不同吸入浓度的七氟烷联合瑞芬太尼对髋关节置换术老年患者术后谵妄的影响

目的观察吸入不同浓度的七氟烷联合瑞芬太尼对接受髋关节置换手术老年患者术后谵妄的影响。方法本课题纳入我院接受髋关节置换手术的老年患者100例,将入选患者分为2组:低浓度组(L组)和高浓度组(H组),每组50名患者。L组的七氟烷吸入浓度为1.5%,H组的七氟烷吸入浓度为3%。术前1 d、术后1 d、术后2 d和术后3 d使用谵妄评定量表中文修订版(CAM-CR)评估谵妄发生情况;分别于麻醉诱导前(T0)、术后1 h(T1)、术后6 h(T2)、术后1 d(T3)抽取外周静脉血,用ELISA法检测S100β蛋白的浓度。结果 H组术后3 d内的POD总发生率明显高于L组(P0.05),H组T1、T2的S100β蛋白水平明显高于L组(P0.05),复苏时间明显延长(P0.05)。结论吸入3%的七氟烷联合瑞芬太尼可导致接受髋关节置换术老年患者术后谵妄的发生率增高,吸入1.5%的七氟烷联合瑞芬太尼的麻醉方式具有较高的安全性。     

术前睡眠质量对老年患者术后谵妄发生的影响

目的探讨术前睡眠质量对老年患者术后谵妄(POD)发生的影响。方法选择择期全凭静脉麻醉下经腹行肿瘤根治术患者,年龄65~86岁,BMI 18~25kg/m2,ASAⅠ-Ⅲ级。术前根据匹兹堡睡眠质量指数(pittsburgh sleep quality index,PSQI)分为睡眠障碍组(≥5分,D组)和睡眠正常组(5分,C组),每组50例,男71例,女29例。两组均采用丙泊酚、舒芬太尼和罗库溴铵进行麻醉诱导和维持,麻醉深度维持在BIS值40~60。记录术中丙泊酚、舒芬太尼、阿托品、麻黄碱、艾司洛尔、硝酸甘油等使用情况,记录麻醉时间、手术时间、PACU停留时间和术后住院时间,记录术后1~5d数字疼痛(NRS)评分和恢复质量评分量表-40(QoR-40)总分。采用意识模糊评定量表(CAM)于术前1d和术后1~5d进行谵妄评估。结果 D组术前PSQI评分明显高于C组(P0.05)。两组患者术中丙泊酚、舒芬太尼用量和血管活性药使用例数差异无统计学意义,麻醉时间、手术时间和PACU停留时间差异无统计学意义。D组术后住院时间明显长于C组(P0.05)。术后1、2和3d,D组NRS评分明显高于C组,QoR-40总分明显低于C组(P0.05)。术后1~5d,两组总计21例(21.0%)发生POD,其中D组15例(30.0%)和C组6例(12.0%),D组POD发生率明显高于C组(P0.05)。D组POD患者的谵妄持续时间明显长于C组(P0.05)。术后2dD组POD发生率明显高于C组(P0.05)。结论术前睡眠障碍可增加老年患者POD发生率并对术后早期恢复质量产生负面影响,应引起重视。     

喷他左辛在老年患者髋关节置换术后镇痛效果观察

目的观察喷他左辛在老年患者髋关节置换术后镇痛的临床疗效。方法本院行髋关节置换术的老年患者60例,随机分为舒芬太尼镇痛组(A组)和小剂量喷他佐辛联合右美托咪定、舒芬太尼镇痛组(B组)各30例。两组髋关节置换术术后均进行静脉自控镇痛术(PCIA),比较两组患者术后疼痛情况、手术当晚睡眠情况、补救性镇痛药物用量、术后5天内并发症发生情况。结果 6、24小时B组VAS评分低于A组(P0.05);B组手术当晚SRSS评分低于A组(P0.05);B组补救性镇痛药用量低于A组(P0.05),两组并发症统计差异无显著性(P0.05)。结论小剂量喷他佐辛、右美托咪定、舒芬太尼镇痛方案可改善患者睡眠质量,镇痛效果好,术后补救性镇痛药物用量少。     

