重症肌无力患者血清IL-12水平变化及临床意义

目的观察重症肌无力(MG)患者血清白细胞介素12(IL-12)水平变化,并探讨其临床意义。方法采用双抗体夹心ELISA法检测69例MG患者(MG组)及30例健康体检者(NC组)血清IL-12、乙酰胆碱受体抗体(AchRab),AchRab>0.5 nmol/L为阳性;并对35例MG初治者采用糖皮质激素(GC)治疗3个月,同法检测治疗前后血清IL-12、AchRab。结果 MG组血清IL-I2、AchRab分别为(120.95±14.77)pg/mL、(0.69±0.10)nmol/L,NC组分别为(43.19±8.78)pg/mL、(0.37±0.09)nmol/L;两组比较,P均<0.01。AchRab阳性者血清IL-12为(123.07±16.72)pg/mL,高于AchRab阴性者的(110.90±14.72)pg/mL(P<0.01);MG患者血清IL-12水平与AchRab呈正相关(r=0.697,P<0.01)。伴胸腺影像学异常改变者血清IL-12、AchRab水平较均高于胸腺正常者(P均<0.01),但伴胸腺增生与胸腺瘤MG患者比较,P>0.05。GC治疗3个月后,35例MG初治者临床疗效绝对评分为(5.8±2.4)分,低于治疗前的(18.9±2.9)分(P<0.01);血清IL-12、AchRab水平亦均低于治疗前(P均<0.01),但仍均高于NC组(P均<0.01)。结论 MG患者血清IL-12水平升高,其有助于MG的病情及疗效判定。     

常温体外循环间断4∶1温血停跳液灌注的心肌保护

良好的心肌保护方法不仅要提供有效的心肌保护，同时亦为了提供良好的操作环境。不同的心肌保护方法各有特点，不能相互取代。当今心肌保护在于综合利用各种心肌保护方法，相互弥补［1］。1997年至1998年对106例冠脉搭桥患者采取不同的综合心肌保护方法取得较好的效果，现将结果报告如下。 资料与方法 选1997年至1998年CABG术106例随机分为2组，温血组(W组)74例，冷血组(C组)32例。2组病人术前临床资料无明显区别(表1)。常规建立体外循环，右心房二级静脉插管，升主动脉根部动脉插管及顺行停跳液灌注管并接多头灌注管，体外循环装置包括Stockert-Ⅱ型心肺机、滚压式动脉泵非搏动灌注，膜肺、动脉微栓滤器、BCD(氧合血及晶体停跳液混合变温装置)，转流前肝素化3 mg/kg,ACT>480秒，如使用抑肽酶，ACT>720秒，转中预充液内加入肝素1 mg/kg。中度血液稀释至HCT 20%～25％，转流中不进行全身降温及心表降温，病人肛温在室温下下降至33℃～36℃之间。4∶1含血停跳液通过BCD装置由4份氧合血与1份晶体停跳液(ST.Thomas'液15% KCl-20 ml/500 ml及15% KCl -10 ml/500 ml)混合获得。阻断升主动脉后，经主动脉根部灌注高钾4∶1含血停跳液1000 ml，灌注速度200～300 ml/min,灌注压力在158～210 mmHg(1 mmHg=0.133 kPa)之间，直至心脏完全停止电机械活动。以后每间隔一段时间(通常最长约15 min)灌注1次低钾4∶1含血停跳液500 ml，速度200 ml/min左右，2次灌注间隔期间术者行桥—冠状动脉吻合。吻合完毕的大隐静脉上可以持续进行经桥灌注，灌注压力60 mmHg。桥-主动脉吻合依术者选择在阻断或开放升主动脉进行，开放升主动脉之前3 min左右，经主动脉根部及经桥灌注温血，流量100～200 ml/min。     

