超声引导下竖脊肌平面阻滞和胸椎旁神经阻滞用于胸腔镜下肺叶切除术的比较

目的比较超声引导下竖脊肌平面阻滞(erector spinae plane block,ESPB)和胸椎旁神经阻滞(thoracic paravertebral nerve block,TPVB)应用于胸腔镜下肺叶切除术中血流动力学变化及术后联合PCIA的效果。方法选择行胸腔镜下肺叶切除术的患者60例,男38例,女22例,年龄18~64岁,BMI 18~24 kg/m^2,ASAⅠ或Ⅱ级,随机分为ESPB组(E组)和TPVB组(T组),每组30例。E组术前0.4%罗哌卡因25 ml行超声引导下单次ESPB,T组术前0.4%罗哌卡因25 ml行单次TPVB。罗哌卡因注入20 min后用冰块测定阻滞平面。术毕两组均给予PCIA至术后48 h。记录穿刺时间、深度;记录术中血管活性药使用情况、丙泊酚、瑞芬太尼用量;记录镇痛泵首次按压时间、有效按压次数、曲马多补救例数;记录胸闷、皮肤瘙痒等术后不良反应的发生情况。结果与T组比较,E组穿刺时间明显缩短(P<0.05),穿刺深度明显变浅(P<0.05),术中去氧肾上腺素使用率明显降低(P<0.05)。两组术中丙泊酚、瑞芬太尼用量、镇痛泵首次按压时间、有效按压次数、曲马多补救率及术后不良反应差异无统计学意义。结论超声引导下ESPB较TPVB操作更简单快捷,术中低血压发生率更低,术后两种阻滞联合PCIA均能为胸腔镜肺叶切术患者提供有效的镇痛。     

超声引导下腹横肌平面阻滞技术对腹部手术后镇痛的效果

目的观察超声引导下腹横肌平面阻滞技术对腹部手术后镇痛的效果。方法选择64例开腹手术患者,按照随机数字表法分为观察组和对照组,各32例。观察组采用腹横肌平面阻滞(TAPB)+自控静脉镇痛(PCIA)镇痛,对照组行单纯PCIA镇痛。记录2组患者术后清醒拔管即刻(T_0)、2 h(T_1)、6 h(T_2)、12 h(T_3)、24 h(T_4)各时间点的Prince-Henry评分及Ramsay镇静评分。记录穿刺相关并发症及术后各时段镇痛装置按压次数。记录患者满意度及不良反应。结果观察组T_0、T_1、T_2时点Prince-Henry评分明显小于对照组(P0.05)。2组患者不同时间点的Ramsay镇静评分差异均无统计学意义(P0.05)。观察组未发生穿刺相关并发症,术后6 h内镇痛泵按压次数明显少于对照组(P0.05),呕吐发生率明显低于对照组(P0.05),镇痛满意度高于对照组(P0.05),差异均有统计学意义。结论超声引导下腹横肌平面阻滞技术可降低腹部手术后6 h内Prince-Henry评分,减少术后镇痛药物的用量及并发症,术后镇痛满意度高。     

