超声引导下腹横筋膜平面阻滞用于髂嵴前部取骨移植术的效果

目的 探讨超声引导下腹横筋膜平面(TFP)阻滞在髂嵴前部取骨移植术的应用效果。
方法 选择行髂嵴前部取骨移植术患者59例，男32例，女27例，年龄18～64岁，BMI 18～24 kg/m²，ASA Ⅰ或Ⅱ级。将患者随机分为两组：超声引导下TFP阻滞联合全麻组（T组，n=30）和常规全麻组（G组，n=29）。T组行超声引导下术侧TFP阻滞，G组不进行TFP阻滞。记录麻醉诱导前1 min、手术开始后1、10、30、60 min和手术结束时的HR、MAP和呼出气七氟醚浓度（C_ETSev）、术中芬太尼、瑞芬太尼和丙泊酚用量、拔管时间、PACU停留时间。记录术后4、8、12、24、48 h髂骨供区的静息和活动时VAS疼痛评分。记录PCIA总按压次数、有效按压次数、曲马多补救镇痛用量、补救镇痛和患者对髂骨供区镇痛的满意情况。
结果 与G组比较，手术开始后1、10、30 min T组HR明显减慢、MAP明显降低（P＜0.05），手术开始后1 min至手术结束时T组C_ETSev明显降低（P＜0.05）；T组术中芬太尼、瑞芬太尼和丙泊酚用量明显减少（P＜0.05），拔管时间和PACU停留时间明显缩短（P＜0.05）；T组术后4、8、12 h的静息和活动时VAS疼痛评分、术后PCIA总按压次数、有效按压次数、曲马多补救镇痛用量明显减少（P＜0.05）、补救镇痛率明显降低（P＜0.05），患者对髂骨供区镇痛满意率明显升高（P＜0.05）。
结论 超声引导下TFP阻滞用于髂嵴前部取骨移植术麻醉和镇痛效果较好，有利于减少围术期麻醉镇痛药用量，血流动力学平稳，恢复快速，安全性高，患者满意度高。     

腘丛神经阻滞联合收肌管阻滞用于全膝关节置换术患者术后镇痛的效果

目的 观察腘丛神经阻滞（PPB）联合收肌管阻滞（ACB）用于全膝关节置换术（TKA）患者术后镇痛的效果。
方法 选择初次进行全身麻醉下单侧TKA的患者60例,男15例,女45例,年龄50～80岁,BMI 18～30 kg/m²,ASA Ⅰ—Ⅲ级。采用随机数字表法将患者分为两组：PPB联合ACB组（P组）和ACB组（A组）,每组30例。麻醉诱导前,P组采用0.5%罗哌卡因15 ml行ACB,后采用0.5%罗哌卡因20 ml行PPB,A组单纯采用0.5%罗哌卡因15 ml行ACB。记录术中瑞芬太尼总量和手术时间。记录术后4、8、24、48、72 h静息和活动时VAS疼痛评分,术后1、2、3 d主动屈膝最大角度,术后4、8、24 h患肢运动阻滞情况。记录镇痛泵总按压次数、有效按压次数和补救镇痛情况。记录首次下床活动时间、术后住院时间、患者术后满意度评分以及术后不良事件发生情况。
结果 与A组比较,P组术后4、8、24、48、72 h静息时VAS疼痛评分明显降低（P＜0.05）,术后4、8 h时活动时VAS疼痛评分明显降低（P＜0.05）,术后1、2 d主动屈膝最大角度明显增大（P＜0.05）,术后镇痛泵总按压次数和有效按压次数明显减少,补救镇痛率明显降低（P＜0.05）,术后住院时间明显缩短,患者术后满意度评分明显升高（P＜0.05）。两组患肢运动阻滞情况差异无统计学意义。两组均未见术后局麻药中毒、穿刺部位感染、血肿、院内跌倒等不良事件发生。
结论 腘丛神经阻滞联合收肌管阻滞不影响患者下肢的运动功能,有利于患者早期下床活动,缩短术后住院时间,提高患者满意度,促进患者早期康复,为全膝关节置换术患者提供更加完善的镇痛效果。     

