以心跳骤停为首发症状的蛛网膜下腔出血共同特征研究

<正>心跳骤停（cardiac arrest,CA）和蛛网膜下腔出血（subarachnoid hemorrhage,SAH）均是急诊科常见的急危重症,CA可见于多种疾病的各个阶段,复苏成功率不高,甚至造成CA的病因不甚明确。SAH典型表现为剧烈头痛、呕吐、脑膜刺激征,诊断并不困难。而以CA为首发症状的SAH,由于心肺复苏无法常规进行头颅CT检查,给诊断增加了困难。本文通过对16例以CA为首发症状的SAH患者进行回顾性研究,来提高SAH-CA的快速病因诊断,避免漏诊误诊。     

Pulmonary and haemodynamic effects of extracorporeal circulation in the cat and the beneficial effects of prostacyclin

Side-effects of a veno-venous extracorporeal system and possible beneficial effects of prostacyclin (epoprostenol) are analyzed on the cat. Three groups were studied; one control group without extracorporeal circulation and two groups with an extracorporeal flow of 10–12 ml/kg/min, one of which was given prostacyclin (70–110 ng/kg/min). The extracorporeal circulation triggered a decrease in arterial saturation (from 99 to 91 %) and carbon dioxide elimination (increase in arterial to end-tidal PCO₂ by about 1 kpa) a metabolic acidosis (pH7.20), a platelet consumption (50%) and shortened survival time, side-effects reduced by prostacyclin. Further, there was a marked increase in haemoglobin concentration indicating hypovolemia via capillary fluid filtration. None of these side-effects were seen in the control group. Extracorporeal circulation as a trigger for pulmonary dysfunction and for impaired tissue nutrition with possible beneficial effects of prostacyclin is discussed, and also from a clinical point of view (i.e. extracorporeal lung assistance, ECLA), on the basis of the results.     

Effects of sodium nitroprusside (MR7S1) and nitroglycerin on the systemic,renal, cerebral,and coronary circulation of dogs anesthetized with enflurane

Summary In beagle dogs anesthetized with enfluranenitrous oxide, effects of sodium nitroprusside (SNP; MR7S1) and nitroglycerin (NTG) on hemodynamics and main organ circulation were studied to evaluate their effectiveness and safety as hypotensive agents during anesthesia. SNP (MR7S1) infusion (1–10 g/kg/min) decreased arterial blood pressure in a dose-dependent manner. The hypotension was stable during the infusion. After discontinuation of infusion, the blood pressure rapidly returned to the initial level. The hypotension was associated with decreases in cardiac output and total peripheral resistance. NTG infusion (3–10 g/kg/min) decreased arterial blood pressure, too, but the hypotension was less marked and not dose dependent, and the recovery was slower. Neither drug changed the heart rate. Infusion of SNP (MR7S1) and NTG did not change the hypotension induced by the injection of adenosine, SNP, and NTG. Furthermore, cerebral blood flow, cerebral oxygen consumption, and renal blood flow were unchanged during the hypotension produced by either drug. Coronary blood flow was decreased, but this was due to decreases in cardiac oxygen consumption. In conclusion, SNP (MR7S1) is superior to NTG as a hypotensive agent during anesthesia in efficacy, clear dose dependency, and rapid recovery. The hypotension induced by NTG as well as SNP (MR7S1) seems to have no undesirable effects on the circulation of important organs.     

Hypoxia,energy state and pulmonary vasomotor tone

Vasomotor responses to hypoxia constitute a fundamental adaptation to a commonly encountered stress. It has long been suspected that changes in cellular energetics may modulate both hypoxic systemic artery vasodilatation (HSV) and hypoxic pulmonary artery vasoconstriction (HPV). Although limitation of energy has been shown to underlie hypoxic relaxation in some smooth muscles, the response to hypoxia in vascular smooth muscle does not appear to be a simple function of energy stores, but instead may involve perturbations of ATP or energy delivery to mechanisms controlling muscle force, and/or changes associated with anaerobic metabolism. Recent work in pulmonary vascular smooth muscle has demonstrated that energy stores are maintained during hypoxic pulmonary vasoconstriction, and that this is dependent on glucose availability and up-regulation of glycolysis. There is increasing evidence that glycolysis is preferentially coupled to a variety of membrane associated ATP dependent processes, including the Na(+) pump, Ca(2+)-ATPase, and possibly some protein kinases. These and other mechanisms may influence excitation-contraction coupling in both systemic and pulmonary arteries by effects on intracellular Ca(2+) and/or Ca(2+) sensitivity. Hypoxia has also been postulated to have major effects on other cytosolic second messenger systems including phosphatidylinositol pathways, cell redox state and mitochondrial reactive oxygen species production. This review examines the relationship between energy state, anaerobic respiration and hypoxic vasomotor tone, with a particular emphasis on hypoxic pulmonary vasoconstriction.     

