Magnetic, Mechanical and Thermal Modeling of Superconducting, Whole-body, Actively Shielded, 3 T MRI Magnets Wound Using MgB2 Strands for Liquid Cryogen Free Operation.

we present magnetic, mechanical and thermal modeling results for a 3 Tesla actively shielded whole body MRI (Magnetic Resonance Imaging) magnet consisting of coils with a square cross section of their windings. The magnet design was a segmented coil type optimized to minimize conductor length while hitting the standard field quality and DSV (Diameter of Spherical Volume) specifications as well as a standard, compact size 3 T system. It had an overall magnet length and conductor length which can lead to conduction cooled designs comparable to NbTi helium bath cooled 3 T MRI magnets. The design had a magnetic field homogeneity better than 10 ppm (part-per-million) within a DSV (Diameter of Spherical Volume) of 48 cm and the total magnet winding length of 1.37 m. A new class of MgB2 strand especially designed for MRI applications was considered as a possible candidate for winding such magnets. This work represents the first magnetic, mechanical and thermal design for a whole-body 3 T MgB2 short (1.37 m length) MRI magnet based on the performance parameters of existing MgB2 wire. 3 Tesla MRI magnet can operate at 20 K at 67 % of its critical current.

German National Guideline on the management of pilonidal disease: update 2020.

BACKGROUND: The present German National Guideline is an updated version of previous Guideline published in 2014. It aims to compare various treatment methods and to assist physicians with evidence-based recommendations. METHODS: Systemic literature review. RESULTS: Three types of disease manifestation could be differentiated: asymptomatic disease, an acute abscess, and the chronic pilonidal disease. At present, there is no treatment method fulfilling all desired criteria: simple, painless procedure associated with rapid wound healing, and low recurrence rate. Thus, treatment modality should be tailored to disease manifestation and extent. CONCLUSION: Asymptomatic pilonidal disease should not be treated. A pilonidal abscess should be unroofed. After resolution of the acute inflammation, the disease should be treated definitely. As for today, sinus excision is the standard treatment of the chronic pilonidal disease. Wide excision and open treatment of chronic disease is a safe procedure which, however, leads to prolonged secondary healing and time off-work, as well as to considerable recurrence rate. The extent of excision should be as limited as possible. Excision and midline wound closure is associated with impaired outcomes. Today, it has become obsolete. Minimally invasive procedures (e.g., pit picking surgery) represent a treatment option for chronic pilonidal disease. However, the recurrence rate is higher compared to excision procedures. Nevertheless, they may be used for small primary disease. Off-midline procedures should be used for disease not suitable for minimally invasive treatments. The Limberg flap and the Karydakis procedure are two best described methods which are associated with similar short- and long-term results.

[Reticulocyte hemoglobin equivalent as a diagnostic marker for the current iron deficiency : Old wine in new bottles]. / Retikulozyten-Hämoglobin-Äquivalent als diagnostischer Marker der aktuellen Eisendefizienz : Alter Wein in neuen Schläuchen.

The reticulocyte hemoglobin equivalent (RET-He) is presented as a biomarker for the diagnostics and monitoring of iron deficiency. The marker is independent of the acute phase and can be determined within a few minutes by a blood count. Due to the approximately 120-day lifetime of erythrocytes, iron deficiency and changes in the iron status of erythropoiesis can first be recognized at a relatively late stage using classical hematological parameters, such as hemoglobin, mean corpuscular volume, mean cellular hemoglobin content and also with determination of hypochromic erythrocytes (% hypo). The RET-He is a cost-effective parameter for the diagnosis and monitoring of the iron supply for erythropoiesis. Reticulocytes, the precursors of mature erythrocytes, are washed out of the bone marrow into the peripheral blood and normally mature within 2 days to mature erythrocytes. The determination of the reticulocyte number therefore enables a timely statement about erythropoiesis. A measurement of the hemoglobin content of reticulocytes therefore reflects the actual iron metabolism of erythropoiesis and enables assessment of the quality of the cells. Changes in the iron status of erythropoiesis can thus be detected much earlier than by determining only the hemoglobin content of mature erythrocytes, i.e. the mean cellular hemoglobin content. It is recommended that the evaluation of RET-He should be carried out as an inexpensive routine preoperative marker of latent anemia in order to identify patients at risk. In the sense of a perioperative prehabilitation and the enhanced recovery after surgery (ERAS) concept, patients with iron deficiency can be treated proactively at an early stage in order to prevent complications and extended hospital stays.