不同层面腰方肌阻滞对剖宫产产妇术后镇痛的影响

目的 探讨超声引导下前层胸腰筋膜下和前层胸腰筋膜外实施腰方肌阻滞（QLB）对剖宫产术后镇痛的影响。
方法 选择择期腰-硬联合麻醉下行剖宫产手术的产妇113例,年龄23～39岁,体重50～90 kg,ASA Ⅰ或Ⅱ级,孕期>37周。采用随机数字表法将产妇分为两组：前层胸腰筋膜下阻滞组（S组,n=57）和前层胸腰筋膜外阻滞组（E组,n=56）。所有产妇腰-硬联合麻醉用药相同,术毕连接患者自控静脉镇痛（PCIA）泵,S组术毕行超声引导下前层胸腰筋膜下阻滞,E组行超声引导下前层胸腰筋膜外阻滞。记录首次按压PCIA时间,术后24 h内PCIA有效按压次数以及布托啡诺用量。记录QLB实施后6、9、12、24、48 h静息和活动时VAS疼痛评分、BCS舒适度评分以及阻滞平面存在情况。记录头晕、恶心呕吐、肌力减退等不良反应发生情况。
结果 两组首次按压PCIA时间差异无统计学意义。S组术后24 h内PCIA有效按压次数、布托啡诺用量明显少于E组（P＜0.05）。QLB阻滞实施后不同时点静息和活动时VAS疼痛评分、BCS舒适度评分差异均无统计学意义。S组QLB实施后24 h阻滞平面存在的产妇比例明显高于E组（P＜0.05）。S组头晕发生率明显低于E组（P＜0.05）。
结论 超声引导下前层胸腰筋膜下实施腰方肌阻滞应用于剖宫产术后镇痛效果好,不良反应少,是剖宫产术后镇痛更适宜的阻滞层面。     

超声引导下横突-胸膜中点阻滞与胸椎旁神经阻滞用于单孔胸腔镜手术后镇痛效果的比较

目的 比较超声引导下横突-胸膜中点阻滞(MTPB)与胸椎旁神经阻滞(TPVB)用于单孔胸腔镜手术术后镇痛的效果。
方法 选择择期行单孔胸腔镜手术患者80例,男36例,女44例,年龄18～65岁,BMI 19～28 kg/m²,ASA Ⅰ―Ⅲ级。采用随机数字表法分为MTPB组（M组）和TPVB组（P组）,每组40例。手术结束后M组行超声引导下MTPB,P组行TPVB,两组均注射0.5%罗哌卡因15 ml。两组患者术后均采用PCIA。记录神经阻滞操作时间、穿刺深度,记录术后2、6、12、24、48 h安静和咳嗽时VAS疼痛评分,记录镇痛泵首次按压时间、总按压次数、舒芬太尼使用量和补救镇痛例数,记录穿刺相关并发症、镇痛不良反应发生情况。
结果 与P组比较,M组神经阻滞操作时间明显缩短（P<0.05）,进针深度明显变浅（P<0.05）。术后2、6、12、24、48 h两组安静和咳嗽时VAS疼痛评分差异无统计学意义。两组患者术后镇痛泵首次按压时间、总按压次数、舒芬太尼用量和补救镇痛率差异无统计学意义。两组患者术后恶心、呕吐等不良反应差异无统计学意义。
结论 MTPB或TPVB联合术后PCIA应用于单孔胸腔镜手术患者,术后均可取得良好的镇痛效果,但MTPB操作简单、安全,可作为单孔胸腔镜手术患者术后镇痛方案的选择。     

