俯卧位联合仰卧位切开复位内固定治疗三踝骨折的疗效分析

目的探讨仰卧位联合俯卧位切开复位内固定治疗三踝骨折的手术方法及疗效。方法纳入自2012-01—2017-04诊治的72例三踝骨折,19例取仰卧位手术(A组),21例取健侧卧位联合仰卧位手术(B组),32例取俯卧位联合仰卧位手术(C组)。外踝骨折采用解剖或重建钢板固定,内踝骨折采用螺钉固定,后踝骨折采用螺钉或钢板固定。结果 72例均获得随访,随访时间平均18(6~24)个月。3组手术时间比较差异有统计学意义(P0.05),其中C组手术时间较A组与B组短,B组手术时间较A组短。3组术中出血量比较差异有统计学意义(P0.05),其中C组术中出血量较A组与B组少,B组术中出血量较A组少。但3组骨折愈合时间及末次随访时AOFAS评分比较差异无统计学意义(P0.05)。结论三踝骨折采用仰卧位、健侧卧位联合仰卧位、仰卧位联合俯卧位切开复位内固定均可获得满意的疗效,但在仰卧位联合俯卧位下复位固定三踝骨折更直观,手术操作更简单,创伤更小。     

俯卧位与可调节斜卧位对腰椎间盘切除术中腹内压及出血量的影响

目的:比较俯卧与可调节斜卧手术体位对腰椎间盘突出症患者手术过程中腹内压力及术中出血量的影响。方法:选择2007年10月～2009年10月全麻下行腰椎间盘突出症手术患者156例,随机分为两组,其中俯卧位患者78例(A组),可调节斜卧位患者78例(B组)。分别在全麻诱导后(仰卧位)5min、摆放体位后5min和手术结束时测量两组患者气道阻力值,通过尿管测量膀胱内压力来间接反映腹内压力值,记录两组患者的手术时间、术中出血量,并进行对比分析。结果:A组患者手术时间、术中出血量及术中平均单位时间出血量分别为74.4±13.8min、288.7±105.9ml和3.8±0.7ml/min,B组分别为59.2±10.0min、178.1±58.6ml和3.0±0.5ml/min,两组间比较有显著性差异(P0.05)。A组术前仰卧位时的腹内压平均值为765±167Pa,摆放体位后为1063±194Pa,手术结束时为1074±191Pa;B组分别为788±170Pa、809±176Pa和817±186Pa。A组术前仰卧位时的气道阻力为14.1±1.2cmH2O,摆放体位后为17.3±1.9cmH2O,手术结束时为17.6±2.0cmH2O;B组分别为14.2±1.5cmH2O、14.9±1.5cmH2O和15.0±1.6cmH2O。两组术前仰卧位时的气道阻力及腹内压无明显差异(P0.05);A组摆放体位后及手术结束时的腹内压力及气道阻力明显大于术前仰卧位(P0.05),同时A组摆放体位后及手术结束时的腹内压及气道阻力明显大于B组(P0.05)。A组术中出血量与摆放体位后腹内压力有显著相关性(r=0.772,P=0.000),而B组术中出血量与摆放体位后腹内压力无显著相关性(r=0.287,P=0.174)。结论:采用可调节斜卧位行后路腰椎间盘切除术可以降低术中胸腹部受压的几率,减少术中出血量,缩短手术时间。     

单开门椎板成形术联合椎间孔切开术治疗脊髓型合并神经根型颈椎病疗效分析

目的评价颈后路单开门椎管成形术联合椎间孔切开术在治疗颈椎管狭窄症合并单侧神经根型颈椎病中的作用。方法回顾性研究2006年7月至2009年1月44例颈椎管狭窄症合并单侧神经根压迫症状患者,行颈后路单开门椎管成形术联合椎间孔切开术治疗的23例患者为A组,单纯行颈后路单开门椎管成形术治疗的21例患者为B组。引起椎间孔狭窄的原因:椎间盘突出、钩椎关节骨赘形成、关节突增生。神经根症状主要表现为单侧上肢疼痛、感觉减退、肌力下降和反射减弱。A组手术为颈后路单开门椎管成形术联合椎间孔切开术,关节突内侧缘切除范围均小于等于50%;B组仅行颈后路单开门椎管成形术。结果术后随访20～36个月,平均28个月。采用日本骨科协会评分法计算两组髓性症状术后改善率,差异无统计学意义;根性症状术后临床效果评价:A组优18例,良3例,一般2例;B组优7例,良3例,一般9例,差2例。结论对合并有单侧神经根型的颈椎管狭窄症患者,采用颈后路单开门椎管成形术联合椎间孔切开术可取得良好的手术效果。     