高浓度弹力蛋白酶低压力下腔内灌注制备兔腹主动脉瘤模型

目的:探讨高浓度(100IU/mL)弹力蛋白酶在低压力下,短时间腔内灌注制备兔腹主动脉瘤模型的新方法,为腹主动脉瘤的研究提供简便、易制作的动物模型。方法:雄性新西兰大白兔30只,按1:2的比例随机分为对照组(A组)10只,实验组(B组)20只,实验组在低压力下灌注高浓度(100IU/mL)弹力蛋白酶,并维持7~10min,对照组灌注0.9%氯化钠液,所有动物于术后第3周超声检查,后处死所有动物进行大体标本观察并行病理染色(HE、弹力纤维EVG、胶原纤维masson),比较组间病死率及病死率有无差别。结果:实验组动物病死率为15%,对照组病死率为20%,两组比较,差异无统计意义(P0.05)。实验组成瘤率为100%,动脉壁弹力纤维降解,平滑肌细胞减少;对照组成瘤率为0%,动脉壁正常结构未见明显破坏,两组成瘤率比较,差异有统计学意义(P0.001)。结论:腔内灌注高浓度弹力蛋白酶(100IU/mL)在低压力状态下,短时间内可成功制备家兔腹主动脉瘤模型,其病死率低,病死率高。     

二氧化碳充溢降低小儿先天性心脏病手术中气体栓塞的疗效

目的 改良二氧化碳（CO2）充溢技术在小儿先天性心脏病手术中防止气体栓塞的安全性和有效性。 方法 以我院2014年1月~2015年6月心外科的90例先天性心脏病患儿为研究对象,并根据随机数字排列表分为3组(每组30例）。CO210L/min组（CO2流量为10 L/min）,CO25L/min组(CO2流量为5 L/min),对照组不采用CO2充溢法。3组均采用头低位、心脏底部按摩等机械性手法进行排气。对3组术中的排气效果、血气分析中的血CO2分压(PaCO2)、手术时间、主动脉阻断时间以及体外循环时间进行比较。结果 本次研究的所有患者手术均获得了成功,3组患儿的手术时间、主动脉阻断时间以及体外循环之间比较差异均无统计学意义;主动脉开放10 min时,CO210L/min组（16±3）个/min和CO25L/min组（23±4）个/min的脑膜中动脉气泡数量均少于对照组（50±7）个/min,CO210L/min组的气泡数目也少于CO25L/min组,差异具有统计学意义（均P<0.05）;停止体外循环后,3组脑膜中动脉气泡的数量差异无统计学意义;主动脉开放时以及停止体外循环时,3组的PaCO2的差异均无统计学意义。 结论 改良后的CO2充溢技术用于小儿先天性心脏病手术可明显减少气体栓子的数量,气流较大效果更好,且安全性较好。     

新型动脉微栓滤器一体化氧合器在先心病患儿体外循环术中的应用研究

目的旨在初步评估新型动脉微栓滤器一体化氧合器(ALF-MO)在先心病患儿体外循环(CPB)中应用的临床效果。方法自2012年10月至2013年7月,共有44名行心脏直视手术的患儿纳入本研究,其中试验组(n=22)患儿采用含ALF-MO的CPB管路;对照组(n=22)患儿采用常规独立动脉微栓滤器(ALF)的CPB管路。对比研究两组患儿在围CPB期的悬浮红细胞(PRBC)用量、血气变化和术后早期的恢复情况。结果试验组患儿CPB中的预充量明显少于对照组预充量(P0.05)。试验组总PRBC用量显著少于对照组(P0.001)。试验组患儿在CPB30min时的血红蛋白浓度均明显高于对照组(P0.05),代谢缓冲碱BE值明显高于对照组(P0.05);其他时点的各项血气指标两组间均无显著性差异(P0.05)。两组患儿气管插管时间和ICU停留时间比较无统计学差异(P0.05),术后均无死亡,无中枢视神经系统并发症发生。结论应用ALF-MO在先心病患儿CPB中应用是安全可靠的,同时为实施节约用血和改善患儿预后起到积极的推进作用。     

高糖对肾小管上皮细胞ACE/ACE2表达的影响

体外培养的HK-2细胞分为正常对照组(NG组)、高糖组(HG组)、渗透压对照组(MG组),检测细胞ACE、ACE2 mRNA和蛋白表达及细胞上清液血管紧张素Ⅱ的浓度.结果 在NG组,正常培养的HK-2细胞即存在ACE、ACE2 mRNA及蛋白表达.在HG组HK-2细胞,ACE mRNA及蛋白表达较NG组升高,而ACE2mRNA及蛋白表达降低.在HG组血管紧张素Ⅱ水平较NG组显著升高.结果 表明高糖可促进体外培养的HK-2细胞ACE表达、抑制ACE2表达,进而促进血管紧张素Ⅱ合成.