超声引导下腹股沟韧带上髂筋膜阻滞对膝关节镜下交叉韧带重建术患者止血带相关反应的影响

目的 探讨超声引导下腹股沟韧带上髂筋膜阻滞对全麻下行膝关节镜下交叉韧带重建术（ACLR）患者术中止血带相关反应以及缺血-再灌注损伤的影响。

方法 选择行膝关节镜下交叉韧带重建术患者86例，男58例，女28例，年龄18～64岁，BMI 17～28 kg/m²，ASA Ⅰ或Ⅱ级。采用随机数字表法将患者分为两组：超声引导下腹股沟韧带上髂筋膜阻滞联合全麻组（B组）和单纯全麻组（C组），每组43例。B组于超声引导下行腹股沟韧带上髂筋膜阻滞联合全麻，C组仅行全麻，术毕均行静脉自控镇痛。记录麻醉诱导时（T₀）、止血带充气即刻（T₁）、止血带充气后60 min（T₂）、止血带充气后90 min（T₃）、放松止血带即刻（T₄）、放松止血带后10 min（T₅）的HR和MAP，于T₁、T₅时抽取静脉血测定血清丙二醛（MDA）和乳酸（Lac）浓度。记录入PACU即刻（T₆）、术后6 h（T₇）、12 h（T₈）、24 h（T₉）静息和活动时VAS疼痛评分。记录术中丙泊酚和瑞芬太尼总用量、术后镇痛泵总按压次数、镇痛泵有效按压次数和氟比洛氛酯补救镇痛例数。记录术后神经损伤、寒颤、术后恶心呕吐等不良反应的发生情况。

结果 与T₁时比较，T₅时两组血清MDA和Lac浓度明显升高（P<0.05）。与C组比较，T₂—T₅时B组HR明显减慢，MAP明显降低（P<0.05），T₅时B组MDA和Lac浓度明显降低（P<0.05），T₆、T₇时B组静息和活动时VAS疼痛评分明显降低（P<0.05），B组术中丙泊酚和瑞芬太尼总用总量明显减少（P<0.05），B组术后镇痛泵总按压次数、有效按压次数明显减少、氟比洛氛酯补救镇痛率明显降低（P<0.05）。T₈、T₉时两组静息和活动时VAS疼痛评分、术后神经损伤、寒颤、术后恶心呕吐等不良反应发生率差异无统计学意义。

结论 腹股沟韧带上髂筋膜阻滞可减轻止血带相关反应，减轻肢体缺血-再灌注后脂质过氧化反应，减少MDA及Lac等生成，从而减轻缺血-再灌注损伤。     

无背景剂量羟考酮静脉自控镇痛联合髋关节囊周神经阻滞用于老年患者全髋关节置换术后镇痛的效果

目的 探讨无背景剂量羟考酮静脉自控镇痛联合髋关节囊周神经（PENG）阻滞用于老年患者全髋关节置换术（THA）术后镇痛的效果。
方法 选择择期在蛛网膜下腔阻滞下行单侧THA老年患者99例,男38例,女61例,年龄65～85岁,BMI 18～30 kg/m²,ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：有背景剂量羟考酮静脉自控镇痛组（P组,n=49）和无背景剂量羟考酮静脉自控镇痛+PENG阻滞组（N组,n=50）。麻醉开始前,N组在髋关节囊周围注射0.375%罗哌卡因20 ml。两组术后均连接静脉自控镇痛,镇痛泵配方：羟考酮40 mg+托烷司琼4 mg用生理盐水稀释至100 ml。P组设置背景剂量2 ml/h,PCA剂量2.5 ml。N组设置为无背景剂量,PCA剂量5 ml。记录术后48 h羟考酮累积消耗量、镇痛泵总按压次数、有效按压次数以及补救镇痛情况,术后4、12、24、48、72 h的静息和活动时VAS疼痛评分,术前1 d、术后1、2、3 d的匹兹堡睡眠质量指数（PSQI）和术后48 h不良反应的发生情况。
结果 与P组比较,N组术后48 h羟考酮累积消耗量以及补救镇痛比例明显降低（P<0.05）,总按压次数和有效按压次数明显增加（P<0.05）,术后4、12、24 h的静息和活动时VAS疼痛评分明显降低（P<0.05）,术后1、2、3 d PSQI评分明显降低（P<0.05）,术后恶心、呕吐发生率明显降低（P<0.05）。
结论 无背景剂量羟考酮静脉自控镇痛联合PENG阻滞用于老年患者THA的术后镇痛,镇痛效果满意,可减少术后镇痛药物用量,且能够提高术后睡眠质量,减少术后不良反应的发生。     

