Linear and Nonlinear Optics of Broad-Band Laser Pulses: Diffraction

The typical spectrally limited laser pulse in the near-infrared region is narrow-band up to 40-50 fs. Its spectral width Δk is much smaller than the carrying wavenumber k0 (Δk ≪ k0) . For such kinds of pulses, on distances of a few diffraction lengths, the diffraction is of a Fresnel's type and their evolution can be described correctly in the frame of the well-known paraxial evolution equation. The technology established in 1985 of amplification through chirping of laser pulses triggered remarkable progress in laser optics along with the construction of femtosecond (fs) laser facilities producing high intensity fields of the order of 1015-1021 W/cm2. However, the duration of the pulse was quickly shortened from picoseconds down to 5-6 fs, which have a broad-band nature (Δk ∼ k0). The linear and nonlinear propagation dynamics of broad-band pulses is quite different form their narrow-band counterparts. Here, we review the appropriate theoretical approach to study the evolution of the pulse. Moreover, we shed light on the different diffraction regimes inherent to both narrow-band and broad-band laser pulses and compare them to unveil the main differences. Using this very method, in subsequent papers, we will investigate the influence of the dispersion and nonlinearity on the laser pulse propagation in isotropic media.

A giant synovial sarcoma of the left lung

Primary pulmonary synovial sarcoma is an extremely rare and aggressive neoplasm that primarily affects young people and has a poor prognosis. Establishing this diagnosis requires the exclusion of a wide number of other neoplasms with multimodal clinical, imaging, histological, immunohistochemical, and cytogenetic assessment. We present a case of synovial sarcoma of the left lung in a 44-year-old man, diagnosed immunohistochemically after left lower lobectomy with atypical resection of the 5th segment. Imaging, diagnostic workup, histological and immunohistochemical characteristics, surgical treatment, and prognosis are discussed.

Resection and a rare type of reconstruction of the superior vena cava with the left brachiocephalic vein

Resection and reconstruction of the superior vena cava (SVC) are required in a selected group of patients with anterior mediastinal tumors and lung neoplasms. We present the case of a 63-year-old woman who underwent invasive type B2 thymoma resection and a rare type of reconstruction of the superior vena cava using a patch of the left brachiocephalic vein (LBV). The various types of reconstruction of the superior vena cava are discussed.

Can Open Distal Repair Be Safely Used in All Patients with Type A Acute Aortic Dissection?

PURPOSE

The distal suture line during aortic dissection repair can be performed by a closed technique or by an open technique. This study presents a retrospective comparison of both methods regarding their postoperative outcomes.

PATIENTS AND METHODS

120 patients who underwent surgery for acute aortic dissection type A were divided into two groups. In group A (n = 81), open distal anastomosis was performed under hypothermic circulatory arrest and selective cerebral perfusion. In group B (n = 39), distal anastomosis was performed with the aorta cross-clamped under mildly hypothermic cardiopulmonary bypass. Primary outcomes were operative mortality, neurologic morbidity, and long-term survival.

RESULTS

Hospital mortality (17.3% for the open group vs. 12.8% for the closed group, p = 0.53), permanent neurologic dysfunction (8.7% vs. 8.3%, p = 1.0), and temporary neurologic dysfunction (31.9% vs. 22.2%, p = 0.298) were not significantly different between groups. No significant difference in actuarial 5- and 10-year survival was observed (88% vs. 86% and 53 vs. 73%, respectively, p = 0.396). After propensity-score adjustment, the technique of distal aortic repair was not found to be a predictor of the primary outcomes.

CONCLUSION

We conclude that the open repair can be used in most if not all cases of surgical repair of type A acute aortic dissection.

Development of organized pleural empyema as a result of occult foreign body aspiration

Foreign body (FB) aspiration is a rare incident in adults. Many patients cannot recall the episode of aspiration and are hospitalized with complications of an endobronchial FB.

