比较不同分子量羟乙基淀粉对术中血液循环及凝血功能的影响

目的多中心、双盲、平行对照比较术中输注国产6%羟乙基淀粉200/0.5(6%HES200/0.5,盈源)和6%羟乙基淀粉130/0.4(6%HES130/0.4,万汶)对术中血流动力学、血液流变学及凝血功能的影响。方法150例择期手术的患者随机均分为Y组和V组。手术开始后,Y组输注6%HES200/0.51000ml,V组输注6%HES130/0.41000ml。分别于麻醉前(T0)、输注开始时(T1)、输注开始后30min(T2)、60min(T3)、90min(T4)、120min(T5)各时点监测患者血流动力学参数,在麻醉前及输注结束后10min抽血检测凝血功能及血液流变学参数。结果与T0时相比,两组患者T1时MAP均明显下降(P<0.05),V组T4、T5时MAP明显降低(P<0.05);T3时V组HR增快(P<0.05),输液结束后两组凝血酶原时间(PT)及部分凝血酶原时间(APTT)均有所延长(P<0.05),纤维蛋白原下降(FIB)(P<0.05),血小板计数(Plt)减少(P<0.05),但两组组间差异无统计学意义;两组液体均可降低全血高、低切变率(P<0.05),对血浆粘度无明显作用。两组术中输血量及晶体输入量差异无明显统计学意义。结论输入6%HES200/0.5或6%HES130/0.41000ml均可有效维持血流动力学稳定,改善机体微循环,但对凝血功能均有尚可耐受的影响。     

Biological effects of static magnetic fields on the microcirculatory blood flowin vivo: a preliminary report

There have been few studies of the effect of static magnetic fields on microcirculatory haemodynamics in vivo. The rat skinfold transparent chamber technique was used, which provides an excellent means of observing and quantifying direct in vivo microvascular haemodynamic responses to static magnetic fields up to 8 T. An intravital videomicroscope was used to measure the changes in blood flow before and after exposure to a magnetic field for 20 min in a horizontal type superconducting magnet with a bore 100 mm in diameter and 700 mm long. After exposure, microcirculatory blood flow showed an initial increase for about 5 min followed by a gradual decrease and a return to the control value. It is hypothesised that these changes represent rebound hyperaemia following reduced blood flow during exposure.     

Non-invasive evaluation of abdominal aortic properties: lumped circuit model and estimation of its parameters

To non-invasively determine abdominal aortic properties, a five-element lumped circuit model was adopted. The model consists of resistance due to blood viscosity (R1), inertia of blood flow, compliances of the vessel (C1, C2), resistance of the peripheral arteries (R2) and the impedance of the femoral arteries (termination). Patterns of the central velocity of the upper abdominal aorta and the femoral artery are measured by pulsed Doppler echocardiography, and confours of flow volume rates are calculated. The pressure pattern of the lower limb is recorded by a pulse wave rransducer and corrected according to sphygmomanometer values. Contours are transformed into respective Fourier transform components. The current transfer function is described theoretically and calculated from the acquired Fourier components. Values of every element are evaluated by the nonlinear least squares method. In 94 subjects (17–92 years), the values of each element are estimated. R2 values are greater in the elderly group, than in the young group and r₁ (R1/cm) increased with age. This model demonstrates that vessel compliance (c₁+c₂ (C1+C2/cm)) decreases with age, and it is suggested that this may be a useful marker of arteriosclerosis.     

Haemodynamic model of a unilateral iliac stenosis with an aortoiliac bypass

A hydrodynamic model for the part of the human arterial network below the renal arteries has been constructed using specially fabricated distensible tubes and a pulsatile pump to simulate an aortoiliac bypass. The experiments and the computer model indicated that no ‘steal’ occurred due to the insertion of the bypass graft. Also, the results showed that the length of the stenosis had a non-systematic apparent effect on the physiological significance of the obstruction and that the kinetic power represented only a small percentage of the total power. The total power efficiency of the bypass graft was unaffected by its elastic properties. The experimental investigation also indicated that the pressure drop across the stenosis was considerably larger than the drop calculated using the Poiseuille flow relationship when the stenosis was severe. Therefore, a critical arterial stenosis value cannot be defined as an obstruction of a constant percentage reduction of luminal area. It varies directly with the effective cross-sectional area and inversely with the flow rate. The value of angiography in assessing the functional significance of any arterial stenosis is there-fore limited. A better method for evaluation requires quantitative measurements of local blood pressure and blood flow, not only at rest, but also under conditions creating augmented flows due to exercise.     

Haemodynamic effects of the crude venom from nematocysts of the box-jellyfish Chiropsalmus quadrigatus (Habu-kurage) in anaesthetized rabbits.