超声引导下双侧弓状韧带上腰方肌阻滞在宫颈癌根治术患者术后镇痛的效果

目的 探讨超声引导下双侧弓状韧带上腰方肌阻滞对开腹宫颈癌根治术患者术后疼痛的影响。
方法 选择择期行开腹宫颈癌根治术患者59例,年龄21~70岁,BMI 17~27 kg/m²,ASA Ⅰ或Ⅱ级。采用随机数字表法将患者分为两组：弓状韧带上腰方肌阻滞组(Q组,n=29)和对照组(C组,n=30)。Q组于全麻诱导前在超声引导下行双侧弓状韧带上腰方肌阻滞,分别注射0.375%罗哌卡因20 ml;C组不行神经阻滞。两组均采用全凭静脉麻醉,术后均使用患者自控静脉镇痛（PCIA）。记录阻滞后5、15 min感觉阻滞平面、术后1、6、12、24、48 h静息和活动时VAS疼痛评分、PCA有效按压次数、PCA总按压次数,术中丙泊酚和瑞芬太尼用量、术后48 h内补救镇痛率、苏醒时间、首次下床时间、术后住院时间以及术后恶心呕吐（PONV）、皮肤瘙痒、低血压、呼吸抑制、气胸、肾损伤、股四头肌无力等不良反应和阻滞相关并发症发生情况。
结果 术后1、6、12、24、48 h Q组静息和活动时VAS疼痛评分明显低于C组（P<0.05）,PCA有效按压次数和总按压次数明显少于C组（P<0.05）,术中瑞芬太尼用量明显少于C组（P＜0.05）,术后48 h内补救镇痛率明显低于C组（P＜0.05）,苏醒时间、首次下床时间、术后住院时间明显短于C组（P＜0.05）。两组丙泊酚用量差异无统计学意义。Q组术后PONV发生率明显低于C组（P＜0.05）,两组皮肤瘙痒发生率差异无统计学意义。Q组术后未出现低血压、呼吸抑制、气胸、肾损伤、股四头肌无力等阻滞相关并发症。
结论 超声引导下弓状韧带上腰方肌阻滞可明显减轻开腹宫颈癌根治术患者术后疼痛,减少围术期全身麻醉镇痛药用量,降低术后恶心呕吐发生率,促进患者康复。     

胸腰筋膜间平面阻滞对后路腰椎融合术后镇痛效果的影响

目的 探讨超声引导下胸腰筋膜间平面（thoracolumbar interfascial plane, TLIP）阻滞对后路腰椎融合手术病人术后镇痛效果的影响。方法 前瞻性选择2017年4月至2018年5月在我院择期行后路腰椎融合手术病人50例。采用随机数字表法分为两组,每组25例,TLIP阻滞联合静脉自控镇痛（patient controlled intravenous analgesia, PCIA）组（TLIP组）和单纯PCIA组（对照组）。TLIP组,男12例,女13例,年龄为（49.4±7.7）岁;对照组,男10例,女15例,年龄为（49.5±7.1）岁。TLIP组在全麻诱导后行超声引导下双侧TLIP阻滞,每侧注入0.375%罗哌卡因20 ml。两组术后均使用舒芬太尼行PCIA,维持术后24 h内静息疼痛视觉模拟量表（visual analogue scale, VAS）评分≤3分。记录两组病人围手术期阿片类药物用量及补救镇痛例数,术后2、4、6、12、24 h的静息VAS评分和Ramsay镇静评分,术后24 h 内恶心呕吐、头晕、瘙痒和呼吸抑制的发生情况以及TLIP组阻滞相关并发症的发生情况。结果 与对照组比较,TLIP组术中瑞芬太尼用量及术后24 h内PCIA舒芬太尼用量明显减少（P＜0.05）,术后恶心呕吐发生率明显降低（P＜0.05）,两组均未行补救镇痛。两组间各时间点静息VAS评分和Ramsay镇静评分,以及术后头晕、瘙痒和呼吸抑制等发生率的差异均无统计学意义（P均＞0.05）,TLIP组未发生阻滞相关并发症。结论 超声引导下TLIP阻滞可减少后路腰椎融合术病人围术期阿片类药物用量,降低术后恶心呕吐的发生率。     

