The Rate of Postoperative Mortality and Renal and Respiratory Complications are Increased in Patients with Extreme Obesity Undergoing Cardiac Surgery - A Retrospective Observational Cohort Study of 8848 Patients.

Introduction: The importance of obesity as a potential risk factor in open heart surgery is well known. The epidemic of extreme obesity is an increasing public health concern and raises alerts regarding postoperative complications and mortality in patients undergoing cardiac surgery. The study aimed to analyze the impact of extreme obesity (BMI≥40) on the frequency of postoperative complications, as well as early and delayed mortality compared to patients with a lower body mass. Materials and Methodology: This retrospective observational cohort study involved patients, over the age of 18, undergoing cardiac surgery with cardiopulmonary bypass at the Cardiac Surgery Department of the Pomeranian Medical University in Szczecin, Poland between January 1st, 2010 and December 31st, 2018. The patients included in the study were allocated into two subgroups depending on the BMI index (Group I BMI≥40 vs Group II BMI<40). Results: A total of 8848 adult patients of both genders were included. Baseline characteristics for Group I and Group II were mean age 64.07±7.76 vs 65.10±9.68 years (p=0.123), mean BMI 42.13±2.44 vs 28.55±4.23 (p<0.001), with more females in Group I (58.04% vs 29.06%) and more males in Group II (70.94% vs 29.06%), p<0.001. The predicted perioperative risk using the EuroScore Logistics scale was higher in a group with BMI≥40 (p<0.001). Regression analysis with adjustment for confounding factors showed a statistically significant relationship between BMI≥40 and postoperative respiratory failure (OR=1.760, p=0.043), acute kidney injury AKIN2 (OR=2.082, p=0.044) and AKIN3 (OR=2.743, p=0.039). 30-day mortality in the univariate analysis showed a statistically significant relationship, however, after modifying the results with interfering factors, no statistical significance was obtained. Conclusion: The risk of postoperative acute respiratory failure and acute renal injury was increased in patients with BMI≥40. The probability of 30-day survival of patients after cardiac surgery was much lower in people with extreme obesity, although it was related to the dominant comorbidities. The 10-year survival was comparable in both groups.

Risk Management Model for Unmanned Aerial Vehicles during Flight Operations.

Risk management and uncertainty models are practised in all branches of transport. Although unmanned aerial vehicles (UAVs) constitute a branch of the industry rather than transport as a whole, their development is oriented toward increasingly more serious applications involving the transport of goods and people. The constantly growing number of operations employing UAVs requires not only identification of hazard sources or risk assessment recommended by the applicable regulations, but also comprehensive risk management. In order to develop a systematic approach to risk management for air operations of UAVs, the classic risk management method can be used. This work proposes a novel multi-criteria risk model that may serve as the basis for further activities aimed at developing a risk management method for this domain. The model was based on six criteria and validated using a virtual route to risk assessment and valuation.

Identification of Aluminium Powder Properties for Modelling Free Air Explosions.

Aluminium is a component in many energetic formulations. Therefore, its combustion is one of the main thermochemical processes that govern the output from the energetics. Modelling aluminium combustion is a challenging task because the process is highly complex and difficult to measure. Here, tests of aluminium powder were conducted in an effort to isolate the burning of the aluminium and to determine an adequate representation of this process. Charges of 100 g and 500 g were tested, and the size of the Al/air cloud and the ratio of components in the Al/air mixture were determined, which has not been published previously. This information was used to assess the validity of the assumption that the detonation of the mixture was representative of the event. Parameters for the Jones-Wilkins-Lee equation of state for the explosive mixture and detonation products were defined. Simulations of the tests were performed, and the results were consistent with the field test data, indicating that detonation occurred when there was a mixture of 70-75% Al and 25-30% air by mass.

Temperature Measurement of a Bullet in Flight.

