Нарушения транспорта кислорода при комах, обусловленных ишемическим инсультом у шахтеров

Objective: to study oxygen transport impairments in ischemic stroke-induced coma in miners who have been doing underground work for more than 10 years. Subjects and methods. A prospective clinical study was conducted in 48 patients with coma caused by ischemic stroke. Group 1 included 12 miners. Group 2 comprised 36 men not working in coal miners. The groups did not differ in age, disease severity, and admission time. However, the group of miners had a higher incidence of pulmonary complications and therefore higher mortality rates. Comprehensive examination was performed and oxygen delivery index (DO2I), oxygen consumption index (VO2I), oxygen extraction ratio, and arteriovenous oxygen difference were calculated in all those admitted to hospital. Results. In ischemic stroke-induced comas, vasoconstriction resulted in the development of circulatory hypoxia with low DO2I. Then on day 3 respiratory and tissue hypoxia developed in the group of those who had a length of underground service. The relationship between DO2I and VO2I found in the miners suggests that impaired lung oxygenizing function was concurrent with oxygen transport system tension. The fact that there was no significant relationship of the oxygen saturation of hemoglobin in venous blood to VO2I in the miners had a high probability of indicating the development of tissue hypoxia. Such relationships were absent in the patients without underground length of service. Conclusion. The miners with an underground service length of 10 years or more and ischemic stroke-induced comas were found to have rapidly developing, more marked and long-term impairments of central hemodynamics, pulmonary oxygenizing function and hence the oxygen transport system as compared to those with no length of underground service. All the above characteristics are due to the lowered reserve capacities of the cardiovascular irnd respiratory systems upon long-term exposure to poor working conditions. Key words: ischemic stroke, oxygen transport, length of underground service, miner.Цель исследования — изучить нарушения транспорта кислорода у шахтеров с подземным стажем работы более 10 лет, находящихся в коме, обусловленной ишемическим инсультом. Материал и методы. Проспективное клиническое исследование проведено у 48 человек, находящихся в коме, обусловленной ишемическим инсультом. В I группу исследования вошли 12 шахтеров. Группу исследования II составили 36 мужчин, не связанных с угольной отраслью. Группы не различались по возрасту, тяжести исходного состояния, срокам поступления. Однако в группе шахтеров было больше легочных осложнений и, как следствие этого, более высокая летальность. Всем поступившим проводилось комплексное обследование, рассчитывались индекс доставки кислорода (ИДО2), индекс потребления кислорода (ИПО2), коэффициент экстракции кислорода, артерио-венозная разница по кислороду. Результаты. При комах, обусловленных ишемическим инсультом, вазоконстрикция приводит к развитию циркуляторной гипоксии со снижением индекса доставки кислорода. В дальнейшем, на 3-и сутки, в группе с подземным стажем развивается дыхательная и тканевая гипоксия. Выявленная у шахтеров взаимосвязь между ИДО2 и ИПО2 дает основания полагать, что нарушение оксигени-рующей функции легких сочеталось с напряжением системы транспорта кислорода. Отсутствие достоверной взаимосвязи насыщения гемоглобина венозной крови кислородом от ИПО2 у шахтеров с большой долей вероятности говорит о развитии тканевой гипоксии. У больных без подземного стажа таких зависимостей не было. Заключение. У шахтеров со стажем подземной работы 10 и более лет при комах, обусловленных ишемическим инсультом, выявляются быстроразвивающиеся, более выраженные и продолжительные нарушения центральной гемодинамики, оксигениру-ющей функции легких и, как следствие этого, системы транспорта кислорода в сравнении с пациентами, не имеющими подземного стажа работы. Все вышеуказанные особенности являются результатом снижения резервных возможностей сердечно-сосудистой и дыхательной систем из-за длительного воздействия неблагоприятных условий производства. Ключевые слова: ишемический инсульт, транспорт кислорода, подземный стаж, шахтер

Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens

The performance of time-resolved photoemission experiments at fs-pulsed photon sources is ultimately limited by the e–e Coulomb interaction, downgrading energy and momentum resolution. Here, we present an approach to effectively suppress space-charge artifacts in momentum microscopes and photoemission microscopes. A retarding electrostatic field generated by a special objective lens repels slow electrons, retaining the k-image of the fast photoelectrons. The suppression of space-charge effects scales with the ratio of the photoelectron velocities of fast and slow electrons. Fields in the range from −20 to −1100 V/mm for Ekin = 100 eV to 4 keV direct secondaries and pump-induced slow electrons back to the sample surface. Ray tracing simulations reveal that this happens within the first 40 to 3 μm above the sample surface for Ekin = 100 eV to 4 keV. An optimized front-lens design allows switching between the conventional accelerating and the new retarding mode. Time-resolved experiments at Ekin = 107 eV using fs extreme ultraviolet probe pulses from the free-electron laser FLASH reveal that the width of the Fermi edge increases by just 30 meV at an incident pump fluence of 22 mJ/cm2 (retarding field −21 V/mm). For an accelerating field of +2 kV/mm and a pump fluence of only 5 mJ/cm2, it increases by 0.5 eV (pump wavelength 1030 nm). At the given conditions, the suppression mode permits increasing the slow-electron yield by three to four orders of magnitude. The feasibility of the method at high energies is demonstrated without a pump beam at Ekin = 3830 eV using hard x rays from the storage ring PETRA III. The approach opens up a previously inaccessible regime of pump fluences for photoemission experiments

Oxygen Transport Impairments in Miners with Ischemic Stroke-Induced Comas

Objective: to study oxygen transport impairments in ischemic stroke-induced coma in miners who have been doing underground work for more than 10 years. Subjects and methods. A prospective clinical study was conducted in 48 patients with coma caused by ischemic stroke. Group 1 included 12 miners. Group 2 comprised 36 men not working in coal miners. The groups did not differ in age, disease severity, and admission time. However, the group of miners had a higher incidence of pulmonary complications and therefore higher mortality rates. Comprehensive examination was performed and oxygen delivery index (DO2I), oxygen consumption index (VO2I), oxygen extraction ratio, and arteriovenous oxygen difference were calculated in all those admitted to hospital. Results. In ischemic stroke-induced comas, vasoconstriction resulted in the development of circulatory hypoxia with low DO2I. Then on day 3 respiratory and tissue hypoxia developed in the group of those who had a length of underground service. The relationship between DO2I and VO2I found in the miners suggests that impaired lung oxygenizing function was concurrent with oxygen transport system tension. The fact that there was no significant relationship of the oxygen saturation of hemoglobin in venous blood to VO2I in the miners had a high probability of indicating the development of tissue hypoxia. Such relationships were absent in the patients without underground length of service. Conclusion. The miners with an underground service length of 10 years or more and ischemic stroke-induced comas were found to have rapidly developing, more marked and long-term impairments of central hemodynamics, pulmonary oxygenizing function and hence the oxygen transport system as compared to those with no length of underground service. All the above characteristics are due to the lowered reserve capacities of the cardiovascular irnd respiratory systems upon long-term exposure to poor working conditions. Key words: ischemic stroke, oxygen transport, length of underground service, miner