和复合气管内表面麻醉的情况下完成气管插管,丙泊酚血浆靶浓度为3.5 μg/ml,舒芬太尼半数有效效应室靶浓度为0.23 ng/ml.     

舒芬太尼诱发患者呼吸抑制的药效学与年龄因素的关系

目的 评价舒芬太尼诱发患者呼吸抑制的药效学与年龄因素的关系.方法 择期拟行腹部手术患者40例,ASA分级Ⅰ或Ⅱ级,根据年龄不同分为中青年组(25～64岁,M组)和老年组(65～80岁,E组),每组20例.采用序贯法进行试验,靶控输注舒芬太尼,M组和E组初始效应室靶浓度分别设为0.40、0.35μg/ml,相邻靶浓度之比为0.9,发生呼吸抑制,则下一例患者采用低一级浓度,否则采用高一级浓度.呼吸抑制的诊断标准:VT≤5 ml/kg、RR≤8次/min、SpO2≤94%、PETCO2≥55mmHg和/或呼吸暂停≥15 s.计算舒芬太尼诱发患者呼吸抑制的半数有效浓度(EC50)及其95%可信区间(95%CI).结果 M组和E组舒芬太尼诱发患者呼吸抑制的EC50及其95%CI分别为0.61(0.54～0.70)μg/ml、0.41(0.38～0.45)μg/ml,E组EC50低于M组(P＜0.05).结论 舒芬太尼诱发呼吸抑制的效力与年龄因素有关,老年患者对舒芬太尼诱发呼吸抑制更敏感.     

丙泊酚复合瑞芬太尼抑制人工流产扩宫时体动反应25例的研究

目的:研究丙泊酚复合瑞芬太尼抑制人工流产扩张宫颈时体动反应的半数有效效应室靶浓度.方法:25例拟实施人工流产术患者,经静脉靶控输注瑞芬太尼复合丙泊酚,丙泊酚维持效应室靶控浓度5.4 μg/mL,瑞芬太尼效应室靶控浓度从0.7 μg/L开始,相邻靶浓度比值为1.2.结果:25例患者镇静深度满意,术中无知晓;当瑞芬太尼效应室靶控浓度升高到2.51 μg/L时,出现第1例无体动反应.其中2例出现呼吸抑制,3例出现血压下降超过基础值的30%,2例出现心率减慢.结论:瑞芬太尼复合效应室靶浓度为5.4 μg/mL丙泊酚时,抑制人工流产患者扩宫时体动反应的EC50为2.17 μg/L,95%可信区间为1.92～2.45 μg/L.     

七氟醚吸入诱导下瑞芬太尼抑制喉罩插入反应的半数有效血浆靶控浓度

目的 探讨1.7％七氟醚(1.0 MAC)吸入诱导下瑞芬太尼抑制喉罩插入反应的半数有效血浆靶控浓度(Cp50).方法 择期乳腺纤维瘤手术患者,年龄22～59岁,ASA Ⅰ或Ⅱ级.初始七氟醚吸入浓度为8％,氧流量4L/min,待患者意识消失后调整挥发罐浓度使七氟醚呼气末浓度为1.7％(1.0 MAC),维持3 min后靶控输注(TCI)瑞芬太尼,待计算效应室浓度等于血浆靶控浓度时行喉罩插入.瑞芬太尼血浆靶浓度按序贯法确定,起始浓度为6 ng/ml,相邻浓度比值为1.2.结果 最终有36例患者纳入本研究.TCI瑞芬太尼抑制喉罩插入反应的Cp50为1.91 ng/ml,95％可信区间(CI)为1.75～2.10 ng/ml.结论 七氟醚吸入诱导下TCI瑞芬太尼抑制喉罩插入反应的Cp50为1.91 ng/ml,95％CI为1.75～2.10 ng/ml.     

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.     

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.     

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.     

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.     

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.     

Anesthésie générale chez l’enfant : quid des pratiques en 2010 ?

Introduction

The practice of pediatric anesthesia requires a regular update of scientific knowledge and technical skills. To provide the most adequate Continuing Medical Education programs, it is necessary to assess the practices of pediatric anesthesiologists. Thus, the objective of this survey was to draw a picture of the current clinical practices of general anesthesia in children, in France.

Material and methods

One thousand one hundred and fifty questionnaires were given to anesthesiologists involved in pediatric cases. These questionnaires collected information on various aspects of clinical practice relative to induction, maintenance, recovery from general anaesthesia and also classical debated points such as children with Upper Respiratory Infection (URI), emergence agitation, epileptoid signs or anaesthetic management of adenoidectomy. Differences in practices between CHG (general hospital), CHU (teaching hospital), LIBERAL (private) and PSPH (semi-private) hospitals were investigated.

Results

There were 1025 questionnaires completed. Fifty-five percent of responders worked in public hospitals (CHG and CHU); 77% had a practice that was 25% or less of pediatric cases. In children from 3 to 10 years: 72% of respondents used always premedication and two thirds performed inhalation induction in more than 50% of cases. For induction, 53% used sevoflurane (SEVO) at 7 or 8%. Respondents from LIBERAL used higher SEVO concentrations. Tracheal intubation was performed with SEVO alone (37%), SEVO and propofol (55%) and SEVO with myorelaxant (8%), 93% of respondents used a bolus of opioid. For maintenance, the majority of respondents used SEVO associated with sufentanil; desflurane and remifentanil were more frequently used in CHU. Two thirds of respondents used N₂O. Depth of anesthesia was commonly assessed by hemodynamic changes (52%), end tidal concentration of halogenated (38%) or automated devices based on EEG (7%). In children with URI, 98% of respondents used SEVO for anesthesia. To control the airway 42% used a tracheal tube, 30% a laryngeal mask and 20% a facial mask. Emergence agitation was an important concern for two thirds of respondents, while epileptoid signs were considered as important by only 20%. Eighty-nine percent of respondents practiced anesthesia for adenoidectomy. Anesthesia was induced by inhalation of SEVO 7–8% (41%), 6% (39%) or 4% (12%), 66% put an intravenous line (less frequently in LIBERAL). 67% of the responders managed adenoidectomy without any device to control the airway (more frequently in LIBERAL), 32% administrated a bolus of opioid (less frequently in LIBERAL).

Discussion

This survey demonstrated that the practices regarding general anesthesia in children are relatively homogenous. Most of the differences appeared between LIBERAL and the others structures; the anaesthetic management for adenoidectomy illustrates these findings.     

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.