Effect of local blood circulation and absolute torque on muscle endurance at two different knee-joint angles in humans

The effects of the local blood circulation and absolute torque on muscle endurance at different knee-joint angles were determined. The rate of muscle deoxygenation (using near-infrared spectroscopy), and the rate of muscle fatigue (using the slope of integrated electromyography, iEMG) were evaluated concurrently. Nine healthy subjects performed submaximal (50% maximal voluntary contraction, MVC) static knee extension at 50° (extended position, EXT) and 90° (flexed position, FLEX) joint angles until the target torque could no longer be maintained: that time was measured as the endurance time. They exercised with the circulation occluded (OCCL), and without (FREE) to study the possible effects of the local circulation. Although MVC torque was independent of joint angle [mean (SD) FLEX 250.6 (51.7) N·m and EXT 246.5 (46.6) N·m], significantly shorter (P<0.01) endurance time in FLEX [FREE 71.1 (10) s and OCCL 63.1 (8.8) s] than at EXT [FREE 115.3 (30) s and OCCL 106.7 (29.1) s] were obtained in both circulatory conditions. The iEMG-time slope was significantly greater in FLEX at the proximal and distal portion (P<0.05) in both circulatory conditions. Muscle deoxygenation rate in OCCL was significantly greater (P<0.05) at FLEX [20.8 (8.0)%] than EXT [10.9 (4.0)%]. The results would suggest that different knee-joint angle affects muscle endurance even if the local circulation is controlled. Circulatory disturbance would further reduce muscle endurance in EXT, but not in FLEX. Because of the greater muscle internal force in FLEX, local blood flow might be already limited even with a free circulation. The greater muscle deoxygenation and muscle fatigability would be related to the shorter muscle endurance in FLEX. Electronic Publication     

交感神经在肺泡缺氧性肺血管收缩反应中的作用

在大鼠毁髓模型上观察缺氧与不缺氧情况下电刺激肺血管的脊髓交感中枢时体、肺循环的变化。常氧时电刺激脊髓T_(1～3)节段时P_(pa)、PVR增高(P<0.05);毁髓去神经支配大鼠吸入12%O_2低氧气体后仍能引起肺血管收缩反应(HPV),但PVR上升幅度较正常大鼠降低。在缺氧基础上电刺激T_(1～3)节段引起P_(pa)、PVR大幅度增高(P<0.05),约为常氧时电刺激效应的二倍;酚妥拉明可抑制这一反应。提示交感神经兴奋对HPV的形成有一定的促进作用。缺氧时体循环对交感兴奋的反应减弱。     

Pulmonary blood volume and interventricular circulation time in physically trained and untrained subjects

Summary Resting pulmonary plasma and blood volumes (PPV and PBV), interventricular circulation time (IVCT), cardiac and stroke index (CI and SI), heart rate (HR), total plasma and blood volumes (PV and BV) were determined in athletes (two male groups representing different types of sport activities, and one female group) and compared with those of non-athletes (one male and one female group).In addition to high maximal aerobic power, the athletes were characterized by greater SI, BV and PV and lower resting HR than non-athletes. PPV and PBV were significantly larger and IVCT significantly longer in the trained than in the untrained groups, probably reflecting an improved capacity of the pulmonary circulation. PPV as per cent of PV was almost equal in all the groups, indicating the same distribution of plasma between the pulmonary and systemic circulation. The data also indicate that total blood volume is an important determinant of the magnitude of the pulmonary vascular bed. The increased volume of flowing blood and increased stroke volume in athletes probably allows for a reduction in flow velocity and thereby a reduction in kinetic energy.     

Cardiovascular and hormonal changes following haemorrhage in the anaesthetized Brattleboro rat with an extracorporeal circulation

An extracorporeal circulation technique was developed for use in rats to provide equilibrated blood samples for multiple hormone assays. The inclusion of the extracorporeal circulation did not significantly alter arterial blood pressure, cardiac output, heart rate or central venous pressure in either Brattleboro rats with hereditary diabetes insipidus (BDI) or normal rats of the parent Long Evans (LE) strain. Plasma adrenaline and noradrenaline levels did not alter in either BDI or LE rats following inclusion of the extracorporeal circulation but the vasopressin concentration rose significantly in the LE rats. The impaired recovery of the mean arterial blood pressure following haemorrhage in the BDI rats compared with normal LE animals was not further influenced by the inclusion of the extracorporeal circulation. Plasma vasopressin and adrenaline (but not nor-adrenaline) levels were significantly raised during, and after, haemorrhage in the LE rats while in the BDI rats only plasma adrenaline levels were significantly increased. These results show that the insertion of an extracorporeal circulation into an anaesthetized BDI or LE rat does not adversely affect the cardiovascular system despite the increase in baseline plasma vasopressin concentration in normal rats, and its subsequent removal provides an additional equilibrated blood sample for multiple hormone assay within the same animal. The increased release of both adrenaline and vasopressin (but not noradrenaline) after haemorrhage in the same animal is detected using this technique, and the importance of vasopressin to the normal recovery process confirmed.