New Approaches to the Surgical Treatment of Lung and Bronchial Tumors in Children

Today, it is relevant to search for new, better methods of surgical treatment of tumors and organ-preserving and video-assisted surgery is gaining more and more popularity. The aim of the study was to improve the results of surgical treatment of children with primary and secondary (metastatic) lung tumors using high-frequency live tissue welding (HF LTW) in order to increase the treatment effectiveness. Novelty of the study lies in the expanding the knowledge of the new researched method, for enhancement of survivability relatively to chemotherapy and radiation methods, that are studied in the previous works. Advantages of the introduced method are bloodless, fast, low traumatic operations 103 case reports in children with primary and metastatic lung tumors were analyzed, including 34 patients with benign and malignant lung tumors and 69 children with metastatic bronchial and pulmonary lesions undergoing treatment from 2002 to 2018 were examined. Benign lung tumors were diagnosed in 17 patients. Malignant tumors were observed in 17 patients, including 11 lung carcinoid tumors. Metastatic bronchial and pulmonary lesions most often occurred with osteosarcoma (28) and nephroblastoma (17). In 34 children with primary tumors, 37 were undergone surgical interventions. Most often, atypical resection was used – 16 (43.3%), in particular, with carcinoid – in 7 (43.8%) patients and with hamartoma – in 4 (25%) patients. In metastatic lesions, in most cases, the same resection was performed. From 58 resections 25 (43%) were performed for osteosarcoma and 15 (26%) for nephroblastoma. The HF LTW method was used in 29 patients for benign and malignant primary tumors and in 62 (73%) surgical procedures for lung metastases to remove a tumor, vascular coagulation and sealing of the lung tissue. Using HF LTW surgical operations of different directions and volumes can be performed effectively in benign, malignant and metastatic bronchial and pulmonary lesions in children.

Open-Closed-Loop Iterative Learning Control with the System Correction Term for the Human Soft Tissue Welding Robot in Medicine

By combining manual welders (with intelligence and versatility) and automatic welding systems (with accuracy and consistency), an intelligent welding system for human soft tissue welding can be developed in medicine. This paper presents a data-correction control approach to human welder intelligence, which can be used to control the automated human soft tissue welding process. Human soft tissue welding can preconnect the excised tissue, and the shape of the tissue at the junction ensures the recovery of the operative organ function. This welding technology has the advantages of rapid operation, minimal tissue damage, no need for suture materials, faster recovery of the mechanism and properties of the living tissue, and the maintenance of the function of the organs. Model of the welding system is identified from the data; an open-closed-loop iterative learning control algorithm is then proposed to improve the tracking accuracy of the system. The algorithm uses the tracking error of current and previous to update the control law. Meanwhile, to further improve the accuracy under the conditions of external interference, a system correction term is added to the proposed ILC algorithm, which can be adjusted according to the system’s errors and output and improve the capability of the target tracking greatly. A detailed convergence analysis for the ILC law has been given. Simulation results verify the feasibility and effectiveness of the proposed method for GTAW control tasks.

Experimental investigation of temperature-dependent denaturation behavior of type-I Collagen

Precise investigation of the temperature and the duration for collagen denaturation is critical for a number of applications, such as adjustment of temperature and duration during a laser-assisted tissue welding or collagen-based tissue repair products (films, implants, cross-linkers) preparation procedures. The result of such studies can serve as a guideline to mitigate potential side effects while maintaining the functionality of the collagen. Though a variety of collagen denaturation temperatures have been reported, there has not been a systematic study to report temperature-dependent denaturation rates. In this study, we perform a set of experiments on type-I collagen fiber bundles, extracted from the rat-tail tendon, and provide an Arrhenius model based on the acquired data. The tendons are introduced to buffer solutions having different temperatures, while monitoring the contrast in the crimp sights with a wide field microscope, where collagen fibers bend with respect to their original orientation. For all tested temperatures of 50°C–70 °C and tissues that were extracted from 5 rats, increasing the temperature reduced the contrast. On the average, we observed a decay of the contrast to half of its initial value at 37, 157, and 266 seconds when the collagen was introduced to 70 °C, 65 °C, and 60 °C buffer solutions, respectively. For the lower temperatures tested we only observed to be only about 20% and 2 % decay in the crimp contrast after > 2 hours at 55 °C and 50 °C, respectively. The observed denaturation behavior is also in line with Arrhenius Law, as expected. We are looking forward to expand this study to other types of collagen as a future work. Overall, with further development the data and model we present here could potentially serve as a guideline to determine limits for welding and manufacturing process of collagen-based tissue repair agents.

Effects of Compression Force and Heating Power on Bipolar Tissue Welding

Bipolar tissue welding is often performed with a set of laparoscopic forceps in a minimal invasive surgery to achieve less bleeding and shorter recovery time. However, problems such as tissue sticking, thermal damage, and joint failure need to be solved before the process can be reliably used in more surgical procedures. In this study, experiments were conducted to examine the effect of process parameters and dynamic impedance for prediction of the size of denatured tissue zone during welding. A weld lobe that defines suitable process conditions was constructed. It is found that tissue denaturation starts from the center of the heated region. Dynamic impedance is strongly affected by the compression level and heating power. The size of denatured tissue zone can be predicted with the heating energy; however, the prediction is strongly dependent on the compression level.

Dynamic Electrical Impedance in Bipolar Tissue Welding

Bipolar tissue welding is a material joining process where high frequency alternating current is applied to biological tissue in medical procedures such as wound closure and blood vessel sealing. The process is often performed with a set of laparoscopic forceps in a minimal invasive surgery to achieve less bleeding and shorter recovery time. However, problems such as tissue sticking, thermal damage, and joint failure often occur and need to be solved before the process can be reliably used in more surgical procedures. In this study, experiments were conducted to investigate dynamic behavior of the tissue welding process through electrical impedance measurements. Both scissor-type and parallel electrodes were used with various compression and power settings in the experiment. It was found that the electrical impedance of tissue was lower when parallel electrodes were used. It can be used to understand the results and dynamic behavior of the tissue welding process, including the size of heat affected zone, tissue sticking, and the compression force effect.