A comparative study of an Yb-doped fiber gain-managed nonlinear amplifier seeded by femtosecond fiber lasers

In this work, we show that the nonlinear evolution of femtosecond seed pulses with different parameters (temporal and spectral shapes, repetition rate, pulse energy) in an Yb-fiber amplifier leads to gain-managed nonlinear amplification, enabling robust generation of high-peak-power and nearly transform-limited pulses after external compression. We demonstrate a compressed pulse duration of 33 fs with an energy of 80.5 nJ and a peak power of 2.29 MW for a source with a repetition rate of 30 MHz. For a second seed source with a repetition rate of 125 MHz, we obtained a pulse duration of 51 fs with an energy of 22.8 nJ and a peak power of 420 kW. Numerical simulations incorporating rate equations and nonlinear propagation in the amplifier provide evolutions that agree well with the experimental results. The discrepancies in the amplifier’s absorption edge appearing at low repetition rates and higher pump powers are attributed to the temperature dependence of the amplifier’s gain cross-sections. Here, we experimentally verify this attribution and thus underline the importance of accounting for the fiber core temperature for precise modelling of the short-wavelength spectral edge of the output pulses in nonlinear Yb-fiber amplifiers. We also measure, for the first time, the relative intensity noise of an amplifier operating in the gain-managed nonlinear regime. The measurements reveal a significant contribution of the amplification process to the overall output noise of the system.

Managing Unintentional Iatrogenic Triple Lumen Central Venous Catheter (TLCVC) Arterial Puncture

Unintentional arterial puncture by central venous catheter insertion/placing can result in destructive complications especially if a large bore (>7F) catheter was used. Unplanned immediate catheter ejection with manual external compression is hazardous due to potential torrential blood leakage or formation of a pseudoaneurysm. Endovascular removal with a vascular closure device deployment is preferred in this situation. The aim of this case report is to discuss the alternative strategies if the vascular closure device fails to secure hemostasis.

Immediate Effect of Trunk Flexion And Extension Isometric Exercise Using An External Compression Device On Electromyography of The Hip Extensor And Trunk Range of Motion Of Healthy Subjects

Background: Low back pain (LBP) is a very common symptom experienced by individuals across all age groups. Previous study established that using a device known as Active Therapeutic Movement version 2 (ATM®2) has been developed to improve pain and joint range of motion (ROM) in patients with LBP. However, no study has examined the physiological change in the muscle through ATM®2-based exercise thus far. This study aimed to determine the immediate effects of ATM®2 exercise on the contraction timing, back extension endurance, muscle fatigue, and trunk ROM of lumbar and lower limb muscles in healthy subjects.Methods: Thirty-six healthy subjects (mean age=23.16±2.3) volunteered to participate in this study. Subjects were instructed to perform ROM test using sit and reach test, back extensor endurance test using Biering-Sorensen test, erector spinae (ES), lumbar multifidus (LM) fatigue and onset time of Gluteus maximus (GM) in prone hip extension using electromyography before and after trunk flexion and extension isometric exercises.Results: The ROM in trunk flexion showed a significant increase by 7.9% after exercise compared to that before exercise (p<0.05). Relative GM contraction onset timing significantly decreased after exercise (p<0.05). The result of the Sorensen test after exercise showed a trend of increase in duration time. Muscle fatigue in the LM, however, showed a significant increase (p<0.05), whereas muscle fatigue in the ES was reduced without statistical significance.Conclusions: The results base on this study showed a significant increase in the trunk ROM after trunk flexion and extension isometric exercise using an external compression device, while the relative contraction onset timing in the GM significantly reduced. Furthermore, the muscle endurance test after exercise showed a trend of increase in the duration time with a decreasing trend in muscle fatigue in the ES. Exercise based on ATM®2 is an effective exercise protocol with an effect on biomechanics of healthy subjects. This exercise may be suitable in clinical practice for patients with LBP, for which long-term effects can be expected.

External compression of left main bronchus by a large patent ductus arteriosus: a case report

In neonates and infants, the trachea and main bronchus may be compressed by adjacent cardiovascular structures. Compression of the main bronchi by the patent ductus arteriosus is rare and causes a variety of respiratory problems. Surgical closure of the patent ductus arteriosus that compresses the main bronchus as soon as possible is an effective treatment option. Rapid clinical recovery is expected after surgical closure of the patent ductus arteriosus. We present a case of patent ductus arteriosus which caused obstruction of the left main bronchus.

Chimerization of Monitor Flap in a Vascularized Ulnar Nerve Flap Is an Efficient Way for Vascularity Monitoring and the Reinnervation Checkup after Its Transplantation

Background Free vascularized ulnar nerve flaps (VUNF) are effective method for long nerve defects reconstruction. However, the monitorization of its microvascular circulation and the nerve regrowth can be challenging since it is usually designed as a buried flap. We designed a skin paddle based on a septocutaneous perforator from the ulnar artery that can be dissected and raised in conjunction with the vascularized ulnar nerve flap, which aims to improve postoperative monitorization to optimizing the clinical results. Methods We retrospectively reviewed 10 cases with long nerve defects who underwent reconstruction using VUNF between June 2018 and June 2019, including eight acute brachial plexus injuries, 1 multiple nerve injury due to a rolling machine accident, and 1 sequalae of nerve injury after arm replantation. All the demographic data, surgical details, outcomes, and perioperative complications were recorded. Results We evaluated 10 male patients, with a mean age of 34 ± 16 years. Cases included 5 antegrade, 4 retrograde, and 1 U-shaped VUNF. All chimeric skin paddles survived, and all of the underlying nerves presented with adequate circulation and functional improvement. There were no intraoperative or microvascular complications. One skin paddle had a transitory postoperative circulation compromise due to external compression (bandage) which resolved spontaneously after pressure release. Conclusion VUNF chimerization of a septocutaneous perforator skin flap is a relatively easy and efficient method for postoperative monitorization of the nerve’s microvascular circulation as well as beneficial for postoperative Tinel’s sign checkup to confirm the success of the nerve coaptation. The outcome is potentially improved.