舒芬太尼与瑞芬太尼各自复合丙泊酚静脉麻醉在腹腔镜胆囊切除术的效果比较

目的:比较腹腔镜胆囊切除术(LC)中采用舒芬太尼与瑞芬太尼各自复合丙泊酚静脉麻醉复合丙泊酚静脉麻醉的应用效果。方法:纳入2017年3月―2018年3月行LC的患者90例,随机均分为两组,分别行舒芬太尼复合丙泊酚麻醉(舒芬太尼组)与瑞芬太尼复合丙泊酚麻醉(瑞芬太尼组),比较两组麻醉各时间段的血流动力学指标与血清应激指标、自主呼吸恢复时间、睁眼时间和拔管时间、术后视觉模拟(VAS)评分、术前与术后的简易精神状态量表(MMSE)评分以及麻醉复苏期不良反应情况。结果:与瑞芬太尼组比较,舒芬太尼组在麻醉诱导气管插管即刻、CO_2气腹后5min、拔管即刻的心率与平均动脉压、血清皮质醇与和去甲肾上腺素水平均明显降低(均P0.05);自主呼吸恢复时间、睁眼时间和拔管时间均明显延长(均P0.05);术后2、6、12h的VAS评分均明显降低(均P0.05);术后1d的MMSE评分明显升高(P0.05);总不良反应发生率明显降低(P0.05)。结论:相比瑞芬太尼复合丙泊酚麻醉,舒芬太尼复合丙泊酚静脉麻醉用于LC更有利于维持患者血流动力学稳定,应激反应更小,患者术后痛觉感受更轻,认知功能恢复更快,不良反应少。     

瑞芬太尼复合丙泊酚靶控输注在老年腹腔镜胆囊切除术中的应用

目的探讨瑞芬太尼复合丙泊酚靶控输注在老年腹腔镜胆囊切除术(LC)中的应用效果。方法随机将接受LC的70例老年患者分为2组,每组35例。观察组采用瑞芬太尼复合丙泊酚靶控输注麻醉,对照组采用瑞芬太尼复合丙泊酚持续静脉输注麻醉。通过警觉/镇静评分系统(OAA/S)对麻醉效果进行评定,并比较2组患者的呼吸恢复时间、睁眼时间、拔管时间。结果 2组患者术中、术后各个时间段OAA/S评分差异无统计学意义(P0.05);观察组患者的呼吸恢复时间、睁眼时间、拔管时间均优于对照组,差异有统计学意义(P0.05)。结论老年患者LC时应用瑞芬太尼复合丙泊酚靶控输注麻醉效果优秀,安全性高。麻醉撤药后患者苏醒快,利于老年人术后恢复。     

支气管内超声引导针吸活检术的麻醉方法

目的 观察支气管内超声引导针吸活检术(EBUS-TBNA)的不同麻醉方法的效果,寻求较佳的EBUS-TBNA手术麻醉方法.方法 60例择期EBUS-TBNA手术患者,ASA Ⅰ～Ⅱ级,随机分为3组:舒芬太尼组(S组)、瑞芬太尼组(R组)和舒芬太尼+瑞芬太尼组(SR组),每组20例.麻醉方式采用静脉输注丙泊酚全麻复合TCI舒芬太尼和或瑞芬太尼辅助2％利多卡因局部表面麻醉,术中维持双频谱指数( BIS)50 ～60.记录患者进入手术室后5min(T0)、手术开始后30min( T1)和术毕定向力恢复时(T2)心率、平均动脉压、脉搏氧饱和度及呼吸频率、手术开始后30min动脉血气、术中呛咳次数、丙泊酚和利多卡因用量、术毕至定向力恢复时间、患者满意度和不良反应发生情况.结果 (1)R组T1时呼吸频率下降明显(P＜0.05),S组和R组动脉二氧化碳分压高于SR组(P＜0.05).(2)R组和SR组术中呛咳次数、术毕至定向力恢复时间明显减少(与S组比,P＜0.05).(3)三组患者丙泊酚、利多卡因用量、麻醉满意度及不良反应差异无统计学意义(P＞0.05).结论 静脉输注小剂量舒芬太尼与瑞芬太尼,同时复合丙泊酚静脉全麻并辅助局部麻醉可以满足EBUS-TBNA的手术要求,安全、有效,可作为EBUS-TBNA的常规麻醉方法之一.     

