右美托咪定通过腺苷A1受体调节大鼠压力反射敏感性

目的观察腺苷A1受体在右美托咪定调节压力反射敏感性(baroreflex sensitivity,BRS)中的作用。方法健康成年雄性SD大鼠32只,体重240~280g,按随机数字表随机分为四组:对照组(C组)、选择性腺苷A1受体阻断剂组(P组)、右美托咪定组(D组)、选择性腺苷A1受体阻断剂+右美托咪定组(PD组),每组8只。C组泵注生理盐水40 ml·kg~(-1)·h~(-1)负荷量15 min,维持泵注10 ml·kg~(-1)·h~(-1);P组腹腔注射选择性腺苷A1受体阻断剂8-环戊基-1,3-二丙基黄嘌呤(DPCPX)1mg/kg,泵注同C组方案的生理盐水;D组右美托咪定负荷量100μg/kg,维持量100μg·kg~(-1)·h~(-1)持续泵注;PD组腹腔注射DPCPX 1mg/kg并泵注右美托咪定,泵注剂量同D组。采用苯肾上腺素升压法于泵注前(T_0)、泵注后60min(T_1)和泵注后120min(T_2)测定BRS。结果与T_0时比较,T_1和T_2时D组和PD组BRS明显升高(P0.05)。与C组和P组比较,T_1和T_2时D组和PD组BRS均明显升高(P0.05)。与D组比较,T_1和T_2时PD组BRS明显降低(P0.05)。结论右美托咪定可能通过腺苷A1受体增加大鼠BRS。     

右美托咪定复合布托啡诺在剖宫产术后镇痛的应用

目的研究右美托咪定复合布托啡诺用于剖宫产术产妇自控静脉镇痛(PCIA)的安全性和临床效果。方法选择择期硬膜外麻醉下行剖宫产术产妇60例,年龄24～43岁,身高153～171cm,体重53～93kg,ASAⅠ或Ⅱ级,采用随机数字表法将产妇分为两组(n=30)。对照组(C组):胎儿娩出断脐后静脉给予生理盐水30ml,术后PCIA(布托啡诺3μg·kg~(-1)·h~(-1),背景输注速率2ml/h,每次按压0.5ml,锁定时间10min);右美托咪定组(D组):胎儿娩出断脐后静脉给予右美托咪定0.5μg/kg,术后PCIA(布托啡诺3μg·kg~(-1)·h~(-1)复合右美托咪定0.05μg·kg~(-1)·h~(-1),背景输注速率2ml/h,每次按压0.5ml,锁定时间10min)。记录术后6、12、24和48h安静、运动和宫缩状态下的VAS评分;术后48h内产妇泌乳后取乳汁,采用高效液相色谱质谱联用法(HPLCMS/MS)测定乳汁中右美托咪定浓度并计算相对婴儿摄取量(RID);记录术后产妇满意度以及不良反应的发生情况。结果与C组比较,D组在术后6、12、24h安静、运动和宫缩状态下VAS评分明显降低(P0.05),D组在术后48h运动VAS评分明显降低(P0.05);D组产妇满意度明显高于C组(P0.05);D组右美托咪定RID值为(0.197±0.114)%;两组术后均未发生低血压、低氧血症、呼吸抑制、心动过缓以及恶心和呕吐等不良反应。结论健康产妇围术期使用右美托咪定可安全哺乳。术后镇痛使用布托啡诺复合0.05μg·kg~(-1)·h~(-1)右美托咪定能够提供满意的镇痛效果。     