A rare case of recurrent mediastinal malignant paraganglioma of thyroid origin: a case report

Paraganglioma is a neuroendocrine tumor that originates from extraadrenal chromaffin cells. Primary thyroid paraganglioma is an extremely rare neoplasm. In this study, an exceptionally uncommon case of recurrent mediastinal malignant paraganglioma with primary origin from thyroid gland is presented. Median resternotomy, resection of left brachiocephalic vein, and extirpation of the mediastinal tumor were performed successfully. Commonly, it is preoperatively misdiagnosed and has unpredictable biological behavior. Incorrect diagnosis results in disastrous consequences for the patient, and consequently, correct pre- and postoperative diagnoses promise an optimal treatment plan and good prognosis. Long-term follow-up is indicated in all patients due to the risk of recurrence and distant metastases.

A metachronous second primary lung cancer after laryngectomy for laryngeal carcinoma

A combination of laryngeal carcinoma and subsequent primary lung cancer is rare yet important in terms of therapeutic strategy and prognosis.

Anterior chest wall resection and reconstruction due to recurrent chondrosarcoma: a case report

Chest wall chondrosarcoma is a rare malignant tumor with aggressive biological behavior. The only available treatment for primary or recurrent chondrosarcoma consists of radical surgical resection because of its well-known chemo- and radioresistance. Repeated resection for recurrent chondrosarcoma is challenging because of the altered anatomy, scarring, harvested muscles, and close proximity to vital thoracic organs. We present an uncommon case of recurrent chest wall chondrosarcoma resected in the Department of Thoracic Surgery, which we reconstructed with Symbotex mesh and reinforced by omentoplasty. In addition, we created a brief review of the prevalence, diagnostics, surgical treatment, reconstructive options, and prognosis for this condition.

Damage Threshold in Ablation Regime Induced by Femtosecond Laser Irradiation on Transparent Media

The current work is a case study of ongoing in-depth extensive fundamental research on the plasma formation and relaxation dynamics in transparent media induced by mid- and short-wavelength infrared laser pulses. The experimental investigation is performed on a 35 fs-laser system setup. The working parameters such as laser energy and the number of pulses are varied. The experimental measurements are applied on borosilicate glass samples doped with gold nanoparticles. The effects of the applied laser pulses and their consequence on laser-induced ablation damage thresholds are investigated and discussed. The results from this case study provide valuable information and a deeper understanding plasma formation and dynamics induced by femtosecond infrared laser pulses in solid transparent glass media.

The Effect of Femtosecond Laser Pulse Irradiation on the Properties of Advanced Medical Grade PDMS Polymer

The study investigates the effect of the femtosecond laser pulse irradiation on the modification and activation effects of medical-grade polydimethylsiloxane (PDMS) polymer. The motivation of the research is based on the continuous interest and variety of applications of the PDMS material in medicine and implantable neural interface devices. The PDMS is the preferred material due to its exceptional properties such as high biocompatibility and biostability, mechanical flexibility and stability, optical transparency from UV to near IR spectral region, and cost-effectiveness. The experimental investigation is performed by a femtosecond laser system with a pulse duration of 35 fs operating at a repetition rate of 1 kHz. Consistent sets of measurements are performed to analyze and characterize the effect of the laser beam parameters on the optical absorption, and surface morphology concerning the laser-treated zones. The morphology and the optical properties of the PDMS are investigated to activate its surface for successful metallization of the modified tracks. The reported findings and observations specify favourable results of the implementation of the ultrafast laser-based method for micro- or nano-processing of optically transparent biopolymers for interface devices in bioengineering technologies such as neural implants and interface applications. 