This study answers a primary question concerning how the temperature changes during the flight of a bullet. To answer the question, the authors performed unique research to measure the initial temperatures of bullet surfaces and applied it to four kinds of projectiles in a series of field experiments. The technique determines the temperature changes on metallic objects in flight that reach a velocity of 300 to 900 m/s. Until now, the tests of temperature change available in the literature include virtual points that are adopted to ideal laboratory conditions using classic thermomechanical equations. The authors conducted the first study of its kind, in which is considered four projectiles in field conditions in which a metallic bullet leaves a rifle barrel after a powder deflagration. During this process, heat is partly transferred to the bullet from the initial explosion of the powder and barrel-bullet friction. In this case, the temperature determination of a bullet is complex because it concerns different points on the external surface. Thus, for the first time the authors measured the temperatures at different position on the bullet surface. Moreover, the authors showed that basic thermodynamic equations allow for the credible prediction of such behavior if the initial conditions are identified correctly. This novel identification of the initial conditions of temperature and velocity of flying bullets was not presented anywhere else up to now.

Mechanical Properties of Brass under Impact and Perforation Tests for a Wide Range of Temperatures: Experimental and Numerical Approach.

The originally performed perforation experiments were extended by compression and tensile dynamic tests reported in this work in order to fully characterize the material tested. Then a numerical model was presented to carry out numerical simulations. The tested material was the common brass alloy. The aim of this numerical study was to observe the behavior of the sample material and to define failure modes under dynamic conditions of impact loading in comparison with the experimental findings. The specimens were rectangular plates perforated within a large range of initial impact velocities V0 from 40 to 120 m/s and in different initial temperatures T0. The temperature range for experiments was T0 = 293 K to 533 K, whereas the numerical analysis covered a wider range of temperatures reaching 923 K. The thermoelasto-viscoplastic behavior of brass alloy was described using the Johnson-Cook constitutive relation. The ductile damage initiation criterion was used with plastic equivalent strain. Both experimental and numerical studies allowed to conclude that the ballistic properties of the structure and the ballistic strength of the sheet plates change with the initial temperature. The results in terms of the ballistic curve VR (residual velocity) versus V0 (initial velocity) showed the temperature effect on the residual kinetic energy and thus on the energy absorbed by the plate. Concerning the failure pattern, the number of petals N was varied depending on the initial impact velocity V0 and initial temperature T0. Preliminary results with regard to temperature increase were recorded. They were obtained using an infrared high-speed camera and were subsequently compared with numerical results.

Blast Test and Failure Mechanisms of Soft-Core Sandwich Panels for Storage Halls Applications.

In this paper, an experimental investigation is presented for sandwich panels with various core layer materials (polyisocyanurate foam, mineral wool, and expanded polystyrene) when subjected to a justified blast load. The field tests simulated the case for when 5 kg of trinitrotoluene (TNT) is localized outside a building's facade with a 5150 mm stand-off distance. The size and distance of the blast load from the obstacle can be understood as the case of both accidental action and a real terroristic threat. The sandwich panels have a nominal thickness, with the core layer equal 100 mm and total exterior dimensions of 1180 mm × 3430 mm. Each sandwich panel was connected with two steel columns made of I140 PE section using three self-drilling fasteners per panel width, which is a standard number of fasteners suggested by the producers. The steel columns were attached to massive reinforced concrete blocks via wedge anchors. The conducted tests revealed that the weakest links of a single sandwich panel, subjected to a blast load, were both the fasteners and the strength of the core. Due to the shear failure of the fasteners, the integrity between the sandwich panel and the main structure is not provided. A comparison between the failure mechanisms for continuous (polyisocyanurate foam and expanded polystyrene) and non-continuous (mineral wool) core layer materials were conducted.

Numerical assessment of the human body response to a ground-level explosion.

