腰椎术后手术部位感染的危险因素分析及列线图模型建立

目的 探讨开放性腰椎后入路手术患者术后手术部位感染（SSI）的相关危险因素,并建立与验证术后SSI的列线图风险预测模型。
方法 选择2017年1月至2021年12月行开放性腰椎后入路手术的患者920例,男422例,女498例,年龄≥18岁,BMI≥18.5 kg/m²,ASA Ⅰ—Ⅳ级。将患者按照7∶3随机分为训练数据集和验证数据集,并基于训练数据集建立预测模型。采用Lasso回归结合二元Logistic回归最终筛选的预测因素构建列线图模型。使用C指数、校准曲线及决策曲线（DCA）等对列线图模型的区分度、校准度及临床适用度进行分析评估。
结果 本研究中发生SSI的有17例（1.85%）,训练集中有10例（1.55%）,验证集中有7例（2.54%）。列线图模型中的预测因素包括术前低白蛋白血症（OR=36.928,95%CI 6.585～235.997,P<0.001）、肥胖（BMI≥28.0 kg/m²）（OR=4.994,95%CI 1.202～24.781,P=0.032）和术后3天内切口渗出（OR=6.133,95%CI 1.473～28.775,P=0.014）。该模型的C指数为0.879（95%CI 0.760～0.998）。校准曲线显示良好的一致性。DCA曲线分析显示当SSI发生风险阈值＞1%时,该列线图更具临床价值。
结论 术前低白蛋白血症、肥胖及术后3 d内切口渗出是行开放性腰椎后入路患者术后发生SSI的危险因素,基于以上危险因素构建的风险预测模型可以较好地预测术后SSI的发生。     

老年营养风险指数联合中性粒细胞/淋巴细胞比值对术后急性肾损伤的预测价值

目的 探讨老年营养风险指数（GNRI）联合中性粒细胞/淋巴细胞比值（NLR）对老年患者结直肠癌根治术后急性肾损伤（AKI）的预测价值。
方法 选择择期全麻下行结直肠癌根治术老年患者670例,男375例,女295例,年龄≥65岁,BMI 16～35 kg/m²,ASA Ⅰ—Ⅲ级。收集患者临床资料,根据术后7 d内是否发生AKI将患者分为两组：AKI组和非AKI组。采用单因素分析和多因素Logistic回归分析确定老年患者结直肠癌根治术后AKI的独立危险因素。绘制受试者工作特征（ROC）曲线,并通过ROC曲线下面积（AUC）评价术前NLR、术前GNRI及联合检测对老年患者结直肠癌根治术后AKI的预测价值。采用决策曲线分析法（DCA）确定术前NLR、术前GNRI及联合检测时预测老年患者结直肠癌根治术后AKI的临床实用性。
结果 有89例（13.3%）患者发生术后AKI。单因素分析显示：与非AKI组比较,AKI组年龄≥75岁、合并糖尿病、使用血管紧张素转换酶抑制剂/血管紧张素受体阻滞剂、术前NLR、手术时间≥3 h、术中低血压及术中输红细胞比例明显升高（P＜0.05）,BMI≥28 kg/m²比例及术前GNRI明显降低（P＜0.05）。多因素Logistic回归分析显示：合并糖尿病（OR=2.140,95％CI 1.125～4.070,P=0.020）、术前NLR值升高（OR=1.608,95％CI 1.414～1.830,P＜0.001）和术中低血压（OR=2.326,95％CI 1.106～4.892,P=0.026）为老年患者结直肠癌根治术后AKI的独立危险因素,术前GNRI值升高（OR=0.868,95％CI 0.838～0.899,P＜0.001）为保护因素。术前NLR、术前GNRI及联合检测预测老年患者结直肠癌根治术后AKI的AUC分别为0.713（95％CI 0.677～0.747）、0.774（95％CI 0.741～0.805）和0.850（95％CI 0.820～0.876）。DCA曲线分析显示,当阈值为0.10～0.95时,术前GNRI联合术前NLR预测老年患者结直肠癌根治术后AKI的净获益率优于术前NLR或GNRI的单独预测。
结论 术前NLR和术前GNRI可用于预测老年患者结直肠癌根治术后AKI的发生风险,且二者联合预测老年患者结直肠癌根治术后AKI风险的效能和净获益率更高。     

