Measurement of kinetic parameters in skeletal muscle by magnetic resonance imaging with an intravascular agent.

The purpose of this work was to investigate the use of an intravascular contrast agent to determine perfusion kinetics in skeletal muscle. A two-compartment kinetic model was used to represent the flux of contrast agent between the intravascular space and extravascular extracellular space (EES). The relationship between the image signal-to-noise ratio (SNR) and errors in estimating permeability surface area product (Ktrans), interstitial volume (ve), and plasma volume (vp) for linear and nonlinear curve-fitting methods was estimated from Monte Carlo simulations. Similar results were obtained for both methods. For an image SNR of 60, the estimated errors in these parameters were 10%, 22%, and 17%, respectively. In vivo experiments were conducted in rabbits to examine physiological differences between these parameters in the soleus (SOL) and tibialis anterior (TA) muscles in the hind limb. Values for Ktrans were significantly higher in the SOL (3.2+/-0.9 vs. 2.0+/-0.5x10(-3) min-1), as were values for vp (3.4+/-0.8 vs. 2.1+/-0.7%). Differences in ve for the two muscles (8.7+/-2.2 vs. 8.5+/-1.6%) were not found to be significant. These results demonstrate that relevant physiological metrics can be calculated in skeletal muscle using MRI with an intravascular contrast agent.     

X线、超声联合导向介入治疗布-加氏综合征

目的:探讨X线、超声联合导向下对布 加氏综合征的介入治疗方法和临床应用价值。方法:本组病人 30例,采用X线和超声联合导向。穿刺下腔静脉闭塞或狭窄部位,经球囊扩张后在X线、超声联合定位置入支架 成形。结果:28例成功,占93%。无严重并发症。术后患者症状明显缓解,下腔静脉压基本恢复正常(治疗前 2.8±0.51kPa,治疗后0.7±0.2kPa)。结论:采用X线、超声联合导向介入治疗布 加氏综合征是一种成功率高、 损伤小、效果可靠的治疗方法。     

Epidural block for obstetrics: Comparison of bolus injection of local anesthetic with gravity flow technique

Study Objective: To test the hypothesis that slow administration of local anesthetic into the epidural space by gravity flow reduces the incidence of signs and symptoms of unintended injection.

Design: Prospective, randomized study.

Setting: Teaching hospital.

Patients: 600 ASA physical status I and II parturients scheduled for labor and delivery or elective cesarean section.

Interventions: After identification of the epidural space with pulsations of an air-fluid column, parturients for vaginal delivery (n = 380) were randomized to receive a test dose of 3 ml 3% 2-chloroprocaine with epinephrine 20 μg, two doses of 7 ml bupivacaine 0.03 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow (Group 1) given over 30 seconds or by bolus injection (Group 2) given over 5 seconds through the epidural needle; parturients for Cesarean delivery (n = 220) were randomized to receive a test dose and two doses of 6 ml lidocaine 2 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow or by bolus injection through the epidural needle. Changes in maternal heart rate (HR) and blood pressure, signs of intravascular injection, and adverse effects of epidural bupivacaine-sufentanil were recorded after each dose.

Measurements and Main Results: Gravity flow administration (Group 1) was associated with a smaller increase in mean maternal HR (p < 0.001), less hypotension (p < 0.01), sedation (p < 0.01), nausea (p = 0.01), and segmental spread (p < 0.0001) than were corresponding doses given by traditional bolus injection (Group 1) for vaginal or Cesarean deliveries. The incidence of systemic toxicity was zero of 300 (0%) with gravity flow and 4 of 300 (1.3%) by bolus injection, p = 0.12, Fisher's exact test. No patient in either group had an accidental intrathecal injection.

Conclusion: Gravity flow administration of local anesthetic-opioid solution during epidural block for obstetrics was associated with fewer signs of systemic drug absorption and cardiovascular perturbations than was the traditional bolus injection. This study supports the current opinion that slow administration of local anesthetic during epidural black contributes to fewer adverse events.     

