允许性高碳酸血症对老年糖尿病患者术后认知功能的影响

目的 探讨允许性高碳酸血症对老年糖尿病患者术后认知功能的影响。
方法 选择全麻下行腹腔镜上腹部手术的老年糖尿病患者60例，将患者随机分为两组：允许性高碳酸血症通气糖尿病组（DH组）和常规通气糖尿病组（DR组），每组30例。另选择全麻下行腹腔镜上腹部手术非糖尿病老年患者60例，将患者随机分为两组：允许性高碳酸血症通气非糖尿病组（NH组）和常规通气非糖尿病组（NR组），每组30例。麻醉诱导后行机械通气，调控呼吸参数使DH组和NH组维持PaCO₂ 45～65 mmHg，DR组和NR组维持PaCO₂ 35～45 mmHg。记录气腹前5 min及气腹后5、15、30 min的P_ETCO₂，并采集以上时点桡动脉、颈内静脉血样行血气分析，记录pH值、PaCO₂，计算动脉-颈内静脉血氧含量差（Da-jvO₂）和脑氧摄取率（CERO₂）。检测麻醉诱导前及术后3 d的血清S100β蛋白浓度。记录术前1 d和术后1、3、7 d的蒙特利尔认知评估量表（MoCA）评分和术后认知功能障碍（POCD）的发生情况。
结果与气腹前5 min比较，四组气腹后5、15、30 min时P_ETCO₂和PaCO₂明显升高，pH值、Da-jvO₂和CERO₂明显降低（P<0.05）。与麻醉诱导前比较，四组术后3 d血清S100β蛋白浓度均明显升高（P<0.05）。与术前1 d比较，四组术后1、3 d MoCA评分均明显降低（P<0.05）。与DR组比较，DH组气腹前5 min及气腹后5、15、30 min时P_ETCO₂明显升高，pH值、Da-jvO₂和CERO₂明显降低，术后3 d血清S100β蛋白浓度明显降低，术后1、3 d MoCA评分明显升高，POCD发生率明显降低（P<0.05）。与NR组比较，NH组气腹前5 min及气腹后5、15、30 min时P_ETCO₂明显升高，pH值、Da-jvO₂和CERO₂明显降低，术后3 d血清S100β蛋白浓度明显降低，术后1、3 d MoCA评分明显升高，POCD发生率明显降低（P<0.05）。与NH组比较，DH组气腹前5 min及气腹后5、15、30 min时Da-jvO₂和CERO₂明显升高，术后3 d血清S100β蛋白浓度明显升高，术后1、3 d MoCA评分明显降低（P<0.05）。
结论允许性高碳酸血症可改善老年糖尿病患者术中脑氧代谢，降低术后血清S100β蛋白浓度，降低术后认知功能障碍的发生率。     

脑氧饱和度监测下控制性降压对老年高血压患者术后谵妄的影响

目的 探讨脑氧饱和度(rSO₂)监测下控制性降压对老年高血压患者术后谵妄（POD）的影响。方法 择期全麻下行鼻泪道手术的老年高血压患者110例,男53例,女57例,年龄65~85岁,ASA Ⅱ或Ⅲ级,高血压Ⅰ或Ⅱ级,采用随机数字表法分为两组：rSO₂监测组（S组）和对照组（C组）,每组55例。两组均采用乌拉地尔联合艾司洛尔控制性降压,维持MAP≥基础值的70%,且MAP≥55 mmHg;当S组rSO₂<基础值的80%或rSO₂最低值<基础值的50%,并且持续时间大于10 s,则逐步提升血压直至rSO₂恢复至≥基础值的80%或绝对值＞50%。C组rSO₂监护仪施行遮盖处理。记录入室后吸氧5 min（T0）、控制性降压15 min（T1）、30 min（T2）、控制性降压结束后5 min（T3）、拔管后10 min（T4）的HR、MAP、rSO₂;记录rSO₂基础值、术中最低值及较基础值下降的最大百分比;术后1、2、3 d采用谵妄评定方法 中文修订版（CAM-CR量表）对患者进行POD评估。结果 与T0时比较,T1—T2时两组MAP明显下降（P<0.05）,C组rSO₂明显下降（P<0.05）,T3—T4时逐渐回升至术前水平。T1—T2时S组rSO₂明显高于C组（P<0.05）,术中rSO₂最低值明显高于C组（P<0.05）,rSO₂较基础值下降的最大百分比明显低于C组（P<0.05）。术后1 d S组POD发生率明显低于C组（P<0.05）。结论 rSO₂监测下控制性降压能减少老年高血压患者鼻泪道手术后谵妄的发生,提高围术期安全性。     

