Analysis of a two-crystal delay line for femtosecond pulses of the X-ray free electron laser

Using the methods of statistical optics the formation of delayed X-ray pulses in the diffraction reflection of an incident pulse with an arbitrary degree of temporal coherence from a system of parallel crystals with different lattice periods is considered. The results are of interest for constructing delay lines in experiments with a time resolution of the pump-and-probe type and realizing of the self-seeding mode to increase the degree of temporal coherence of the X-ray free-electron laser radiation. A rigorous theory of dynamic diffraction in Bragg geometry is applied to the diffraction reflection of short X-ray pulses from a system of two parallel crystals with arbitrary thicknesses, and also, for a system of two pairs of parallel crystals. The dependence of the delay time and the intensity of the delayed pulses on the thickness of the crystals and the distances between them are analyzed. Since the pulses from the X-ray free electron laser have high spatial coherence, i. e. a small angular divergence, but very poor temporal coherence, special attention is paid to the effect of the degree of temporal coherence on the width of the energyspectrum of the incident pulses and on the influence of this width on the intensity of the delayed pulse

Theory and Applications of X-ray Standing Waves in Real Crystals

Theoretical aspects of x-ray standing wave method for investigation of the real structure of crystals are considered in this review paper. Starting from the general approach of the secondary radiation yield from deformed crystals this theory is applied to different concreat cases. Various models of deformed crystals like: bicrystal model, multilayer model, crystals with extended deformation field are considered in detailes. Peculiarities of x-ray standing wave behavior in different scattering geometries (Bragg, Laue) are analysed in detailes. New possibilities to solve the phase problem with x-ray standing wave method are discussed in the review. General theoretical approaches are illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table

Optimization of protective lung ventilation in thoracic surgery

Background: Today protective ventilation is the predominant ventilation methodology. It includes the use of low tidal volume, inspiratory pressure limitation, and the application of positive end-expiratory pressure. However, several retrospective studies have shown that tidal volume, inspiratory pressure, and Positive End-Expiratory Pressure (PEEP) are not associated with patients’ treatment outcomes, but could be associated only when they influence driving pressure.Objective: Optimization of the strategy of protective one-lung ventilation under the control of driving pressure, to reduce early postoperative respiratory complications in patients operated for lung cancer.Material and methods: A prospective controlled study was conducted on 110 patients undergoing extended anatomical lung resections with subsequent comparison of clinical results depending on the level of driving pressure during one-lung ventilation. Postoperative pulmonary complications based on the Melbourne scale that appeared within 3 days after surgery became the endpoint.Results: A correlation was established between the level of driving pressure and the level of PaO2 in the intraoperative period – high inverse (r = – 0.901). The greatest value in the development of postoperative respiratory failure is driving pressure, exceeding 15 cm of water (Odds ratio = 18.25). In the first 3 days, postoperative pulmonary complications, determined by the Melbourne group scale, occurred in 9 (8.2%) patients in whom the driving pressure exceeded 15 cm of water, and in 3 patients (2.7%) with a driving pressure level less than 15 cm of water (p = 0.016).Conclusion: Driving pressure excess with values of more than 15 cm of water significantly increases the incidence of postoperative pulmonary complications. Fixed PEEP will be inappropriate both high and low, and individualized PEEP titrated by CStat may reduce driving pressure and become the next step in protective one-lung ventilation