This paper presents the results of a numerical analysis of the behaviour of a human body after a ground-level explosion. The explosions were generated by condensed charges for different stand-off distances and various masses of explosive. The detonations points were located at distances of 1.0 and 2.0 meters from the dummy (human model) obstacle. The different masses of spherically-shaped TNT charges (0.4-1.0 kg) were initiated centrally. The blast wave propagation was generated using a coupled numerical design, which included Eulerian and Lagrangian descriptions for different domains, i.e. the dummy, air, and explosive domains. The main objective of this work was to present the actual pressures and accelerations around the dummy and the body motion caused by the rapid shock of the pressure action. Reaction forces and moments of anatomical joints were provided. Furthermore, the safety criteria presented in the official standards were compared to the simulation results. In this research, different positions against the loading masses were analysed. In each analysis the same standing human model was used. The dummy geometry was based on a medium size male (1.79 m, 84.8 kg). The human body was modelled as consisting of separate, rigid parts (with adequate masses and inertia moments) connected by joints exhibiting nonlinear behaviour. Anatomical ranges of motion were taken into consideration, and a dedicated numerical technique was proposed to model the resistance moment vs. the range of motion relations for the most important human body joints.

The Use of Vacuum-Assisted Closure in Purulent Complications and Difficult-To-Heal Wounds in Cardiac Surgery.

BACKGROUND: Sternal wound infections are a serious and potentially fatal complication of cardiac surgery. OBJECTIVES: The aim of the study was to analyze the results of using the vacuum-assisted closure (VAC) system over a 4-year period. MATERIAL AND METHODS: Quantitative VAC performance data from a retrospective review of a consecutive cohort of 47 patients treated with VAC for post-cardiac surgery wound complications were collected and statistically analyzed. In the study group 35 patients developed infections of the post-operative chest wound. In 12 other patients wound dehiscence was observed, but repeated cultures did not reveal the presence of any bacteria. RESULTS: The statistical analysis identified the following as significant risk factors: age, female sex, being overweight, a high total logistic EuroScore, the use of both internal thoracic arteries for bypass grafting, and diabetes. In the wound negative culture group the total length of hospital stay was significantly shorter than in the wound positive culture group. Mortality in this group was 0.0% vs. 5.7% in the wound positive culture group. In the study material, Gram-negative bacteria were responsible for 77% of the post-operative wound infections, with only 14% Gram-positive wound cultures. No complications were related to VAC use. CONCLUSIONS: The use of negative-pressure wound therapy with other concomitant surgical procedures is a good method of treating infected wounds as well as non-contaminated dehiscence of the wound and sternum. Considering that most of the infections within the authors' department are caused by Gram-negative bacteria, it would be beneficial to consider modifying the model of preventive antibiotic treatment to cover the Gram-negative spectrum in addition to the Gram-positive bacteria currently targeted.

Surgeon's viewpoint on lung transplantation in cystic fibrosis patients - preliminary report.

INTRODUCTION: The surgeon's viewpoint on a patient with cystic fibrosis differs from that of a pediatrician or internist. The problems a cystic fibrosis specialist encounters are different from those faced by the surgeon who takes over the patient in a very advanced, often terminal stage of the disease. Hence, the main problem for the surgeon is the decision concerning the surgery (lung transplantation, pneumonectomy, lobectomy). It is, therefore, important to lay down fundamental and appropriate rules concerning the indications and contraindications for lung transplantation, especially in patients with cystic fibrosis. AIM: The aim of this study was to analyze the methods of qualifying and preparing patients for surgery, as well as carrying out the procedure of transplantation and postoperative short and long-term care. MATERIAL AND METHODS: The investigation was carried out on 16 patients with cystic fibrosis. Three were operated on and 10 were on the waiting list for transplantation. Two patients on the waiting list died, one patient was disqualified from transplantation. During qualification for lung transplantation, strict indications, contraindications and other factors (such as blood type, patient's height, coexisting complications) were taken under consideration. RESULTS: All the 3 patients after lung transplantation are alive and under our constant surveillance. Ten patients await transplantation, though four of them are suspended due to hepatitis C infection. Two patients on the waiting list died: one from respiratory insufficiency and the other in the course of bridge to-transplant veno-venous extracorporeal membrane oxygenation due to hepatic failure. One patient has been disqualified because of cachexia. CONCLUSIONS: Since lung transplantation is the final treatment of the end-stage pulmonary insufficiency in cystic fibrosis patients, the number of such procedures in cystic fibrosis is still too low in Poland. The fast development of these procedures is highly needed. It is necessary to develop better cooperation between different disciplines and specialists, especially between pediatricians and surgeons. The correct choice of the suitable moment for lung transplantation is crucial for the success of the procedure.

