Compression of mediastinal structures treated by extra-anatomic bypass grafting

Extra-anatomic bypass grafts have been used to treat complex and recurrent forms of coarctation of the aorta. Here we describe the use of an extra-anatomic bypass graft from the ascending to supraceliac aorta to treat an unusual complication of compression of mediastinal structures caused by a bucket handle graft.     

Measurement of volatile organic compounds inside automobiles

The objective of the current study was to evaluate the types and concentrations of volatile organic compounds (VOCs) in the passenger cabin of selected sedan automobiles under static (parked, unventilated) and specified conditions of operation (i.e., driving the vehicle using air conditioning alone, vent mode alone, or driver's window half open). Data were collected on five different passenger sedan vehicles from three major automobile manufacturers. Airborne concentrations were assessed using 90-min time-weighted average (TWA) samples under U.S. Environmental Protection Agency (USEPA) Method IP-1B to assess individual VOC compounds and total VOCs (TVOCs) calibrated to toluene. Static vehicle testing demonstrated TVOC levels of approximately 400-800 microg/m(3) at warm interior vehicle temperatures (approximately 80 degrees F), whereas TVOCs at least fivefold higher were observed under extreme heat conditions (e.g., up to 145 degrees F). The profile of most prevalent individual VOC compounds varied considerably according to vehicle brand, age, and interior temperature tested, with predominant compounds including styrene, toluene, and 8- to 12-carbon VOCs. TVOC levels under varied operating conditions (and ventilation) were generally four- to eightfold lower (at approximately 50-160 microg/m(3)) than the static vehicle measurements under warm conditions, with the lowest measured levels generally observed in the trials with the driver's window half open. These data indicate that while relatively high concentrations of certain VOCs can be measured inside static vehicles under extreme heat conditions, normal modes of operation rapidly reduce the inside-vehicle VOC concentrations even when the air conditioning is set on recirculation mode.     

航天员训练中心模拟设备的制作和应用

本文介绍了俄罗斯航天员训练中心模拟设备设计的基本概念及应用情况。在研制和使用模拟器设备加采用了以下几条原则：分层原则，模块原则，通用原则，整合原则，文中还介绍了中性浮力水槽，离心机，综合训练模拟器，ＴＵ－１５４ＭＬＫ－１和ＩＬ－７６ＭＤＫ失重飞机等训练设备。     

Transcatheter embolization in the management of pulmonary hemorrhage

A group of 306 patients with acute pulmonary hemorrhage were evaluated by means of bronchial arteriography and treated with transcatheter embolization. Specific causes for bleeding included lung abscess, chronic pneumonia, tuberculosis, lung cancer, and bronchiectasis. In 120 patients the hemoptysis was massive, with volumes exceeding 500 ml/day. The majority (n = 225) were treated during peak hemorrhage. Embolization was performed with one of three methods: particulate embolization with polyurethane or velour, obturation with the angiographic catheter combined with peripheral embolization by means of infused albumin macroaggregates, and regional infusion of sclerosing agents. Effective hemostasis was obtained initially in 278 patients (90.8%), including 87.5% of those treated during peak hemorrhage. In 26 of 28 cases without initial response, the pulmonary artery was the source of bleeding. Recurrent bleeding, within 1-4 days, requiring surgery was observed in 39 patients with initially successful hemostasis. Of 158 patients who were treated without surgery, subsequent episodes of hemoptysis occurred in 36. Combined methods of embolization may improve the efficacy of treatment of operable and inoperable patients with lung disease complicated by hemorrhage.     

Energy expenditure associated with CPAP and T-piece spontaneous ventilatory trials. Changes following prolonged mechanical ventilation

The use of portable metabolic carts to assess energy expenditure (EE) by measuring oxygen consumption (VO2) and carbon dioxide production (VCO2) has recently been applied to patients undergoing weaning from mechanical ventilation. The VO2 and EE can be used to estimate changes in the work of breathing (WOB) associated with different weaning strategies. The purpose of this study was to use VO2 and EE to assess changes in the WOB when assisted mechanical ventilation (AMV) was replaced with two spontaneous ventilatory trial (SVT) techniques: continuous positive airway pressure (CPAP) and T-piece. Nine difficult-to-wean patients were studied during the initial weaning period following 26 +/- 18 days (mean +/- SD) of mechanical ventilatory support. The VO2 and EE during all AMV were 296 +/- 75 ml/min and 2069 +/- 519 kcal/day, respectively. Compared to the baseline AMV levels, during CPAP overall VO2 and EE increased 14 percent and 13 percent, respectively, and during T-piece overall VO2 and EE increased 20 percent and 19 percent, respectively. Respiration rate (f) increased and tidal volume (VT) decreased during both SVTs compared to AMV although no significant change in minute ventilation was seen. The WOB, as judged from changes in VO2, was only 5 percent higher during T-piece compared to CPAP; however, patients tolerated an average of only 141 +/- 45 min on T-piece vs 165 +/- 29 minutes on CPAP. We conclude that during the initial weaning stages in patients who have received prolonged mechanical ventilatory support, the WOB associated with SVTs is increased compared to AMV but that the WOB associated with T-piece is not significantly greater than that for CPAP.