Abstract：

HK-2 cells cultured in vitro were divided into three groups: normal glucose group ( NG ), high glucose group( HG), and mannitol group(MG). The expression of angiotensin-converting enzyme( ACE ) and ACE2 mRNA in HK-2 cells was detected. The concentration of angiotensin Ⅱ ( Ang Ⅱ ) in the culture medium was detected. The mRNA and protein expression of ACE and ACE2 existed in normal cultured HK-2 ( NG group ). In comparison with NG group, the mRNA and protein expressions of ACE in HG group increased significantly ( P＜0. 01 ), and the expression of ACE2 mRNA decreased significantly( P＜0. 01 ). The level of Ang Ⅱ in HG group was significantly higher than in NG group( P＜0. 05 ). The result show that high glucose may induce ACE expression and inhibit ACE2 expression, then promote synthesis of Ang Ⅱ in proximal tubular cells.     

MG132对兔颈总动脉球囊损伤后狭窄部位泛素和Caspase-3表达的影响

目的 采用球囊拉伤新西兰白兔颈总动脉,复制出血管损伤后狭窄模型;在损伤血管局部应用蛋白酶体抑制剂MG132,观察蛋白酶体抑制剂MG132对球囊损伤后血管狭窄部位泛素和Caspase-3表达的影响.方法 将新西兰白兔30只随机分成对照组、球囊损伤组和MG132组,喂养8周后取颈总动脉损伤段血管制成病理切片,采用免疫组织化学法观察泛素蛋白和Caspase-3蛋白的变化.结果 免疫组织化学法检测到球囊损伤组颈总动脉管壁泛素蛋白表达加强;而MG132组与球囊损伤组比泛素蛋白表达明显减少(P<0.01).Caspase-3蛋白表达显著增加(P<0.01).结论 局部应用蛋白酶体抑制剂MG132能抑制颈总动脉管壁泛素蛋白表达,并增强Caspase-3蛋白表达.     

加压输液袋应用于危重症患儿有创血压监测的效果分析

目的探讨输液加压袋持续冲洗应用于危重症患儿持续有创动脉血压监测(IABP)的效果。方法选取符合纳入标准使用有创动脉血压监测的100例危重症患儿,采用随机双盲法将其分为对照组和干预组,两组各50例,两组都使用0.5U/mL肝素钠盐水,对照组使用输液泵持续2mL/h泵入配合间断冲管,干预组使用加压输液袋(压力设置为150mmHg,通过压力传感器自动以2mL/h速度匀速缓慢滴入)持续冲管配合间断冲管,观察两组患儿动脉置管时间、动脉走向瘀斑的发生情况。结果干预组患儿动脉走向发生瘀斑的现象明显少于对照组,动脉置管留置时间长于对照组,差异具有统计学意义(P0.05)。结论使用加压输液袋有效地降低有创动脉血压监测患儿动脉走向瘀斑的发生率,延长动脉置管留置时间,减轻患儿痛苦,减少护士工作量。     

氟伐他汀改善高血压患者脉压和动脉弹性临床研究

目的　观察氟伐他汀对降压治疗中高血压患者脉压和动脉弹性功能的影响。方法　选择 3 0例正在规律服用降压药物治疗并且脉压≥ 60mmHg的高血压患者 ,分为安慰剂组 (15例 )和氟伐他汀组 (15例 ) ,分别加服安慰剂 (1片每天 )或氟伐他汀 (40mg/d) ,治疗 3个月。观察治疗前、后肱动脉血压 ,脉搏波传导速度 (PWV) ,大动脉和小动脉弹性指数 (C1和C2 ) ,从桡动脉压力波形实时获得的中心动脉血压、压力反射波增强指数 (AI)。结果　安慰组治疗后各项指标均无显著改变。氟伐他汀组治疗后肱动脉收缩压与脉压分别降低 8 0± 12 9mmHg (P =0 0 3 1)与 5 7± 9 3mmHg (P =0 0 3 3 ) ,中心动脉收缩压与脉压分别降低 9 7± 12 4mmHg (P =0 0 0 9)与 7 1± 9 3mmHg (P =0 0 1) ,中心动脉下降幅度大于肱动脉 ;舒张压和心率无显著改变 ;C2 升高 (P =0 0 3 ) ;AI降低 (P =0 0 2 6) ;PWV和C1无显著改变。结论　氟伐他汀通过改善高血压患者小动脉弹性和外周压力波反射 ,具有缩小脉压的作用     