Glycated hemoglobin HbA1c - a new risk marker for the outcome of cardiac surgery?

INTRODUCTION: About 30% of patients undergoing cardiac surgery are diabetic, and glycated hemoglobin (HbA1c) is a reliable marker for long-term glucose control. The aim of our study was to examine whether tight glucose control before a cardiac operation results in a better outcome of the surgical treatment. MATERIAL AND METHODS: We performed a retrospective record review of 350 diabetic patients undergoing cardiac surgery in our institution. Preoperative glycemia control was assessed by measurement of the glycated hemoglobin level. The patient population was divided into three groups: group I - patients with HbA1c below 7% (n = 195); group II - patients with HbA1c between 7% and 8% (n = 88); and group III - patients with HbA1c above 8% (n = 67). RESULTS: The demographic data and operating risk in all groups of patients were similar. There were 2 deaths (1.02%) in group I, 2 deaths (2.27%, p = 0.78) in group II and 3 deaths (4.47%, p = 0.20) in group III. Cardiac accidents occurred in 9 patients (4.60%) from group I, 7 patients (7.95%, p = 0.20) from group II, and in 6 patients (9.05%, p = 0.40) from group III. Cerebrovascular accidents (CVA) occurred in 7 (3.58%), 5 (5.68%, p = 0.67) and 5 (7.46%, p = 0.61) patients, respectively. Acute renal dysfunction requiring renal replacement therapy occurred in 4 patients from group I (2.05%), 3 patients from group II (3.40%, p = 0.78) and 4 patients from group III (5.97%, p = 0.23). CONCLUSIONS: A large percentage of diabetic patients referred for cardiac operations have poorly controlled glycemia. Optimal preoperative glycemia control results in lower postoperative mortality and morbidity. In addition, the preoperative HbA1c level is a good indicator of the risk of postoperative complications in diabetic patients undergoing cardiac operations.

Predictors of short- and mid-term recurrence of atrial fibrillation after surgical radiofrequency ablation: a six-month transtelephonic electrocardiogram monitoring study.

BACKGROUND: Occurrence of symptomatic, paroxysmal or persistent atrial fibrillation (AF) prior to admission to hospital for the purposes of cardiac surgery constitutes an indication forconsideration of simultaneous surgical radiofrequency (RF) ablation of such tachyarrhythmia. The aim of this study was to evaluate the efficacy of surgical RF ablation in the treatment of AF with the application of ECG teletransmission in monitoring patients during a 6-month follow-up period. Furthermore, clinical and echocardiographic risk factors for arrhythmia recurrences were subject to analysis. As per authors' knowledge and literature review, so far no papers devoted to the assessment of efficacy of surgical RF ablation with the use of systematic ECG teletransmission have been published. METHODS: The study enrolled 61 patients (20 females) suffering from AF who underwent cardiac surgeries and were additionally subject to surgical RF ablation. The mean age of the subjects was 64 ± 9 years. Efficacy of the procedure was monitored with the application of a system enabling transtelephonic transmission of ECG signal. The study cohort was monitored in the period of 6 months. 2198 ECG recordings were obtained for analysis. RESULTS: In the post-hospital follow-up period, no recurrences of AF were observed in the case of 40 (65%) subjects. Post-hospital failure of the surgical RF ablation procedure was associated with an early episode of AF during hospitalization (p = 0.0012), application of monopolar electrode (p = 0.0325) as well as with the surgical procedure performed to treat mitral stenosis (p = 0.0268). CONCLUSIONS: Moreover, it was observed that the group of patients without arrhythmia recurrence in the follow-up period was more frequently administered with antiarrhythmic medications (p = 0.0409) and statin (p = 0.0453) prior to the ablation procedure, with statin being more often applied after the procedure (tendency, p = 0.0747). As opposed to ablation in one atrium, biatrial ablation did not result in fewer late arrhythmia recurrences.