两种颈后路单开门手术方法对颈椎曲度指数及活动度的影响

[目的]探讨两种颈后路单开门手术方法对术后患者神经功能改善率、颈椎曲度指数、颈椎活动度的影响及其临床意义.[方法]自2008年6月～2011年9月,78例脊髓型颈椎病患者接受颈后路单开门椎管扩大成形术.A组41例患者行改良术式,即保留颈半棘肌肌止,切除C3椎板,C4-7“锚定法”单开门椎管扩大成形术.B组37例患者行传统C3-7单开门椎管成形术.计算两组患者神经功能改善率及术前术后颈椎曲度指数、颈椎活动度的变化,研究两组间差异.[结果]两组患者术后神经功能改善恢复率,A组为(57.5±19.4)％,B组为56.3±19.8％,两组间差异无统计学意义,术后颈椎曲度指数丢失百分比,A组丢失(2.86±2.44)％,B组丢失(5.31±2.12)％,B患者手术前后颈椎曲度指数丢失明显多于A组.术后颈椎活动度,A组患者术后丢失(8.27±5.03).,B组患者术后丢失(11.06±6.97)°,两组差异有统计学意义(P＜0.01).[结论]保留颈半棘肌肌止,C3椎板切除,C4-7“锚定法”单开门椎管扩大椎管成形术,与传统术式相比具有同样的神经功能改善率,同时能有效防止颈椎曲度指数及颈椎活动度的丢失.     

T_1斜坡角度与颈后路单开门椎管扩大成形术后颈椎曲度变化关系的探讨

[目的]探讨测量T1斜坡(T1Slope)角度与颈后路单开门椎管扩大成形术后颈椎曲度变化的关系。[方法]本组96例病例均进行颈后路单开门椎管扩大成形术,术前测量T1Slope角度及C2~7Cobb角度。随访12~42个月,术后再次测量C2~7Cobb角度。96例患者术前根据T1Slope角度均值(26.07°)分为两组,26.07°为A组,26.07°为B组。了解T1Slope角度与术前及术后C2~7Cobb角度是否存在统计学意义,继而推断出术前测量T1Slope角度与颈后路术后颈椎曲度变化的关系。[结果]本组病例T1Slope角度与全体样本C2~7Cobb角度之间存在线性相关,并存在正相关(r=0.77,P0.05)。A组术后发生颈椎前凸角度丢失倾向较B组大,差异具有明显统计学意义(t=7.20,P0.05)。两组JOA评分术后改善率无明显差别;两组术后Odom’s分级评价,A组优良率为57.14%,B组优良率为83.33%,两组相比差异有统计学意义(x2=84.96,P0.05)。[结论]T1Slope是一种与SVAC2密切相关的测量方法,T1Slope角度与C2~7Cobb角度存在正相关,对颈椎矢状位平衡方面的评估起着重要的作用;对于颈后路单开门椎管扩大成形术患者,术前有较大的T1Slope,术后有更大的发生前凸角度丢失的可能,可作为术前预判术后颈椎曲度改变的一个参数。     

超声骨刀与高速磨钻在颈后路单开门椎管扩大成形术中的应用对比

目的对比分析超声骨刀与高速磨钻应用于颈后路单开门椎管扩大成形术的有效性与安全性。方法回顾性分析2014年10月至2015年12月在南方医科大学南方医院行颈后路单开门椎管扩大成形术的32例颈椎椎管狭窄症患者的临床资料,其中超声骨刀组11例、高速磨钻组21例。对比分析两组手术节段、手术时间、术中出血量、术后引流量、日本骨科学会(JOA)评分、JOA改善率、围术期并发症发生率等指标。结果超声骨刀组和高速磨钻组手术时间、术中出血量分别为(150±22)min和(169±35)min、(191±116)m L和(216±123)m L,两组比较,差异无统计学意义(P0.05);超声骨刀组术后引流量为(164±84)m L,低于高速磨钻组的(236±93)m L(P0.05)。两组患者术后神经功能明显改善,JOA评分均优于术前(P0.05),但两组术后JOA评分、改善率及改善优良率比较,差异均无统计学意义(P0.05)。超声骨刀组术中出现1例硬膜撕裂,两组均未出现脑脊液漏及伤口感染病例。结论颈后路单开门椎管扩大成形术中应用超声骨刀具有术后引流少和相对高效的优点,其安全性和有效性与高速磨钻相似。     

3节段与5节段微型钛板固定行后路单开门颈椎管扩大成形术的手术情况及疗效比较

目的在多节段脊髓型颈椎病(Cervical spondylotic myelopathy,CSM)行颈后路单开门椎管扩大成形术治疗中,比较3节段与5节段微型钛板固定的手术情况及疗效。方法回顾性分析自2015年7月-2018年3月采用该术式治疗的CSM患者73例,按微型钛板固定方式分成两组:A组43例,仅对C_3、C_5、C_7节段行微型钛板固定; B组30例,术中对C_3-C_7节段均行钛板固定。对比两组患者的手术情况、医疗费用和临床疗效。结果与B组相比,A组患者的手术时间显著缩短,术中出血量亦显著减少,手术费用显著降低,差异均有统计学意义(P0.05)。A、B两组患者术后1个月和1年的JOA评分均显著升高(P0.05),但术后的JOA改善率组间差异均无统计学意义(P0.05)。B组术后3个月和1年的颈椎曲度显著小于A组(P0.05),组间颈椎活动度的变化差异无统计学意义(P0.05)。两组术后3个月内的轴性症状分级和总发生率差异均无统计学意义(P0.05)。结论微型钛板联合颈后路单开门椎管扩大成形术治疗多节段CSM可取得良好疗效; 3节段"跳跃式"固定有助于缩短手术时间、减少出血量,并显著降低手术费用,具有明显优势。     

