Fractional flow reserve and complex coronary pathologic conditions.

Fractional flow reserve (FFR) is a well-validated index for assessing the physiologic significance of a coronary stenosis in most clinical conditions encountered in today's catheterisation laboratory. The aim of this paper is to provide a short overview of the theoretical background of the coronary pressure-derived FFR index and its clinical applicability in guiding complex coronary intervention procedures.     

高温高湿环境下守岛官兵训练时脑血流和脑电生理的变化研究

目的 探讨高温高湿环境下守岛官兵训练前后脑血流和脑电生理的变化,为临床防治热致疾病提供依据.方法 从守岛官兵中随机抽取在常温常湿环境下温度(27.40±1.37)℃,湿度(50.25±6.76)%]新兵100名为常温新兵组,高温高湿环境下(温度≥35℃,湿度≥80%)新兵100名为高温新兵组;高温高湿环境下服役2～3 年的官兵100名为高温老兵组.受试者负重15 kg,分次在3000 m/15 min,5000 m/30 min和10 000 m/45 min内完成跑步训练.10 000 m训练后,根据受试者脑血流高低又分为脑血流增高组(24名)、脑血流降低组(46名)和脑血流正常组(230名).训练前后行经颅多普勒血流诊断仪和脑电图仪检测.结果 (1)3000 m训练后3组受试官兵脑平均血流速度(Vm)较训练前均显著增高(P＜0.01),但5000 m和10 000 m训练后,常温新兵组降低6%和16%,高温老兵组降低5%和15%,高温新兵组降低14%和31%,比常温新兵组和高温老兵组低(P＜0.01);(2)10 000 m训练前后3组脑电图均在正常范围,3组比较差异无统计学意义(P＞0.05);(3)10 000 m训练后脑血流增高组和降低组脑电图比正常血流组活跃(P＜0.01).结论 高温高湿环境下10 000 m训练对官兵的脑血流有较大的影响,但对脑电生理无影响,老兵在此环境下则表现出较好的热耐受力和适应性.     

拉萨地区高原肺水肿经颅多普勒21例分析

目的:通过经颅多普勒(TCD)检测,了解高原肺水肿(HAPE)患者颅内脑底动脉环上的主要动脉血流动力学及各血流的生理参数,为高原肺水肿的诊断及治疗提供一些参考.方法:将已确诊的HAPE患者,与颞窗通过低频脉冲多普勒(2MHZ),获得颅内脑底动脉环上的主要动脉的多普勒超声频移信号,进行TCD检测.结果:TCD检测后了解到颅内脑底动脉环上的主要动脉:颈内动脉末梢、大脑中动脉、大脑前动脉血流速度(收缩期血流速度,平均血流速度,舒张末期血流速度)与正常人的TCD测值相比明显增快,但舒张末期血流速度(VE )增快较收缩期血流速度(VP )不明显,故频谱仍为低阻波形,搏动指数(PI)、收缩期血流速度与舒张末期血流速度的比值(S/D)正常,阻力指数有所降低.结论:经TCD检测可知高原肺水肿患者在高原(在低氧环境下),颅内主要脑血管扩张,脑血流量增加即颈内动脉系统的MCA,ACA,PICA血流速度(Vs,Vm,Vd)增快,通过TCD检查可为高原医生早期诊断及治疗提供参考.     

Physiological consequences of a high work of breathing during heavy exercise in humans

The healthy respiratory system has a remarkable capacity for meeting the metabolic demands placed upon it during strenuous exercise. For example, in order to regulate alveolar partial pressure of oxygen and carbon dioxide during heavy workloads, a 20-fold increase in alveolar ventilation can occur. The high metabolic costs and subsequent increased work of breathing associated with this ventilatory increase can result in a number of limitations to the healthy respiratory system. Two examples of respiratory system limitations that are associated with a high work of breathing are expiratory flow limitation and exercise-induced diaphragmatic fatigue. Expiratory flow limitation can lead to an inability to increase alveolar ventilation () in the face of increasing metabolic demands, resulting in gas exchange impairment and diminished endurance exercise performance. Furthermore, the high ventilatory requirements of endurance athletes and the inherent anatomical differences in females could make these groups more susceptible to expiratory flow limitation. Fatigue of the diaphragm has also been documented after strenuous exercise and may be related to a mechanism which increases sympathetic vasoconstrictor outflow and reduces limb blood flow during prolonged exercise. This competition between the muscles of respiration and locomotion for a limited cardiac output may have dramatic consequences for exercise performance. This brief review summarizes the literature as it pertains to the work of breathing, expiratory flow limitation, and exercise-induced diaphragmatic fatigue in healthy humans.     

后腹腔镜手术CO2气腹对脑氧供需平衡的影响

目的探讨后腹腔镜CO2气腹对脑氧供需平衡的影响. 方法选择后腹腔镜下肾及肾上腺肿瘤切除术20例,ASAⅠ～Ⅱ级,分别于气腹前,气腹后10、30、60 min和关气腹后30 min,抽取颈静脉球血和桡动脉血进行血气分析,比较不同时点动脉血PH(aPH )、颈静脉球PH(jvPH)、动脉血二氧化碳分压(PaCO2)、动脉血糖(aGS)、动脉血乳酸(aLac)、颈内静脉血氧分压(PjvO2)、颈内静脉血氧饱和度(SjvO2)、颅内动静脉氧含量差(AjvDO2)、颈内静脉血二氧化碳分压(PjvCO2)、血糖(jvGS)和乳酸(jvLac)的变化. 结果与气腹前比较,气腹后各时间点aPH、jvPH显著降低(P＜0.05);PaCO2、PjvCO2气腹后各时间点与气腹前相比显著升高(P＜0.05);AjvDO2气腹后各时点与气腹前相比显著下降(P＜0.05);jvLac气腹后各时间点与气腹前相比有降低趋势,但无统计学差异(P＞0.05);aGS、 jvGS气腹前后无显著变化(P＞0.05). 结论后腹腔镜手术期间,脑血流量显著增加,未发现脑无氧代谢增加的证据.     