Exceeding the Boundaries of the Paraxial Spatiotemporal Nonlinear Optics and Filamentation for Ultrashort Laser Pulses

An impressive phenomenon of observed plasma instability and conical emission under the propagation of ultrashort laser pulses in the air is reported. The discussed novel findings demonstrating nonlinear effects are incapable to be explained in the standard spatiotemporal paraxial optics. Three main mechanisms are investigated. The first one is related to the nonlinear nonparaxial mechanisms for waveguiding of femtosecond pulses, and the second one considers the mechanism of single filament formation at weak ionization. The third mechanism demonstrates a new physical effect leading to collision ionization with intensities in the range of 10¹⁰-10¹¹ W/cm². Furthermore, a new ionization regime of instability is suggested at intensities below the critical thresholds for multiphoton and tunnel ionization. The experimental results and findings are supported by theoretical analyses and numerical simulations.

Two cases with postintubation tracheal stenosis after COVID-19 pneumonia

Only a small percent of all intubated SARS-CoV-2-positive patients survive because of the development of severe respiratory and multiorgan failure. The development of tracheal stenosis after orotracheal intubation or tracheostomy is a dangerous complication with gross consequences for the patient and medical staff. Endoscopic interventional procedures could be used in simple tracheal stenosis and surgical resection and anastomosis are reserved for complex stenosis or after unsuccessful endoscopic treatment. We present two cases with tracheal stenosis as a complication of prolonged intubation in COVID-19 survivors which was diagnosed up to 6 months after discharge. Clinical management and surgical techniques are also discussed.

A rare case of posttraumatic aortic rupture, treated with an endovascular stent graft implantation and complicated with esophageal rupture

BACKGROUND

Esophageal necrosis and perforation after thoracic endovascular aortic repair (TEVAR) for ruptured traumatic aortic aneurysm is extremely rare. It is difficult to manage, and patients rarely survive without treatment. Although, there is no certain consensus in relation with the optimal treatment we present a subsequent successful management of both life-threatening conditions.

CASE PRESENTATION

A 52-year-old man experienced a blunt chest trauma after motor vehicle collision with mild symptoms of pain and fractured ribs. On the 12th day he had severe chest pain and computed tomography (CT) revealed a ruptured traumatic thoracic aortic aneurysm with massive mediastinal hematoma. An emergency thoracic endovascular aortic repair (TEVAR) was performed. Several days later the patient developed a fever. CT suspected a pneumomediastinum, a sign of esophageal rupture, but no confirmation from esophagography and esophagoscopy was achieved. Because of deteriorated septic condition, patient was referred for exploratory thoracotomy. The rupture was found and esophagectomy was performed, with an esophagostomy and gastrostomy to enable enteral nutrition. Almost one year after the esophagectomy, gastric conduit reconstruction through the retrosternal route was performed. The patient was still alive and symptom-free more than 1 year after the reconstruction and no infection of the stent graft was observed.

CONCLUSION

We successfully managed a rare case of esophageal necrosis after TEVAR for ruptured traumatic thoracic aortic aneurysm. It is essential to diagnose the esophageal necrosis at an early stage and provide appropriate treatment to increase survival.

A mediastinal malignant thyroid paraganglioma: A case report and literature review

Introduction and importance

Thyroid cancer is the most common endocrine malignancy, while primary paraganglioma of the thyroid gland (TP) is an unusual tumour and in rare cases, this disease tends to mimic thyroid cancer. They are rare extra-adrenal neuroendocrine tumours originating from the neural crest, and are found almost exclusively in the head and neck area.

Case presentation

We present a case of a 53-year-old man, in whom a mediastinal lesion originating from the left lobe of the thyroid gland was found on routine ultrasound and subsequent computed tomography (CT).

Clinical discussion

Total thyroidectomy and lymph dissection were performed. A review of the literature was made and a discussion was held regarding the diagnosis, the importance of surgical treatment and further behaviour.

Conclusion

Surgical removal of the thyroid gland is the main treatment, followed by radiation therapy. The diagnosis and differential diagnosis with other thyroid tumours is extremely important in terms of subsequent behaviour and prognosis.

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Lesions like the one we described should be operated on.

