Growth of Escherichia coli in propofol, lidocaine, and mixtures of propofol and lidocaine

BACKGROUND: Microorganisms grow rapidly in propofol. Extrinsic contamination of propofol is thought to be a source of postoperative sepsis and wound infection. We studied growth of a strain of Escherichia coli in thiopental, propofol, lidocaine, and mixtures of propofol and lidocaine. METHODS: The pathogen was exposed to 2.5% thiopental; 1.0% propofol; 1.0%, 2.0% and 4.0% preservative-free lidocaine; and propofol solutions containing 0.25%, 0.5%, 1.0%, 2.0%, or 4.0% lidocaine for 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 h at room temperature, respectively. The inocula from these suspensions were cultured for 48 h at 37 degrees C after the antimicrobial activity of the local anesthetics in the inocula was inactivated by a 1:1000 dilution with distilled water. RESULTS: No organisms grew after exposure to 2.5% thiopental. The exposure of E. coli to propofol increased the colony count to approximately 90 times the control count. The colony counts of E. coli after exposure to 1.0%, 2.0% and 4.0% lidocaine and 0.25%, 0.5%, 1.0%, 2.0% and 4.0% lidocaine in 1.0% propofol were lower than the counts after exposure to 1.0% propofol (P = 0.0048, 0.0027, 0.0003, 0.0503, 0.0188, 0.0080, 0.0044, and 0.0001, respectively). The growth rate of the microorganism was significantly higher in cultures exposed to 1.0% propofol than that in cultures exposed to lidocaine alone or lidocaine-propofol mixtures (P < 0.0001, respectively). CONCLUSION: Lidocaine possesses bacteriostatic activity against E. coli. Addition of lidocaine to propofol confers its bacteriostatic activity to the mixture and may decrease the hazard of infection associated with the extrinsic contamination of propofol.     

Hepatic clearance of drugs. II. Experimental evidence for acceptance of the “well-stirred” model over the “parallel tube” model using lidocaine in the perfused rat liverin situ preparation

Theoretical analysis of two models of hepatic drug clearance revealed that one powerful discriminator between them is the effect of changes of hepatic blood flow on either the emergent drug concentration or the availability of a highly extracted compound when operating under linear conditions. Lidocaine (extraction ratio 0.997) was employed in the discriminatory studies. The behavior of this drug under linear conditions (input lidocaine concentrations < 5 mg/ liter) to changes in hepatic blood flow rate (10–16 ml/min per liver) was examined in the perfused rat liver in situpreparation. The steady-state output lidocaine concentration in the blood leaving the liver was predicted better by a well-stirred model than by a parallel tube model. As anticipated, the clearance of a poorly extracted compound, antipyrine (extraction ratio 0.08),was unaltered by changes in hepatic blood flow. These experimental findings, and the data from the literature, point to the acceptance of the well-stirred model, which describes the liver as a well-stirred compartment with the drug in the hepatic venous blood being in equilibrium with that in the liver.Supported in part by National Institutes of Health Grant GM 16496 and the Patent Fund, Graduate Division, University of California, San Francisco.Abstracted in part from a dissertation submitted by K. Sandy Pang to the Graduate Division, University of California, San Francisco, California, in partial fulfillment of the Doctor of Philosophy degree requirements.     

Towards a pain-free venepuncture

A randomised, prospective trial was conducted to assess the efficacy of various means of alleviating the pain of subcutaneous lidocaine infiltration. One hundred and twenty-two patients were randomly allocated to different groups to receive buffered lidocaine 1%, warmed lidocaine 1% or infiltration by the counter-irritation technique. A visual analogue pain score was recorded at different stages of cannulation and results showed that pain scores were significantly lower in the group receiving buffered lidocaine 1% (p < 0.02) and in the counter-irritation group (p < 0.05). Thus buffering lidocaine 1% and administration of lidocaine 1% by the counter-irritation technique is effective in relieving the pain of lidocaine infiltration.     

The incidence of transient neurological symptoms after spinal anaesthesia with lidocaine compared to prilocaine

The purpose of this double-blind study was to investigate the incidence of transient neurological symptoms after the use of isobaric lidocaine and isobaric prilocaine for spinal anaesthesia. Seventy patients (ASA 1-2, age between 18 and 70 years) were randomly assigned to two groups of 35 patients each, to receive either isobaric 2% lidocaine 4 ml or isobaric 2% prilocaine 4 ml intrathecally, at the L3-4 interspace. One patient in the prilocaine group could not be included because data were incomplete. On the first postoperative day, patients were evaluated for transient neurological symptoms. Pain was scored on a 10-point scale. Seven patients (20%) in the lidocaine group had transient neurological symptoms with a mean pain score of 5.3, whereas no patient in the prilocaine group had these complaints (p = 0.006). Symptoms disappeared within 4 days. Prilocaine results in a lower incidence of transient neurological symptoms than lidocaine intrathecally and therefore it is more suitable for short surgical procedures.     

