七氟醚与异氟醚对老年患者持续输注顺式阿曲库铵肌松效应的影响

目的 比较吸入等效浓度七氟醚和异氟醚麻醉下对老年患者持续输注顺式阿曲库铵肌松效应的影响.方法 全麻下行耳鼻喉或颌面外科手术老年患者60例,随机均分为三组.七氟醚组(S组)和异氟醚组(Ⅰ组)分别吸入等效浓度(呼气末浓度1 MAC)七氟醚和异氟醚维持麻醉,对照组(C组)靶控输注丙泊酚(血浆靶浓度为2～3 μg/ml)维持麻醉,同时三组均持续输注顺式阿曲库铵,使T1稳定在基础值的10％,采用TOF-Watch SX肌松监测仪行拇内收肌肌松监测.记录初始剂量顺式阿曲库铵起效时间、术中输注速率、恢复指数(T1恢复25％至75％)和TOFr恢复至0.9的时间.结果 给药30 min后各时点S组和Ⅰ组顺式阿曲库铵输注速率小于C组(P＜0.05).给药45 min后各时点I组顺式阿曲库铵输注速率高于S组(P＜0.05).结论 等效浓度七氟醚和异氟醚麻醉下均能增强老年患者持续输注顺式阿曲库铵的肌松效应.     

丙泊酚-七氟醚静吸复合麻醉对阿曲库铵药效学的影响

目的 观察七氟醚对阿曲库铵肌松效应的影响.方法 68例择期腹部手术的全麻患者,ASA Ⅰ或Ⅱ级,年龄18～67岁,随机均分为丙泊酚-七氟醚静吸复合麻醉组(七氟醚组)和丙泊酚静脉麻醉组(对照组).监测腩电双频指数(BIS),使用加速度肌松监测仪刺激前臂尺神经,观察拇内收肌的收缩反应,记录阿曲库铵的起效时间、无反应时间、肌松维持时间以及恢复指数等指标.结果 两组肌松起效时间、无反应时间以及T1 25%时间差异无统计学意义,但七氟醚组25%四个成串刺激比(TOFr)恢复时间、恢复指数及拔管时间均比对照组明显延长(P<0.05).结论 七氟醚麻醉能明显增强阿曲库铵的肌松效应.     

异氟醚、地氟醚对维库溴铵残余肌松作用的影响

目的　观测异氟醚、地氟醚对维库溴铵的残余肌松作用的影响。方法　选择 4 9例ASAⅠ～Ⅱ级成年择期全麻手术病人 ,随机分为三组 :丙泊酚组 (Ⅰ组 ,18例 ) ;异氟醚组 (Ⅱ组 ,17例 ) ;地氟醚组 (Ⅲ组 ,14例 )。全麻诱导气管插管后维库溴铵均以 90 μg·kg-1·h-1的速度静脉泵入。Ⅰ组丙泊酚泵入速度为 4～ 10mg·kg-1·h-1;Ⅱ组、Ⅲ组分别吸入呼气末浓度为 1MAC的异氟醚或地氟醚 ,使用Biometer加速度仪观测T1恢复至 2 5 %、75 %及TOF比值 (T4/T1)恢复至 0 7的时间。结果　三组间病人的性别、年龄、体重、身高、芬太尼总量、麻醉持续时间、血液动力学变化均无显著性差异 (P >0 0 5 )。上述恢复时间 ,Ⅱ组、Ⅲ组与Ⅰ组比较均延长 ,有显著差异 (P <0 0 5 ) ;Ⅱ、Ⅲ组比较差别无统计学意义 (P >0 0 5 )。三组间恢复指数 (T1从 2 5 %～ 75 %时间 )比较无显著差异 (P >0 0 5 )。结论　异氟醚、地氟醚均可延长维库溴铵的残余肌松作用 ,但两者比较无明显差别。临床应用中应注意监测四个成串刺激 (TOF)等 ,减少术后残余肌松作用所致的并发症     