达米弱刺激通气型口垫在全身麻醉患者苏醒期的应用

目的观察达米弱刺激通气型口垫(达米口垫)作为一种创新型过渡性口咽通气道在麻醉苏醒期的安全性和有效性。方法选取行气管插管全身麻醉腹部手术且拔管后出现意识未完全恢复清醒、伴有舌后坠或呼吸不畅的患者200例,男153例,女47例,年龄26～66岁,体重42～91 kg,ASAⅠ—Ⅲ级。随机分为四组:达米口垫组(D组)、口咽通气道组(K组)、鼻咽通气管组(B组)和传统托颌组(C组),每组50例。拔管后气道管理措施:D组经口置入达米弱刺激通气型口垫;K组置入口咽通气道;B组经鼻置入鼻咽通气道;C组出现气道梗阻情况时予以托颌通气处理。记录拔除气管导管前即刻(T_0)、拔管后5 min(T_1)、拔管后10 min(T_2)、拔管后15 min(T_3)的血流动力学指标(HR、BP、SpO_2)、血气分析指标(PaCO_2、PaO_2、pH值);记录通气道留置时间、调整通气道次数,以及PACU停留时间、拔管后通气过程中舒适度。记录不良反应的发生情况。结果与D组比较,T_1时C组HR明显增快(P0.05),T_2时K组、C组HR明显增快(P0.05),T_3时K组HR明显增快(P0.05),T_2、T_3时K组、B组MAP明显升高(P0.05),T_3时B组、C组PaCO_2明显升高(P0.05),T_1—T_3时K组、B组、C组PaO_2明显降低(P0.05),T_2时C组、T_3时B、C组pH值明显升高(P0.05)。与T_0时比较,T_1时四组HR明显减慢,MAP明显降低(P0.05),T_2时D组HR减慢,D组、B组MAP明显降低(P0.05),T_3时K组、B组HR明显增快,MAP明显升高(P0.05),T_1—T_3时四组PaO_2、pH值明显降低,PaCO_2明显升高(P0.05)。四组不同时点SpO_2差异无统计学意义。与D组比较,K组通气道留置时间和调整通气道次数明显增多(P0.05),C组PACU停留时间明显延长(P0.05),K组、C组拔管后舒适度明显降低(P0.05)。C组躁动发生率明显升高(P0.05)。结论达米弱刺激通气型口垫在气管插管全身麻醉恢复期能够有效维持呼吸道的通畅,具有循环影响小、舒适度高、不良反应小等优点,优于传统口咽、鼻咽通气道。     

硫酸镁预处理对单肺通气所致缺血再灌注肺损伤的影响

目的观察硫酸镁预处理对单肺通气缺血再灌注所致肺损伤的保护作用。方法择期在胸腔镜下行肺叶切除术患者80名,随机分为硫酸镁组(M组,n=40)和对照组(C组,n=40)。硫酸镁组给予硫酸镁静脉输注,对照组给予等量生理盐水。分别于麻醉诱导前1分钟(T_0)、单肺通气前1分钟(T_1)、单肺通气结束前1分钟(T_2)、双肺通气30分钟(T_3)时测定血清丙二醛(MDA)的浓度;从患侧肺叶取小块正常肺组织,测定该肺组织血红素氧合酶(HO-1)的含量;术后2h抽取桡动脉血1ml作血气分析,计算氧合指数。结果 T_3时刻血清MDA浓度M组低于C组(P0.05),术侧肺叶组织HO-1浓度M组高于C组(P0.05),术后2小时时肺氧合指数M组高于C组(P0.05)。结论硫酸镁预处理对单肺通气患者的缺血再灌注损伤具有保护作用,其机制可能与上调肺组织HO-1的表达水平,抑制细胞脂质过氧化反应有关。     

允许性高碳酸血症对单肺通气后肺功能及萎陷侧肺炎症反应的影响

目的观察允许性高碳酸血症对胸腔镜下肺叶切除术患者单肺通气后肺功能及萎陷侧肺炎症反应的影响。方法拟于胸腔镜下行肺叶切除术的患者50例,ASAⅡ或Ⅲ级,年龄38~65岁。患者随机分为两组,每组25例。术中维持PaCO_235~45mm Hg(C组)和55~65mm Hg(H组)。分别于单肺通气前1min(T_1)、单肺通气后30min(T_2)、萎陷肺复张后30min(T_3)抽取动脉血5ml,行动脉血气分析并计算呼吸指数(RI);收集外周静脉血及萎陷侧肺下叶肺泡灌洗液,检测TNF-α、IL-6和IL-10水平;记录气道峰压、潮气量、气道平台压,并计算动态肺顺应性(Cdyn)。结果与C组比较,T_2时H组气道峰压明显降低(P0.05);T_2、T_3时H组萎陷侧肺泡灌洗液IL-10水平和Cdyn明显升高(P0.05),TNF-α、IL-6水平、RI明显降低(P0.05)。结论允许性高碳酸血症能有效抑制肺叶切除术患者单肺通气后萎陷侧肺的炎症反应,改善肺脏弥散功能及顺应性。     