右美托咪定复合乌司他丁对老年胃肠肿瘤切除术患者术后谵妄的影响

目的观察右美托咪定复合乌司他丁对老年患者行腹腔镜下胃肠肿瘤切除手术术后谵妄(POD)的影响。方法选择2015年9月至2016年1月择期行腹腔镜下胃肠肿瘤切除术患者180例,男97例,女83例,年龄65~80岁,ASAⅡ或Ⅲ级,采用随机数字表法随机分为四组:右美托咪定组(D组)、乌司他丁组(U组)、右美托咪定+乌司他丁组(DU组)和生理盐水组(C组),每组45例。麻醉诱导前,D组给予右美托咪定负荷剂量0.5μg/kg,输注15min后以0.3μg·kg~(-1)·h~(-1)持续泵注,手术结束前40min停止输注;U组静注乌司他丁10 000U/kg,15~20min内完成;DU组先静注乌司他丁10 000U/kg,15~20min内完成,再给予右美托咪定负荷剂量0.5μg/kg,输注15min后以0.3μg·kg~(-1)·h~(-1)持续泵注,手术结束前40min停止输注;C组给予等容量生理盐水。记录手术时间、术中出血量、尿量和补液量;于术前1d(T0)、手术开始(切皮)后1h(T_1)、术后第1天(T_2)、术后第2天(T_3)、术后第3天(T_4)采血检测多巴胺(DA)、肾上腺素(AD)、去甲肾上腺素(NE)浓度;T_0和T_2~T_4时由精神科医师采用谵妄评定量表中文修订版(CAM-CR)对患者谵妄情况进行评估,记录谵妄的发生例数。结果与T_0时比较,T_1~T_4时U组和C组DA、AD和NE浓度明显升高,T_1时D组和DU组的DA浓度明显升高,T_1、T_2时D组和DU组的AD浓度明显升高(P0.05);T_2~T_4时D组和DU组DA和AD浓度明显低于C组和D组,T_1~T_4时D组和DU组的NE浓度明显低于C组和D组(P0.05)。D组、U组和DU组POD发生率明显低于C组(P0.05);D组、U组和DU组POD发生率差异无统计学意义。结论单独使用右美托咪定或乌司他丁可以降低老年患者腹腔镜下胃肠肿瘤切除手术POD发生率,两种药物复合使用并不能进一步降低POD发生率。     

右美托咪定对剖宫产围术期体温及并发寒颤的影响

目的探讨右美托咪定对于蛛网膜下腔阻滞后剖宫产术围术期体温变化和寒颤的影响。方法选取2017年8—12月急诊或择期行剖宫产手术的足月单胎妊娠孕妇80例,年龄23～45岁,妊娠38～40周,ASAⅠ或Ⅱ级,随机分为右美托咪定组(D组)和对照组(C组),每组40例。胎儿娩出断脐后,D组给予右美托咪定0.5μg·kg~(-1)·h~(-1)至缝皮结束,C组则给予生理盐水0.125 ml·kg~(-1)·h~(-1)作为对照。记录产妇麻醉前(T_1)、断脐后(T_2)、术毕(T_3)及返回病房(T_4)时的膀胱温,并于以上时点采用Wrench寒颤分级法评估寒颤强度分级。术后采用状态焦虑量表对产妇进行焦虑评分。结果与T_1时比较,T_2—T_4时两组膀胱温明显降低(P0.05)。两组不同时点膀胱温差异无统计学意义。T_3、T_4时D组寒颤强度分级明显低于C组(P0.05)。D组术后焦虑评分明显低于C组[(41.1±10.6)分vs (51.6±13.1)分,P0.05]。结论右美托咪定对预防蛛网膜下腔阻滞后剖宫产患者围术期寒颤和焦虑具有显著效果,但并不能改变患者围术期的低体温率。     

不同剂量右美托咪定对腹腔镜下胃肠手术老年患者围术期应激反应的影响

目的观察不同剂量右美托咪定对腹腔镜下胃肠手术老年患者围术期应激反应的影响。方法择期行腹腔镜下胃肠手术老年患者80例,性别不限,年龄≥65岁,ASAⅠ或Ⅱ级。随机分为四组,每组20例。所有患者均采用全凭静脉麻醉。D1、D2组和D3组麻醉诱导前10min静脉泵注右美托咪定0.5μg/kg,插管后分别静脉泵注右美托咪定0.2、0.5、0.8μg·kg~(-1)·h~(-1)至术毕前30min;C组麻醉诱导前10min静脉泵注7ml生理盐水,插管后静脉泵注生理盐水10ml/h至术毕前30min。记录术中麻醉药物用量,记录给药前(T_0)、气管插管后即刻(T_1)、气腹后5min(T_2)、气腹后60min(T_3)、拔管后即刻(T_4)和拔管后10min(T_5)的HR、SBP、DBP,分别于T_0、T_1、T_3、T_5时抽取桡动脉血,测定Glu、Cor、E和NE浓度。结果 D1组、D2组和D3组术中瑞芬太尼的用量明显少于C组,且D2组和D3组明显少于D1组(P0.05)。与T_0时比较,T_1~T_5时C组HR明显增快(P0.05)。T_2~T_5时,D2组和D3组的HR明显慢于C组和D1组,SBP明显低于C组(P0.05);T_1时D2组和D3组Cor和NE浓度也明显低于C组(P0.05)。T_3和T_5时,D2组和D3组Glu、Cor、E和NE浓度明显低于C组,D2组和D3组Cor和NE浓度明显低于D1组(P0.05)。结论与0.2和0.8μg·kg~(-1)·h~(-1)右美托咪定静脉泵注维持比较,0.5μg·kg~(-1)·h~(-1)能更有效抑制腹腔镜下胃肠手术老年患者围术期应激反应。     

