肺超声评分评价肺保护性通气策略对老年开腹手术患者肺损伤的影响

目的通过肺超声评分探讨肺保护性通气策略减轻老年开腹手术患者肺损伤的作用。方法选择2019年8月至2020年6月择期开腹手术患者50例,男33例,女17例,年龄65～80岁,BMI 18～25 kg/m~2,ASAⅠ—Ⅲ级。采用随机数字表法将患者分为两组:对照组(C组)和肺保护性通气组(P组),每组25例。所有患者常规麻醉诱导,采用容量控制的通气模式。C组设置V_T 8 ml/kg,不使用呼气末正压(PEEP);P组设置V_T 6 ml/kg, PEEP 6 cmH_2O,每间隔30 min给予手法肺复张。采用床旁超声评估患者双侧共12个区域的肺部超声,各区域分数累积为肺超声评分(LUS)。记录入室时(T_0)、麻醉诱导气管插管后5 min(T_1)、手术开始后2 h(T_2)、手术结束时(T_3)、气管导管拔除后15 min(T_4)、2 h(T_5)、术后1 d(T_6)的LUS评分、HR、MAP、SpO_2、PaO_2和PaCO_2。记录T_1—T_3时的氧合指数(PaO_2/FiO_2)、气道峰压(Ppeak)、吸气末平台压(Pplat)和驱动压力(ΔP)。记录术后7 d内肺部并发症(PPCs)的发生情况。结果与T_0时比较,T_1—T_5时C组和P组LUS评分明显升高(P0.05)。与T_1时比较,T_2—T_3时C组PaO_2/FiO_2明显降低(P0.05),P组ΔP明显降低(P0.05)。与C组比较,P组T_2—T_5时LUS评分明显降低(P0.05),T_2—T_3时PaO_2/FiO_2明显升高(P0.05)、ΔP明显降低(P0.05)。C组术后7 d内PPCs发生率为20%,P组未发生PPCs(P0.05)。结论床旁肺超声监测下,老年开腹手术患者在全麻期间和术后早期LUS评分升高,肺通气丢失。肺保护性通气策略可降低患者围术期的肺超声评分,减少肺通气损失,降低术后7 d的肺部并发症发生率。     

滴定个体化呼气末正压对全麻俯卧位脊柱手术老年患者呼吸功能的影响

目的探讨滴定个体化呼气末正压(PEEP)对全麻俯卧位脊柱手术老年患者术中呼吸和循环的影响。方法选择择期全麻下行俯卧位脊柱手术老年患者80例,男39例,女41例,年龄≥65岁,ASAⅡ或Ⅲ级。根据术中是否滴定获取个体化PEEP将患者随机分为两组:滴定组和对照组,每组40例。滴定组从0 cmH_2O开始递增至20 cmH_2O,PEEP变化梯度为2 cmH_2O获取个体化PEEP;对照组PEEP恒定为5 cmH_2O并通气至手术结束。记录滴定过程中每个PEEP水平持续1 min时动态肺顺应性(Cdyn),将Cdyn最大时的PEEP定为个体化PEEP。记录俯卧位时(T_0)、PEEP通气10 min(T_1)、30 min(T_2)、60 min(T_3)、手术结束(T_4)、拔管后20 min(T_5)的MAP、HR、CVP,记录T_0—T_4时平均气道压(Pmean)和Cdyn。T_0—T_5时行血气分析,计算肺内分流率(Qs/Qt)和氧合指数(OI)。记录机械通气过程中去氧肾上腺素使用和术后肺部并发症情况。结果滴定组所获取的个体化PEEP为(12.38±2.67)cmH_2O。T_0—T_5时两组MAP、HR、CVP差异无统计学意义。T_0—T_4时两组Pmean差异无统计学意义。T_2—T_4时滴定组Cdyn明显高于对照组(P0.05),Qs/Qt明显低于对照组(P0.05)。T_2—T_5时滴定组OI明显高于对照组(P0.05)。滴定组去氧肾上腺素使用率明显高于对照组[10例(25%) vs 3例(8%),P0.05]。滴定组术后肺部并发症发生率明显低于对照组[2例(5%) vs 8例(20%),P0.05]。结论与恒定PEEP 5 cmH_2O比较,俯卧位脊柱手术老年患者术中滴定个体化PEEP,能够更好地改善氧合,降低肺内分流率,减少术后肺部并发症。     