老年患者髋膝关节置换术后谵妄风险评估表的构建及效果评价

目的 构建老年患者髋膝关节置换术后谵妄（POD）的风险评估表并评价效果。
方法 选择2021年3月至2022年5月行髋膝关节置换术的老年患者474例和2022年1—5月的同质患者153例，分别作为训练集和验证集。根据是否发生POD将患者分成两组：非POD组和POD组。采用单因素和多因素Logistic回归分析训练集并确定发生POD的独立危险因素。采用Homser-Lemeshow拟合优度检验评价模型的一致性。根据OR值对所选变量进行赋值后建立POD风险评估表，通过受试者工作特征（ROC）曲线评价风险评估表的预测效能。将训练集和验证集根据截断值进行风险分层分为：低危和高危。计算不同风险分层的POD发病率，评估风险评估表的适用性。
结果训练集中有58例（12.2%）发生POD，验证集中有19例（12.4%）发生POD。多因素Logistic回归分析结果显示，年龄≥85岁、ASA Ⅲ或Ⅳ级、简易智力状态检查量表（MMSE）评分≤24分、术前睡眠障碍、合并神经系统疾病、全麻、术中未使用右美托咪定为POD的独立危险因素。风险评估表以截断值44.5分进行危险分层，其预测POD的ROC曲线下面积（AUC）为0.956（95%CI 0.937～0.975）。训练集和验证集使用风险预测评估表将患者分为低危和高危，与低危患者比较，高危患者POD发病率均明显升高（P<0.001）。
结论采用年龄≥85岁、ASA Ⅲ或Ⅳ级、MMSE评分≤24分、术前睡眠障碍、合并神经系统疾病、全麻、术中未使用右美托咪定构建的POD风险评估表，对行髋膝关节置换术的老年患者进行危险分层，能有效识别发生POD的高危患者。     

胆囊结石患者并发急性胆源性胰腺炎的影响因素分析及列线图预测模型构建

目的 由胆囊结石诱发的急性胆源性胰腺炎（ABP）起病急,进展迅速,严重时危及生命。然而目前对于胆囊结石诱发ABP的机制及危险因素并非十分明确,且缺乏预测手段。因此,本研究探讨胆囊结石患者并发ABP的相关危险因素,并构建ABP发生风险的预测模型。方法 选取江苏省太仓市第一人民医院2018年1月—2021年3月期间收治的503例因腹痛入院并确诊为胆囊结石的患者为研究对象,收集患者临床资料、实验室指标以及ABP发生的情况。用单因素与多因素分析筛选ABP发生的危险因素,用ROC曲线分析各因素预测ABP的曲线下面积（AUC）与最佳截断值,构建列线图预测模型量化患者风险,并用校准曲线及决策曲线分析评估其临床预测效能。结果 503例胆囊结石患者中,119例（23.66%）并发ABP。与无ABP的患者比较,发生ABP的患者的APACHE Ⅱ评分、胆囊大小异常比例、多发胆囊结石比例、胆总管结石比例、血清淀粉酶（AMS）、C-反应蛋白（CRP）、降钙素原（PCT）以及中性粒细胞和淋巴细胞计数比值（NLR）均升高,而胆囊壁厚度减低（均P<0.05）;ROC曲线分析结果显示,APACHE Ⅱ评分、胆囊壁厚度、AMS、CRP、PCT、NLR的AUC分别为0.681、0.769、0.886、0.734、0.869、0.822,最佳截断值分别为13.89、1.89 mm、382.10 U/L、18.69 mg/L、5.76 μg/L、3.05;多因素Logistic回归分析显示,胆囊壁厚度（<1.89 mm）、多发胆囊结石、AMS（≥382.10 U/L）、CRP（≥18.69 mg/L）、PCT（≥3.68 g/dL）及NLR（≥3.05）是胆囊结石患者并发ABP发生的独立危险因素（均P<0.05）;根据上述独立影响因素构建的列线图的C指数为0.691（95% CI=0.661~0.735）,风险阈值0.14,并且列线图模型的临床净收益显著高于任何单个指标预测结果。结论 胆囊壁厚度、多发胆囊结石、AMS、CRP、PCT以及NLR为胆囊结石患者并发ABP密切相关,基于以上因素构建的列线图模型对胆囊结石患者ABP发生的早期识别与预警有一定的临床价值。     