Quench, Normal Zone Propagation Velocity, and the Development of an Active Protection Scheme for a Conduction Cooled, R&W, MgB2 MRI Coil Segment.

The development of coils that can survive a quench is crucial for demonstrating the viability of MgB2-based main magnet coils used in MRI systems. Here we have studied the performance and quench properties of a large (outer diameter: 901 mm; winding pack: 44 mm thick × 50.6 mm high) conduction-cooled, react-and-wind (R&W), MgB2 superconducting coil. Minimum quench energy (MQE) values were measured at several coil operating currents (I op ), and distinguished from the minimum energy needed to generate a normal zone (MGE). During these measurements, normal zone propagation velocities (NZPV) were also determined using multiple voltage taps placed around the heater zone. The conduction cooled coil obtained a critical current (I c ) of 186 A at 15 K. As the operating currents (I op ) varied from 80 A to 175 A, MQE ranged from 152 J to 10 J, and NZPV increased from 1.3 to 5.5 cm/s. Two kinds of heater were involved in this study: (1) a localized heater ("test heater") used to initiate the quench, and (2) a larger "protection heater" used to protect the coil by distributing the normal zone after a quench was detected. The protection heater was placed on the outside surface of the coil winding. The test heater was also placed on the outside surface of the coil at a small opening made in the protection heater. As part of this work, we also developed and tested an active protection scheme for the coil. Such active protection schemes are of great interest for MgB2-based MRIs because they permit exploitation of the relatively large MQE values of MgB2 to enable the use of higher J e values which in turn lead to competitive MgB2 MRI designs. Finally, the ability to use a quench detection voltage to fire a protection heater as part of an active protection scheme was also demonstrated.

Common surgical procedures in pilonidal sinus disease: A meta-analysis, merged data analysis, and comprehensive study on recurrence.

We systematically searched available databases. We reviewed 6,143 studies published from 1833 to 2017. Reports in English, French, German, Italian, and Spanish were considered, as were publications in other languages if definitive treatment and recurrence at specific follow-up times were described in an English abstract. We assessed data in the manner of a meta-analysis of RCTs; further we assessed non-RCTs in the manner of a merged data analysis. In the RCT analysis including 11,730 patients, Limberg & Dufourmentel operations were associated with low recurrence of 0.6% (95%CI 0.3-0.9%) 12 months and 1.8% (95%CI 1.1-2.4%) respectively 24 months postoperatively. Analysing 89,583 patients from RCTs and non-RCTs, the Karydakis & Bascom approaches were associated with recurrence of only 0.2% (95%CI 0.1-0.3%) 12 months and 0.6% (95%CI 0.5-0.8%) 24 months postoperatively. Primary midline closure exhibited long-term recurrence up to 67.9% (95%CI 53.3-82.4%) 240 months post-surgery. For most procedures, only a few RCTs without long term follow up data exist, but substitute data from numerous non-RCTs are available. Recurrence in PSD is highly dependent on surgical procedure and by follow-up time; both must be considered when drawing conclusions regarding the efficacy of a procedure.

Demonstration of a Conduction Cooled React and Wind MgB2 Coil Segment for MRI Applications.

