Blood pressure estimation using pulse transit time models

Abstract. Blood pressure (BP) is an important indicator of human health. Common methods for measuring BP continuously are either invasive, intermittent or they require using a cumbersome cuff. Pulse Transmit Time (PTT) -based measurement can be an alternative for such methods, as it ensures continue and non-invasive monitoring. However, since the method is indirect, it requires careful modelling of PTT-BP relation. In this thesis, three approaches of BP estimation from PTT are tested: linear regression, nonlinear Moens and Korteweg model and nonlinear model developed by Gesche. In the experiments, cardiovascular pulses for PTT were sensed using two fiber optics based accelerometers developed at the University of Oulu. To evaluate feasibility of presented models, the results were compared with reference BP values, measured using methods accepted for the commercial use. There were two groups of data. One was compared with BP measured using invasive catheter. Second group was compared with BP measured using volume clamp method. Obtained results suggest, that the presented calculation methods in present state still require further development in order to provide accurate BP values, however, they can be potentially used for observation of BP changes

Developing Method for Evaluating Attractiveness, Accessibility and Safety of Visiting Historical Recreational and Tourist Sites

The main purpose of the article is to present a method for assessing the attractiveness, accessibility and safety of historical recreational and tourist places, including facilities related to military tourism and dark tourism. The paper seeks to introduce the issues of the above-mentioned forms of tourism and – based on a survey – identify factors that make recreational and tourist space accessible and safe. The authors present and analyze the indicators and measures of the assessment, as well as demonstrate the procedure of evaluation. On the basis of surveys conducted on a group of one hundred experts in the field of tourism and recreation, the ten most important elements of space were selected. Subsequently, using weight values, we proceeded to indicate the strength of impact imposed by individual elements of space on the attractiveness and accessibility of facilities and the safety of visitors. Furthermore, determining the weight values allowed for the use of the weighted sum method during the assessment. Surveys were conducted from June to September 2017. The method was verified against one of the historical recreational places located in Poland – the Wolf ’s Lair in Gierłoż. The developed method allowed us to assess the attractiveness, accessibility and safety of historical recreational and tourist facilities. The results of evaluation of the Wolf ’s Lair in Gierłoż proved instrumental in identifying elements that have a positive impact on the level of tourism development, and those that are either missing or may be inadequate

A conceptual database model for the identification of degraded areas and areas proposed for planned revitalisation

For revitalization programs to be effective, territorial governments have to introduce consolidated measures that support the planning, organization and implementation of revitalization measures to benefit local communities and economies, and to alleviate crisis situations in degraded areas. Such measures require unlimited access to data that accurately describe social, economic and environmental conditions. In view of the above, the main aim of this study was to propose a conceptual database model for the identification of degraded areas and areas proposed for planned revitalization under revitalization programs implemented in developed rural areas. The detailed objectives of the presented research were to describe the components of the proposed database and the sources of data for developing municipal revitalization programs. The diagram of the database model supporting the initial stages of revitalization was also presented. The research methodology involved analyses, inference and deduction. A questionnaire survey, conducted among geography, spatial planning, urban development and environmental experts, was used as a research tool in the study. The results of the questionnaire confirmed the validity of the components of the proposed database model

The role of natural environment in the development of tourism in the Kashubian Lake District (on the example of Kartuzy county)

The aim of this article was to present a particular role of natural environment in the development of tourism in Kashubian Lake District. In the research process there have been shown natural conditions of one of the most touristically attractive region of Polish lake districts, i.e. The Kashubian Lake District on the example of Kartuzy county. The natural resources mentioned in the study were analysed with the help of spot bonitation, thanks to which there were appointed main areas of touristic attractiveness. A supplement of the conducted research was a survey carried out among tourists spending holiday on the presented area, examining to what extent natural ressources determine the concentration of touristic traffic

Determinanty rozwoju osadnictwa letniskowego na przykładzie gminy Stężyca

W opracowaniu przedstawiono wyniki badań dotyczących przestrzeni wypoczynku indywidualnego na działkach letniskowych. Jest to próba identyfikacji uwarunkowań rozwoju osadnictwa letniskowego na przykładzie gminy Stężyca położonej w centralnej części Pojezierza Kaszubskiego. W artykule wskazano uwarunkowania związane z miejscem lokalizacji działek letniskowych oraz z motywacjami i oczekiwaniami ich właścicieli. W rezultacie przeprowadzonych badań stwierdzono, że rozwój osadnictwa letniskowego w gminie Stężyca determinują przede wszystkim walory przyrodnicze i krajobrazowe oraz dobra dostępność czasowa i przestrzenna, nie mniej ważny pozostaje również motyw więzi rodzinnych i sentyment do miejsca urodzenia

Development determinants of holiday settlement: Case study of the gmina of Stężyca

The article presents the results of research on a specific recreation space – holiday plots. It is an attempt to identify the conditions for the development of holiday settlements, using the example of the gmina of Stężyca situated in the centre of the Kashubian Lake District. The authors indicate the conditions related to the location of holiday plots, as well as the motivations and expectations of their owners. As a result of the study, it was concluded that natural and landscape assets, as well as temporal and spatial accessibility determined the development of the holiday settlement in the gmina of Stężyca. Equally significant factors are family ties and sentiment towards their place of birth

A method for measuring blood pressure and cardiorespiratory oscillations

Studies with magnetoencephalography (MEG) are still quite rarely combined simultaneously with methods that can provide a metabolic dimension to MEG investigations. In addition, continuous blood pressure measurements which comply with MEG compatibility requirements are lacking. For instance, by combining methods reflecting neurovascular status one could obtain more information on low frequency fluctuations that have recently gained increasing interest as a mediator of functional connectivity within brain networks. This paper presents a multimodal brain imaging setup, capable to non-invasively and continuously measure cerebral hemodynamic, cardiorespiratory and blood pressure oscillations simultaneously with MEG. In the setup, all methods apart from MEG rely on the use of fibre optics. In particular, we present a method for measuring of blood pressure and cardiorespiratory oscillations continuously with MEG. The potential of this type of multimodal setup for brain research is demonstrated by our preliminary studies on human, showing effects of mild hypercapnia, gathered simultaneously with the presented modalities

Blood pressure wave propagation : a multisensor setup for cerebral autoregulation studies

Objective. Cerebral autoregulation is critically important to maintain proper brain perfusion and supply the brain with oxygenated blood. Non-invasive measures of blood pressure (BP) are critical in assessing cerebral autoregulation. Wave propagation velocity may be a useful technique to estimate BP but the effect of the location of the sensors on the readings has not been thoroughly examined. In this paper, we were interested in studying whether the propagation velocity of a pressure wave in the direction from the heart to the brain may differ compared with propagation from the heart to the periphery, as well as across different physiological tasks and/or health conditions. Using non-invasive sensors simultaneously placed at different locations of the human body allows for the study of how the propagation velocity of the pressure wave, based on pulse transit time (PTT), varies across different directions. Approach. We present a multi-sensor BP wave propagation measurement setup intended for cerebral autoregulation studies. The presented sensor setup consists of three sensors, one placed on each of the neck, chest and finger, allowing simultaneous measurement of changes in BP propagation velocity towards the brain and to the periphery. We show how commonly tested physiological tasks affect the relative changes of PTT and correlations with BP. Main results. We observed that during maximal blow, valsalva and breath hold breathing tasks, the relative changes of PTT were higher when PTT was measured in the direction from the heart to the brain than from the heart to the peripherals. In contrast, during a deep breathing task, the relative change in PTT from the heart to the brain was lower. In addition, we present a short literature review of the PTT methods used in brain research. Significance. These preliminary data suggest that the physiological task and direction of PTT measurement may affect relative PTT changes. The presented three-sensor setup provides an easy and neuroimaging compatible method for cerebral autoregulation studies by allowing measurement of BP wave propagation velocity towards the brain versus towards the periphery

Measurement of Cerebral Circulation in Human

In this chapter, we review state-of-the-art non-invasive techniques to monitor and study cerebral circulation in humans. The measurement methods can be divided into two categories: direct and indirect methods. Direct methods are mostly based on using contrast agents delivered to blood circulation. Clinically used direct methods include single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI) with contrast agents, xenon computed tomography (CT), and arterial spin labeling (ASL) MRI. Indirect techniques are based on measuring physiological parameters reflecting cerebral perfusion. The most commonly used indirect methods are near-infrared spectroscopy (NIRS), transcranial Doppler ultrasound (TCD), and phase-contrast MRI. In recent years, few more techniques have been intensively developed, such as diffuse correlation spectroscopy (DCS) and microwave-based techniques, which are still emerging as methods for cerebral circulation monitoring. In addition, methods combining different modalities are discussed and, as a summary, the presented techniques and their benefits for cerebral circulation will be compared

Prototype of an opto-capacitive probe for non-invasive sensing cerebrospinal fluid circulation

In brain studies, the function of the cerebrospinal fluid (CSF) awakes growing interest, particularly related to studies of the glymphatic system in the brain, which is connected with the complex system of lymphatic vessels responsible for cleaning the tissues. The CSF is a clear, colourless liquid including water (H2O) approximately with a concentration of 99 %. In addition, it contains electrolytes, amino acids, glucose, and other small molecules found in plasma. The CSF acts as a cushion behind the skull, providing basic mechanical as well as immunological protection to the brain. Disturbances of the CSF circulation have been linked to several brain related medical disorders, such as dementia. Our goal is to develop an in vivo method for the non-invasive measurement of cerebral blood flow and CSF circulation by exploiting optical and capacitive sensing techniques simultaneously. We introduce a prototype of a wearable probe that is aimed to be used for long-term brain monitoring purposes, especially focusing on studies of the glymphatic system. In this method, changes in cerebral blood flow, particularly oxy- and deoxyhaemoglobin, are measured simultaneously and analysed with the response gathered by the capacitive sensor in order to distinct the dynamics of the CSF circulation behind the skull. Presented prototype probe is tested by measuring liquid flows inside phantoms mimicking the CSF circulation