甲状腺髓样癌术后生存影响因素分析及列线图的构建

背景与目的 目前用于评估甲状腺髓样癌（MTC）预后的主要方式采用TNM分期系统，但该系统不能个体化预测患者的预后。因此，需要建立专门针对MTC的精准预后指标体系。本研究分析影响MTC患者术后生存的因素，并构建MTC术后生存列线图。方法 选取2004—2015年SEER数据库MTC数据，共筛选出符合条件的1 884例患者纳入研究。将患者按3∶1随机分为训练集（1 413例）和验证集（471例），比较两组临床数据基线特征差异。采用单因素和多因素Cox回归模型筛选影响MTC生存的独立因素，Kaplan-Meier生存曲线分析其对预后的影响。基于Cox回归分析筛选出的结果建立MTC术后患者生存列线图。通过一致性指数（C-index）、ROC曲线、曲线下面积（AUC）、校准曲线和决策曲线分析（DCA）对列线图进行验证和评估。结果 单因素分析结果显示，性别、年龄、原发肿瘤分期、淋巴结转移、远处转移、是否甲状腺全切除、肿瘤是否侵犯甲状腺被膜、是否行放射治疗均影响患者预后（均P<0.05）；Cox回归分析结果显示，性别、年龄、远处转移、侵犯甲状腺被膜、是否行甲状腺全切除术、是否放疗为MTC患者的独立预后因素（均P<0.05）。Kaplan-Meier生存曲线显示，男性患者、年龄≥49岁、伴远处转移、肿瘤侵犯甲状腺被膜、未行甲状腺全切除术、接收放疗患者预后更差。用患者性别、年龄、远处转移、甲状腺被膜受侵、手术方式构建了MTC患者2、5、10年的生存列线图。该列线图训练集的C-index为0.755（95% CI=0.741~0.769），验证集为0.725（95% CI=0.699~0.769）。ROC曲线用于评估列线图的区分度，在训练集2、5、10年的AUC值分别为0.79、0.779、0.766；在验证集分别为0.78、0.725、0.733。校准曲线结果显示该列线图预测的生存率和实际生存率具有一致性。DCA将列线图与AJCC第6版TNM分期的临床相比，该列线图的在5年和10年生存评估中均显示出更大的净收益。结论 性别、年龄、远处转移、甲状腺被膜侵犯、手术方式是影响MTC患者生存的独立因素；MTC术后生存列线图模型在一定程度上能够更准确地进行患者个体生存预测，帮助临床医师做出适当的个体化临床决策。     

复发性鼻咽癌患者鼻内镜手术围术期输血的危险因素及预测模型的建立

目的：筛选复发性鼻咽癌患者鼻内镜手术围术期输血的危险因素,建立列线图预测模型。
方法：回顾性分析2021年1月至2023年5月行鼻内镜手术的262例复发性鼻咽癌患者的临床资料,根据围术期是否输血分为两组：未输血组和输血组。通过单因素和多因素Logistic回归分析筛选围术期输血的危险因素,构建列线图预测模型,绘制受试者工作特征（ROC）曲线并计算曲线下面积（AUC）。
结果：有46例（17.6%）患者在鼻内镜手术围术期输血。多因素Logistic回归分析显示,术前Hb浓度70～<100 g/L（OR=6.178,95%CI 2.271～16.805,P<0.001）、术前白蛋白浓度25～<35 g/L（OR=2.126,95%CI 1.021～4.424,P=0.044）、手术分型Ⅲ或Ⅳ型（OR=4.725,95%CI 1.634～13.584,P=0.004）是复发性鼻咽癌患者鼻内镜手术围术期输血的独立危险因素。列线图模型的AUC为0.769（95%CI 0.701～0.838）,敏感性为67.6%,特异性为76.1%。
结论：复发性鼻咽癌患者鼻内镜手术围术期输血的独立危险因素是术前Hb浓度70～<100 g/L、术前白蛋白浓度25～<35 g/L、手术分型Ⅲ或Ⅳ型,基于以上危险因素建立的列线图模型对围术期输血有良好的预测能力。     

预后营养指数与老年女性冠心病人群发生骨质疏松症的关联性及预测价值

目的 分析预后营养指数（prognostic nutritional index,PNI）与老年女性冠心病人群发生骨质疏松症（osteoporosis,OP）的关联性及其预测价值。方法 收集2019年6月至2022年2月就诊于石家庄市人民医院和石家庄市第五医院的181例老年女性冠心病病人的临床资料,根据是否合并OP分为OP组和对照组。先后通过单因素分析和多因素Logistic回归分析PNI对老年女性冠心病人群患OP的影响,分析PNI与骨密度的相关性,采用ROC曲线分析PNI对OP的预测价值。结果 在老年女性冠心病人群中,PNI≥45是发生OP的保护因素（P＜0.05）;PNI与骨密度值呈线性相关（r=0.538,P＜0.001）。根据ROC曲线：相对无PNI模型,含PNI模型的曲线下面积（AUC）增加了0.0453（P＜0.05）。结论 PNI是老年女性冠心病人群中发生OP的独立影响因素,且与骨密度相关,对OP的发生有预测价值;PNI可能对于OP和冠心病的协同防治有临床意义。     