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Examination of surgical specimen is more accurate than transcutaneous biopsy.

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Cervicotomy is an appropriate approach but extension to sternotomy could occur.

New Approach toward Laser-Assisted Modification of Biocompatible Polymers Relevant to Neural Interfacing Technologies

We report on a new approach toward a laser-assisted modification of biocompatible polydimethylsiloxane (PDMS) elastomers relevant to the fabrication of stretchable multielectrode arrays (MEAs) devices for neural interfacing technologies. These applications require high-density electrode packaging to provide a high-resolution integrating system for neural stimulation and/or recording. Medical grade PDMS elastomers are highly flexible with low Young’s modulus < 1 MPa, which are similar to soft tissue (nerve, brain, muscles) among the other known biopolymers, and can easily adjust to the soft tissue curvatures. This property ensures tight contact between the electrodes and tissue and promotes intensive development of PDMS-based MEAs interfacing devices in the basic neuroscience, neural prosthetics, and hybrid bionic systems, connecting the human nervous system with electronic or robotic prostheses for restoring and treating neurological diseases. By using the UV harmonics 266 and 355 nm of Nd:YAG laser medical grade PDMS elastomer is modified by ns-laser ablation in water. A new approach of processing is proposed to (i) activate the surface and to obtain tracks with (ii) symmetric U-shaped profiles and (iii) homogeneous microstructure This technology provides miniaturization of the device and successful functionalization by electroless metallization of the tracks with platinum (Pt) without preliminary sensitization by tin (Sn) and chemical activation by palladium (Pd). As a result, platinum black layers with a cauliflower-like structure with low values of sheet resistance between 1 and 8 Ω/sq are obtained.

EGFR mutation status yield from bronchoalveolar lavage in patients with primary pulmonary adenocarcinoma compared to a venous blood sample and tissue biopsy

Background

In recent years, there has been a revolution in the genomic profiling and molecular typing of lung cancer. A key oncogene is the epidermal growth factor receptor (EGFR). The gold standard for determining EGFR mutation status is tissue biopsy, where a histological specimen is taken by a bronchoscopic or surgical method (transbronchial biopsy, forceps biopsy, etc.). However, in clinical practice the tissue sample is often insufficient for morphological and molecular analysis. Bronchoalveolar lavage is a validated diagnostic method for pathogenic infections in the lower respiratory tract, yet its diagnostic value for oncogenic mutation testing in lung cancer has not been extensively investigated. This study aims to compare the prevalence of EGFR mutation status in bronchoalveolar lavage and peripheral blood referring to the gold standard - tissue biopsy in patients with primary lung adenocarcinoma.

Methods

Twenty-six patients with adenocarcinoma were examined for EGFR mutation from tissue biopsy, peripheral blood sample and bronchoalveolar lavage.

Results

Thirteen patients had wild type EGFR and the other 13 had EGFR mutation. EGFR mutation from a peripheral blood sample was identified in 38.5% (5/13) of patients, whereas EGFR mutation obtained from bronchoalveolar lavage (BAL) was identified in 92.3% (12/13). This study demonstrates that a liquid biopsy sample for EGFR status from BAL has a higher sensitivity compared to a venous blood sample.

Diagnostic value and complication rate of ultrasound-guided transthoracic core needle biopsy in mediastinal lesions

BACKGROUND

Ultrasound-guided transthoracic core needle biopsy (US-TCNB) is a promising method for establishing the correct diagnosis of mediastinal masses. However, the existing studies in this area are scant and with small samples.

PURPOSE

To evaluate the diagnostic value and the complication rate of US-TCNB, particularly large bore cutting biopsy in patients with mediastinal lesions.