颈椎管成形术与椎板切除内固定术后C5神经根麻痹比较

目的 比较颈后路单开门椎管成形术与椎板切除内固定术治疗多节段脊髓型颈椎病术后颈5(C5)神经根麻痹的发生率,并分析其原因.方法 2005年1月至2010年6月,因多节段颈脊髓病变分别接受椎管成形术的患者27例(A组):男21例,女6例;年龄33～80岁,平均60.4岁;减压3～6个节段.同期接受椎板切除内固定术的患者41例(B组):男31例,女10例;年龄22～77岁,平均58.7岁;减压3-6个节段.术后随访12～46个月(平均22个月);两组手术前后以Cobb法测量颈椎前凸角度,以Ishihara法测定颈椎曲度指数(cervical curvature index,CCI),并记录术后C5神经根麻痹的发生情况.比较B组中9例C5神经根麻痹患者(B1组)与32例无C5神经根麻痹患者(B2组)的手术前后颈椎前凸角度及CCI.结果 A组C5神经麻痹发生率为3.7％( 1/27),B组发生率为22.0％(9/41),差异有统计学意义(x2=4.32,P＜ 0.05),10例C5神经根麻痹患者平均于术后14个月肌力恢复至4级以上.B1组手术前后CCI改变率为38.07％±18.03％,B2组为22.81％±12.71％,两组差异有统计学意义(t=2.88,P＜0.05).结论 相比颈后路椎板切除内固定术,椎管成形术后C5神经根麻痹发生率低.C5神经根麻痹可能与颈后路术后颈椎前凸增加有关,神经根拴系效应是其重要的发病机制之一.     

C3～C7与C3～C6节段单开门椎管扩大成形术后轴性痛的差异

目的:研究保留C7棘突、椎板及其附着颈后肌群能否减少单开门椎管扩大成形术后轴性痛的发生。方法:纳入2010年4月～2011年4月在我院接受开门节段为C3～C6(A组,26例)或C3～C7(B组,27例)颈后路单开门椎管扩大成形术的患者53例,记录随访时(通过门诊和电话随访)两组病例神经功能恢复及颈椎活动度变化情况,同时比较两组患者术后轴性痛发生的时间、初始疼痛程度VAS评分及完全缓解所需时间的差异。结果:两组患者术后1年随访时JOA评分、神经功能改善率、颈椎活动度及颈椎活动度改变率均无明显统计学差异(P>0.05)。A组轴性痛的发生率为30.7%(8/26),其中轻度5例,中度3例;B组发生率为33.3%(9/27),其中轻度4例,中度4例,重度1例,两组轴性痛发生率和初始疼痛程度分级均无明显统计学差异(P>0.05)。A组病例初始VAS评分平均为3.0分,B组为4.4分,两组间差异有显著性(P<0.05);A组病例疼痛出现时间平均为术后57.3d,B组为25.4d,两组间差异显著(P<0.05);A组疼痛完全缓解的时间为术后99.1d,B组为165.9d,两组间有统计学差异(P<0.05)。结论:与传统C3～C7颈后路单开门椎管扩大成形术相比,C7棘突、椎板及其后方附着颈后肌群的保留并不影响术后颈椎活动度和神经功能的恢复,且可以降低初始轴性痛的VAS评分,并延迟轴性痛发生时间、减少完全缓解所需时间,可提高患者生活质量。     

颈椎后路成形术保留C7韧带复合体的术后比较研究

目的讨论保留C7棘突上肌肉韧带复合体的单开门椎管扩大成形术是否可以延迟和降低轴性症状的发生。方法回顾性分析行颈后路单开门椎管扩大成形术节段为C3-6（A组,24例）和C3-7（B组,25例）的49例的临床资料。结果术后1年JOA评分、神经功能改善率、颈椎活动度改变率差异无统计学意义（P〉0.05）。轴性症状的发生率、初始VAS评分、轴性疼痛术后出现时间差异有统计学意义（P〈0.05）。结论保留C7棘突上肌肉韧带复合体与传统C3-7颈后路单开门椎管扩大成形术相比,不影响神经功能恢复和颈椎活动度,且可以降低轴性症状的发生率、初始轴性症状疼痛程度,并可以延迟轴性症状发生时间从而提高患者生活质量。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

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.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

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.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

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.