Evaluation of the level of antibodies against Chlamydophila (Chlamydia) pneumoniae in post-surgery heart ischaemia patients and their clinical conditions - a six-year study.

INTRODUCTION: Inflammatory conditions modulated by Chlamydophila (Chlamydia) pneumoniae are considered to play an important role in the onset of atherosclerosis. In this paper we present the results of progressive observation of C. pneumoniae antibody titres in patients who underwent coronary artery bypass graft (CABG). MATERIAL AND METHODS: The objective of our research was a prospective observation of antibody titres in IgA and IgG class antibodies against C. pneumoniae using indirect immunofluorescence in a group of 155 post-surgery CABG patients suffering from heart ischaemia. The microbiological test results were compared with patients' present coronary complaints evaluated on the CCS scale during a six-year period. RESULTS: Six years after CABG, 128 patients (82.6%) are still alive. During the study a positive serological conversion of antibody titres was observed in 36 patients in the IgA class antibodies, and in 26 patients in the IgG class. The group of patients with no antibodies against C. pneumoniae decreased from 23.2 to 3.4%, while the group of patients with antibodies in both IgG and IgA classes increased from 52.3 to 83.9%. The average CCS degree decreased from 3.18 before CABG to 1.65 in the present study. CONCLUSIONS: These results show no connection between the serological symptoms of chronic C. pneumoniae infection and coronary complaints evaluated on the CCS scale during a six-year study on post-CABG patients suffering from heart ischaemia. The surgical treatment of heart ischaemia brought about long-term improvement in the coronary condition of the observed group of patients.

[Use of minimally invasive direct coronary bypass (MIDCAB) in reoperative coronary surgery]. / Wykorzystanie technik maloinwazyjnych (MIDCAB) podczas powtórnych operacji tetnic wiencowych.

The authors presented the method and early results of minimally invasive direct coronary arteries reoperation in 5 patients, approximately 7, 5 years after the first CABG operation. In all patients venous grafts were occluded. there was a different approach used in every patient: small left or right anterior thoracotomy through IV or V intercostal space, laparotomy with partial low sternotomy or simultaneous combined approach through thoracotomy and sternotomy/laparotomy. The following arteries were grafted: left anterior descending, right posterior descending, LAD with right coronary artery and LAD with marginal branch. All patients were extubated in the operating room. There were no serious perioperative complications observed. Patients were transferred to cardiology department on the 5th-7th postoperative day.

[Assessment of early results of cardiac surgery in patients over 65 years of age]. / Ocena wczesnych wyników operacji kardiochirurgicznych u chorych po 65 roku zycia.

The aim of the study was determine the influence of age on the outcome of cardiac surgery and reveal risk factors important for the outcome of cardiac surgery in patients over the age of 65 years. Early results of surgical treatment was analyzed in 1741 cases operated in extracorporeal circulation. The patients were divided into two groups. The study group consisted of 375 patients over 65 years of age, while the control group consisted of 1366 patients younger than 65 years. It was shownfound that higher mortality in the study group was associated with low ejection fraction, urgency of surgery, class III and IV of CCS, and BMI > 26. Mortality in the control group was associated with female sex, elevated serum creatinine, bacterial endocarditis, tobacco smoking, urgency of surgery, class III and IV of CCS. Factors significantly influencing mortality in both groups were compared. Mortality in group A in comparison with group B was influenced by low ejection fraction, urgency of surgery, class III and IV of CCS and tobacco smoking. The EuroSCORE was calculated for both groups. It was shown that the EuroSCORE scale allows assessment of operative risk for patients over 65 years of age. Although mortality and morbidity in cardiac surgery are elevated for patients older than 65 years, the outcome is influenced more by risk factors than by age alone.