台州地区皮肤性病门诊患者生殖支原体感染情况及不同治疗方案有效性评估

目的了解台州地区泌尿生殖道生殖支原体(MG)的感染情况并对治疗方案进行评估。方法对2016年5月至2019年7月在台州市第一人民医院皮肤性病门诊进行泌尿生殖道性病感染患者用恒温扩增检测技术(SAT技术)进行MG检测,同时进行淋球菌(NG)、沙眼衣原体(CT)、解脲支原体(UU)等检测,并对阿奇霉素治疗组、多西环素治疗组、莫西沙星治疗组疗效进行有效性评估。结果 3 842例中,男性2 850例,女性992例。所有检测患者MG阳性率为6.48%(249例),其中男性MG阳性率为7.23%(206例),女性为4.33%(43例),两组差异有统计学意义(χ2=10.164,P=0.001);21～30岁组MG阳性率为8.04%(83/1 032), 60岁组为7.05%(11/156),41～50岁组为4.82%(45/933);男性与女性在MG单独或合并感染分布特点上差异无统计学意义(P均 0.05)。阿奇霉素治疗组、多西环素治疗组、莫西沙星治疗组治疗有效率为12/35、29/47、82.8%(101/122),MG感染三组不同方案治疗有效率差异有统计学意义(χ~2=32.046,P 0.001)。结论 MG在泌尿生殖系统感染中是一种重要的病原菌,男性发病率高,没有年龄分布差异,常以单独感染形式存在,以UU、CT合并感染最多,莫西沙星有很好的治疗效果。     

Comparison of Arterial and Venous Blood Flow Between Patients with Pressure Dressing or a New Hemostatic Puncture Closure Device After Cardiac Catheterization

The aim of the study was to compare arterial and venous flow volume in the punctured leg in patients given a conventional pressure dressing and those given a new hemostatic puncture closure device (Angio-Seal) after cardiac catheterization. We prospectively measured blood flow in 25 patients with pressure dressing (group A) and 25 patients with Angio-Seal (group B) after cardiac catheterization. Duplex sonographic measurements were performed at the superficial femoral artery and vein of the punctured leg. In group A measurements were performed before catheterization, during pressure dressing, and after removal of pressure dressing. In group B we performed the measurements before catheterization and after closure of the puncture site with Angio-Seal. Mean arterial and venous blood flow of the superficial femoral artery and vein were calculated. Statistical evaluation was performed using the one-sample Wilcoxon test. In group A there was a significant reduction of blood flow volume in both the femoral artery, from a mean of 119 mL/min before puncture to 78 mL/min with pressure dressing, and the femoral vein, from 114 mL/min before puncture to 82 mL/min with pressure dressing (P < 0.0001). After removal of pressure dressing the blood flow rose to 119 mL/min in the femoral artery and 116 mL/min in the femoral vein. In group B there was no change in flow volume before and after catheterization (femoral artery: 117 vs 118 mL/min, femoral vein 119 vs 120 mL/min, P = ns). We conclude that the use of pressure dressing after cardiac catheterization caused a significant reduction in arterial and venous blood flow (about 30%) during immobilization. The new Angio-Seal closure device did not affect arterial or venous flow.     