七氟醚复合瑞芬太尼对老年患者维库溴铵药效的影响

目的研究七氟醚与瑞芬太尼静-吸复合全麻下老年患者维库溴铵的肌松效应。方法择期行腹腔镜胆囊切除术患者30例,ASAⅠ或Ⅱ级,按年龄分为老年组(65～80岁)和青年组(25～45岁),每组15例。七氟醚和瑞芬太尼诱导后,维持七氟醚呼气末浓度1.0MAC,瑞芬太尼0.05～0.1μg·kg-1·min-1持续输注。维持PETCO2 35～38mmHg。观察T1最大抑制时间(起效时间),T1恢复至25%的时间(T125%)、T1恢复至50%的时间(T150%)、恢复指数(RI)、TOFr(T4/T1)=0.7的时间。结果老年组起效时间、T125%、T150%、RI、TOFr(T4/T1)=0.7的时间均明显长于青年组(P<0.05)。结论老年患者吸入七氟醚全身麻醉中,适当减小维库溴铵的剂量即能达到满意的肌松效果,使患者术后肌力尽早恢复,提高老年患者围术期麻醉安全。     

七氟醚对罗库溴铵肌松效应的影响

目的 观察七氟醚对罗库溴铵肌松作用的影响.方法 成人全麻手术患者60例随机均分为三组.每组20例.Ⅰ组丙泊酚静脉麻醉,Ⅱ组吸入七氟醚(1 MAC)15 min,Ⅲ组吸入七氟醚(1 MAC)45 min.在麻醉平稳(Ⅱ、Ⅲ组在呼气末七氟醚浓度稳定在1 MAC)后静脉注射罗库溴铵0.6 mg/kg,记录TOFr的变化.结果 Ⅱ、Ⅲ组罗库溴铵的起效时间分别为97.60 s和94.50 s,明显短于Ⅰ组的119.90 s(P<0.05);Ⅱ和Ⅲ组完全肌松时间(T1消失)明显长于Ⅰ组(32.7 min和44,6 min vs.21.3 min)(P<0.05),Ⅲ组明显长于Ⅱ组(P<0.05);TOF的T2～T4出现的时间及TOFr恢复到25%、50%和75%的时间,Ⅱ、Ⅲ组均长于Ⅰ组,且Ⅲ组长于Ⅱ组(P<0.05).结论 持续吸入1 MAC七氟醚能随吸人时间延长而增强罗库溴铵的神经肌肉阻滞效应.     

七氟醚对罗库溴铵肌松效应的影响

目的 研究吸入不同浓度的七氟醚对不同剂量的罗库溴铵肌松效应的影响.方法 90例择期手术患者随机均分为六组.记录各组静注罗库溴铵后其起效时间、四个成串刺激(TOF)无反应时间、T1 25%恢复时间、T1 75%恢复时间及恢复指数(T1 25%恢复到75%的时间).结果 静注等效剂量的罗库溴铵Ⅲ组与Ⅰ组、Ⅳ组与Ⅱ组比较,起效时间差异无统计学意义.而静注等效剂量的Ⅴ组与Ⅰ组、Ⅵ组与Ⅱ组比较,起效时间明显缩短(P＜0.05);在无反应时间、T1 25%恢复时间、T1 75%恢复时间及恢复指数上,复合吸入七氟醚的Ⅲ到Ⅵ组较注入等效剂量的罗库溴铵Ⅰ组与Ⅱ组比较均有明显的延长(P＜0.05或P＜0.01);Ⅱ组与Ⅲ组之间以及Ⅳ组与Ⅴ组之间罗库溴铵的肌松维持时间差异无统计学意义.结论 七氟醚能明显延长罗库溴铵的作用时间,有时间依赖及剂量依赖趋势.     

七氟醚对顺式阿曲库铵肌松效应的影响

目的 研究七氟醚对顺式阿曲库铵肌松效应的影响.方法 60例腹部手术患者随机均分为三组,气管插管后效应室靶控输注丙泊酚(P组)、1.7%七氟醚(S1组)或2.2%七氟醚(S2组)15 min后注入2Ed95的顺式阿曲库铵,待T1恢复至5%左右后接微量泵,手动调节顺式阿曲库铵输注速率,维持T1在3%～5%,记录顺式阿曲库铵的起效时间、T1恢复至5%的时间、每30分钟的输注速率、T1 25%和75%恢复时间及恢复指数.结果 与P组比较,S1组和S2组的起效时间明显缩短,T1恢复到5%的时间明显延长,输注30、60、90 min时的速率明显减慢(P＜0.01),S1组与S2组T1的25%和75%恢复时间明显延长(P＜0.05或P＜0.01);与S1组比较,S2组的起效时间明显缩短(P＜0.01),输注60 min时的速率明显减慢(P＜0.05),与输注30 min时的速率比较,S1组和S2组在输注60、90 min时的速率均减慢(P＜0.05).结论 七氟醚能明显延长顺式阿曲库铵的作用时间,有时间依赖及剂量依赖趋势.     