右美托咪定用于预防腹腔镜胆囊切除术后恶心呕吐的效果

目的观察右美托咪定预防腹腔镜胆囊切除术后恶心呕吐的效果。方法选择择期行腹腔镜胆囊切除术的患者70例,男17例,女53例,年龄20~65岁,ASAⅠ或Ⅱ级。随机分为两组:右美托咪定组(R组)和地塞米松组(D组),每组35例。R组于麻醉诱导前静脉注射右美托咪定,背景剂量为0.5μg/kg,10min内注射完毕,后以0.5μg·kg~(-1)·h~(-1)维持输注。D组给予地塞米松8mg静脉注射。观察患者入室(T_1)、插管前(T_2)、插管后5min(T_3)、手术开始后5 min(T_4)、手术开始后30min(T_5)、缝皮时(T_6)、拔管后5min(T_7)的血压和心率。记录术中七氟醚的吸入浓度、停七氟醚至拔管的时间、手术时间及麻醉时间。观察患者8、24、48h内有无发生恶心呕吐。结果两组患者术后8、24、48h的恶心发生率和呕吐发生率差异无统计学意义。T2~T7时R组HR明显低于D组(P0.05),两组间MAP差异无统计学意义。结论与静脉注射地塞米松8mg比较,静脉注射右美托咪定负荷量0.5μg/kg(10min),维持量0.5μg·kg~(-1)·h~(-1),对减少腹腔镜胆囊术后恶心呕吐的发生有相同的效果。     

不同剂量右美托咪定复合舒芬太尼在老年患者肝癌射频消融术中的应用

目的探讨右美托咪定复合舒芬太尼0.3μg/kg在老年患者肝癌射频消融术(radio frequency ablation,RFA)中的适宜应用剂量。方法选择择期行RFA患者60例,男53例,女7例,年龄65～84岁,BMI 18.1～35.4kg/m2,ASAⅡ或Ⅲ级,Child-Pugh A或B级,随机分为三组,每组20例。射频治疗前20min开始泵注右美托咪定,D1组:0.3μg·kg~(-1)·h~(-1);D2组:0.5μg·kg~(-1)·h~(-1);D3组:0.7μg·kg~(-1)·h~(-1),同时给予舒芬太尼0.3μg/kg缓慢静滴。于入室时(T_0)、给药20min时(T_1)、消融开始时(T_2)、消融开始后10min时(T_3)和术毕时(T_4)测定Ramsay评分。记录术毕、术后2、4、8、16h的VAS评分;记录依托咪酯、硝酸甘油、乌拉地尔和纳洛酮用量;记录术中知晓、呼吸道梗阻、穿刺针移位和肝被膜下血肿、一过性高血压、低血压、心动过缓和口干等不良反应情况。结果与T_0时比较,T_2和T_3时D2和D3组Ramsay评分明显升高(P0.05);与D1组比较,D2、D3组术后2、4和8hVAS评分明显降低(P0.05),D2和D3组依托咪酯、硝酸甘油、乌拉地尔用量明显减少(P0.05);与D2组比较,D1组术中知晓明显增多(P0.05),D3组纳洛酮用量明显增多(P0.05),D3组呼吸道梗阻、一过性高血压、心动过缓发生率明显增多(P0.05)。结论右美托咪定0.5μg·kg~(-1)·h~(-1)复合舒芬太尼0.3μg/kg在老年RFA中可提供良好的清醒镇痛效果,减少呼吸道梗阻等不良反应的发生,是较为合理的临床用药剂量。     