Rapid flow rates for the resuscitation of hypovolemic shock

Nine dogs were hemorrhaged to approximately 40% of their blood volume and then were resuscitated with a crystalloid solution (Normosol) at various flow rates. Three study groups with three dogs in each group were resuscitated at 15 mL/min/kg (Group 1), 6 mL/min/kg (Group 2), and 4 mL/min/kg (Group 3). Central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), mean arterial pressure, and cardiac output (CO) were monitored during the hemorrhage and the resuscitation from shock. During the infusion of fluids, Group 1 animals demonstrated an elevation of the PAWP of 31 mm Hg and elevation of CVP to 23.2 mm Hg; CO rose to 8.4 L/min. In Group 2 animals CO rose to 6.1 L/min; CVP was 10.5 mm Hg; and PAWP was 25 mm Hg. Group 3 animals had a rise in CO to 5 L/min; CVP and PAWP rose to 4.5 mm Hg and 6.8 mm Hg, respectively. In this experimental shock study, infusion of crystalloids at 6 mL/min/kg appeared to result in an improved physiologic response, although no statistical difference was demonstrated. Further studies are necessary to demonstrate the optimum flow rate for resuscitation of hypovolemic shock using crystalloids.     

The effect of augmenting portal venous inflow on intrahepatic pressure and resistance in the isolated perfused porcine liver

BACKGROUND/AIMS: The literature regarding the relationship between portal venous flow and pressure is controversial. The aim of this study was to examine the effects of doubling portal venous inflow on hepatic hemodynamics. METHODOLOGY: Portal venous pressure, intrahepatic portal venous resistance, hepatic arterial pressure and intrahepatic arterial resistance were assessed during basal portal venous inflow (756 +/- 142 mL/min; mean +/- SD) and enhanced portal venous inflow (1512 +/- 284 mL/min) in an isolated perfused normal porcine liver model (n = 6). Hepatic arterial flow was maintained constant throughout the experiments. RESULTS: During the period of enhanced portal venous flow there was an increase in: portal venous pressure (from 9 +/- 2 to 22 +/- 7 mm Hg, P = 0.0076); the difference between portal venous and hepatic venous pressures (from 2 +/- 2 to 10 +/- 5 mm Hg; P = 0.0289); hepatic arterial pressure (from 84 +/- 9 to 151 +/- 33 mm Hg, P = 0.0019); and intrahepatic arterial resistance (from 0.3488 +/- 0.0637 to 0.6387 +/- 0.2020, P = 0.0046). CONCLUSIONS: The increases in hepatic artery pressure and intrahepatic arterial resistance are a result of the hepatic arterial 'buffer response', a phenomenon not previously demonstrated in vitro. The magnitude of the observed changes in portal venous and hepatic venous pressure leads to the conclusion that, in the porcine liver, the intrahepatic venous resistance sites react by constricting to increases in portal venous inflow.     

Single-needle membrane plasmapheresis. In vivo comparison of plasma separator performances

Plasma filtration characteristics of three hollow fiber plasma separation filters (Plasmaflo Hi-05, Extraplex BL 550 and CPS-10) were studied in a single-needle setting by means of the double headpump. Plasma exchange was carried out in 12 patients during a total number of 59 sessions. For each filter, a mean total ultrafiltration volume of +/- 3,000 ml was obtained over a period from 92 to 121 min. The lowest and highest obtained mean filtration flows were 26.7 +/- 2.5 and 36.6 +/- 1.7 ml/min for Extraplex BL 550 and CPS-10, respectively (p less than 0.01). The pre- and postplasmapheresis pressures, measured in the bubble trap chamber as an indirect estimation of transmembrane pressure, were lower for the Plasmaflo Hi-05 than for the two other filters under study; pressures remained unaltered during the session. Blood pressure showed a minor but significant decline during plasmapheresis with the Plasmaflo filter. A reduction after plasmapheresis by more than 40% of the immunoglobulins IgE, IgG, IgM and IgA, and of complement factors C3 and C4 was seen for each of the filters and no significant differences between the filters were observed. An additional study on 6 filters with constant blood flow and TMP showed minor differences in the transmembrane pressure necessary to obtain a given filtration volume per unit of time and similar sieving coefficients for immunoglobulins. This study demonstrates that with this single-needle technique a satisfying immunoglobulin extraction performance was obtained for each of the filter types studied; however, there existed minor but significant differences in the patient hemodynamic status according to the membrane used.     