Haemodynamic effects of saline-extracted venom from nematocysts isolated from tentacles of the box-jellyfish Chiropsalmus quadrigatus (Habu-kurage) were investigated. In anaesthetized rabbits, i.v. injections of the venom produced hypotension following a transient hypertension. Mean femoral arterial blood flow markedly decreased immediately after the injection and femoral vascular resistance increased. Left ventricular dP/dt remarkably decreased after a transient and small increase, and heart rate decreased. Left ventricular end-diastolic pressure markedly elevated. All of the above changes by 0.2-5 microg/kg of the venom expressed as the amount of protein were seen dose-dependently and occurred without tachyphylaxis. In five of seven animals received an injection of the venom at 10 microg/kg, irreversible cardiac arrest occurred. Changes produced by 1 or 2 microg/kg of the venom were significantly attenuated either by heating the venom at 40 degrees C for 10min or by pretreatment with diltiazem. These results indicate that the venom from Habu-kurage has both vasoconstrictor and cardiodepressive effects, and suggest that these thermolabile actions may be due partly to activation of voltage-dependent calcium channels and probably subsequent calcium-overload.     

Ⅱ型糖尿病和高血压患者血液动力学改变的相关因素分析

目的：探讨糖病和高血压血管并发症的发生机理。方法：分别测定高血压（ＨＴ）组、Ⅱ型糖尿病（ＮＩＤ－ＤＭ）组及Ⅱ型糖尿病合并高血压组和对照组的胰岛素水平、血脂、心脏彩超和血液流变学指标。结果：３个试验组的周围总阻（ＴＰＲ）、甘油三酯（ＴＧ）和胰岛素面积（ＩｎｓＳ）均明显增高,其中ＨＴ组和ＮＩＤＤＭ合并ＨＴ组的左室收缩期峰值室壁应力（ＰＳＳ）也明显增高：ＮＩＤＤＭ合并ＨＴ组ＩｎｓＳ明显高于其他三组,三试     

非转流经典原位肝移植术中的容量管理

目的探讨非转流经典原位肝移植术中的循环变化和容量管理。方法选取本院肝胆外科择期行非转流经典原位肝移植术患者64例,术中记录各时段出血量、尿量及补液种类、补液量,监测血流动力学、血气、生化指标、凝血机能、血糖和体温变化等。结果血流动力学在无肝期和新肝早期变化显著(P<0.01),pH值和碱剩余(BE)值也有显著变化(P<0.05或P<0.01),电解质和凝血功能由于术中不断及时调整纠正变化不大。结论非转流经典原位肝移植术时机体循环变化和内环境紊乱较为显著,术中容量管理十分重要。应选择合适液体合理补液以及使用血管活性药物和相关药物,维持血流动力学和内环境的相对稳定,尽可能避免发生与容量相关的并发症。     

Effects of carvedilol and propranolol on circulatory regulation and oxygenation in cirrhosis: A randomised study

Background and aimsNewer studies suggest that carvedilol, a beta-blocker with a moderate anti-alpha-1 activity, is superior to propranolol in reducing the portal pressure and risk of variceal bleeding. The effect on arterial blood pressure is a matter of concern especially in decompensated patients.Aimsto assess potential differential effects of beta-blockers and beta-blockers with moderate anti-alpha-1 activity on selected haemodynamic, humoral, and respiratory characteristics in cirrhosis.MethodsPatients with cirrhosis and portal hypertension were randomised to receive carvedilol (n = 16) or propranolol (n = 13). Cardiac, systemic and splanchnic parameters along with oxygen saturation and plasma renin were measured at inclusion and after 3 months.ResultsArterial blood pressure, heart rate, and cardiac output decreased equally, central circulation time and systemic vascular resistance increased significantly but similarly. Central blood volume, plasma volume and arterial compliance were unaltered. The QT_c interval and renin levels decreased in the carvedilol group, however not significantly different from the propranolol group. Arterial oxygen saturation and alveolar arterial oxygen gradient remained constant in both groups. Hepatic venous pressure gradient decreased equally in the carvedilol and propranolol groups (−17% and −20%, non significant).ConclusionsSystemic haemodynamics and pulmonary effects of carvedilol and propranolol are modest and this study could not demonstrate any significant difference between the two treatments.     

Endogenous insulin and insulin sensitivity. An important determinant of skeletal muscle blood flow in chronic heart failure?

Aim Patients with heart failure have a reduced sensitivity to insulin’sactions on glucose metabolism and a compen-satory increase inendogenous plasma insulin levels. As insulin has a selectivevasodilatory action in skeletal muscle, we have studied theassociation between insulin sensitivity and central and regionalhaemodynamics in patients with heart failure. Methods Ten patients with stable symptomatic heart failure were studied.We used non-invasive techniques to measure cardiac output, forearmblood flow, superior mesenteric artery blood flow and rightrenal artery blood flow. Blood samples were assayed for noradrenaline,renin and atrial natriuretic peptide levels. Insulin sensitivitywas assessed using the low dose short insulin tolerance test. Results There was a significant inverse correlation between forearmblood flow and insulin sensitivity (r=–0·67, P=0·03),patients with lesser degrees of insulin sensitivity having thegreater forearm blood flows. There was no correlation with theother haemodynamic or neurohumoral parameters. Patients withgreater insulin resistance tended to have higher circulatingendogenous insulin levels, although this relationship did notreach statistical significance (r=–0·53, P=0·12). Conclusions Insulin sensitivity appears to be an important determinant ofskeletal muscle blood flow in heart failure. We speculate thatthis is secondary to the increased circulating endogenous insulinlevels, and suggest that the therapeutic potential of exogenousinsulin merits further investigation.