初产妇产后抑郁风险列线图模型的建立

目的建立预测初产妇产后抑郁的风险列线图模型,为临床及早识别高危产妇和采取相关预防措施提供参考。方法采用爱丁堡产后抑郁量表和Zung抑郁自评量表对264例初产妇进行调查,对产后抑郁的独立危险因素进行Logistic回归分析,将筛选出的独立危险因素建立列线图预测模型并进行验证。结果 Logistic回归分析显示,孕次≥3次、文化程度低、夫妻感情不和睦、居住条件不满意、妊娠结局不良、产后睡眠不良及产后亲友关系不融洽是初产妇产后抑郁的独立危险因素(P0.05,P0.01)。基于以上7项独立危险因素建立列线图模型,经验证C-index指数为0.815。结论初产妇产后抑郁影响因素较多,列线图预测模型可有效预测初产妇产后抑郁的发生。     

高龄冠心病患者冠状动脉旁路移植术后缺血性卒中风险预测模型的建立与评价北大核心CSCD

目的探讨我国高龄(年龄≥75岁)冠心病患者冠状动脉旁路移植术后缺血性卒中的危险因素,建立相关风险预测模型并进行评价。方法回顾性纳入2015年1月至2021年9月期间就诊于首都医科大学附属北京安贞医院,拟行冠状动脉旁路移植术的1553例高龄冠心病患者,其中男1121例(72%),女432例(28%);中位年龄77(75,78)岁,收集其临床资料。通过单因素分析和多因素logistic回归分析,探讨影响高龄冠心病患者旁路移植术后缺血性卒中的危险因素,建立风险预测模型,构建列线图,并检验模型的区分度和校准度。结果全部患者均完成冠状动脉旁路移植术,术后发生缺血性卒中35例,发生率2.25%(35/1553)。多因素logistic回归分析结果显示:糖尿病(0R=2.61,95%CI 1.31~5.32)陈旧性心肌梗死(0R=3.62,95%CI:1.61~7.63)、收缩压(0R=1.03,95%CI:1.01~1.04)、椎动脉狭窄程度(0R=1.01,95%CI:1.00~1.02)是导致冠状动脉旁路移植术患者术后缺血性卒中的独立危险因素。通过列线图呈现模型,采用ROC曲线评价模型区分度,测得ROC曲线下面积为0.757,区分度较优。行Hosmer-Lemeshow拟合优度检验评价模型校准度(χ^(2)=6.209,P=0.624)具有较好的一致性。结论糖尿病、陈旧性心肌梗死、收缩压和椎动脉狭窄程度是高龄冠心病患者冠状动脉旁路移植术后缺血性卒中的独立危险因素,由此建立的风险预测模型具有良好的区分度和校准度。     

肝细胞癌患者肝切除术后严重并发症列线图风险预测模型的建立与评价

背景与目的：肝切除术后并发症的发生率较高,早期筛查术后严重并发症发生的高风险人群对于降低术后严重并发症的发生率具有重要意义。本研究通过分析肝细胞癌患者术后严重并发症发生的危险因素,建立术后严重并发症发生的个体化列线图风险预测模型,以期为肝细胞癌患者围术期管理的优化提供参考依据。 方法：回顾性分析广西医科大学第一附属医院肝胆外科2018年1月—2020年6月行肝切除术的854例肝细胞癌患者资料,采用单因素分析与Logistic回归分析筛选术后严重并发症的影响因素,并建立列线图风险预测模型,采用Bootstrap法对模型进行内部验证,并应用ROC曲线及校准曲线评价模型的区分度及校准度。 结果：854例患者中86例（10.1%）发生术后严重并发症（≥III级）。单因素分析与Logistic回归分析结果显示,肝硬化（OR=1.905,95% CI=1.153~3.147,P=0.012）、手术方式（OR=3.412,95% CI=1.618~7.192,P=0.001）、术中血浆输注（OR=2.518,95% CI=1.51~4.199,P<0.001）、手术时间（OR=1.003,95% CI=1.002~1.005,P<0.001）、术后白蛋白水平（OR=0.922,95% CI=0.873~0.973,P=0.003）、术后天门冬氨酸氨基转移酶水平（OR=1.001,95% CI=1.000~1.002,P=0.006）是肝细胞癌患者肝切除术后严重并发症的独立影响因素。列线图模型预测术后严重并发症发生风险的C-指数为0.774,ROC曲线显示列线图模型预测术后严重并发症发生风险的曲线下面积为0.788（95% CI= 0.74~0.836）。 结论：基于6个临床因素建立的肝细胞癌患者肝切除术后严重并发症的个体化列线图风险预测模型预测效能良好,可用于早期识别高风险患者,为医务人员采取防治措施提供依据。     