Abdominal Aortic Junctional Tourniquet - Stabilized (AAJTS) can be applied both successfully and rapidly by Combat Medical Technicians (CMTs)

Background‘Non-compressible’ haemorrhage is the leading cause of preventable battlefield death, often requiring surgical or radiological intervention, which is precluded in the pre-hospital environment. One-fifth of such bleeds are junctional and therefore potentially survivable. We examine the use of the Abdominal Aortic Junctional Tourniquet - Stabilized (AAJTS) among UK Combat Medical Technicians (CMTs) as a device to control junctional haemorrhage with external compression of the abdominal aorta—compression of junctional haemorrhage previously considered ‘non-compressible.’ This follows animal studies showing that the AAJTS achieves control of haemorrhage and improves physiological parameters.MethodsCMTs were selected and applied the AAJTS to each other following a 1-hour training package. A consultant radiologist-operated hand-held ultrasound monitored flow changes in the subjects’ common femoral artery. CMTs were then surveyed for their opinions as to utility and function.Results21 CMTs were screened and 17 CMTs participated with 34 total applications (16 day and 18 low-light). 27/34 (79%) achieved a successful application. The median application time was 75 s in daylight and 57 s in low-light conditions. There was no significant difference in Body Mass Index (p=0.23), median systolic blood pressure (p=0.19), nor class of CMT (p=0.10) between successful and unsuccessful applications. Higher systolic blood pressure was associated with longer application times (p=0.03). Users deemed the device easy to use (median score 4.4 on a 5-point Likert scale).ConclusionCMTs can use AAJTS successfully after a 1-hour training session in the majority of applications. Application was successful in both daylight and low-light conditions. Self-reported usability ratings were high.

Coagulation in Lymphatic System

The lymphatic system maintains homeostasis of the internal environment between the cells in tissues and the blood circulation. The coagulation state of lymph is determined by conditions of coagulation factors and lymphatic vessels. Internal obliteration, external compression or abnormally increased lymphatic pressure may predispose to localized lymphatic coagulation. In physiological conditions, an imbalance of antithrombin and thrombokinase reduces lymphatic thrombosis. However, the release of factor X by lymphatic endothelium injury may trigger coagulation casacade, causing blockage of lymphatic vessels and lymphedema. Heterogeneity of lymphatic vessels in various tissues may lead to distinct levels and patterns of coagulation in specific lymphatic vessels. The quantitative and qualitative measurement of clotting characteristic reveals longer time for clotting to occur in the lymph than in the blood. Cancer, infections, amyloidosis and lymph node dissection may trigger thrombosis in the lymphatic vessels. In contrast to venous or arterial thrombosis, lymphatic thrombosis has rarely been reported, and its actual prevalence is likely underestimated. In this review, we summarize the mechanisms of coagulation in lymphatic system, and discuss the lymphatic thrombosis-related diseases.

Aorto-oesophageal fistula: rarest cause of haematemesis - is it salvageable?

A 60-year-old man presented with severe abdominal pain, two episodes of massive haematemesis and chest discomfort. CT angiography showed a saccular aneurysm of the juxtaphrenic aorta with possible oesophageal erosion. Upper GI endoscopy revealed external compression of the lower oesophagus—near total luminal obstruction with impending rupture of the aortic aneurysm. Emergency aneurysmal repair by interposition grafting using 20 mm Dacron graft with oesophageal–gastric reconstruction done. Postoperative period was uneventful

Dural Sinus Thrombosis after Resection of Vestibular Schwannoma using Suboccipital Retrosigmoid Approach - Thrombosis Classification and Management Proposal.

ObjectiveDural sinus thrombosis is one of the complications after posterior fossa surgery. However, that topic is not described well with regard to vestibular schwannoma surgery using the unique suboccipital retrosigmoid approach.MethodsWe analyzed retrospectively medical records and radiological investigations of 116 patients. The including criteria were: histopathologically confirmed vestibular schwannoma operated on using the retrosigmoid approach, preoperative and postoperative contrast enhanced MRI, at least 1-year follow-up. ResultsThe patient group included 36% males, 64% females. The average age was 47.3±13.9 years. 60% of tumors were classified as T4b according to the Hannover scale and their mean volume was 13.73±10.28 cm3. There were no signs of thrombosis preoperatively. In 26 (22%) cases, postoperative changes in the dural sinuses were found. In 7 (27%) cases there was an external compression by the hemostatic agent, in 19 (73%) cases a thrombus was visualized in the sinus lumen. The size of the sinus, age, tumor size were not risk factors for thrombosis, whereas an intraoperative sinus injury was a statistically significant risk factor (p=0.0012). All of the patients diagnosed with thrombosis were in good clinical condition in distant follow-up (mRankin=0). Complete recanalization was observed in 58% of cases after 1-year follow-up.ConclusionsPostoperative changes in the dural venous sinuses are a frequent finding after vestibular schwannoma surgery using the suboccipital retrosigmoid approach. Intraoperative dural injury is a risk factor for thrombosis. Thrombosis in that group of patients is usually asymptomatic and does not influence the prognosis.