Non-specific bronchial hyper-responsiveness in children with allergic rhinitis: Relationship with the atopic status

An increased prevalence of bronchial hyper-responsiveness (BHR) has been demonstrated in children from a general population, and in non-asthmatic adults with allergic rhinitis. Thus, also children with allergic rhinitis are expected to be at higher risk of BHR. We evaluated the prevalence of BHR in a sample of non-asthmatic children with allergic rhinitis by means of the methacholine (Mch) bronchial challenge, and by monitorizing the airway patency using the daily peak expiratory flow variability (PEFv). Fifty-one children (ranged 6–15 years of age) with allergic rhinitis, ascertained by skin prick test to inhalant allergens, underwent a 14-day peak expiratory flow monitoring, and a Mch bronchial provocation challenge. Thirty healthy children matched for age, and sex served as control group. Thirty-one children in the rhinitis group (61%), and six (20%) in the control group were Mch+ (Mch provocative dose causing a 20% fall of forced expiratory volume in 1 s respect to baseline <2250  μ g, equivalent to 11.50  μ mol). In rhinitic children the PEFv did not significantly differ between Mch+ and Mch− subjects, but the total serum immunoglobulin E (IgE) were higher among Mch+. The persistent form of rhinitis was significantly associated to Mch positivity. Non-asthmatic children with allergic rhinitis displayed a high prevalence of BHR. The BHR was significantly associated with persistent rhinitis and with higher total IgE levels. Nevertheless, the spontaneous changes in airway patency, as expressed by PEFv, were within normal limits both in Mch+ and Mch− children.     

单光子发射计算机断层扫描在颅脑创伤后的临床研究

目的 探索单光子发射计算机断层扫描（SPECF）在脑外伤评估及预后方面的价值的依据。方法 28例中、重度颅脑损伤患者分别于伤后3天、10天及3～4周接受SPECF、CT检查及临床评定。3个月后所有患者行脑外伤综合征的临床测试，对首检SPECF显像阳性者复查SPECF，分析首检SPECF显像阳性者与损伤程度的关系，动态观察SPECF显像与预后的关系。结果 SPECF显像阳性与脑损伤程度有关，首检SPECF显像阳性提示预后良好，复查SPECF显像阳性提示多出现脑外伤综合征。对幕上损伤患者表现的小脑症状、体征可以做出合理的解释。结论 在中至重度颅脑损伤后SPECF显像与CT扫描比较更敏感，脑SPECF具有无创性、功能性及灵敏性高等特点，是脑外伤后功能评估、预后判断及临床研究的可靠方法。     

Brain perfusion territory imaging applying oblique-plane arterial spin labeling with a standard send/receive head coil.

A new method for the selective spin labeling of left- or right-sided supplying arteries of the brain without the need for additional RF coils is demonstrated. A clinical 1.5 T scanner was used. The spatial selectivity of the labeling process is based on the limited coverage of the excitation field of a standard send/receive head coil together with an oblique positioning of the labeling plane. A computer simulation was used to optimize key labeling parameters under the condition of laminar flow. The validity of the computer model results was confirmed by MRI measurements with a flow model. For human studies, a double-inversion continuous arterial spin labeling (CASL) sequence was modified to allow for arbitrary positioning of the labeling plane. The obtained perfusion-weighted images showed a clear delineation of the perfusion territories of the selected arteries in the anterior circulation of the brain and good gray/white matter contrast.     

MR流量测定的实验研究

目的探讨MR流量测量与不同感兴趣区(ROI)直径的关系。方法使用Philips 1.5T双梯磁共振机流量测定程序,测量2mm内径塑胶管中不同流量的水(0.5、1.0、1.5、2.0、2.5ml/s),不同流向(流入及流出方向)、不同ROI位置(测量图中心区和偏中心区)与不同的ROI直径(直径0.5、1.0、1.5、2.0mm)流量变化关系,统计计算标准的ROI直径。结果在不同流量、流向和测量位置中,流量与ROI直径大小存在明显的直线相关(r>0.95,P<0.05),ROI直径大小显著地影响测量结果,当ROI直径取值等于测量图直径的0.6040±0.0480时,所测结果与实际流量一致。在不同流量下的不同流向及ROI位置对流量测定无影响(P>0.05)。结论对直径2mm流量测定,应选取测量图上直径的0.6040±0.0480 ROI进行。     

Cerebral perfusion during human liver transplantation

Summary. During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (V_mean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients V_mean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The V_mean (40±13 cm s^-1 [mean±SD]), thoracic electrical impedance (TI) (30±7 Ohm), heart rate (97±19 beats min^-1), mean arterial pressure (84±9 mmHg) and arterial carbon dioxide tension (PaCO₂, 4.5±0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6±2.7 to 5.4±1.41 min^-1), stroke volume (SV, 79±26 to 56±15 ml) and PI (1.2±0.3 to 0.9±0.2) decreased (P<0.05). During reperfusion, CO (9.9±4.01 min^-1), SV (105±40 ml), Pa_CO2 (5.5±0.6 kPa), Vmean (57±17 cm s^-1) and PI (1.2±0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension.