Aleksander Sobotnicki

Development and evaluation of a novel system for inducing orthostatic challenge by tilt tests and lower body negative pressure

Lower body negative pressure (LBNP) is a method derived from space medicine, which in recent years has been increasingly used by clinicians to assess the efficiency of the cardiovascular regulatory mechanisms. LBNP with combined tilt testing is considered as an effective form of training to prevent orthostatic intolerance. We have developed a prototype system comprising a tilt table and LBNP chamber, and tested it in the context of the feasibility of the device for assessing the pilots’ efficiency. The table allows for controlled tilting in the range from −45 to +80° at the maximum change rate of 45°/s. The LBNP value can smoothly be adjusted down to −100 mmHg at up to 20 mmHg/s. 17 subjects took part in the pilot study. A 24-minute scenario included −100 mmHg supine LBNP, head up tilt (HUT) and −60 mmHg LBNP associated with HUT, separated by resting phases. The most noticeable changes were observed in stroke volume (SV). During supine LBNP, HUT and the combined stimulus, a decrease of the SV value by 20%, 40% and below 50%, respectively, were detected. The proposed system can map any pre-programed tilt and LBNP profiles, and the pilot study confirmed the efficiency of performing experimental procedures.

Bioimpedance spectroscopy monitoring — Designing challenges and description of the acquired results

Non-invasive body composition measurement methods aid in the health condition evaluation. Constantly improving, are becoming more and more popular among the specialists. Those methods consist of various imaging techniques and ways for obtaining electrical signals generated by the human body. One of those non-invasive methods, based on the human body impedance is the bioimpedance spectroscopy. The general principle is to check the feedback for few different frequencies of alternating current with fixed amplitude. Bioimpedance spectroscopy allows to measure the composition of the body or the hydration level for certain body areas, eg. chest or abdomen. Its widely used by dieticians, cardiologists and neurologists. Bioimpedance spectroscopy is the main subject of this article. In the introduction to this study, you can find the nature behind the research, the idea, range and the need for research of that kind. Moreover, in the article there is a comparison between methods that are based on two and four electrodes. The device, which has been created in ITAM Zabrze, has also been briefly described. In addition, way of processing the data, so it could be used to calculate the necessary parameters (Fat Free Mass (FFM), Fat Mass (FM), Total Body Water (TBW), Intercellular Water (ICW) and Extracellular Water (ECW), has also been presented. The problems with and methods for Cole-Cole model creation, basing only on a part of curve, measured with bioimpedance spectroscopy, have also been discussed.

Idea and measurement methods used in bioimpedance spectroscopy

Increasing popularity of devices used to measure body composition and the competition on that specific sector of the market resulted in increased interest in this subject matter. There are more and more articles appearing that treat of that subject and construction design descriptions. The aim of this article is to present the nature of the impedance measurement of the human body and to present various measurement methods, focusing especially on the electrical bioimpedance measurement. The article describes the device used for body composition measurement, that was created in the ITAM in Zabrze. Also, a short review of bioimpedance measurement devices has been made, describing their advantages and disadvantages, along the description of other measurement methods.

The Application of the Region Growing Method to the Determination of Arterial Changes

The paper discusses segmentation of medical images depicting aortic aneurysms and atherosclerotic changes in coronary vessels. The region growing method was deployed for segmentation. Before segmentation with the aforementioned method, the images were subjected to edging in order to acquire significant information, such as the size of the analyzed structure and pixel distribution. Edging paired with the region growing method ensures proper isolation of pixels with the same intensity, without the unwanted pixel overflow. In order to verify the method, results obtained by various authors were referred to, and a statistical analysis was performed to calculate the Dice coefficient.

Detection of aorta anatomical structures characterized by various levels of pixel intensity

The paper discusses image processing which takes into account the split/merge method. Owing to the automation of the method, it was possible to split elongated anatomical structures (the aorta in the case under scrutiny) into sections which consist of regions containing pixels of the same intensity level. The analyzed image was initially processed then filtered, respectively. The segmentation stage, which took place afterwards, was followed by a statistical analysis and interpretation of image features. The paper presents a method of obtaining significant numerical and symbolic information in image processing.