主动脉瓣置换术后室间隔厚度对主动脉瓣跨瓣压差的影响

目的 探讨主动脉瓣置换术后室间隔厚度对主动脉瓣跨瓣压差的影响.方法 2005年1月至2010年12月,接受主动脉瓣置换术患者273例,全部为单纯主动脉瓣狭窄.根据手术时使用的主动脉瓣不同品牌,将患者分为3组:Regent组、On-x组、其他品牌组.定义术后跨瓣压差大小为:轻度(0～30 mm Hg,1 mm Hg=0.133 kPa)、中度(30 ～60 mm Hg)及重度(大于60 mm Hg).分别比较术前、术后测量的左心室收缩期末径、左心室舒张期末径、左心室射血分数(EF值)和室间隔厚度.结果 3组患者术前的左心室收缩期末径、左心室舒张期末径及EF值差异无统计学意义(P＞0.05).Regent组患者,术后跨瓣压差为重度的患者术前室间隔厚度明显多于轻、中度(P＜0.05).使用On-x组患者,术后跨瓣压差为重度与中度的患者术前室间隔厚度者明显多于轻度组(P＜0.05).其他品牌组患者,术后跨瓣压差为重度的患者术前室间隔厚度明显多于中、轻度组(P＜0.05).结论 行主动脉瓣置换术后,术前室间隔厚度大于13.6 mm的患者其主动脉瓣跨瓣压差较厚度小于13.6 mm的患者显著增高.室间隔厚度大于15.3 mm的患者,应同期行室间隔部分切除或替换无支架瓣膜以减少主动脉瓣替换后的跨瓣压差.     

单纯超声心动图引导下经皮球囊主动脉瓣成形术治疗先天性主动脉瓣狭窄的中期结果

目的评价单纯超声心动图引导下经皮球囊主动脉瓣成形术治疗先天性主动脉瓣狭窄的中期结果。方法回顾性分析2016年1月至2017年11月在我中心接受单纯超声心动图引导下经皮球囊主动脉瓣成形术连续12例先天性主动脉瓣狭窄患者的临床资料,其中男7例、女5例,平均年龄(18.27±15.30)岁。术前平均峰值跨瓣压差61.8~110.0(80.30±24.50)mm Hg,50%患者合并主动脉瓣反流。结果 12例患者均顺利完成手术。平均主动脉瓣环直径为(18.65±3.17)mm,球囊直径(17.62±3.77)mm,球囊瓣环直径比为0.92±0.07。术后即刻平均峰值跨瓣压差16~51(36.72±12.33)mm Hg,与术前差异有统计学意义(P=0.000)。随访期内平均峰值跨瓣压差21~58(37.06±13.52)mm Hg,与术后即刻差异无统计学意义(P=0.310)。术后即刻和随访期内58%患者合并主动脉瓣反流,与术前差异无统计学意义(P=0.682)。结论单纯超声心动图引导下经皮球囊主动脉瓣成形术治疗先天性主动脉瓣狭窄安全可行,具有很高的成功率和极低的并发症发生率。     

单个主动脉瓣叶牛心包置换术治疗儿童室间隔缺损合并主动脉瓣反流

目的 探讨儿童单个主动脉瓣叶牛心包置换在室间隔缺损合并严重主动脉瓣反流患儿中的疗效。 方法回顾性分析2006年3月至2009年9月武汉亚洲心脏病医院室间隔缺损合并严重主动脉瓣关闭不全42例患儿行单个主动脉瓣叶牛心包置换术的临床资料。其中男28例、女14例,平均年龄2～14 （9.0±3.6） 岁。所有心功能分级（NYHA）均为Ⅱ级。 结果 手术没有死亡以及并发症的发生。术后即刻经食管超声心动图提示手术成功修复主动脉瓣,瓣叶均对合正常。所有患者主动脉瓣反流均在轻度以内,跨主动脉瓣峰压差为（14.2±2.8） mm Hg。住院时间11 d,没有任何不良症状。全组患者随访32～72 （50±16） 个月。术后心功能均为Ⅰ级,无反流17例,轻度反流21例,中度反流4例。跨主动脉瓣峰压差为（12.4±3.2） mm Hg。随访中无死亡和需要二次手术患者。随访观察中未见牛心包瓣叶结构性衰败。 结论 对于室间隔缺损合并重度主动脉瓣关闭不全的患者,单个主动脉瓣叶牛心包置换术具有良好的血流动力学和中期效果。     