肺动态顺应性指导个体化呼气末正压通气对老年患者腹腔镜结直肠癌术中肺功能的影响

目的 观察肺动态顺应性（Cdyn）指导个体化呼气末正压通气（PEEP）对老年患者腹腔镜结直肠癌术中肺功能的影响。
方法选择择期行腹腔镜结直肠癌根治术的老年患者68例，男37例，女31例，年龄65～79岁，BMI<30 kg/m²，ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：个体化PEEP组（P组）和对照组（C组），每组34例。P组在插管完成即刻、气腹-屈氏体位建立即刻、气腹结束即刻行肺复张及PEEP滴定试验，C组设置固定PEEP 5 cmH₂O。记录P组3次滴定时最佳PEEP和实际V_T。记录气管插管完成后10 min（T₁）、气腹-屈氏体位建立后10 min（T₂）、60 min（T₃）、手术结束拔管前（T₄）PaO₂、PaCO₂、P_ETCO₂，计算氧合指数（OI）、死腔/潮气量比值（Vd/V_T）、肺泡-动脉血氧分压差（A-aDO₂）、驱动压和Cdyn。采用ELISA法测定麻醉诱导前（T₀）、拔管后10 min（T₅）的白细胞介素-8（IL-8）、肿瘤坏死因子-α（TNF-α）、肺Clara细胞分泌蛋白（CC16）及肺泡表面活性物质-D（SP-D）的浓度。记录术后肺部并发症（PPCs）的发生情况。
结果 P组滴定最佳PEEP的中位数为4 cmH₂O。与C组比较，P组T₄时PaO₂、OI明显升高，T₁、T₃、T₄时Cdyn明显升高，T₁—T₄时驱动压明显降低，T₅时CC16血清浓度明显降低（P<0.05）。两组T₁—T₄时PaCO₂、P_ETCO₂、A-aDO₂、Vd/V_T差异无统计学意义。两组术后3 d均未发生严重PPCs。
结论 在老年患者腹腔镜结直肠癌根治术中，采用压力控制通气下肺动态顺应性指导个体化PEEP的肺保护通气策略，可提高患者术中肺动态顺应性，降低驱动压，改善手术结束时氧合，降低术后CC16血清浓度，改善术中肺功能。     

基于肺超声评分评估压力控制容量保证通气模式对腹腔镜胃癌根治术患者肺通气的影响

目的 探讨基于肺超声评分（LUS）评估压力控制容量保证通气（PCV-VG）模式与容量控制通气（VCV）模式对腹腔镜胃癌根治术患者通气功能及术后肺部并发症（PPCs）的影响。
方法 选择择期行腹腔镜胃癌根治术患者80例,男67例,女13例,年龄45～75岁,ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：VCV通气模式组（V组）和PCV-VG通气模式组（P组）,每组40例。所有患者常规麻醉诱导,采用保护性通气策略：VT 7 ml/kg,呼气末正压（PEEP）5 cmH₂O,FiO₂ 40%。采用床旁肺超声评估患者双侧肺部共12个区域的LUS。记录入室时（T0）、麻醉诱导气管插管后20 min（T1）、建立人工气腹后30 min（T2）、气管导管拔除后15 min（T5）的LUS评分。行血气分析记录PaO₂、PaCO₂。记录T1、T2、气腹后1 h（T3）、手术结束时（T4）的气道峰压（Ppeak）、平台压（Pplat）、气道平均压（Pmean）、动态肺顺应性（Cdyn）、VT。记录术后3、7 d内PPCs的发生情况。
结果 与T0时比较,T1、T2、T5时P组整体、前部、外侧、后部、左肺、右肺、上肺及下肺LUS明显降低（P＜0.05）;T2时V组整体及部分区域（后部、下肺及右肺）LUS明显降低,T5时V组整体及部分区域（外侧、下肺及左肺）LUS明显升高（P＜0.05）。与V组比较,T1、T2、T5时P组整体及各区域LUS评分均明显降低,PaO₂明显升高,T1、T5时PaCO₂明显降低,T1—T4时Ppeak明显降低,Pmean、Cdyn明显升高,T4时Pplat明显降低（P＜0.05）。术后3 d内P组PPCs发生率明显低于V组［4例（10%）vs 11例（28%）,P＜0.05］。
结论 LUS能够显示手术期间PCV-VG模式和VCV模式下肺通气的非均匀性和体位性变化。肺保护性通气策略下,PCV-VG模式明显改善了腹腔镜胃癌根治术患者术中肺通气及氧合功能。     