压力控制容量保证通气模式对肺切除术患者术后肺部并发症的影响

目的观察压力控制容量保证(PCV-VG)通气模式对肺切除术患者术后肺部并发症(PPCs)的影响。方法选择择期全麻下行胸腔镜肺切除术患者42例,男19例,女23例,年龄18～65岁,ASAⅠ或Ⅱ级。将患者随机分为两组:自双肺通气开始至手术结束始终使用PCV-VG模式通气组(P组)和始终使用容量控制通气(VCV)模式通气组(V组),每组21例。P组双肺通气期间V_T 8 ml/kg,单肺通气(OLV)期间V_T 6 ml/kg,压力上升时间设置为0.5 s; V组双肺通气期间设置V_T 8 ml/kg, OLV期间设置V_T 6 ml/kg,吸气暂停时间为0 s。记录术后1、2、3 d和出院前PPCs的发生情况。记录OLV前(T_0)、OLV 30 min(T_1)、OLV 60 min(T_2)和OLV结束后(T_3)的吸气峰压(PIP)、驱动压(ΔP)、动态肺顺应性(Cdyn)以及PaO_2、PaCO_2和氧合指数(PaO_2/FiO_2)。结果术后1 d P组PPCs发生率明显低于V组[2例(9%) vs 8例(38%),P0.05]。术后2、3 d和出院前两组PPCs发生率差异无统计学意义。T_0—T_3时P组PIP明显低于V组(P0.05)。与T_0时比较,T_1、T_2时两组PIP和ΔP明显升高(P0.05),Cdyn明显降低(P0.05)。T_0—T_3时两组ΔP、Cdyn、PaO_2、PaCO_2和PaO_2/FiO_2差异无统计学意义。结论 PCV-VG模式优于VCV模式,可明显减少肺切除患者术后1 d肺部并发症的发生,降低术中吸气峰压。     

呼气末正压通气对腹腔镜宫颈癌根治术患者眼压和视神经鞘直径的影响

目的观察腹腔镜下宫颈癌根治术中,5 cmH_2O的呼气末正压通气(PEEP)对患者眼内压(IOP)和颅内压的影响。方法选择我院择期行腹腔镜下宫颈癌根治术的患者60例,年龄45～65岁,BMI 20～25 kg/m~2,ASAⅠ或Ⅱ级。采用随机数字表法分为两组,PEEP为5 cmH_2O组(PEEP组)和无PEEP组(ZEEP组),每组30例。两组均采用静脉麻醉诱导气管插管,诱导完成机械通气后,PEEP组设置呼气末正压为5 cmH_2O,ZEEP组呼气末正压设置为0。记录麻醉诱导前(T_0)、麻醉后气腹前10 min平卧位(T_1)、气腹Trendelenburg体位后5 min(T_2)、30 min(T_3)、恢复平卧位气腹消失后(T_4)和术后30 min(T_5)时的IOP、视神经鞘直径(ONSD)、PaO_2、PaCO_2,同时记录T_1—T_4时肺动态顺应性(Cdyn)、气道峰压(Ppeek)和T_0—T_5时HR和MAP。结果与T_0时比较,T_1时两组IOP明显降低(P0.01),T_2—T_3时IOP明显延长(P0.01),T_2—T_3时ZEEP组ONSD明显延长(P0.01),T_3时PEEP组ONSD明显延长(P0.05)。T_1—T_4时PEEP组PaO_2、Cdyn明显高于ZEEP组(P0.05)。T_1时PEEP组Ppeek明显高于ZEEP组(P0.05)。结论在腹腔镜宫颈癌根治术手术中,气腹和Trendelenburg体位下应用5 cmH_2O的PEEP改善患者氧合的同时不引起IOP和颅内压的增高。     

最佳呼吸末正压肺保护通气策略对腹腔镜下结直肠癌根治术患者氧合功能的影响

目的探讨最佳呼吸末正压(PEEP)肺保护通气策略对腹腔镜下结直肠癌根治术患者围术期氧合功能的影响。方法择期行腹腔镜下结直肠癌根治术患者54例,男36例,女18例,年龄65～85岁,ASAⅡ或Ⅲ级。随机分为两组:传统组(T组)和保护组(P组),每组27例。T组设置V_T 9 ml/kg且无PEEP和肺复张(RMs);P组通过肺动态顺应性(Cdyn)PEEP滴定确定患者最佳PEEP值,设置低V_T 7 ml/kg联合最佳PEEP,每30分钟RMs一次。于麻醉诱导后10 min(T_1)、每次RMs后30 min(T_2、T_3、T_4)记录Cdyn及气道平台压(Pplat)、并在T_1—T_4、拔管后30 min(T_5)及术后第3天(T_6)采集动脉血样本,计算氧合指数(OI),记录术前和T_6时的改良临床肺部感染评分(mCPIS)。结果与T组比较,T_3、T_4时P组Cdyn明显升高(P0.05),T_4—T_6时P组OI明显升高(P0.05),T_6时P组mCPIS明显降低(P0.05)。结论最佳PEEP联合低V_T和RMs的肺保护通气策略可改善腹腔镜结直肠癌根治术患者围术期氧合,降低mCPIS。     