This study is a contribution to the development of technology for an MgB2-based, cryogen-free, superconducting magnet for an MRI system. Specifically, we aim to demonstrate that a react and wind coil can be made using high performance in-situ route MgB2 conductor, and that the conductor could be operated in conduction mode with low levels of temperature gradient. In this work, an MgB2 conductor was used for the winding of a sub-size, MRI-like coil segment. The MgB2 coil was wound on a 457 mm ID 101 OFE copper former using a react-and-wind approach. The total length of conductor used was 330 m. The coil was epoxy impregnated and then instrumented for low temperature testing. After the initial cool down (conduction cooling) the coil Ic was measured as a function of temperature (15-30 K), and an Ic of 200 A at 15 K was measured.

German national guideline on the management of pilonidal disease.

PURPOSE: The present national guideline aims to provide recommendations for physicians involved in the treatment of patients with pilonidal disease. It has been published previously as an extended version in German language. METHODS: This is a systemic literature review. The present guideline was reviewed and accepted by an expert panel in a consensus conference. RESULTS: Some of the present guideline conclusions were based on low- to moderate-quality trials. Therefore, an agreement was necessary in those cases to provide recommendations. However, recommendations regarding the most frequently used surgical procedures were based on numerous prospective randomized trials. CONCLUSIONS: An asymptomatic pilonidal disease does not require treatment. A pilonidal abscess should be incised. After regression of the acute inflammation, a definitive treatment method should be applied. An excision is the standard treatment method for the chronic pilonidal disease. Open wound healing is associated with a low postoperative morbidity rate; however, it is complicated by a long healing time. The minimally invasive procedures (e.g., pit picking surgery) represent a potential treatment option for a limited chronic pilonidal disease. However, the recurrence rate is higher compared to open healing. Excision followed by a midline wound closure is associated with a considerable recurrence rate and increased incidence of wound complications and should therefore be abandoned. Off-midline procedures can be adopted as a primary treatment option in chronic pilonidal disease. At present, there is no evidence of any outcome differences between various off-midline procedures. The Limberg flap and the Karydakis flap are most thoroughly analyzed off-midline procedures.

Abdominal organ donation: surgical aspects and recommended practice guidelines for controlled donation of brain-dead donor.

The shortage of organ donors along with the increased number of waiting recipients have created the need for new strategies to expand the organ pool from donations after brain death. Organ procurement from brain-dead deceased donors is a complex task. Multiple, complicated operations are performed simultaneously. Very often, this involves numerous physicians and transplant coordinators. An extensive coordination between the thoracic and abdominal surgical teams is crucial for the successful procurement of all suitable organs. The quality of donor organs and the successful recovery therefore depends on a good communication. Organ procurement for transplantation should generally be performed in a calm and dignified atmosphere. The last wishes of the organ donor itself or the relatives must be respected unconditionally. In general, a dignified and respectful treatment of the organ donor is a condition sine qua non for each person involved in the process of organ procurement. The purpose of this article was to focus on the surgical aspects of organ donation after brain death. The proposed recommendations, in cases where they are applicable, are acceptable, however, one should never forget the importance of the ethical side of the issue with respect to the doctor-donating side relationship.

Operating on penetrating trauma to the mediastinal vessels.

BACKGROUND AND AIMS: Patients with penetrating trauma of the major vessels of the chest are infrequently encountered. This is due to the fact that the majority of these patients die on scene, as well as due to the overall dramatic decline in the incidence of penetrating trauma in the Western world. A certain proportion of survivors are physiologically stable and can be transferred to adequate care. Patients who are physiologically unstable must be dealt with by the surgeons available without delay. Rapid diagnosis and operation can salvage patients who would otherwise be lost, and all general surgeons should be capable of recognizing these injuries and intervening if a trauma and/or cardiothoracic surgeon is not immediately available. MATERIAL AND METHODS: Technical description of practical emergency surgery approaches to patients bleeding to death from penetrating mediastinal vessel injuries. RESULTS: The scope of this review familiarizes the "uninitiated" surgeon with the operative management of this rare and lethal type of injuries. Technical aspects are described, and pitfalls as well as tips and tricks of the trade are discussed. CONCLUSIONS: Patients with penetrating injuries to the mediastinal vessels can be saved by swift and knowing operative management of this rare and lethal type of injuries, even if a trauma and/or cardiothoracic surgeon is not immediately available.