右美托咪定对丙泊酚或七氟醚全麻患者脑状态指数的影响

目的观察右美托咪定对全麻患者脑状态指数的影响。方法选择择期上腹部手术的全麻患者80例,男39例,女41例,年龄25~65岁,ASAⅠ或Ⅱ级。所有患者分为四组:丙泊酚组(P组),靶控输注丙泊酚血浆浓度3.0~4.0μg/ml;丙泊酚+右美托咪定组(PD组),靶控输注丙泊酚血浆浓度1.5~2.5μg/ml,右美托咪定0.5μg/kg,输注5 min,再持续输注0.6μg·kg~(-1)·h~(-1);七氟醚组(S组),吸入1.5%~2.5%七氟醚;七氟醚+右美托咪定组(SD组),吸入1%~1.5%七氟醚,右美托咪定0.5μg/kg,输注5min,再持续输注0.6μg·kg~(-1)·h~(-1)。术中所有患者镇静指数维持在45~55。分别于麻醉前、右美托咪定持续输注30、60min测定脑状态指数(记忆加工指数、谵妄指数)。结果麻醉前四组脑状态指数差异无统计学意义。右美托咪定持续输注30、60 min时PD组记忆加工指数和谵妄指数均明显低于P组(P0.05),SD组均明显低于S组(P0.05)。结论全麻中复合应用右美托咪定能够降低患者的脑状态指数。     

右美托咪定复合舒芬太尼静脉镇痛对剖宫产术后镇痛效果及产后抑郁的影响

目的观察右美托咪定复合舒芬太尼对剖宫产术后镇痛效果、产后抑郁发生情况以及脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)的影响。方法择期行剖宫产产妇60例,年龄25~35岁,ASAⅠ或Ⅱ级,采用随机数字表法分为右美托咪定复合舒芬太尼组(D组)和舒芬太尼组(S组)。D组静脉泵注右美托咪定1μg·kg~(-1)·h~(-1)至术毕,接镇痛泵(舒芬太尼0.02μg/kg+右美托咪定0.08μg/kg+阿扎司琼20mg+生理盐水稀释至105ml);S组静脉泵注生理盐水1μg·kg~(-1)·h~(-1)至术毕,接镇痛泵(舒芬太尼0.02μg/kg+阿扎司琼20mg+生理盐水稀释至105ml)。术后4h(T1)、8h(T2)、12h(T3)、24h(T4)、48h(T5)分别采用视觉模拟评分(VAS)、Ramsay镇静评分法评价疼痛、镇静程度,并记录术毕(T0)至术后各时间段镇痛泵有效按压次数。记录术后48h不良反应发生率。根据爱丁堡产后抑郁量表(Edinburgh postnatal depression scale,EPDS)分别记录产妇术后1周和6周的EPDS评分。检测产后1周和6周的血清BDNF浓度。结果 T2,T4和T5时D组VAS评分明显低于S组(P0.05);T0—T4各时间段D组镇痛泵有效按压次数明显少于,术后恶心呕吐发生率明显低于S组(P0.05)。产后1周和6周D组EPDS评分明显低于,BDNF浓度明显高于S组(P0.05)。结论右美托咪定明显增加舒芬太尼在剖宫产术后的镇痛作用,减轻产后抑郁的程度,EPDS与剖宫产术后抑郁病情正相关,BDNF似可作为预测术后产后抑郁发生及临床疗效评定生物指标。     

右美托咪定对异体肾移植患者围术期肾功能的影响

目的研究右美托咪定对同种异体肾移植患者围术期肾功能的影响。方法选择行同种异体肾移植患者60例,男36例,女24例,年龄25~45岁,ASAⅡ或Ⅲ级,随机分为两组:右美托咪定组和对照组,每组30例。右美托咪定组麻醉诱导前给予右美托咪定1μg/kg泵注10min,随后以0.6μg·kg~(-1)·h~(-1)维持泵注至手术结束前30min;对照组以等容量生理盐水维持至手术结束前30min。记录两组患者在麻醉诱导前(T_1)、吻合血管开放前(T_2)、吻合血管开放后即刻(T_3)、吻合血管开放后30min(T_4)和手术结束后(T_5)的HR和SBP,于T_2、T_4、术后24h(T6)及术后48h(T7)采取静脉血检测血尿素氮(BUN)、血肌酐(Cr)、IL~(-1)8和半胱氨酸蛋白酶抑制剂C(Cys C)的浓度;记录术中液体输注量和尿量。结果 T_3时右美托咪定组HR明显慢于对照组;T_2、T_3时右美托咪定组SBP明显高于对照组(P0.05)。与T_2时比较,T6、T7时两组Cys C、BUN、Cr浓度明显降低,且T7时右美托咪定组Cys C浓度明显低于对照组(P0.05)。与T_2时比较,T6、T7时两组IL~(-1)8浓度明显降低,且右美托咪定组降低幅度明显大于对照组(P0.05)。右美托咪定组围术期尿量明显多于对照组(P0.05)。两组术中液体输注量差异无统计学意义。结论围术期应用右美托咪定可有效保护肾移植患者的肾功能。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.