MATERIAL AND METHODS

This retrospective study includes 566 patients with mediastinal lesions suspicious of malignancy evaluated between March 2004 and December 2018. Inclusion criteria: 1. Patients with mediastinal lesions detected on thoracic CT scan; 2. Lesions more than 15 mm; 3. Negative histological diagnosis after bronchoscopic biopsy; 4. Normal coagulation status; 5. Cooperative patient; 6. Written informed consent. US visualization of the mediastinal lesions was successful in 308 (54.4%). In all of them, US-TCNB was performed. All patients with mediastinal lesions unsuitable for US visualization were evaluated for a CT-guided transthoracic needle biopsy (CT-TTNB), which was done if the presence of a safe trajectory was available (n = 41, 7.2%). All patients inappropriate for image-guided TTNB were referred to primary surgical diagnostic procedures (n = 217, 38.3%).

RESULTS

The US-TCNB is a highly effective (accuracy 96%, sensitivity 95%) and safe tool (2.6% complications) in the diagnosis of all subgroups mediastinal lesions. It is non-inferior to CT-TTNB (90%) and comes close to the effectiveness of surgical biopsy techniques (98.4%), but is less invasive and with a lower complication rate.

CONCLUSION

US-TCNB of mediastinal lesions is highly effective and safe tool which is particularly helpful in critically ill patients.

Nanomembrane-Based Therapeutic Plasmapheresis after Non-Invasive Ventilation Failure for Treatment of a Patient with Acute Respiratory Distress Syndrome and Myasthenia Gravis: A Case Report

Acute respiratory distress syndrome (ARDS) is characterized by a widespread inflammation of the lungs, causing severe hypoxemia. Several mediators have been associated with it and almost all of them are small enough to be filtrated through a nanomembrane. We present a case report of a 41-year-old man with myasthenia gravis in remission; he developed ARDS caused by pneumonia. Although he performed well on both non-invasive and invasive mechanical ventilation, his oxygenation continued to deteriorate. As a last resort of treatment, we decided to apply nanomembrane-based apheresis to cleanse his plasma from the harmful inflammatory mediators. After 3 sessions of plasmapheresis, his condition improved and he was successfully weaned from mechanical ventilation. The obtained results gave us ground to assume that the removal of bioactive molecules can be a useful adjunct to protective mechanical ventilation in ARDS.

Neo-esophago-sternocutaneous fistula after coloesophagoplasty: A case report

Revision surgery following colon interposition is a challenging problem. We describe a case of successful surgery for neo-esophago-sternocutaneous fistula as a late complication following coloesophagoplasty for intractable benign stricture. The cutaneous part of the fistula was excised and the distal part of the sternum was resected. On the anterior wall of the colon graft, there was a large defect that communicated with the posterior wall of the osteomyelitis-transformed sternum with sinus track formation. After excising the edges of the neoesophagus defect, Roux-en-Y neo-esophagojejunostomy and gastrostomy were carried out.

[Surgical treatment of pulmonary sequestration--20 years experience]

AIM

To study our experience in the diagnostics and treatment of pulmonary sequestration and to evaluate the long-term postoperative results.

MATERIAL AND METHODS

Between Jan 1989 and Jan 2009. 8 patients (3 men, 5 women, mean age of 23.9 years) were operated on for lung sequestration. Sequestration was intralobar in 6 cases and extralobar in 2 cases. The abnormality was discovered by chance in 2 patients. The most frequent clinical manifestation was those of recurrent bronchopneumonia. Chest X-rays showed an apparently benign, posterobasal image in 75% of the cases. Arteriography was performed in 2 patients and revealed an abnormal systemic artery. Computerized tomography imaging with i.v. contrast confirmed the diagnosis in 6 patients. The intralobar type of sequestration was treated by lobectomy, and the extralobar type by sequestrectomy.

RESULTS

The operative mortality and the morbidity rates were nil. The mean in-hospital stay was 7.75 days. The long-term postoperative results (follow-up from 5 to 20 years) are considered excellent.

CONCLUSION

The surgery is a method of choice in the treatment of pulmonary sequestration. with low rate of postoperative complications and excellent long-term results.