不同流速经鼻湿化快速充气通气联合无创通气对肥胖患者全麻诱导期胃进气的影响

目的 通过胃窦超声检查评估不同流速经鼻湿化快速充气通气（THRIVE）联合无创通气（NIV）在全麻诱导时对肥胖患者胃进气的影响。
方法 选择择期全麻手术患者72例,男29例,女43例,年龄18～64岁,BMI 30.0～39.9 kg/m²,ASA Ⅰ或Ⅱ级。随机分为三组：H30组、H50组、H70组,每组24例。三组均行THRIVE 30 L/min预给氧5 min后行全麻诱导。全麻诱导后三组分别接受相应氧流量大小（30、50、70 L/min,FiO₂ 100%）的THRIVE联合NIV（10 cmH₂O）行压力控制给氧。气管插管期,各组继续行对应流速THRIVE以提供窒息氧合。入室时以及诱导通气结束时,采用超声监测患者仰卧位胃窦部进气情况,超声图像出现“彗尾征”则定义为胃进气阳性（GI⁺）。记录全麻诱导期GI⁺的发生情况;记录入室时以及诱导通气结束时的胃窦部横截面积（CSA）;记录插管过程中SpO₂最低值以及诱导通气结束时PaO₂、PaCO₂、P_ETCO₂等呼吸参数;记录术后恶心呕吐、反流误吸、鼻咽部不适和气压伤等不良事件的发生情况。
结果 全麻诱导期H70组GI⁺发生率明显高于H30组、H50组（P<0.05）。与入室时比较,诱导通气结束时H70组胃窦部CSA明显增大（P<0.05）。诱导通气结束时H70组CSA明显大于与H30组、H50组（P<0.05）。插管过程中H50组、H70组SpO₂最低值明显高于H30组（P<0.05）;诱导通气结束时H50组、H70组PaO₂明显高于H30组,PaCO₂明显低于H30组（P<0.05）。三组恶心呕吐发生率差异无统计学意义。三组均无一例反流误吸、鼻咽部不适和气压伤。
结论 THRIVE 50 L/min联合NIV 10 cmH₂O压控给氧能为肥胖患者全麻诱导期提供较好的氧合,且明显降低胃进气发生率。     