系数倍率法测定膀胱镜检表面麻醉剂中盐酸利多卡因的含量

目的：研究不经提取直接测定膀胱镜检表面麻醉剂中盐酸利多卡因的含量。方法：采用系数倍率法，选择测定的波长为270nm和280nm。结果：盐酸利多卡因线性关系良好，r=0．9993,，平均回收率为100．1％。结论：该方法可靠、简便、准确，可作为医院制剂的质量控制。     

利多卡因——卵磷脂微乳处方的初步研究

目的 :以卵磷脂微乳为载体 ,制备利多卡因透皮给药系统。方法 :伪三元相图考察油包水型微乳形成区域 ;测定微乳黏度 ,正交分析法筛选微乳处方 ;紫外分光光度法直接测定微乳中盐酸利多卡因浓度。结果 :助表面活性剂的种类和Km(表面活性剂 /助表面活性剂用量比 )对微乳形成区域有显著性影响 ,正丙醇和异丙醇所形成的微乳区较大 ;低纯卵磷脂微乳形成区域较高纯卵磷脂大 ;醇的种类对微乳的黏度均有显著的影响 ,Km 对微乳的黏度有较大影响。选定紫外检测波长为 2 6 2nm ,盐酸利多卡因浓度在 0 .0 2～ 0 .5mg/mL范围内线性关系良好 (R =0 .9999)。平均回收率 ( 10 0 .17± 0 .16 ) %。日内差与日间差分别为 0 0 137±0 0 12 1,0 0 119± 0 0 115。结论 :选择混合表面活性剂利于制备微乳 ,醇的种类与用量对于利多卡因透皮微乳体系处方的选择具有重要意义。     

针刺对急性心肌梗死合并室性心律失常60例临床对照研究

[目的]探讨针刺对急性心肌梗死合并室性心律失常的疗效及其机制。[方法]采用临床对照设计方案,治疗组与对照组人数之比为1:1,观察60例急性心肌梗死合并室性心律失常患者,治疗组采用针刺治疗,特定针刺手法和选穴,对照组采用利多卡因,按常规剂量静脉推注和静脉点滴。[结果]治疗组和对照组疗效无显著差别(P>0.05)。[结论]针刺治疗急性心肌梗死合并室性心律失常与利多卡因疗效相近,认为急性心肌梗死合并心律失常患者基本病因为:“心脉不畅,心神失养”;本质是“心血瘀阻,心神失调”;病属虚实夹杂证。同时确立了治疗大法为“理气通脉,养心安神”。     

利多卡因对免蛛网膜下腔出血后脑血管痉挛的防治

目的：研究枕大池注入利多卡因是否能缓解蛛网膜下腔出血后脑血管的痉挛。方法：30只新西兰大白兔随机分为假手术组、蛛网膜下腔出血组出血组、利多卡因治疗组（治疗组），每组10只。出血组和治疗组的动物于枕大池注入自体动脉血1．5ml，假手术组注入1．5ml生理盐水，30min后假手术组和出血组的动物从枕大池注入0．1ml生理盐水，治疗组注入0．1 ml 2％利多卡因。72h后观察脑基底动脉管腔面积，另测定术前和72h后血浆中的内皮素（ET）和降钙基因相关肽（CGRP）。结果：各组术前的血浆ET，CGRP无显著差别（P〉0．05）；术后72h出血组的血浆ET高于假手术组和治疗组（P〈0．05），各组术后血浆ET比术前高（P〈0．01或P〈0．001）；术后72h血浆CGRP没有统计学差别（P〉0．05），与术前比较，假手术组和出血组的术后CGRP低于术前水平（P〈0．01或P〈0．001）；出血组的血管腔面积低于假手术组和治疗组（P〈0．001）。结论：枕大池注入利多卡因能减轻兔蛛网膜下腔出血后脑血管痉挛。     

小儿围手术期利多卡因连续硬膜外镇痛与芬太尼静脉镇痛的比较

目的:对小儿患者全麻联合硬膜外麻醉及术后镇痛与全麻后芬太尼静脉给药镇痛效果进行比较.方法:将91例行下肢手术的小儿患者随机分为硬膜外利多卡因组(n=61)及静脉芬太尼组(n=30).在手术过程中,控制呼气末安氟醚浓度,使患儿血压及心率变化范围维持在术前数值的10%以内.术后6,24 h,测定家长视觉模拟量表(PVAS)、目标疼痛评分(OPS)、恶心及呕吐的发生率.结果:硬膜外利多卡因组安氟醚用量显著低于静脉芬太尼组(P＜0.05).硬膜外利多卡因组6 h后目标疼痛评分(OPS)显著低于静脉芬太尼组.6,24 h后硬膜外利多卡因组家长视觉模拟量表(PVAS)评分显著低于静脉芬太尼组.两组术后恶心及呕吐发生率没有显著差异.结论:全麻联合硬膜外麻醉与单独全麻相比呼气末安氟醚浓度显著降低.小儿术后,持续硬膜外自控镇痛与芬太尼静脉自控镇痛相比,患儿硬膜外自控镇痛术后疼痛评分显著降低,两组均无严重并发症.