选择性肺叶隔离技术在胸椎结核开胸手术中的应用

目的探讨选择性肺叶隔离技术在开胸胸椎结核手术中的应用价值。方法选择本院2016年8月至2018年3月择期全麻下右侧开胸胸椎结核病灶清除内固定手术患者48例,男30例,女18例,年龄31～65岁,BMI 18～27 kg/m~2,ASAⅡ或Ⅲ级。随机分为支气管封堵器组(E组)和双腔支气管导管组(D组),每组24例。两组患者麻醉诱导后,E组单腔支气管导管插管后,纤维支气管镜引导下置入支气管封堵器;D组置入双腔支气管导管。术中纯氧吸入,氧流量3 L/min,容量限定-压力控制通气,双肺通气期间V_T 8～10 ml/kg,RR 10～14次/分,I∶E 1∶1.5;单肺通气(OLV)期间:V_T 7 ml/kg,RR 12～16次/分,I∶E 1∶1.5。分别于OLV前5 min (T_0)、OLV 30 min(T_1)、关胸双肺通气5 min (T_2)记录气道峰压(Ppeak)、平台压(Pplat)、动态胸肺顺应性(Cdyn);分别于T_0、 T_1、 T_2和术后18 h(T_3)时抽取动脉血和中心静脉血,记录pH、PaCO_2,并计算Qs/Qt、氧合指数(OI);在T_0、T_3时用酶联免疫吸附法测定支气管肺泡灌洗液中IL-6、TNF-α的浓度,术后访视患者有无咽喉疼痛或声音嘶哑;观察术后7 d呼吸循环并发症。结果 T_1时E组Ppeak、Pplat明显低于D组,Cdyn明显高于D组(P0.05)。T_2、T_3时E组pH明显高于D组(P0.05);T_1、T_3时E组PaCO_2明显低于D组(P0.05),OI明显高于D组(P0.05);T_3时E组TNF-a和IL-6明显低于D组(P0.05)。术后E组咽部疼痛、声音嘶哑明显低于D组(P0.05)。结论在开胸胸椎手术中,选择性肺叶隔离技术可以降低OLV气道压力、改善Cdyn,促进CO_2排出和改善OI,降低肺损伤,降低术后咽部疼痛和声音嘶哑,有利于维持患者内环境的稳定。     

超声引导下竖脊肌平面阻滞联合静脉镇痛用于肝叶切除术患者的效果

目的观察超声引导下单次竖脊肌平面阻滞(erector spinae plane block,ESPB)联合静脉镇痛用于肝叶切除术患者的效果。方法择期肝叶切除术患者90例,男63例,女27例,年龄30～65岁,BMI 20～29 kg/m~2, ASAⅠ或Ⅱ级,随机分为三组:单次ESPB联合静脉镇痛组(EP组)、硬膜外镇痛组(EA组)、单纯自控静脉镇痛组(IA组),每组30例。三组患者均采用全身麻醉。EP组于麻醉诱导前行0.33%罗哌卡因30 ml+地塞米松5 mg单次ESPB。EA组患者于麻醉诱导前行T_(10～11)间隙穿刺置入硬膜外导管,术毕硬膜外镇痛。EP组和IA组术毕使用静脉镇痛泵。记录ESPB的阻滞平面和术后2、6、12、24和48 h的静息和咳嗽时VAS评分;记录镇痛泵按压次数、追加曲马多例数;记录皮肤瘙痒、恶心呕吐、尿潴留、胸闷等不良反应发生情况和ESPB相关并发症;记录患者对术后镇痛的满意度评分。结果 EP组痛觉阻滞范围,T_5—T_(12)脊神经支配区域16例,T_4—T_(11)脊神经支配区域11例,T_6—L_1脊神经支配区域3例。术后2、6、12、24和48 h EP组和EA组静息和咳嗽时VAS评分明显低于IA组(P0.05)。EP组和EA组镇痛泵按压次数和追加曲马多例数明显少于IA组(P0.05)。三组均未出现呼吸抑制不良反应。EP组术后恶心呕吐发生率明显低于IA组(P0.05),EA组皮肤瘙痒和尿潴留发生率明显高于IA组(P0.05)。EP组和EA组患者对术后镇痛效果的总体满意度评分明显高于IA组(P0.05)。结论超声引导下竖脊肌平面阻滞联合患者自控静脉镇痛技术用于肝叶切除术后镇痛能够获得硬膜外镇痛的效果,且不良反应发生率低,患者满意度更高。     