Simple active air evacuation procedure for right ventricular failure caused by intracoronary air embolism

In cardiac surgical cases such as valve replacement, right ventricular failure caused by intracoronary air embolism sometimes occurs after aortic declamping and during weaning from cardiopulmonary bypass (CPB). The details are reported of a de-airing method which involves simply rotating the arterial cannula towards the base of the heart, with no need for a particular circuit. This method was used in ten patients who, following open-heart surgery, suffered postoperative right ventricular failure due to air embolism in the right coronary artery that did not respond to other de-airing methods. The technique resolved the problem in all patients, who were quickly weaned from CPB and ultimately discharged. Rotation of the arterial cannula may represent a simple means of resuscitating patients who have suffered right ventricular dysfunction that is unrelieved by other, conventional methods.     

Effects of adenosine on human coronary arterial circulation

Adenosine is a potent vasodilator used extensively to study the coronary circulation of animals. Its use in humans, however, has been hampered by lack of knowledge about its effects on the human coronary circulation and by concern about its safety. We investigated in humans the effects of adenosine, administered by intracoronary bolus (2-16 micrograms), intracoronary infusion (10-240 micrograms/min), or intravenous infusion (35-140 micrograms/kg/min) on coronary and systemic hemodynamics and the electrocardiogram. Coronary blood flow velocity (CBFV) was measured with a 3F coronary Doppler catheter. The maximal CBFV was determined with intracoronary papaverine (4.5 +/- 0.2.resting CBFV). In normal left coronary arteries (n = 20), 16-micrograms boluses of adenosine caused coronary hyperemia similar to that caused by papaverine (4.6 +/- 0.7.resting CBFV). In the right coronary artery (n = 5), 12-micrograms boluses caused maximal hyperemia (4.4 +/- 1.0.resting CBFV). Intracoronary boluses caused a small, brief decrease in arterial pressure (similar to that caused by papaverine) and no changes in heart rate or in the electrocardiogram. The duration of hyperemia was much shorter after adenosine than after papaverine administration. Intracoronary infusions of 80 micrograms/min or more into the left coronary artery (n = 6) also caused maximal hyperemia (4.4 +/- 0.1.resting CBFV), and doses up to 240 micrograms/min caused a minimal decrease in arterial pressure (-6 +/- 2 mm Hg) and no significant change in heart rate or in electrocardiographic variables. Intravenous infusions in normal patients (n = 25) at 140 micrograms/kg/min caused coronary vasodilation similar to that caused by papaverine in 84% of patients (4.4 +/- 0.9.resting CBFV). At submaximal infusion rates, however, CBFV often fluctuated widely. During the 140-micrograms/kg/min infusion, arterial pressure decreased 6 +/- 7 mm Hg, and heart rate increased 24 +/- 14 beats/min. One patient developed 1 cycle of 2:1 atrioventricular block, but otherwise, the electrocardiogram did not change. In eight patients with microvascular vasodilator dysfunction (delta CBFV, less than 3.5 peak/resting velocity after a maximally vasodilating dose of intracoronary papaverine), the dose-response characteristics to intracoronary boluses and intravenous infusions of adenosine were similar to those found in normal patients.(ABSTRACT TRUNCATED AT 400 WORDS)     

Impact of bolus volume on small intestinal intra-luminal impedance in healthy subjects

AIM: To assess the impact of bolus volume on the characteristics of small intestinal (SI) impedance signals.METHODS: Concurrent SI manometry-impedance measurements were performed on 12 healthy volunteers to assess the pattern of proximal jejunal fluid bolus movement over a 14 cm-segment.Each subject was given 34 boluses of normal saline (volume from 1 to 30 mL) via the feeding tube placed immediately above the proximal margin of the studied segment.A bolus-induced impedance event occurred if there was > 12%...     