输尿管软镜碎石术后尿路感染的危险因素分析及预测模型构建

目的:分析影响输尿管软镜碎石术后尿路感染的危险因素,建立列线图预测模型。方法:采用便利抽样法,选取2019年4月—2021年7月阜南县人民医院收治的327例行输尿管软镜碎石术患者为研究对象,根据术后30 d内是否发生尿路感染分为感染组与未感染组,采用多因素logistics回归模型筛选术后尿路感染的独立影响因素,基于独立影响因素建立列线图预测模型,并评估模型的区分度与准确度。结果:输尿管软镜碎石术患者术后尿路感染发生率为14.37%（47/327）;多因素logistic回归分析显示,术前尿路感染、合并糖尿病、留置尿管时间>7 d、肾盂内压>30 mmHg为影响术后尿路感染的独立危险因素（P<0.05）,预防性应用抗菌药物为保护性因素（P<0.05）;基于输尿管软镜碎石术后尿路感染的独立影响因素建立列线图预测模型,内部验证结果显示列线图模型的校准曲线预测值与实际值基本一致,Hosmer-Lemeshow拟合优度检验χ²=8.199,P=0.315,ROC曲线下面积为0.805（95%CI:0.729～0.877）,DCA曲线分析阈值范围为0...     

老年稳定性冠心病患者认知衰弱风险预测模型的建立

目的 建立老年稳定性冠心病患者认知衰弱风险的列线图模型,为临床早期识别和干预提供参考.方法 便利选取848例老年稳定性冠心病患者,采用 自制一般资料调查表、蒙特利尔认知评估量表、临床痴呆评定量表、衰弱表型量表进行评估;Logistic回归分析确定认知衰弱的独立危险因素,同时建立认知衰弱风险列线图预测模型并进行内部验证.结果 老年稳定性冠心病患者认知衰弱发生率为11.9％;Logistic回归分析显示,年龄≥70岁、每晚睡眠时间≤6 h、有糖尿病史、心力衰竭、有高血压史、每周运动次数≤5次为老年稳定性冠心病患者认知衰弱的独立危险因素(P＜0.05,P＜0.01);基于上述6个危险因素建立的列线图,C-index为0.835(95％CI 0.771～0.899),H-L偏差度检测x2=9.145(P=0.103).结论 列线图模型能够有效预测老年稳定性冠心病患者认知衰弱风险,可进一步开展外部验证研究.     

个体化预测老年急性胆囊炎患者发生术后感染的风险列线图模型的建立

目的 探讨个体化预测老年急性胆囊炎患者发生术后感染的风险列线图模型的建立。方法 回顾性分析2018年1月至2019年12月因急性胆囊炎于眉山市人民医院行胆囊切除术治疗的233例老年患者的临床资料,分别使用单因素法和多因素Logistic回归法分析术后感染的独立危险因素。然后用筛选出的独立危险因素建立列线图预测模型,并对模型的预测性及准确度进行验证。结果 年龄≥70岁（OR 3.032,95%CI 1.289～7.132）、糖尿病（OR 3.321,95%CI 1.452～7.599）、肝硬化（OR 2.543,95%CI 1.004～6.438）、胆囊结石（OR 9.051,95%CI 1.833～44.687）、胆囊周边积液（OR 3.264,95%CI 1.428～7.459）及白细胞计数＞10×10⁹/L（OR 3.873,95%CI 1.673～8.966）是老年急性胆囊炎患者发生术后感染的独立危险因素。基于以上6项独立危险因素,建立相关列线图预测模型,并对该模型进行验证,内部验证和外部验证的C-index指数分别为0.782和0.735。校正曲线分析显示,训练集和验证集的校正曲线和理想曲线拟合均较好,预测值同实测值均基本一致。ROC曲线分析显示,训练集和验证集的曲线下面积（AUC）分别为0.852（95%CI 0.821～0.883）和0.838（95%CI 0.812～0.864）,说明本次列线图模型具有良好的预测精准度。结论 年龄≥70岁、糖尿病、肝硬化、胆囊结石、胆囊周边积液及白细胞计数＞10×10⁹/L是老年急性胆囊炎患者发生术后感染的独立危险因素,相关列线图模型的建立对临床筛查高危人群和制定针对性防治措施具有指导意义,临床应用价值较高。     