胸椎旁程控间歇脉冲注药对胸腔镜肺叶切除患者术后急性疼痛和早期恢复质量的影响

目的探讨胸椎旁程控间歇脉冲注药对胸腔镜肺叶切除患者术后镇痛效果和早期恢复质量的影响。方法选择拟在本院行胸腔镜下肺叶切除患者46例,男23例,女23例,年龄45～70岁,BMI 18.5～30.0 kg/m~2,ASAⅠ或Ⅱ级。随机分为两组:胸椎旁程控间歇注药组(P组)和持续静脉自控镇痛组(V组),每组25例。麻醉诱导前,P组超声引导下T_(4-5)椎旁间隙穿刺置管后注入局麻药混合溶液20 ml(0.75%罗哌卡因15 ml+2%利多卡因5 ml),术后椎旁镇痛泵给予0.2%罗哌卡因;V组不予穿刺置管,术后静脉镇痛泵给予羟考酮0.8 mg/kg。记录术后1 h(T_2)、4 h(T_3)、24 h(T_4)和48 h(T_5)静息、咳嗽时NRS评分和Ramsay镇静评分;记录术后48 h内补救镇痛情况;记录术前(T_0)、术后24 h(T_4)、48 h(T_5)的15项恢复质量评分量表(QoR-15)评分;记录术中舒芬太尼、瑞芬太尼和丙泊酚用量;术前(T_0)、单肺通气结束时(T_1)和术后24 h(T_4)采集桡动脉血,采用AimPlex多因子流式检测技术检测血清IL-6、IL-10、TNF-α、IFN-γ浓度;记录术后48 h内爆发痛、恶心呕吐、心动过速、头晕等发生情况。结果与V组比较,T_2、T_4、T_5时P组静息时NRS评分明显降低,T_2—T_5时P组咳嗽时NRS评分明显降低,T_2、T_3时P组Ramsay镇静评分明显降低,T_4、T_5时P组QoR-15评分明显增高,P组术中瑞芬太尼、舒芬太尼用量明显减少,T_4时P组血清IL-6浓度明显降低,P组术后心动过速和头晕发生率明显降低(P0.05)。与T_0时比较,T_1时两组血清IL-6浓度、P组血清IL-10浓度明显升高,T_4时两组血清IL-6、IL-10浓度明显升高(P0.05);与T_1时比较,T_4时两组血清IL-6、IL-10浓度明显升高(P0.05)。两组补救镇痛率差异无统计学意义。结论胸椎旁程控间歇脉冲注药可为胸腔镜肺叶切除患者提供满意的镇痛和镇静效果,提高患者早期恢复质量,减少术后不良反应的发生。     