牛心包主动脉瓣叶置换术在主动脉瓣二瓣化畸形合并主动脉瓣反流中的应用

目的探讨主动脉瓣叶牛心包置换术在主动脉瓣二瓣化畸形合并主动脉瓣反流患者中的疗效。方法回顾性分析2008年6月至2013年12月武汉亚洲心脏病医院主动脉瓣二瓣化畸形合并主动脉瓣重度反流的79例患者行主动脉瓣叶牛心包置换术的临床资料。其中男60例、女19例,平均年龄12~78(38±14)岁。全组心功能分级(NYHA)均为Ⅱ级。主动脉窦管交界及升主动脉扩张患者26例。结果全组无死亡及并发症发生。术后即刻经食管超声心动图提示手术成功重建主动脉瓣,瓣叶均有正常对合,所有患者主动脉瓣反流均在1级以内,跨主动脉瓣峰压差(14.2±2.8)mm Hg。住院时间15 d,没有任何不良症状。全组患者随访9~64(50±16)个月。术后心功能均为Ⅰ级。末次随访显示:主动脉瓣反流0级57例,1级16例,2级5例,3级1例;跨主动脉瓣峰压差(12.4±3.2)mm Hg;主动脉窦管交界及升主动脉扩张患者窦管交界平均直径为2.7 cm,窦管交界形态正常;超声测量主动脉瓣对合缘高度为0.58 cm。随访中无死亡和需要二次手术患者。随访中未见牛心包瓣叶结构性衰败。结论对于主动脉瓣二瓣化畸形合并严重主动脉瓣反流的患者,主动脉瓣三叶牛心包置换术具有良好的血流动力学和中期效果。对于主动脉窦管交界及升主动脉扩张的患者,需要同期行主动脉窦管交界及升主动脉成形术。     

应用不同品牌机械瓣行主动脉瓣置换术患者的血流动力学变化

目的 探讨应用不同品牌19 mm机械瓣行单纯主动脉瓣置换术后早期血流动力学变化情况。 方法回顾性分析2007年1月至2012年1月北京安贞医院116例单纯主动脉瓣狭窄患者行主动脉瓣置换术后血流动力学变化,其中男61例、女55例,年龄（52±13） 岁。根据使用的瓣膜品牌将患者分为3组： SJ.Regent瓣膜组,38例（33%）,男20例、女18例,平均年龄（52±15） 岁; Carbomedics瓣膜组,40例（34%）,男21例、女19例,平均年龄（51±17） 岁。On-X瓣膜组,38例（33%）,男20例、女18例,平均年龄（55±16） 岁。比较患者术前和术后左心室收缩期末内径、左心室舒张期末内径、射血分数（EF）值、室间隔厚度、左心室壁厚度、主动脉瓣瓣上流速、跨瓣压差以及术后有效瓣口面积指数（EOAI）。 结果 三组患者术前及术后的左心室收缩期末内径、左心室舒张期末内径、EF值、室间隔厚度、左心室壁厚度差异均无统计学意义 （P＞0.05）。主动脉瓣瓣上流速和跨瓣压差术前、术后有差异有统计学意义。SJ.Regent瓣膜组和Carbomedics瓣膜组患者较On-X瓣膜组患者的术后主动脉瓣瓣上流速 ［（244.30±33.67） cm/s vs. （249.69±79.13） cm/s vs. （294.83±52.05） cm/s］和跨瓣压差［（27.77±3.33） mm Hg vs. （33.58±18.90） mm Hg vs. （38.56±13.21） mm Hg］明显偏小,其差异有统计学意义。 结论 运用19 mm机械瓣进行主动脉瓣置换术,SJ.Regent和Carbomedics瓣膜较On-X瓣膜有更好的血流动力学效果。     