Optimization of postoperative hypotension correction in thoracic surgery

Introduction. Arterial hypotension is the reasonable cause for intravenous injections of crystalloid solutions. However, as far as this statement is fair in the patients that underwent extensive scheduled thoracic operations at that moment is not defined.Aim. To reduce the number of complications in patients following thoracic operations by definition of optimum strategy for correction of postoperative hypotension.Methods. The retrospective analysis of 154 patients who were divided into 2 groups was conducted. In 58 patients, for correction of arterial blood pressure we used noradrenaline, in other cases (96 patients) noradrenaline in combination with infusion therapy was administered. The comparative analysis of the perioperative volemic status, levels of hemoglobin, urea, creatinine, a lactate, glucose, paO2 , paCO2 , ScvO2 , SaO2 , pvCO2 -paCO2 , duration of noradrenaline application and also a range of the postoperative complications was carried out.Results and conclusions. It is revealed that correction of hypotension with crystalloid solutions in thoracic patients results at and conclusions increased risk of pneumonia development. At the same time, infusion therapy in the early postoperative period in thoracic patients did not reduce the risk of intense kidney failure development. Severity of postoperative complications according to Clavien-Dindo classification was higher in patients who had infusion therapy. At the same time, duration of vasopressor support showed no change

CHANGES IN THE LEVEL OF NT-proBNP AND MEAN PULMONARY ARTERY PRESSURE FOLLOWING BRONCHOPLASTIC LOBECTOMY OR PNEUMONECTOMY AS MARKERS OF RIGHT VENTRICULAR DYSFUNCTION

Background There are scanty data of right ventricular dysfunction markers after major pulmonary resection.Objective To study the changes of plasma level of N-terminal pro-brain natriuretic peptide (NT-proBNP) and its association with pulmonary artery pressure (PAP) as markers of right ventricular dysfunction in patients who underwent bronchoplastic lobectomy or pneumonectomy.Material and Methods The study population consisted of 36 patients aged 40–65 who underwent major  pulmonary resection for lung cancer in 2016–2018. Patients were stratified into two groups according to the type of surgical procedure: bronchoplastic lobectomy, the main group (n = 19), and pneumonectomy, control group (n = 17). They were then analyzed for plasma NT-proBNP concentration, operative time, blood loss, intraoperative fluid administration, intraoperative urine output, and mean PAP level before and after an operation.Results The mean PAP level correlated positively with the plasma NT-proBNP concentration in the pneumonectomy group (Pearson r = 0.916754; p < 0.001). This correlation was no evident in the subset of patients undergoing bronchoplastic lobectomy at the same determination point (Pearson r = 0.234741; p = 0.330).Conclusion The mean PAP increased significantly after pneumonectomy and is closely correlated with plasma  NTproBNP concentration. These findings support the conclusion that bronchoplasty is preferable over pneumonectomy for lung cancer patients

Postoperative delirium in elderly patients after thoracic surgery

Background. Postoperative delirium is one of the most severe and common complications of thoracic surgery in elderly patients.Objective. To establish a simple and accurate method for predicting the development of postoperative delirium in patients after thoracic surgery.Material and Methods. We performed an observational cohort study of 303 patients who underwent lobectomy for oncological diseases. The nature of anesthesia and surgical intervention, features of the volume status and hemodynamic changes during the perioperative period were analyzed, laboratory indicators of this period were evaluated.Results. Of 303 patients, 43 (14.2%) developed postoperative delirium. Non-modifiable factors for the development of postoperative delirium included age, history of cerebrovascular accident, alcohol misuse disorder, chronic heart failure, more severe physical status according to the ASA (American Society of Anesthesiologists) Physical Status Classification System. Modifiable factors are the following: the duration of one-lung ventilation, episodes of perioperative hypotension and hypoxemia, the use of opioids, the intensity of the pain syndrome in the postoperative period, and reduced oxygen transport function of the blood. A number of laboratory parameters (blood albumin, blood glucose, leukocytosis), reflecting the degree of surgical stress, may also be useful in postoperative delirium predicting.Conclusion. A prognostic coefficient was compiled with a concordance of 99.9 and Somers' D 0.998. It is equal to the sum of the products: (–3.5367) multiplied by pain intensity on a 10 cm Visual Analogue Scale an hour after surgery; 2.2037 multiplied by the blood albumin level the morning after surgery;    (–4.8151) multiplied by the blood glucose level the morning after surgery