超声引导下竖脊肌平面阻滞联合腹横肌平面阻滞用于两切口食管癌根治术后镇痛的效果

目的探索超声引导下竖脊肌平面阻滞(erector spinae plane block, ESPB)联合腹横肌平面阻滞(transversus abdominis plane block, TAPB)用于右胸及上腹两切口食管癌根治术后镇痛的效果及其对患者满意度的影响。方法择期行两切口食管癌根治术的患者40例,男23例,女17例,年龄30～65岁,BMI 18～30 kg/m~2,ASAⅠ或Ⅱ级。所有患者随机分为ESPB联合TAPB镇痛组(ET组)和单纯患者自控静脉镇痛(PCIA)组(IA组)。ET组全麻诱导前行超声引导下ESPB、超声引导下TAPB,分别于操作结束20 min后测定阻滞范围,IA组不予阻滞,两组术毕均采用PCIA。记录患者入手术室后(T_0)、气管插管时(T_1)、手术切皮时(T_2)、手术30 min (T_3)、60 min (T_4)、90 min时(T_5)、手术结束时(T_6)的HR、MAP;术后1、6、12、24、48 h静息和咳嗽时VAS评分;镇痛泵按压次数;镇痛泵药液输注总量;术后不良反应发生情况和患者总体满意度。结果 ESPB 20 min后可阻滞T_3—T_9脊神经支配区域,TAPB 20 min后可阻滞T_9—L_1脊神经支配区域。与T_0时比较,T_2时IA组HR明显增快、MAP明显升高(P0.05),T_0和T_2时ET组HR和MAP差异无统计学意义。T_2—T_6时IA组HR明显快于ET组、MAP明显高于ET组(P0.05)。ET组术后1、6、12、24、48 h静息和咳嗽时VAS评分明显低于IA组(P0.05),术后0～24 h和0～48 h镇痛泵按压次数和药液输注总量明显少于IA组(P0.05),术后恶心、呕吐发生率明显低于IA组(P0.05),患者满意度评分明显高于IA组(P0.05)。结论超声引导下单次竖脊肌平面阻滞联合腹横肌平面阻滞用于经右胸及上腹两切口食管癌根治术可有效抑制术中血流动力学波动,其术后镇痛效果优于单纯患者自控静脉镇痛,患者总体满意度更高。     

甲基强的松龙对肺叶切除术患者单肺通气时肺功能和炎症反应的影响

目的探讨甲基强的松龙(甲强龙)对肺叶切除术患者单肺通气时肺功能和炎症反应的影响。方法选择择期拟行肺叶切除术患者60例,男46例,女14例,年龄18~60岁,ASAⅠ或Ⅱ级,采用随机数字表法分为两组:甲强龙组(M组)和对照组(C组),每组30例。M组于麻醉诱导前30min静脉注射甲强龙2mg/kg,C组于相同时点静脉注射等量生理盐水。分别记录单肺通气前(T_0)、单肺通气30min(T_1)、单肺通气1h(T_2)、恢复双肺通气10min(T_3)及术毕(T_4)时的MAP、气道峰压(Ppeak)、气道平台压(Pplat)及动态肺顺应性(Cdyn),并于上述时间点抽取桡动脉血行血气分析,检测PaO_2和PaCO_2,计算氧合指数(OI)、肺泡-动脉血氧分压差(A-aDO_2)及呼吸指数(RI)。分别于T_0、T_4、术后6h(T_5)及术后24h(T_6)采集中心静脉血样,采用ELISA法检测血清TNF-α、IL-6及IL-10的浓度。记录术后72h肺部并发症的发生情况。结果与T_0时比较,T_1、T_2时两组MAP、Cdyn明显降低,Ppeak、Pplat明显升高(P0.05);T_1~T_4时OI明显降低,A-aO_2、RI明显升高(P0.05);T_4~T_6时血清TNF-α、IL-6及IL-10浓度明显升高(P0.05)。与C组比较,T_1、T_2时M组Ppeak、Pplat明显降低,Cdyn明显升高(P0.05);T_4~T_6时M组血清TNF-α、IL-6浓度明显降低,IL-10浓度明显升高(P0.05)。两组患者术后72h肺部并发症发生率差异无统计学意义。结论甲强龙可有效改善肺叶切除术患者单肺通气时动态肺顺应性,优化呼吸动力学,减轻机体炎症反应,但对肺氧合及换气功能无明显影响。     

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.     

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.     

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.     

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.