主动脉瓣成形术治疗儿童主动脉瓣疾病30例

目的总结我院用主动脉瓣成形术治疗儿童主动脉瓣疾病的方法和结果。方法回顾性分析我院2005年1月至2017年12月30例行主动脉瓣成形术患儿的临床资料,其中男17例、女13例,年龄4个月～16岁,平均年龄(6.7±4.3)岁,体重5.6～62.4(23.7±14.1)kg。结果 30例患者均存活,围术期无严重并发症,术后平均跨瓣压差(21.1±17.0)mm Hg。随访9个月～13年,共有4例患儿出现中度以上的主动脉瓣狭窄或关闭不全,其中1例行再次手术。其余患者瓣膜功能良好。结论主动脉瓣成形术安全可靠,近中期效果良好,少数患者仍需再次手术,可作为治疗儿童主动脉瓣疾病的首选术式。     

一岁内重度肺动脉瓣狭窄经胸肺动脉瓣球囊扩张成形术疗效分析

目的总结经胸肺动脉瓣球囊扩张成形术对低龄婴儿重度肺动脉瓣狭窄的即刻疗效及近中期随访结果,探讨一站式肺动脉瓣球囊扩张术的有效方法。方法 2006年3月至2010年3月,阜外心血管病医院采用经胸肺动脉瓣球囊扩张成形术治疗32例重度肺动脉瓣狭窄婴儿患者,男23例,女9例;月龄5 d~11个月(4.59±3.21个月);体重2.3~10.5 kg(6.48±2.05 kg)。均在全身麻醉、气管内插管和超声引导下进行肺动脉瓣球囊扩张。术后随访超声心动图,测量肺动脉瓣跨瓣压差,评估肺动脉瓣反流程度。结果手术成功率为100%,均未出现严重并发症,术后血流动力学稳定,跨瓣压差由术前的82±27 mm Hg下降至23±12 mm Hg(t=15.28,P0.05);4例患者出院时复查超声心动图提示:跨瓣压差仍高于40 mm Hg。所有患者三尖瓣反流均明显改善,无反流17例,微小量反流13例,中量反流2例;血氧饱和度均大于95%。随访1个月~4年(16±11个月),疗效满意,所有患者均生长发育良好,肺动脉瓣跨瓣压差17±10 mm Hg,仅1例肺动脉瓣跨瓣压差大于40 mm Hg;发生肺动脉瓣反流24例,主要为少量反流23例,仅1例中量反流。结论经胸肺动脉瓣球囊扩张成形术是治疗新生儿及婴幼儿重度肺动脉瓣狭窄一种安全有效的方法。     

自体心包片加宽瓣膜面积的二尖瓣成形术

目的 总结自体心包片加宽瓣膜面积的二尖瓣成形术的临床疗效,探讨其手术技巧和适应证.方法 2004年7月至2008年6月治疗45例单纯二尖瓣瓣膜病变病人,二尖瓣狭窄10例,关闭不全35例,其中先天性8例,风湿性21例,退行性7例,感染性心内膜炎9例.应用自体心包片行后瓣叶加宽14例,前瓣叶加宽8例,前、后瓣叶都加宽23例;镜式成形12例;人工腱索12例,腱索转移6例,乳头肌开窗4例.全部病例均瓣环成形,应用Duran环16例,Carpentier环29例.并比较手术前、后心功能变化.结果 无死亡病例.1例风湿性瓣膜闭合不好,术中改瓣膜置换术.术中食管超声示二尖瓣无反流38例,少量反流6例;二尖瓣有效瓣口面积平均(2.8±0.6)cm~2,跨瓣压差平均(6.21 ±1.34)mm Hg(1 mm Hg=0.133 kPa).平均随访(18.0±2.1)个月.复查超声示二尖瓣无反流35例,少量反流9例.有效瓣12面积平均(2.5±0.8)cm~2,跨瓣压差平均(7.21±0.45)mmHg,均无需再手术.术前、术后左心室舒张末期内径(56±6)mm对(48±7)mm,P<0.05;射血分数(0.45±0.23)对(0.51±0.24),P<0.05;左心房内径(62±23)mm对(50±11)mm,P<0.05.心功能明显改善,瓣膜功能好.结论 自体心包片加宽瓣膜面积补偿瓣叶和(或)腱索的短缩,增加瓣叶活动,增加瓣膜闭合面积,结合瓣环成形,临床疗效肯定.手术操作简单,且自体心包相容性好,术后无需抗凝.     