肺保护性通气在老年患者腹腔镜子宫内膜癌根治术中的应用

目的探讨肺保护性通气在老年患者腹腔镜子宫内膜癌根治术中的应用效果。方法选择2019年6月至2020年6月择期行腹腔镜子宫内膜癌根治术的老年女性患者60例,年龄65～80岁,BMI 20～28 kg/m~2,ASAⅠ或Ⅱ级。采用随机数字表法将患者分为两组:肺保护性通气组(P组)和常规机械通气组(R组),每组30例。P组设置V_T 7 ml/kg、呼气末正压通气(PEEP) 7 cmH_2O、每30分钟规律手法肺复张一次;R组仅设置V_T 9 ml/kg,未采用PEEP和肺复张。记录气腹前即刻、气腹后2 h、手术结束即刻的气道峰压(Ppeak)、气道平台压(Pplat)、肺动态顺应性(Cdyn)及血清IL-6、IL-8、TNF-α浓度。记录气腹前即刻和出复苏室即刻的氧合指数(PaO_2/FiO_2)。结果与气腹前即刻比较,气腹后2 h、手术结束即刻两组Pplat、Ppeak及血清IL-6、IL-8、TNF-α浓度均明显升高(P0.05),Cdyn明显降低(P0.05);出复苏室即刻两组PaO_2/FiO_2明显降低(P0.05)。与R组比较,P组气腹后2 h、手术结束即刻Pplat、Ppeak及血清IL-6、IL-8、TNF-α浓度明显降低(P0.05),Cdyn明显升高(P0.05);出复苏室即刻PaO_2/FiO_2明显升高(P0.05)。结论肺保护性通气可以减轻老年患者腹腔镜子宫内膜癌根治术围术期呼吸功能损伤和炎症反应,可安全用于老年患者腹腔镜子宫内膜癌根治术。     

肺保护性通气策略对腹腔镜胃癌根治手术老年患者肺氧合功能及术后肺部并发症的影响

目的探讨肺保护性通气策略(lung protective ventilation strategy,LPVS)对腹腔镜胃癌根治手术老年患者肺氧合功能及术后肺部并发症(postoperative pulmonary complications,PPCs)的影响。方法选择接受腹腔镜胃癌根治手术的老年患者115例,男69例,女46例,年龄≥65岁,ASAⅠ—Ⅲ级,随机分为两组:常规容量控制通气组(CV组,n=57)和肺保护性通气组(PV组,n=58)。记录插管后10 min(T_1)、气腹后10 min(T_2)、气腹后60 min(T_3)、气腹结束10 min(T_4)时的气道峰压(Ppeak),计算肺顺应性(Cdyn),并在T_1—T_4时抽取动脉血进行血气分析,计算氧合指数(OI)、肺泡动脉血氧分压差(A-aDO_2);记录术后第2天改良肺部感染评分(mCPIS);记录术后7 d内PPCs发生情况。结果与T_1时比较,T_2时两组Cdyn均明显降低(P0.05);T_3—T_4时PV组Cdyn明显高于CV组(P0.05);T_3—T_4时PV组OI明显高于CV组、A-aDO_2明显低于CV组(P0.05)。术后第2天PV组mCPIS明显低于CV组(P0.05)。术后7 d内PV组PPCs发生率明显低于CV组(P0.05)。结论肺保护性通气策略能明显改善老年腹腔镜胃癌根治手术老年患者的肺氧合功能,降低术后肺部并发症,具有一定的肺保护作用。     

小潮气量联合低PEEP对老年腹腔镜胆囊切除术患者术中氧合功能及肺功能的影响

目的探讨小潮气量联合低呼气末正压通气(PEEP)对老年腹腔镜胆囊切除术患者术中氧合功能及肺功能的影响。方法择期行腹腔镜胆囊切除术的老年患者共计100例,年龄65～74岁,ASA分级Ⅰ～Ⅱ级,体重指数(BMI)30kg/m~2。采用随机软件将纳入患者随机分为小潮气量联合低PEEP组(T组)和常规容量控制通气组(C组),每组各50例。记录两组患者手术开始即刻(T_0)、气腹后15分钟(T_1)、撤除气腹后15分钟(T_2)、拔除气管导管前(T_3)气道峰压(Ppeak)、平均气道压(Pmean)并计算动态肺顺应性(Cdyn)。于T_0、T_1、T_3时点进行血气分析记录动脉氧分压(PaO_2)、动脉CO_2分压(PaCO_2)并计算氧合指数(OI)。结果 T组患者T_1、T_2时点Ppeak、Pmean显著低于C组患者,但Cdyn显著高于C组患者,差异有统计学意义(P0.05)。两组患者T_0、T_1、T_3时点PaO_2、PaCO_2和OI差异均无统计学意义(P0.05)。结论小潮气量联合低PEEP有助于维持老年腹腔镜胆囊切除术患者术中肺功能及氧合功能。     