Non-invasive evaluation of segmental pressure drop and resistance in large arteries in humans based on a Poiseuille model of intra-arterial velocity distribution

STUDY OBJECTIVE--The aim of the study was to evaluate in hypertensive subjects the longitudinal pressure drop and segmental resistance in a large artery in relation to shearing forces of the circulating blood column at the arterial wall. DESIGN--Arterial diameter, blood velocity, and flow were measured in the brachial artery using pulsed Doppler apparatus. Blood viscosity was measured at 96 s-1 with a low shear viscometer. Segmental resistance per unit arterial length was calculated using the basic Poiseuille resistance expression from the ratio between blood viscosity and the fourth power of arterial diameter. Longitudinal pressure drop was deduced as the product between segmental resistance and blood flow. The Poiseuille model of velocity distribution also enabled wall shear rate and stress to be calculated from the ratio between blood velocity and arterial diameter and from the product between shear rate and blood viscosity respectively. PATIENTS--19 ambulatory male patients with mild to moderate hypertension and 11 normotensive male controls of similar age were studied. RESULTS--Compared to controls, hypertensive patients had higher arterial diameter (p less than 0.001) lower blood velocity (p less than 0.05), higher blood viscosity (p less than 0.01), lower segmental resistance and pressure drop (p less than 0.001, p less than 0.01) and lower shear rate and stress (p less than 0.01, p less than 0.05). A negative correlation existed in the overall normotensive and hypertensive population between pressure drop and mean blood pressure (r = -0.55, p less than 0.01). CONCLUSION--The hypertensive state is associated with a clear reduction in large artery segmental resistance and longitudinal pressure drop concomitantly with a decrease in shear conditions at the arterial wall. The mechanisms of reduced resistance and pressure drop are related to decreased wall shear and increased diameter of the artery, both of which reduce the frictional forces at the blood-arterial wall interface.     

Factors affecting bronchial blood flow through bronchopulmonary anastomoses in dogs

Most of the bronchial arterial blood flow (Qbr) drains through bronchopulmonary anastomoses into the pulmonary circulation, and the remainder goes into the systemic venous system via the bronchial veins. We studied the relationship between blood flow through bronchopulmonary anastomoses, and alveolar pressure and pulmonary vascular pressures as well as hydrostatic pressure in the bronchial veins in 10 adult dogs. The pulmonary artery and vein of the experimental left lower lobes (LLL) of open-chested, anesthetized dogs were isolated and connected to reservoirs. That part of the Qbr that flowed through bronchopulmonary anastomoses into the reservoirs was continuously measured at constant pulmonary vascular pressures of 0 cm H2O relative to the lung base. Any bronchial blood volume that retained within the LLL was estimated from changes in lobe weight. The lobe was distended with 5% CO2 and air, at alveolar pressures of 5, 10, or 20 cm H2O in a random sequence. Because bronchial veins drain into the azygos vein, the bronchial venous pressure was elevated by snaring the azygos vein. The mean anastomotic Qbr was 4.4 +/- 1.1 (mean +/- SEM) ml/min and it decreased by 23 and 39% when alveolar pressure was raised from 5 cm H2O to 10 and 20 cm H2O respectively (p less than 0.05). Approximately 75% of the total anastomotic Qbr was collected from the pulmonary venous reservoir at all alveolar pressures. When both pulmonary artery and venous pressures were increased higher than the alveolar pressure (zone III), azygos snaring increased the anastomotic Qbr by 13 and 31% at alveolar pressures of 10 and 20 cm H2O, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Nitroglycerin for portal hypertension. A controlled comparison of the hemodynamic effects of graded doses

Nitroglycerin is reportedly an effective treatment for portal hypertension. However, the effects of graded doses have not been examined. We administered nitroglycerin intravenously to 10 patients with alcoholic cirrhosis, beginning at 10 micrograms/min and doubling the dose every 10 min thereafter until mean arterial pressure fell 10-15 mmHg. We compared the response to that of 10 patients receiving a control infusion. The median infusion rate of nitroglycerin was 40 micrograms/min (range 10-160 micrograms/min). Nitroglycerin significantly reduced cardiac output as well as pulmonary artery, pulmonary capillary and mean arterial pressure. The overall effects of nitroglycerin on the hepatic venous pressure gradient and azygous (gastroesophageal collateral) blood flow were heterogeneous. However, the hepatic venous pressure gradient significantly increased in nitroglycerin-treated patients with high pulmonary capillary pressures (greater than or equal to 12 mmHg) compared to control patients with similar cardiac filling pressures at both median and maximum rates of infusion. Nitroglycerin is therefore not a uniformly effective treatment for portal hypertension. Cardiac filling pressure may be a determinant of the splanchnic hemodynamic response to nitroglycerin.