肛周脓肿术后复发形成肛瘘的影响因素分析及预测模型建立

目的分析肛周脓肿患者术后复发形成肛瘘的影响因素,构建预测术后复发形成肛瘘的列线图模型并验证模型的预测效果。 方法采取便利抽样法,选取2019年1月至2022年2月重庆市大足区人民医院收治的419例肛周脓肿患者,按照7∶3随机分为建模组（293例）与验证组（126例）,术后随访3个月,根据是否复发形成肛瘘分为肛瘘组与非肛瘘组。采用单因素和多因素Logistic回归分析筛选肛周脓肿患者术后复发形成肛瘘的独立危险因素,然后利用R 3.6.3软件建立列线图模型。以验证组对模型进行外部验证,绘制受试者工作特征（ROC）曲线、校准曲线证实列线图模型的预测效能。 结果术后3个月内有140例（33.41%）患者复发形成肛瘘,其中建模组96例（32.76%）,验证组44例（34.92%）。Logistic回归模型显示,糖尿病史（OR=3.101,95% CI：1.620~5.935）、肥胖（OR=3.157,95% CI：1.707~5.587）、有脓肿病史（OR=4.120,95% CI：2.201~7.713）、深部肛周脓肿（OR=3.686,95% CI：1.988~6.833）、肠道来源致病菌（OR=3.140,95% CI：1.679~5.872）和单纯切开引流术（OR=2.284,95% CI：1.548~5.152）是肛周脓肿患者术后复发形成肛瘘的危险因素（均P<0.01）。利用以上6个风险预测指标构建列线图模型,其内部验证的ROC曲线下面积为0.829（95% CI：0.781~0.877）、H-L检验χ²=7.203,P=0.515,外部验证的ROC曲线下面积为0.857（95% CI：0.787~0.927）,H-L检验χ²=5.079,P=0.477,校准曲线斜率均接近1,两组验证方式均提示模型预测效果与实际发生风险有良好一致性。 结论肥胖、糖尿病史、深部肛周脓肿、肠道来源致病菌、脓肿病史、单纯切开引流术是影响肛周脓肿患者术后复发形成肛瘘的危险因素,基于以上6个因素构建的列线图具有良好的区分度和准确性,可为肛周脓肿患者术前治疗策略制定提供参考。     

直肠癌术后吻合口漏的术前危险因素分析及预测模型构建

目的 探讨直肠癌术后发生吻合口漏的术前危险因素并构建预测模型。方法 回顾性分析2007-01-01至2016-12-31中国人民解放军中部战区总医院普通外科收治的行直肠癌根治术并作一期吻合的330例病人的临床资料,分析发生吻合口漏的术前危险因素。应用R软件完成列线图预测模型。通过受试者工作特征曲线（ROC）和校准曲线评估列线图预测模型的能力。另收集2017-01-01至2018-12-31收治的行直肠癌根治术并作一期吻合的57例病人资料作为外部验证数据。结果 330例中有42例术后发生吻合口漏（12.7%）。单因素分析结果显示,吻合口漏发生与术前营养支持、肿瘤距肛门距离、BMI、营养风险筛查评分（NRS2002）、美国麻醉师协会（ASA）评分、血红蛋白、前白蛋白相关（P均＜0.05）。多因素Logistic回归分析结果显示,BMI≥25、NRS2002评分>3分、肿瘤距肛门距离≤10 cm、血红蛋白<120 g/L是术后发生吻合口漏的独立危险因素。根据多因素回归分析结果构建列线图预测模型,受试者工作特征曲线下面积（AUC）为0.874（95%CI 0.823-0.925）。内部验证显示,模型的一致性指数为0.869。外部验证采用时段验证,AUC为0.787（95%CI 0.632-0.942）。结论 BMI≥25、NRS2002评分>3分、肿瘤距肛门距离≤10 cm及血红蛋白<120 g/L是吻合口漏的独立危险因素,基于这些变量的列线图可作为临床决策参考。     