[Evisceration of intestines following abdominal stab wounds: epidemiology and clinical aspects of emergency room management]. / Eviszeration von Darm nach Stichverletzung des Abdomens: Häufigkeit und klinische Aspekte des klinischen Schockraummanagements.

STUDY AIM: The aim of the study was an estimation of the incidence and clinical aspects of emergency room (ER) parameters of penetrating abdominal injury patients with bowel evisceration. STUDY DESIGN AND METHODS: The study involved a retrospective cohort analysis of ER data from the Chris Hani Baragwanath Academic Hospitals, Soweto, Johannesburg, South Africa between September 2000 to May 2005. RESULTS: Out of 9,010 ER patients, 4,390 suffered penetrating injuries with 8 out of 71 eviscerations due to a single gunshot wound, 60 out of 71 eviscerations due to single stab wounds and 3 further patients suffered multiple injuries. The ER mortality was 1 out of 71(1.6 %) with an average ER mortality of 4.2 %. The only death seen was a single abdominal gunshot wound with vascular injury. The causative mortality due to abdominal stab wounds with evisceration of the bowels was therefore zero. The heart rate in patients with abdominal stab wounds with and without bowel evisceration showed no significant difference, thus mesentery tearing or vagal overstimulation could not be seen, neither with bradycardia nor hypotension. CONCLUSION: Evisceration itself is not a cause for increased mortality or cardiovascular instability seen in the ER. There is ample time for diagnostic procedures before laparotomy is performed.

Is there a difference in outcome (long-term recurrence rate) between emergency and elective pilonidal sinus surgery?

AIM: The influence of surgical craftsmanship and decision making on long-term recurrence rate has not been investigated yet. METHODS: A total of 586 patients with surgery for primary pilonidal sinus disease were subjected to a telephone interview 7-25 years after surgery to determine 10- and 20 year recurrence rate using Kaplan Meier Statistics. RESULTS: Results show that 546 patients had elective surgery showing a recurrence rate of 23.1% (actuarial 10.6-17% after 5-10 years). Forty patients had urgent off-time surgery with crude long-term recurrence rate 30%; actuarial 25.6-28.9% after 5-10 years); P=0.028; logrank. Mind bogglingly, Methylene blue application was dramatically reduced in the urgent group compared to the elective group, although Methylene blue is known to halve recurrence rate. CONCLUSION: Surgical craftsmanship quality was identical in elective and urgent pilonidal sinus surgery with comparable long-term recurrence rate. Decision making was markedly biased in urgent off-time pilonidal sinus surgery, counteracting the good long-term recurrence rate enabled by proper surgical craftsmanship.

[Costs of delivering allogenic blood in hospitals]. / Kosten der Verabreichung von Blutkonserven im Krankenhaus.

INTRODUCTION: In clinical practice there are medical and economic reasons against the thoughtless use of packed red blood cells (rbc). Therefore, in searching for alternatives (therapy of anemia) the total costs of allogeneic blood transfusions must be considered. Using a practical example this article depicts the actual costs and possible alternatives from the point of view of a hospital in Germany. METHOD: To determine the total costs of allogeneic blood transfusions the actual resource consumption associated with blood transfusions was collated and analyzed at the St. Marien-Hospital in Vechta. RESULTS: The authors were able to show that the actual procurement costs (average. 97 EUR) represent only 55 % of the total costs of 176 EUR. The additional expenses are allocated to personnel (78 %) and materials (22 %). Alternatives, such as i.v. iron substitution or stimulation of erythropoesis might be the more economical solution especially if only purchase prices are compared and the total costs of allogeneic blood transfusions are not considered. DISCUSSION: Analyzing a single hospital limits generalization of the results; however, in the international context the results can be recognized as plausible. So far there have been no comprehensive studies on the true costs of blood preparations, therefore, this article represents a first starting point for closing this gap by conducting additional studies.

[Penetrating gluteal injury due to sledging accident]. / Penetrierende Gluteale Pfählungsverletzung durch Schlittenunfall.