不同通气模式对腹腔镜下Trendelenburg体位患者肺通气的影响

目的 采用电阻抗断层成像(EIT)技术观察容量控制通气(VCV)和压力控制容量保证通气(PCV-VG)模式对腹腔镜下Trendelenburg体位患者全麻术中肺通气的影响。方法 择期全麻下行腹腔镜下Trendelenburg体位妇科手术患者60例,年龄40～65岁,BMI 18～30 kg/m²,ASA Ⅰ或Ⅱ级,采用随机数字表法将患者分为两组：VCV模式组（V组）和PCV-VG模式组（P组）,每组30例。V组术中采用VCV模式,P组采用PCV-VG模式。记录入室后(T0)、插管后5 min(T1)、更改体位（由平卧位更改为Trendelenburg体位）后即刻(T2)、更改体位后30 min(T3)、更改体位后60 min(T4)、更改体位后120 min(T5)、改平卧位(T6)时的MAP、HR、通气中心(CoV)、依赖静止区(DSS)、非依赖静止区(NSS)的面积百分比。记录T1、T3—T5时气道峰压（Ppeak）、pH、PaO₂、PaCO₂、氧合指数（OI）。记录术后7 d内肺部感染、呼吸衰竭等肺部并发症发生情况。结果 T0—T6时两组MAP、HR差异无统计学意义。与V组比较,T3—T6时CoV面积百分比明显升高,DSS面积百分比明显降低（P<0.05）,T3—T5时Ppeak明显降低（P<0.05）,T4、T5时PaO₂、OI明显升高（P<0.05）。两组术后7 d内均无肺部并发症。结论 PCV-VG通气模式可明显改善腹腔镜下Trendelenburg体位患者术中肺通气及肺氧合功能。     

食管癌根治术中肾脏氧饱和度与术后肾功能异常的相关性

目的 探讨食管癌根治术中肾脏区域组织氧饱和度（rSO₂）与术后肾功能异常的相关性。
方法 选择拟行食管癌根治术的患者116例,男93例,女23例,年龄18～64岁,BMI＜24 kg/m²,ASA Ⅱ或Ⅲ级。术中连续监测左侧肾脏rSO₂。设定麻醉诱导后肾脏rSO₂为基础值,当术中肾脏rSO₂绝对值≤50%或低于基础值的75%时,定义为肾脏rSO₂异常下降。记录术前及术后24 h尿素氮（BUN）、血清肌酐（SCr）,术后肾功能异常定义为术后24 h血浆SCr＞130 μmol/L或BUN＞7.5 mmol/L。根据术后是否出现肾功能异常将患者分为两组：肾功能正常组和肾功能异常组。采用列联系数分析术中肾脏rSO₂异常下降与术后肾功能异常的相关性。
结果 有40例（34.5%）患者术中出现肾脏rSO₂异常下降,有45例（38.8%）患者术后出现肾功能异常。二元Logistic回归分析显示男性是术后肾功能异常的危险因素（OR=5.490,95%CI 1.526～19.754,P=0.009）。食管癌根治术中肾脏rSO₂的异常下降与术后肾脏功能异常呈正相关（rs=0.587,P=0.009)。
结论 食管癌根治术中肾脏rSO₂异常下降与术后肾功能异常呈正相关。     

心肺转流期间老年患者局部脑氧饱和度与术后认知功能障碍的相关性

目的 探究老年患者心肺转流（CPB）期间局部脑氧饱和度（rSO₂）与术后认知功能障碍（POCD）的相关性。
方法 选择择期行CPB下心脏手术的老年患者84例,男46例,女38例,年龄≥65岁,BMI 18～29 kg/m²,ASA Ⅱ—Ⅳ级。术中应用近红外光谱技术,持续监测rSO₂。采用神经心理学测试方法评估患者术前1 d和术后第7天的认知功能,采用Z值计分法判定POCD。根据术后第7天是否发生POCD将患者分为两组：非POCD组和POCD组。CPB前期包括入室吸氧前至主动脉插管（期间包括麻醉后、手术开始、劈胸骨、悬吊心包）,CPB中期包括CPB开始至CPB结束（期间包括CPB低温恒温期及搭桥或换瓣）,CPB后期包括主动脉拔管和术毕。记录CPB前期、中期、后期rSO2平均值（rSO_2mean）,术中rSO₂最低值（rSO_2min）。采用Logistic回归和拟合曲线分析患者术中rSO₂与POCD的相关性。
结果 有36例（42.9%）患者发生POCD。多因素Logistic回归分析显示,CPB前期rSO_2mean（OR=1.12,95%CI 1.02～1.24,P=0.02）、CPB中期rSO_2mean（OR=1.55,95%CI 1.24～1.95,P<0.05）、CPB后期rSO_2mean（OR=1.32,95%CI 1.15～1.60,P<0.05）和rSO_2min（OR=1.33,95%CI 1.16～1.52,P<0.05）是发生POCD的独立危险因素。拟合曲线显示,CPB中期rSO_2mean（r=-0.60）和rSO_2min（r=-0.57）均与POCD呈线性负相关(P<0.05)。
结论 术中rSO₂降低与患者CPB术后发生POCD具有相关性。术中rSO₂降低可能是POCD的独立危险因素。     