压力控制容量保证通气模式改善创伤性脑损伤患者早期预后

目的分析不同通气模式下创伤性脑损伤(TBI)患者的呼吸指标、脑组织炎症指标、肺部感染评分,评价压力控制容量保证通气(PCV-VG)模式对创伤性脑损伤患者早期预后的作用。方法选择2017年4月至2020年4月急诊行仰卧位脑血肿清除术的TBI患者100例,男55例,女45例,年龄40～65岁,BMI 18～28 kg/m~2,ASAⅢ或Ⅳ级,术前格拉斯哥昏迷评分(GCS)5～12分。采用随机数字表法将患者分为两组:压力控制容量保证通气组(P组)和容量控制通气组(V组),每组50例。P组采用PCV-VG模式,V组采用VCV模式。于机械通气即刻(T_1)、机械通气后60 min(T_2)、手术结束即刻(T_3)采集桡动脉血进行血气分析,记录T_1—T_3时HR、MAP、PaO_2、PaCO_2、肺部动态顺应性(Cdyn)、气道峰压(Ppeak)及气道平台压(Pplat)。于T_1—T_3时采集颈内静脉血样,采用ELISA法测定血清纤维胶质酸性蛋白(GFAP)、TNF-α、泛素羧基化水解酶1(UCH-L1)浓度;记录术后3 d和7 d的临床肺部感染评分(CPIS)评估肺部感染情况。结果与T_1时比较,T_2时V组PaO_2、Cdyn明显下降(P0.05),Ppeak、Pplat明显升高(P0.05);T_3时两组PaO_2、Cdyn明显下降(P0.05),Ppeak、Pplat明显升高(P0.05);T_2、T_3时两组血清GFAP、TNF-α、UCH-L1浓度均明显升高(P0.05)。与V组比较,T_2、T_3时P组PaO_2、Cdyn明显升高(P0.05),Ppeak、Pplat明显降低(P0.05),血清GFAP、TNF-α、UCH-L1浓度均明显降低(P0.05);术后3 d和7 d P组CPIS明显降低(P0.05)。结论 PCV-VG模式可以改善TBI患者呼吸指标,减轻脑组织炎症反应及肺部感染,从而改善患者早期预后。     

呼气末正压通气对腹腔热灌注化疗患者呼吸力学及肺功能的影响

目的探讨不同呼气末正压通气对腹腔热灌注化疗患者呼吸力学及肺功能的影响。方法选择择期行腹膜癌热灌注化疗的患者90例,男55例,女35例,年龄40~70岁,ASAⅠ~Ⅲ级。随机分为三组,每组30例。A组为容量控制通气(VCV)组,VT10 ml/kg;B组为VCV+低PEEP组,VT6ml/kg,PEEP 5cm H_2O;C组为VCV+高PEEP组,VT6ml/kg,PEEP 10cm H_2O;术中调整RR维持PETCO2 35~45 mm Hg。于气管插管后5 min(T_1)、腹腔热灌注化疗开始前(T2)、化疗结束时(T_3)、气管拔管前(T4)记录气道峰压(Ppeak)、气道平台压(Pplat)和平均气道压(Pmean),计算动态肺顺应性(C_(dyn))。并取桡动脉血进行血气分析,计算氧合指数(OI)、呼吸指数(RI)、肺泡-动脉血氧分压差(A-aDO_2)及死腔率(VD/VT)。记录术后7d内肺部相关并发症情况。结果与A组比较,T_1~T_4时B、C组Ppeak、Pplat、A-aDO_2和RI明显降低,OI和VD/VT明显升高(P0.05);T_2~T_4时B、C组Pmean明显降低,Cdyn和PaO_2明显升高(P0.05)。与T_1比较,T_2~T_4时A组Ppeak、Pplat和Pmean明显升高,C_(dyn)明显降低(P0.05);T_3时B组Ppeak和Pplat明显升高(P0.05),T_2~T_4 Pmean明显升高(P0.05),T3、T4时C_(dyn)明显降低(P0.05);T_2~T_4时C组Ppeak、Pplat和Pmean明显升高(P0.05),T_3、T_4时Cdyn明显降低(P0.05)。与T0时比较,T2~T4时三组PaO_2和OI明显降低,A-aDO_2、RI和VD/VT明显升高(P0.05)。术后7d内B、C组肺部感染、低氧血症和肺不张的发生率明显低于A组(P0.05)。结论小潮气量(6ml/kg)联合PEEP(5cm H_2O)通气可以显著改善腹膜癌患者术中热灌注期间肺功能,降低围术期肺部并发症的发生风险。     

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.     

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.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

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.