不同浓度异氟醚对罗库溴铵肌松作用的影响

目的 观察不同浓度异氟醚对罗库溴铵肌松作用的影响。方法 60例ASA Ⅰ-Ⅱ择期手术患者,随机分为3组,每组20例。组Ⅰ静脉注射罗库溴铵0.6 mg·kg-1;组Ⅱ吸入0.6％异氟醚后静脉注入罗库溴铵0.6mg·kg-1;组Ⅲ吸入1.2％异氟醚后从静脉注入罗库溴铵0.6mg·kg-1。分别记录各组注药后肌松作用的起效时间、作用时间及T1恢复时间。结果 与组Ⅰ相比,组Ⅱ、Ⅲ起效时间明显缩短(P<0.05),TOF无反应期明显延长(P<0.01),T1恢复25％、50％、90％时间明显延长(P<0.01),且组Ⅲ较组Ⅱ延长(P<0.05),恢复指数明显延长,且组Ⅲ较组Ⅱ延长(P<0.05)。结论 吸人异氟醚能明显缩短罗库溴铵起效时间,延长罗库溴铵作用时间,临床合并使用时应注意减少用量。     

性别因素对七氟醚增强顺阿曲库铵或罗库溴铵肌松效应的影响

目的 探讨性别因素对七氟醚增强顺阿曲库铵或罗库溴铵肌松效应的影响.方法 择期全麻手术患者240例,年龄20～60岁,ASA分级Ⅰ或Ⅱ级,BMI 20～30 kg/m2,随机分为2组(n=120):顺阿曲库铵组和罗库溴铵组,各组按性别和麻醉药再分4个亚组(n=30):女性异丙酚组、男性异丙酚组、女性七氟醚组和男性七氟醚组.各异丙酚组靶控输注异丙酚,血浆靶浓度2～6 μg/ml,各七氟醚组吸入七氟醚,于靶控输注或待呼气末七氟醚浓度稳定于1.71%5 min后,静脉注射顺阿曲库铵0.15 mg/kg或罗库溴铵0.6 mg/kg.记录肌松起效时间、肌松作用峰值时间、T1 25%恢复时间和TOFR25%恢复时间.结果 与异丙酚麻醉比较,女性患者七氟醚麻醉时,罗库溴铵TOFR 25%恢复时间延长,顺阿曲库铵肌松作用峰值时间、T1 25%恢复时间和TOFR 25%恢复时间延长,男性患者七氟醚麻醉时,罗库溴铵起效时间缩短,肌松作用峰值时间、T1 25%恢复时间和TOFR 25%恢复时间延长,顺阿曲库铵肌松作用峰值时间、T1 25%恢复时间和TOFR 25%恢复时间延长(P＜0.05或0.01);七氟醚麻醉时与男性患者比较,女性患者罗库溴铵T1 25%恢复时间和TOFR 25%恢复时间缩短,顺阿曲库铵起效时间缩短(P＜0.05或0.01).结论 七氟醚对罗库溴铵肌松的增强作用存在性别差异,男性强于女性;对顺阿曲库铵肌松的增强作用无明显性别差异.     

儿童七氟醚、异氟醚及全静脉麻醉中罗库溴铵的恢复时程

目的 比较罗库溴铵气管插管剂量在儿童七氟醚、异氟醚和全静脉麻醉中恢复时程的差异.方法 51例2～14岁儿童随机均分为七氟醚组(S组)、异氟醚组(I组)和全静脉麻醉组(P组).静脉给予罗库溴铵O.6 mg/kg,比较T1恢复至基础值10%、25%、75%的时间(T10、T25、T75)和恢复指数(RI=T75-T25)在不同麻醉方式下的差异.结果 三组儿童T10、T25差异无统计学意义.I组T75和RI长于P组(P＜0.05),S组与P组比较有延长趋势,但差异无统计学意义.S组与I组所有时点差异均无统计学意义.结论 儿童罗库溴铵气管插管剂量,在七氟醚、异氟醚和全静脉麻醉下的临床作用时间差异无统计学意义,异氟醚麻醉下肌松作用完全恢复时间较在全静脉麻醉下显著延长.     

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 Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

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.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

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.     

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.