预测胰十二指肠切除术后切口疝发病风险列线图模型的建立

目的建立预测胰十二指肠切除（PD）术后发生切口疝的风险列线图模型,为切口疝的早期干预提供依据。 方法回顾性分析2009年1月至2017年1月于邯郸市中心医院行PD术的926患者的临床资料,随访发生切口疝的患者24例（切口疝组）,未发生切口疝的按照1∶5的比例随机抽取120例为非切口疝组。分别使用单因素和Logistic回归多因素分析术后切口疝的独立危险因素,并建立相关列线图预测模型。 结果年龄≥60岁（OR=5.800,95% CI 1.530~21.984）、BMI≥24 kg/m²（OR=4.165,95% CI 1.187~14.613）、糖尿病（OR=5.321,95% CI 1.548~18.285）、呼吸系统疾病（OR=4.565,95% CI 1.225~17.007）、切口感染（OR=6.803,95% CI 1.573~29.419）及手术时间≥6 h（OR=6.934,95% CI 1.938~24.813）是PD术后发生切口疝的独立危险因素（P<0.05）。基于以上6项独立危险因素建立列线图模型,并对该模型进行验证,预测值同实测值基本一致,C-index 0.890（95% CI 0.854~0.926）,说明本研究列线图模型具有良好的精准度和区分度。 结论年龄≥60岁、BMI≥24 kg/m²、糖尿病、呼吸系统疾病、切口感染及手术时间≥6 h是PD术后发生切口疝的独立危险因素,本研究建立的列线图预测模型具有良好的精准性和区分度,有利于临床筛查PD术后发生切口疝的高风险人群和制定针对性规避措施。     

日间经皮肾镜碎石取石术患者延迟出院的危险因素分析和列线图构建

目的探讨日间经皮肾镜碎石取石术（PCNL）患者延迟出院的危险因素,并构建风险预测列线图。 方法回顾性审查370例日间PCNL患者的电子病历,根据患者是否在24 h内出入院,将其分为延迟出院组（61例）和正常出院组（309例）。采用单因素分析比较两组的一般资料、术后1 h生命体征和血液学指标。通过Logistic回归分析确定延迟出院的危险因素,绘制列线图以预测延迟出院的风险,应用校准曲线评估列线图的内部校准性能。 结果370例患者中有61例（16.5%）出现延迟出院,18例（4.9%）住院时间超过48 h。Logistic回归分析显示年龄>65岁（OR：3.992,95%CI：1.792~8.892,P=0.001）、通道数量（OR：3.139,95%CI：1.548~6.367,P=0.002）、术中严重出血（OR：12.207,95%CI：2.761~53.973,P=0.001）、术后1 h体温>38℃（OR：4.623,95%CI：1.445~14.789,P=0.010）、中性粒细胞比率>75%（OR：1.951,95%CI：1.008~3.777,P=0.047）和钾<3.5 mmol/L（OR：5.469,95%CI：1.641~18.226,P=0.006）是日间PCNL患者延迟出院的独立危险因素。延迟出院预测模型的ROC曲线下面积为0.784,通过危险因素构建的列线图具有良好的区分度和准确性。 结论基于年龄、通道数量、术中严重出血、术后感染和低钾血症构建的延迟出院风险预测列线图预测性能良好,可帮助医护人员快速识别术后延迟出院高风险患者,以便尽早实施医疗干预。     

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.     

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.     

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.