0.375%罗哌卡因不同注射速度对后入路腰方肌阻滞术后镇痛效果的影响

目的 探讨0.375%罗哌卡因不同注射速度对超声引导下后入路腰方肌阻滞术后镇痛效果的影响。
方法 拟在择期全麻下行腹腔镜Dixon直肠癌根治术患者60例,男40例,女20例,年龄35～70岁,BMI 18～30 kg/m²,ASA Ⅰ或Ⅱ级,采用随机数字表法分为两组：每侧注射速度40 ml/min组（H组）和每侧注射速度20 ml/min组（L组）,每组30例。全麻诱导前行超声引导下双侧后入路腰方肌阻滞,H组和L组每侧分别以40 ml/min和20 ml/min给予0.375%罗哌卡因20 ml。术后均行舒芬太尼PCIA。记录术中舒芬太尼用量和术后镇痛泵首次按压时间。记录术后4、8、12、24 h静息、运动时VAS疼痛评分、舒芬太尼用量、补救性镇痛例数。记录内脏损伤、局麻药中毒、穿刺血肿等并发症的发生情况。
结果 与L组比较,H组术中舒芬太尼用量明显减少,术后镇痛泵首次按压时间延长（P<0.05）;术后4、8、12、24 h静息、运动时VAS疼痛评分明显降低,舒芬太尼用量明显减少（P<0.05）;补救性镇痛例数明显减少（P<0.05）。两组均无内脏损伤、局麻药中毒、穿刺血肿等并发症发生。
结论 超声引导下后入路腰方肌阻滞中,0.375%罗哌卡因注射速度40 ml/min的术后镇痛效果优于20 ml/min。     

艾司氯胺酮与硫酸镁用于腹腔镜全子宫切除术后镇痛效果的比较

目的 观察和比较艾司氯胺酮与硫酸镁用于腹腔镜全子宫切除术后镇痛的效果。
方法 选择择期在全麻下行腹腔镜全子宫切除术患者135例，年龄18～64岁，BMI 18.5～28.0 kg/m²，ASA Ⅰ或Ⅱ级。采用随机数字表法将患者随机分为两组：艾司氯胺酮组（E组，n=67）和硫酸镁组（M组，n=68）。E组在手术开始前静脉注射艾司氯胺酮0.25 mg/kg，随后持续静脉泵注0.15 mg·kg^-1·h^-1；M组在手术开始前静脉注射硫酸镁50 mg/kg，随后持续静脉泵注8 mg·kg^-1·h^-1。术后行患者自控静脉镇痛（PCIA），配方为氢吗啡酮0.1 mg/kg+帕洛诺司琼0.25 mg。记录术中丙泊酚、瑞芬太尼用量和苏醒时间。记录术后2、6、12、24、48 h氢吗啡酮消耗量（等效界值为0.25 mg）、静息和活动时VAS疼痛评分。记录术后0~2 h、2~6 h、6~12 h、12~24 h和24~48 h内镇痛泵按压次数。记录术后补救镇痛、术后24 h内不良反应发生情况。
结果 与M组比较，E组术中丙泊酚及瑞芬太尼用量明显增加（P＜0.05），苏醒时间明显延长（P＜0.05）。两组术后2、6、12、24、48 h氢吗啡酮消耗量、静息和活动时VAS疼痛评分、术后0~2 h、2~6 h、6~12 h、12~24 h和24~48 h内镇痛泵按压次数、术后补救镇痛率和术后24 h内不良反应发生率差异无统计学意义。
结论 艾司氯胺酮可为腹腔镜全子宫切除术患者提供与硫酸镁相似的术后镇痛效果。     

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.