双气道喉管用于中心气道狭窄气管支架置入术的效果

目的 评价双气道喉管用于中心气道狭窄气管支架置入术的效果。
方法 选择择期行中心气道狭窄气管支架置入术患者42例,男28例,女14例,年龄18~64岁,ASA Ⅱ或Ⅲ级。采用随机数字表法分为两组：双气道喉管组（D组）和普通喉罩组（C组）,每组21例。麻醉诱导后,D组、C组分别置入双气道喉管和普通喉罩,行机械通气。记录麻醉诱导前（T1）、置入喉管/喉罩开始通气时（T2）、手术开始（T3）、支架置入时（T4）及术毕停止麻醉药后5 min（T5）的MAP、HR和SpO₂。分别于支架置入前和置入后抽取动脉血样行血气分析,记录pH值、PaO₂和PaCO₂。记录手术时间和支架置入调整例数。记录气管黏膜损伤、术后声嘶和术后咽痛的发生情况。
结果 T1—T5时两组MAP、HR和SpO₂差异无统计学意义。与C组比较,D组支架置入后pH值、PaO₂明显升高,PaCO₂明显降低,手术时间明显缩短,支架置入调整例数明显减少,气管黏膜损伤、术后声嘶和术后咽痛发生率明显降低（P<0.05）。
结论 双气道喉管用于中心气道狭窄气管支架置入术,可有效减少并发症的发生。     

单肺通气期间不同吸入氧浓度对术中呼吸功能的影响

目的 探讨单肺通气（OLV）期间不同吸入氧浓度（FiO₂）对胸外科手术患者呼吸功能的影响。
方法 选择2020年11月至2021年8月择期行肺叶切除术的患者57例,男40例,女17例,年龄18～64岁,BMI 18～28 kg/m²,ASA Ⅰ或Ⅱ级。将患者随机分为三组：FiO₂ 45%组（L组）、FiO₂ 65%组（M组）和FiO₂85%组（H组）,每组19例。三组分别在OLV期间予以对应的FiO₂。记录术前肺通气功能检查指标,包括用力肺活量（FVC）、第1秒用力呼气量（FEV1）、1秒率（FEV1/FVC）、分钟最大通气量占预计值百分比（MVV%）。于OLV前5 min、OLV后10、20、30、60 min分别经桡动脉与右颈内静脉抽取动静脉血行血气分析,记录SaO₂、PaO₂、PaCO₂、Hb、Lac,并计算氧合指数（PaO₂/FiO₂）、肺内分流率（Qs/Qt）、死腔率（VD/VT）,记录以上各时点肺动态顺应性（Cdyn）、气道峰压（Ppeak）、HR和MAP。
结果 三组术前FVC、FEV1、FEV1/FVC、MVV%差异无统计学意义。OLV后10、20、30 min M组和H组PaO₂明显高于L组（P＜0.05）。OLV后10、20、30、60 min M组和H组PaO₂/FiO₂、Cdyn明显低于L组（P＜0.05）;H组PaO₂/FiO₂、Cdyn明显低于M组（P＜0.05）,Qs/Qt、Ppeak明显高于L组和M组（P＜0.05）。OLV后60 min M组Qs/Qt明显高于L组（P＜0.05）,H组PaO₂明显高于L组（P＜0.05）。OLV前5 min、OLV后10、20、30、60 min三组SaO₂、PaCO₂、Hb、Lac、HR、MAP差异无统计学意义。
结论 OLV期间使用FiO₂ 45%和FiO₂ 65%均可以减少肺内分流,提高肺顺应性,改善氧合。     

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.     

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.     

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.