小儿先天性主动脉瓣疾病不同治疗策略的疗效分析：单中心85例的回顾性队列研究

目的分析先天性主动脉瓣疾病患儿的各类手术方法的早中期治疗结果,为主动脉瓣狭窄或反流患儿的手术方式提供参考。方法回顾性分析2005年1月至2018年12月在复旦大学附属儿科医院进行手术治疗的85例主动脉瓣疾病患儿的临床资料,男64例、女21例,平均年龄45个月(5 d～15岁)。其中18例行主动脉瓣球囊扩张成形术(BAV),8例行主动脉瓣外科交界切开成形术(SAV),27例行主动脉瓣自体心包修补术,16例行机械瓣主动脉瓣置换术,16例行Ross手术。随访(6.25±2.76)年,分析不同手术术后再干预情况和患儿生存状况。结果 85例患儿死亡3例(3.5%),再手术17例(20.0%)。采用SAV、BAV、主动脉瓣自体心包修补术、机械瓣主动脉瓣置换术、Ross手术患儿5年生存率分别为87.4%、88.9%、100.0%、100.0%、100.0%,差异无统计学意义(P0.05);5年免再手术率分别为44.4%、18.4%、100.0%、66.9%、80.5%,差异具有统计学意义(P0.05)。结论先天性主动脉瓣狭窄或反流手术需要根据患儿瓣叶组织病变情况采取手术方式。对于严重病变患儿,首次干预推荐SAV。先天性主动脉瓣狭窄手术中SAV、BAV均为姑息性手术,中远期需进一步评估以及再干预可能;Ross手术和机械瓣主动脉瓣置换术有较低的再干预率,中远期随访表明疗效确切;主动脉瓣自体心包修补术有望成为延期或替代Ross手术和瓣膜置换术的方法。     

主动脉瓣置换术650例临床分析

目的 总结主动脉瓣人工瓣膜置换术的临床经验.方法 主动脉瓣置换手术650例,年龄11～76岁,平均(43.2±12.6)岁.60岁以上52例.风湿性病变475例,先天性瓣叶畸形58例,退行性变49例,感染性心内膜炎(IE)47例,人工瓣膜感染性心内膜炎4例,外伤性2例.合并升主动脉瘤样扩张或主动脉夹层52例,冠心病36例,陈旧性脑血管意外14例,室间隔缺损10例,房间隔缺损2例,动脉导管未闭7例.心功能Ⅲ级385例,Ⅳ级119例.射血分数(EF)平均0.56±0.11,左室舒张末直径平均(LVED)(58.59±12.55)mm,左室舒张末容积(KVEDV)(191.58±89.88)ml,主动脉瓣跨瓣压差13.00～118.25 mm Hg(1mmHg=0.133kda).生物瓣占8.77%.主动脉瓣二次置换9例,同期行冠状动脉旁路术36例,主动脉大血管手术52例.体外循环110～208 mnin,升主动脉阻断54～129min.结果 人工瓣膜直径≤21 mm者术后跨瓣压差平均为30.00 mm Hg,直径>21 mm者术后跨瓣压差平均为23.00mmHg,差异有统计学意义.术后30d内死亡40例,1987-1996年死亡29例(9.21%);1997-2007年死亡11例(3.28%).平均随访58个月.结论 随着手术技术、心肌保护技术和围术期处理技术的提高,生物瓣的使用和对合并缺血性心脏病病人的再血管化,手术并发症和病死率明显下降.     

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.     

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.