We present the case of a rare penetrating sledging injury. A 39-year-old male sitting upright had his sledge burst when sliding into a pit. A stick fractured from the sledge's sitting plate and perforated from the infragluteal fold up to the lumbosacral junction. The man arrived in a conscious and cardiovascular stable condition in the ER, where no clinical evidence of vascular, retroperitoneal and pelvic injury was obvious. The anal external sphincter was uninjured and competent although the perforation enabled a look onto its surface. The foreign body was removed without further bleeding. Sledging injuries typically carry blunt characteristics, mainly with neurotrauma or fracture dislocations. As penetrating sledging injuries are exceptionally rare, strategies are discussed.

[Temporary treatment of uncontrolled intrathoracic hemorrhaging with abdominal towels in combination with a rescue procedure. Damage control procedure of the chest]. / Temporäre Versorgung einer unstillbaren intrathorakalen Blutung mit Bauchtüchern in Kombination mit einer Rettungsprozedur. Ein Damage-control-Verfahren des Thorax.

Case report of a 27-year-old patient who presented with a stab wound in the posterior aspect of the right chest. The patient was physiologically unstable and not responding to fluid resuscitation. A right intercostal drainage was inserted which immediately drained 1100 ml of blood. Thoracotomy was performed where a large clot was removed from the pleural cavity and followed by massive bleeding from the hilum of the lung as well as an intercostal artery posteriorly. Control of the hilar hemorrhaging necessitated right middle lobe resection. Attempts to control the bleeding from the intercostal artery were futile becoming technically more difficult due to a comminuted fracture of the ribs at the site of entry of the knife. During these attempts the patient became moribund. As a last resort the pleural cavity was packed with abdominal towels and the patient was transferred to the intensive care unit (ICU). The patient was returned to surgery after 48 h at which time the packing was removed with no further bleeding. On day 11 postoperatively drainage of the pleural collection was carried out and decortication of the right lower lobe. The patient was discharged 23 days after admission in a good general condition. This case report demonstrates that in exceptional circumstances packing of the pleural cavity to control bleeding can be considered as a method of damage control in penetrating chest trauma.

Liver transplantation in the rat: single-center experience with technique, long-term survival, and functional and histologic findings.

OBJECTIVE: Orthotopic liver transplantation (OLT) in rats is frequently used as an experimental model. Numerous surgical techniques have been developed that enable the investigator to conduct clinically relevant studies. The objective of this study was to develop a rat model of acute and chronic rejection, to explicitly study technical modifications of vascular anastomoses with precision, and to examine histopathologic and functional changes in the graft. MATERIALS AND METHODS: With DA-(RT1av1) rats as donors and Lewis-(RT1) rats as recipients, arterialized OLT was performed using a combined suture, cuff, and splint method. Recipients were divided into 5 groups: syngeneic control rats (group 1), allogeneic control rats (group 2), allogeneic OLT rats with low-dose tacrolimus (FK506) immunosuppression (group 3), allogeneic OLT rats with high-dose tacrolimus immunosuppression (group 4), and allogeneic OLT rats with high-dose tacrolimus immunosuppression and retrograde reperfusion via the infrahepatic caval vein (group 5). After OLT, serum parameters were determined and hepatic biopsy specimens were sampled. We examined the effects of acute rejection with or without immunosuppression therapy at histopathologic evaluation. RESULTS: Liver grafts in syngeneic and allogeneic rats (groups 1, 2, 4, and 5) demonstrated normal serum parameters and histopathologic findings at 10 days after OLT, and 93% survival at 3 months. The simplified technique using 1 suture and 2 cuff anastomoses provided the best short- and long-term survival after OLT in all groups. Retrograde perfusion via the infrahepatic caval vein resulted in lower postoperative liver enzyme values. CONCLUSION: The present model is feasible, enabling comprehensive preclinical experimental research on liver transplantation. Furthermore, we provide helpful instructions for learning this surgical technique.