尖吻蝮蛇毒引起类DIC病因的研究

本文借助 DEAE-sephadex A-50和 Sephadex G-75柱层析从尖吻蝮蛇毒(AAV)内分离并纯化出一种类凝血酶(TLE).这种 TLE 以1.5U/Kg 体重注入麻醉狗的静脉后,观察到血凝筛选试验 Fgn、BPC、PT、TT 和血清 FDP 全部异常;但凝血因子Ⅱ(Quick 二期法)、AT-Ⅲ以及纤维结合蚤白(Fn)含量仍在正常范围内.这提示实验狗血循环内未有凝血酶形成的证据,从而说明 AAV-TLE是 AAV 中毒患者并发类 DIC 综合征的主要病因.     

肺血管扩张在肝肺综合征发病机制中作用的研究进展

肺血管扩张是肝肺综合征的主要发病机制,然而导致HPS肺血管扩张的机制相当复杂,至今仍不清楚.目前认为肺血管内巨噬细胞聚积和雌激素升高导致的血管活性因子增多和活性增强可能与此有关,近年来这方面的研究很多,本文对此作一综述.     

Surface coat of sheep pulmonary intravascular macrophages: Reconstitution,and implication of a glycosyl-phosphatidylinositol anchor

Background: Pulmonary intravascular macrophages (PIMs) of sheep have a globular surface coat that facilitates endocytosis of tracer particles and Escherichia coli lipopolysaccharide, and is disrupted by the heparin and Brefeldin A treatments. The present study investigated the in vivo dynamics of the coat globules following heparin-mediated removal, and the mechanism of globule organization on the plasma membrane of PIMs in vitro. Methods: Sheep were administered heparin at a dose of 50 IU/kg body weight IV, and euthanised at 30 min, 3, 6, 12, 48, and 120 hr (n = 2 for each treatment) after the treatment. Control sheep (n = 2) were injected with normal saline solution. The tissues were processed for an ultrastructural examination and acid phosphatase (ACPase) cytochemistry. Heparintreated lungs were subjected to morphometric analysis of the coat globules. Lung tissues from normal sheep (n = 2) were incubated with phosphatidylinositol-specific-phospholipase C (PIPLC; 2 IU/ml PBS) in vitro for 30 and 75 min. Results: Heparin study: The ultrastructural and morphometric data showed that the coat globules were removed at 30 min and reconstituted within 48 hr of the treatment. The PIMs showed priminent Golgi complexes associated with secretory vesicles, microtubules, and centriole between 3–12 hr of heparin treatment. Acid phosphatase cytochemistry also demonstrated secretory activity in the Golgi complexes of PIMs during the coat reconstitution. PIPLC study: The coat globules of PIMs were removed in a time-dependent mode by the PIPLC treatment without damage to other cell organelles. Conclusions: This study demonstrates a time-dependent reconstitution of the coat of PIMs in conjunction with secretory activity following heparinmediated removal, probably through sequenstration of the globules from blood. This ability is of functional significance as the coat mediates particle endocytosis by the PIMs. The results also suggest the presence of a glycosyl-phosphatidylinositol (GPI) anchor in tethering of globules on the plasma membrane of PIMs to offer a structural basis for their integrity in pulmonary vascular flow. © 1995 Wiley-Liss, Inc.     

Etiology and treatment of acquired coagulopathies in the critically ill patient

Summary Excessive bleeding frequently complicates the care of critically-ill patients. Except in the case of trauma or in patients with known coagulopathies (e.g., hemophilia), the bleeding is generally not directly related to the illness that results in admission to the intensive care unit. In general, the causes of the bleeding can be divided into 3 categories: consumptive coagulopathies (e.g., DIC), bleeding related to ``hepatic issues' (i.e., liver dysfunction, vitamin K deficiency), and iatrogenic causes. This review will discuss the more common causes of bleeding in the critically-ill patient and outline diagnostic and treatment approaches for these patients. New experimental data linking activation of the coagulation and inflammatory systems with the development of multisystem organ failure is briefly discussed. Received: 8 November 1996 Accepted: 18 November 1996