超声引导下胸椎旁连续阻滞对食管癌根治术老年患者术后谵妄的影响

目的观察超声引导下置管连续胸椎旁阻滞(paravertebral block, PVB)用于开胸手术镇痛对患者术后谵妄(postoperative delirium,POD)的影响。方法选择择期在全麻下接受食管癌根治术的老年患者112例,男55例,女57例,年龄65～75岁,BMI 18.5～30 kg/m~2,ASAⅠ或Ⅱ级,随机分为两组:胸椎旁阻滞PVB组(P组)和静脉自控镇痛PCIA组(C组),P组54例,C组58例。P组使用PVB,C组使用舒芬太尼PCIA。记录术后1、2和3 d患者发生POD的情况;术中丙泊酚和瑞芬太尼的用量;患者术后不同时点静息和咳嗽时VAS评分;术后肺不张、恶心呕吐及皮肤瘙痒的发生情况。结果 P组术后POD发生率明显低于C组(P0.05或P0.01);P组术中丙泊酚与瑞芬太尼用量明显少于C组(P0.01);术后不同时点两组静息时VAS评分差异无统计学意义,咳嗽时P组VAS评分明显低于C组(P0.05或P0.01);P组术后肺不张、恶心呕吐和瘙痒发生率明显低于C组(P0.05或P0.01)。结论全身麻醉联合连续胸椎旁阻滞用于老年患者开胸手术镇痛可以提供更充分的术中与术后镇痛,减少麻醉药物使用,降低POD的发生率。     

瑞芬太尼复合丙泊酚用于老年骨科手术患者的麻醉效果

目的探讨瑞芬太尼复合丙泊酚麻醉在老年骨科手术患者中的应用效果。方法随机将92例老年骨科手术患者分为2组,各46例。对照组采用芬太尼复合丙泊酚麻醉,观察组采用瑞芬太尼复合丙泊酚麻醉。结果观察组术后2、4、8 h的MMSE评分均较对照组高,差异有统计学意义(P0.05)。观察组术后呼吸恢复时间、睁眼时间、拔管时间及定向力恢复时间均较对照组短,差异有统计学意义(P0.05)。结论瑞芬太尼复合丙泊酚用于老年骨科手术麻醉,对患者的认知功能影响较小,术后恢复较快。     

氟比洛芬酯复合舒芬太尼镇痛对骨科患者术后谵妄发生率的影响

目的 观察氟比洛芬酯复合舒芬太尼镇痛对骨科患者术后谵妄发生率的影响.方法 拟行择期骨科手术患者370例,年龄≥60岁,随机均分为氟比洛芬酯复合舒芬太尼组(FS组)和脂肪乳复合舒芬太尼组(S组),术后连续3d行PCIA,并随访谵妄的发生(CAM-ICU法)、VAS评分和舒芬太尼使用量.结果 FS组术后谵妄发生率明显低于S组(16.3％ vs.26.2％,RR=0.62,95％ CI 0.41～0.93) (P＜0.05).FS组罹患谵妄的风险是S组的0.57倍(95％ CI 0.34～0.96)(P＜0.05).FS组术后VAS评分及舒芬太尼用量均明显低于S组(P＜0.01).结论 与单纯应用舒芬太尼相比,氟比洛芬酯复合舒芬太尼镇痛能够减少骨科患者术后谵妄的发生率.     

瑞芬太尼或舒芬太尼复合丙泊酚在患儿纤维支气管镜检查中的应用

目的比较瑞芬太尼或舒芬太尼复合丙泊酚用于患儿纤维支气管镜(FOB)检查时的临床效果。方法选择2016年7~8月在本院行FOB检查患儿60例,男37例,女23例,年龄2个月~14岁,体重3.5~45.5kg,ASAⅠ或Ⅱ级,按随机数字表法分为两组:瑞芬太尼组(R组)和舒芬太尼组(S组),每组30例。R组静脉注射瑞芬太尼0.5μg/kg、丙泊酚2.5~3.0mg/kg、咪达唑仑0.5mg;S组静脉注射舒芬太尼0.2μg/kg、丙泊酚2.5~3mg/kg、咪达唑仑0.5mg。记录患儿术中追加麻醉药物情况、纤维支气管镜检查时间及苏醒时间、内镜医师对麻醉效果满意度评分、患儿苏醒期躁动评分等。结果两组患儿丙泊酚消耗量、检查操作时间及苏醒时间差异均无统计学意义。检查过程中,S组躁动发生率(3.3%)明显低于R组(26.7%)(P0.05)。S组苏醒期躁动评分明显低于R组(P0.05);S组内镜医师对麻醉效果满意程度评分明显高于R组(P0.05)。结论瑞芬太尼或舒芬太尼复合丙泊酚可安全用于小儿FOB检查,舒芬太尼复合丙泊酚不良反应发生率更低,并可在一定程度上减轻苏醒期躁动,提高内镜医师对麻醉效果的满意程度。     

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.     

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.     

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.     

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.     

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.