肝细胞癌微血管侵犯危险因素分析及术前预测列线图模型构建

背景与目的 术前有效预测微血管侵犯（MVI）对肝细胞癌（HCC）患者的临床决策、术后辅助治疗和全面的预后评估具有重要的临床价值。因此,本研究探讨HCC合MVI的危险因素并建立术前风险预测列线图模型,以期为临床提供参考。方法 回顾分析2017年1月—2020年11月安徽省立医院收治的535例HCC患者临床资料,将患者按入院时间分为模型组（433例）,验证组（102例）。进行单因素和多因素分析,以确定MVI的独立危险因素,应用R软件建立预测术前HCC的MVI风险的列线图模型,用Bootstrap法进行模型的内部验证,用验证组进行模型的外部验证,采用一致性指数、较正曲线及受试者工作特征（ROC）曲线来评估列线图的预测价值。结果 模型组多因素分析显示,NLR>2.282（OR=1.864,95% CI=1.184~2.933）、GGT>60 IU/L（OR=2.554,95% CI=1.631~4.001）、lgAFP（OR=1.455,95% CI=1.21~1.75）、肿瘤大小（OR=1.177,95% CI=1.084~1.277）、无完整假包膜（OR=2.019,95% CI=1.286~3.171）是术前预测HCC患者MVI的独立危险因素,并以此建立的列线图模型一致性指数在模型组和验证组为分别为0.785（95% CI=0.742~0.828）、0.824（95% CI=0.737~0.91）。模型与校准预测曲线贴合良好,通过Youden指数计算出列线图的最佳临界值为103分,临界值下的敏感度、特异度、阳性预测值和阴性预测值在模型组分别为86%、61%、67%和82%,在验证组中分别为82%、56%、53%和83%。结论 NLR>2.282、GGT>60 IU/L、lgAFP、肿瘤大小、无完整假包膜是HCC发生MVI的独立影响因素,以此建立的列线图模型术前预测MVI效能良好,可直观的分析术前合并微血管侵犯的发生风险,甄别出高风险人群。     

非心脏手术后延迟拔管的危险因素分析及预测模型建立

目的 探讨非心脏手术后延迟拔管的危险因素并建立预测模型。
方法 回顾性分析2020年9—10月接受非心脏手术且术后于PACU进行麻醉苏醒的1 009例患者临床资料。根据术后是否出现延迟拔管将患者分为两组：延迟拔管组（拔管时间＞1 h）和非延迟拔管组（拔管时间≤1 h）。采用LASSO回归和多因素Logistic回归建立预测模型，受试者工作特征（ROC）曲线、曲线下面积（AUC）和决策曲线分析评估该预测模型对非心脏手术后延迟拔管的预测价值。
结果 发生延迟拔管253例（25.1%）。多因素Logistic回归分析
结果 显示，ACCI评分（≥3分）、BMI（≤22.66 kg/m²）、术中罗库溴铵的使用、术中输血、手术时间（≥166 min）、留置导尿管、PACU内丙泊酚的使用和PACU内血管活性药物的使用是术后延迟拔管的独立危险因素（P＜0.05）。预测模型的AUC为0.730（95%CI 0.695～0.765， P<0.001），敏感性81.4%，特异性55.4%。决策曲线分析显示，该预测模型对延迟拔管的预测具有重要临床价值。
结论 ACCI评分（≥3分）、BMI（≤22.66 kg/m²）、术中罗库溴铵的使用、术中输血、手术时间（≥166 min）、留置导尿管、PACU内丙泊酚的使用和PACU内血管活性药物的使用是非心脏手术后延迟拔管的危险因素，基于以上危险因素建立的模型具有较好的预测价值。     

结直肠癌术后肠梗阻的危险因素分析及预测模型建立

目的构建结直肠癌(CRC)术后肠梗阻(POI)的列线图风险预测模型并进行验证。方法回顾性收集2018年6月至2019年8月接受CRC手术患者413例的围术期临床资料,年龄≥18岁,ASAⅠ—Ⅲ级。通过LASSO回归和多因素Logistic回归分析筛选独立危险因素,以此建立列线图模型。通过C-index验证模型的区分度;通过Calibration校正曲线验证模型的一致性;并通过决策曲线分析(DCA)以确定模型的临床有效性。结果共有404例CRC患者纳入分析,其中POI患者74例(18.3%)。列线图风险预测模型中包括开腹手术、术中未用非甾体类抗炎药(NSAIDs)、术前白蛋白(Alb)37.55 g/L和术前球蛋白(Glb)≥28.35 g/L。经内部验证,该模型的C-index为0.799(95%CI 0.746～0.852);Calibration校正曲线显示较好的一致性。DCA曲线表明当POI发生的风险阈值超过4%时,此列线图具有临床使用价值。结论基于开腹手术、术中未用NSAIDs、术前Alb37.55 g/L和术前Glb≥28.35 g/L这4个预测因素构建的列线图预测模型对CRC患者发生POI风险有良好的预测性能。     

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 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.